* arm-protos.h (arm_dllexport_name_p, arm_dllimport_name_p): Constify.

[official-gcc.git] / gcc / reload1.c

/* Reload pseudo regs into hard regs for insns that require hard regs.
   Copyright (C) 1987, 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
   1999, 2000 Free Software Foundation, Inc.

This file is part of GNU CC.

GNU CC is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

GNU CC is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU CC; see the file COPYING.  If not, write to
the Free Software Foundation, 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.  */


#include "config.h"
#include "system.h"

#include "machmode.h"
#include "hard-reg-set.h"
#include "rtl.h"
#include "tm_p.h"
#include "obstack.h"
#include "insn-config.h"
#include "insn-flags.h"
#include "insn-codes.h"
#include "flags.h"
#include "function.h"
#include "expr.h"
#include "regs.h"
#include "basic-block.h"
#include "reload.h"
#include "recog.h"
#include "output.h"
#include "cselib.h"
#include "real.h"
#include "toplev.h"

#if !defined PREFERRED_STACK_BOUNDARY && defined STACK_BOUNDARY
#define PREFERRED_STACK_BOUNDARY STACK_BOUNDARY
#endif

/* This file contains the reload pass of the compiler, which is
   run after register allocation has been done.  It checks that
   each insn is valid (operands required to be in registers really
   are in registers of the proper class) and fixes up invalid ones
   by copying values temporarily into registers for the insns
   that need them.

   The results of register allocation are described by the vector
   reg_renumber; the insns still contain pseudo regs, but reg_renumber
   can be used to find which hard reg, if any, a pseudo reg is in.

   The technique we always use is to free up a few hard regs that are
   called ``reload regs'', and for each place where a pseudo reg
   must be in a hard reg, copy it temporarily into one of the reload regs.

   Reload regs are allocated locally for every instruction that needs
   reloads.  When there are pseudos which are allocated to a register that
   has been chosen as a reload reg, such pseudos must be ``spilled''.
   This means that they go to other hard regs, or to stack slots if no other
   available hard regs can be found.  Spilling can invalidate more
   insns, requiring additional need for reloads, so we must keep checking
   until the process stabilizes.

   For machines with different classes of registers, we must keep track
   of the register class needed for each reload, and make sure that
   we allocate enough reload registers of each class.

   The file reload.c contains the code that checks one insn for
   validity and reports the reloads that it needs.  This file
   is in charge of scanning the entire rtl code, accumulating the
   reload needs, spilling, assigning reload registers to use for
   fixing up each insn, and generating the new insns to copy values
   into the reload registers.  */


#ifndef REGISTER_MOVE_COST
#define REGISTER_MOVE_COST(x, y) 2
#endif
\f
/* During reload_as_needed, element N contains a REG rtx for the hard reg
   into which reg N has been reloaded (perhaps for a previous insn).  */
static rtx *reg_last_reload_reg;

/* Elt N nonzero if reg_last_reload_reg[N] has been set in this insn
   for an output reload that stores into reg N.  */
static char *reg_has_output_reload;

/* Indicates which hard regs are reload-registers for an output reload
   in the current insn.  */
static HARD_REG_SET reg_is_output_reload;

/* Element N is the constant value to which pseudo reg N is equivalent,
   or zero if pseudo reg N is not equivalent to a constant.
   find_reloads looks at this in order to replace pseudo reg N
   with the constant it stands for.  */
rtx *reg_equiv_constant;

/* Element N is a memory location to which pseudo reg N is equivalent,
   prior to any register elimination (such as frame pointer to stack
   pointer).  Depending on whether or not it is a valid address, this value
   is transferred to either reg_equiv_address or reg_equiv_mem.  */
rtx *reg_equiv_memory_loc;

/* Element N is the address of stack slot to which pseudo reg N is equivalent.
   This is used when the address is not valid as a memory address
   (because its displacement is too big for the machine.)  */
rtx *reg_equiv_address;

/* Element N is the memory slot to which pseudo reg N is equivalent,
   or zero if pseudo reg N is not equivalent to a memory slot.  */
rtx *reg_equiv_mem;

/* Widest width in which each pseudo reg is referred to (via subreg).  */
static unsigned int *reg_max_ref_width;

/* Element N is the list of insns that initialized reg N from its equivalent
   constant or memory slot.  */
static rtx *reg_equiv_init;

/* Vector to remember old contents of reg_renumber before spilling.  */
static short *reg_old_renumber;

/* During reload_as_needed, element N contains the last pseudo regno reloaded
   into hard register N.  If that pseudo reg occupied more than one register,
   reg_reloaded_contents points to that pseudo for each spill register in
   use; all of these must remain set for an inheritance to occur.  */
static int reg_reloaded_contents[FIRST_PSEUDO_REGISTER];

/* During reload_as_needed, element N contains the insn for which
   hard register N was last used.   Its contents are significant only
   when reg_reloaded_valid is set for this register.  */
static rtx reg_reloaded_insn[FIRST_PSEUDO_REGISTER];

/* Indicate if reg_reloaded_insn / reg_reloaded_contents is valid */
static HARD_REG_SET reg_reloaded_valid;
/* Indicate if the register was dead at the end of the reload.
   This is only valid if reg_reloaded_contents is set and valid.  */
static HARD_REG_SET reg_reloaded_dead;

/* Number of spill-regs so far; number of valid elements of spill_regs.  */
static int n_spills;

/* In parallel with spill_regs, contains REG rtx's for those regs.
   Holds the last rtx used for any given reg, or 0 if it has never
   been used for spilling yet.  This rtx is reused, provided it has
   the proper mode.  */
static rtx spill_reg_rtx[FIRST_PSEUDO_REGISTER];

/* In parallel with spill_regs, contains nonzero for a spill reg
   that was stored after the last time it was used.
   The precise value is the insn generated to do the store.  */
static rtx spill_reg_store[FIRST_PSEUDO_REGISTER];

/* This is the register that was stored with spill_reg_store.  This is a
   copy of reload_out / reload_out_reg when the value was stored; if
   reload_out is a MEM, spill_reg_stored_to will be set to reload_out_reg.  */
static rtx spill_reg_stored_to[FIRST_PSEUDO_REGISTER];

/* This table is the inverse mapping of spill_regs:
   indexed by hard reg number,
   it contains the position of that reg in spill_regs,
   or -1 for something that is not in spill_regs.

   ?!?  This is no longer accurate.  */
static short spill_reg_order[FIRST_PSEUDO_REGISTER];

/* This reg set indicates registers that can't be used as spill registers for
   the currently processed insn.  These are the hard registers which are live
   during the insn, but not allocated to pseudos, as well as fixed
   registers.  */
static HARD_REG_SET bad_spill_regs;

/* These are the hard registers that can't be used as spill register for any
   insn.  This includes registers used for user variables and registers that
   we can't eliminate.  A register that appears in this set also can't be used
   to retry register allocation.  */
static HARD_REG_SET bad_spill_regs_global;

/* Describes order of use of registers for reloading
   of spilled pseudo-registers.  `n_spills' is the number of
   elements that are actually valid; new ones are added at the end.

   Both spill_regs and spill_reg_order are used on two occasions:
   once during find_reload_regs, where they keep track of the spill registers
   for a single insn, but also during reload_as_needed where they show all
   the registers ever used by reload.  For the latter case, the information
   is calculated during finish_spills.  */
static short spill_regs[FIRST_PSEUDO_REGISTER];

/* This vector of reg sets indicates, for each pseudo, which hard registers
   may not be used for retrying global allocation because the register was
   formerly spilled from one of them.  If we allowed reallocating a pseudo to
   a register that it was already allocated to, reload might not
   terminate.  */
static HARD_REG_SET *pseudo_previous_regs;

/* This vector of reg sets indicates, for each pseudo, which hard
   registers may not be used for retrying global allocation because they
   are used as spill registers during one of the insns in which the
   pseudo is live.  */
static HARD_REG_SET *pseudo_forbidden_regs;

/* All hard regs that have been used as spill registers for any insn are
   marked in this set.  */
static HARD_REG_SET used_spill_regs;

/* Index of last register assigned as a spill register.  We allocate in
   a round-robin fashion.  */
static int last_spill_reg;

/* Nonzero if indirect addressing is supported on the machine; this means
   that spilling (REG n) does not require reloading it into a register in
   order to do (MEM (REG n)) or (MEM (PLUS (REG n) (CONST_INT c))).  The
   value indicates the level of indirect addressing supported, e.g., two
   means that (MEM (MEM (REG n))) is also valid if (REG n) does not get
   a hard register.  */
static char spill_indirect_levels;

/* Nonzero if indirect addressing is supported when the innermost MEM is
   of the form (MEM (SYMBOL_REF sym)).  It is assumed that the level to
   which these are valid is the same as spill_indirect_levels, above.   */
char indirect_symref_ok;

/* Nonzero if an address (plus (reg frame_pointer) (reg ...)) is valid.  */
char double_reg_address_ok;

/* Record the stack slot for each spilled hard register.  */
static rtx spill_stack_slot[FIRST_PSEUDO_REGISTER];

/* Width allocated so far for that stack slot.  */
static unsigned int spill_stack_slot_width[FIRST_PSEUDO_REGISTER];

/* Record which pseudos needed to be spilled.  */
static regset_head spilled_pseudos;

/* Used for communication between order_regs_for_reload and count_pseudo.
   Used to avoid counting one pseudo twice.  */
static regset_head pseudos_counted;

/* First uid used by insns created by reload in this function.
   Used in find_equiv_reg.  */
int reload_first_uid;

/* Flag set by local-alloc or global-alloc if anything is live in
   a call-clobbered reg across calls.  */
int caller_save_needed;

/* Set to 1 while reload_as_needed is operating.
   Required by some machines to handle any generated moves differently.  */
int reload_in_progress = 0;

/* These arrays record the insn_code of insns that may be needed to
   perform input and output reloads of special objects.  They provide a
   place to pass a scratch register.  */
enum insn_code reload_in_optab[NUM_MACHINE_MODES];
enum insn_code reload_out_optab[NUM_MACHINE_MODES];

/* This obstack is used for allocation of rtl during register elimination.
   The allocated storage can be freed once find_reloads has processed the
   insn.  */
struct obstack reload_obstack;

/* Points to the beginning of the reload_obstack.  All insn_chain structures
   are allocated first.  */
char *reload_startobj;

/* The point after all insn_chain structures.  Used to quickly deallocate
   memory allocated in copy_reloads during calculate_needs_all_insns.  */
char *reload_firstobj;

/* This points before all local rtl generated by register elimination.
   Used to quickly free all memory after processing one insn.  */
static char *reload_insn_firstobj;

#define obstack_chunk_alloc xmalloc
#define obstack_chunk_free free

/* List of insn_chain instructions, one for every insn that reload needs to
   examine.  */
struct insn_chain *reload_insn_chain;

#ifdef TREE_CODE
extern tree current_function_decl;
#else
extern union tree_node *current_function_decl;
#endif

/* List of all insns needing reloads.  */
static struct insn_chain *insns_need_reload;
\f
/* This structure is used to record information about register eliminations.
   Each array entry describes one possible way of eliminating a register
   in favor of another.   If there is more than one way of eliminating a
   particular register, the most preferred should be specified first.  */

struct elim_table
{
  int from;                     /* Register number to be eliminated.  */
  int to;                       /* Register number used as replacement.  */
  int initial_offset;           /* Initial difference between values.  */
  int can_eliminate;            /* Non-zero if this elimination can be done.  */
  int can_eliminate_previous;   /* Value of CAN_ELIMINATE in previous scan over
                                   insns made by reload.  */
  int offset;                   /* Current offset between the two regs.  */
  int previous_offset;          /* Offset at end of previous insn.  */
  int ref_outside_mem;          /* "to" has been referenced outside a MEM.  */
  rtx from_rtx;                 /* REG rtx for the register to be eliminated.
                                   We cannot simply compare the number since
                                   we might then spuriously replace a hard
                                   register corresponding to a pseudo
                                   assigned to the reg to be eliminated.  */
  rtx to_rtx;                   /* REG rtx for the replacement.  */
};

static struct elim_table * reg_eliminate = 0;

/* This is an intermediate structure to initialize the table.  It has
   exactly the members provided by ELIMINABLE_REGS. */
static struct elim_table_1
{
  int from;
  int to;
} reg_eliminate_1[] =

/* If a set of eliminable registers was specified, define the table from it.
   Otherwise, default to the normal case of the frame pointer being
   replaced by the stack pointer.  */

#ifdef ELIMINABLE_REGS
  ELIMINABLE_REGS;
#else
  {{ FRAME_POINTER_REGNUM, STACK_POINTER_REGNUM}};
#endif

#define NUM_ELIMINABLE_REGS (sizeof reg_eliminate_1/sizeof reg_eliminate_1[0])

/* Record the number of pending eliminations that have an offset not equal
   to their initial offset.  If non-zero, we use a new copy of each
   replacement result in any insns encountered.  */
int num_not_at_initial_offset;

/* Count the number of registers that we may be able to eliminate.  */
static int num_eliminable;
/* And the number of registers that are equivalent to a constant that
   can be eliminated to frame_pointer / arg_pointer + constant.  */
static int num_eliminable_invariants;

/* For each label, we record the offset of each elimination.  If we reach
   a label by more than one path and an offset differs, we cannot do the
   elimination.  This information is indexed by the number of the label.
   The first table is an array of flags that records whether we have yet
   encountered a label and the second table is an array of arrays, one
   entry in the latter array for each elimination.  */

static char *offsets_known_at;
static int (*offsets_at)[NUM_ELIMINABLE_REGS];

/* Number of labels in the current function.  */

static int num_labels;
\f
static void maybe_fix_stack_asms        PARAMS ((void));
static void copy_reloads                PARAMS ((struct insn_chain *));
static void calculate_needs_all_insns   PARAMS ((int));
static int find_reg                     PARAMS ((struct insn_chain *, int,
                                               FILE *));
static void find_reload_regs            PARAMS ((struct insn_chain *, FILE *));
static void select_reload_regs          PARAMS ((FILE *));
static void delete_caller_save_insns    PARAMS ((void));

static void spill_failure               PARAMS ((rtx, enum reg_class));
static void count_spilled_pseudo        PARAMS ((int, int, int));
static void delete_dead_insn            PARAMS ((rtx));
static void alter_reg                   PARAMS ((int, int));
static void set_label_offsets           PARAMS ((rtx, rtx, int));
static void check_eliminable_occurrences        PARAMS ((rtx));
static void elimination_effects         PARAMS ((rtx, enum machine_mode));
static int eliminate_regs_in_insn       PARAMS ((rtx, int));
static void update_eliminable_offsets   PARAMS ((void));
static void mark_not_eliminable         PARAMS ((rtx, rtx, void *));
static void set_initial_elim_offsets    PARAMS ((void));
static void verify_initial_elim_offsets PARAMS ((void));
static void set_initial_label_offsets   PARAMS ((void));
static void set_offsets_for_label       PARAMS ((rtx));
static void init_elim_table             PARAMS ((void));
static void update_eliminables          PARAMS ((HARD_REG_SET *));
static void spill_hard_reg              PARAMS ((unsigned int, FILE *, int));
static int finish_spills                PARAMS ((int, FILE *));
static void ior_hard_reg_set            PARAMS ((HARD_REG_SET *, HARD_REG_SET *));
static void scan_paradoxical_subregs    PARAMS ((rtx));
static void count_pseudo                PARAMS ((int));
static void order_regs_for_reload       PARAMS ((struct insn_chain *));
static void reload_as_needed            PARAMS ((int));
static void forget_old_reloads_1        PARAMS ((rtx, rtx, void *));
static int reload_reg_class_lower       PARAMS ((const PTR, const PTR));
static void mark_reload_reg_in_use      PARAMS ((unsigned int, int,
                                                 enum reload_type,
                                                 enum machine_mode));
static void clear_reload_reg_in_use     PARAMS ((unsigned int, int,
                                                 enum reload_type,
                                                 enum machine_mode));
static int reload_reg_free_p            PARAMS ((unsigned int, int,
                                                 enum reload_type));
static int reload_reg_free_for_value_p  PARAMS ((int, int, enum reload_type,
                                                 rtx, rtx, int, int));
static int reload_reg_reaches_end_p     PARAMS ((unsigned int, int,
                                                 enum reload_type));
static int allocate_reload_reg          PARAMS ((struct insn_chain *, int,
                                                 int));
static void failed_reload               PARAMS ((rtx, int));
static int set_reload_reg               PARAMS ((int, int));
static void choose_reload_regs_init     PARAMS ((struct insn_chain *, rtx *));
static void choose_reload_regs          PARAMS ((struct insn_chain *));
static void merge_assigned_reloads      PARAMS ((rtx));
static void emit_input_reload_insns     PARAMS ((struct insn_chain *,
                                                 struct reload *, rtx, int));
static void emit_output_reload_insns    PARAMS ((struct insn_chain *,
                                                 struct reload *, int));
static void do_input_reload             PARAMS ((struct insn_chain *,
                                                 struct reload *, int));
static void do_output_reload            PARAMS ((struct insn_chain *,
                                                 struct reload *, int));
static void emit_reload_insns           PARAMS ((struct insn_chain *));
static void delete_output_reload        PARAMS ((rtx, int, int));
static void delete_address_reloads      PARAMS ((rtx, rtx));
static void delete_address_reloads_1    PARAMS ((rtx, rtx, rtx));
static rtx inc_for_reload               PARAMS ((rtx, rtx, rtx, int));
static int constraint_accepts_reg_p     PARAMS ((const char *, rtx));
static void reload_cse_regs_1           PARAMS ((rtx));
static int reload_cse_noop_set_p        PARAMS ((rtx));
static int reload_cse_simplify_set      PARAMS ((rtx, rtx));
static int reload_cse_simplify_operands PARAMS ((rtx));
static void reload_combine              PARAMS ((void));
static void reload_combine_note_use     PARAMS ((rtx *, rtx));
static void reload_combine_note_store   PARAMS ((rtx, rtx, void *));
static void reload_cse_move2add         PARAMS ((rtx));
static void move2add_note_store         PARAMS ((rtx, rtx, void *));
#ifdef AUTO_INC_DEC
static void add_auto_inc_notes          PARAMS ((rtx, rtx));
#endif
static rtx gen_mode_int                 PARAMS ((enum machine_mode,
                                                 HOST_WIDE_INT));
static void failed_reload               PARAMS ((rtx, int));
static int set_reload_reg               PARAMS ((int, int));
static void reload_cse_delete_noop_set  PARAMS ((rtx, rtx));
static void reload_cse_simplify         PARAMS ((rtx));
extern void dump_needs                  PARAMS ((struct insn_chain *, FILE *));
\f
/* Initialize the reload pass once per compilation.  */

void
init_reload ()
{
  register int i;

  /* Often (MEM (REG n)) is still valid even if (REG n) is put on the stack.
     Set spill_indirect_levels to the number of levels such addressing is
     permitted, zero if it is not permitted at all.  */

  register rtx tem
    = gen_rtx_MEM (Pmode,
                   gen_rtx_PLUS (Pmode,
                                 gen_rtx_REG (Pmode,
                                              LAST_VIRTUAL_REGISTER + 1),
                                 GEN_INT (4)));
  spill_indirect_levels = 0;

  while (memory_address_p (QImode, tem))
    {
      spill_indirect_levels++;
      tem = gen_rtx_MEM (Pmode, tem);
    }

  /* See if indirect addressing is valid for (MEM (SYMBOL_REF ...)).  */

  tem = gen_rtx_MEM (Pmode, gen_rtx_SYMBOL_REF (Pmode, "foo"));
  indirect_symref_ok = memory_address_p (QImode, tem);

  /* See if reg+reg is a valid (and offsettable) address.  */

  for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
    {
      tem = gen_rtx_PLUS (Pmode,
                          gen_rtx_REG (Pmode, HARD_FRAME_POINTER_REGNUM),
                          gen_rtx_REG (Pmode, i));

      /* This way, we make sure that reg+reg is an offsettable address.  */
      tem = plus_constant (tem, 4);

      if (memory_address_p (QImode, tem))
        {
          double_reg_address_ok = 1;
          break;
        }
    }

  /* Initialize obstack for our rtl allocation.  */
  gcc_obstack_init (&reload_obstack);
  reload_startobj = (char *) obstack_alloc (&reload_obstack, 0);

  INIT_REG_SET (&spilled_pseudos);
  INIT_REG_SET (&pseudos_counted);
}

/* List of insn chains that are currently unused.  */
static struct insn_chain *unused_insn_chains = 0;

/* Allocate an empty insn_chain structure.  */
struct insn_chain *
new_insn_chain ()
{
  struct insn_chain *c;

  if (unused_insn_chains == 0)
    {
      c = (struct insn_chain *)
        obstack_alloc (&reload_obstack, sizeof (struct insn_chain));
      INIT_REG_SET (&c->live_throughout);
      INIT_REG_SET (&c->dead_or_set);
    }
  else
    {
      c = unused_insn_chains;
      unused_insn_chains = c->next;
    }
  c->is_caller_save_insn = 0;
  c->need_operand_change = 0;
  c->need_reload = 0;
  c->need_elim = 0;
  return c;
}

/* Small utility function to set all regs in hard reg set TO which are
   allocated to pseudos in regset FROM.  */

void
compute_use_by_pseudos (to, from)
     HARD_REG_SET *to;
     regset from;
{
  unsigned int regno;

  EXECUTE_IF_SET_IN_REG_SET
    (from, FIRST_PSEUDO_REGISTER, regno,
     {
       int r = reg_renumber[regno];
       int nregs;

       if (r < 0)
         {
           /* reload_combine uses the information from
              BASIC_BLOCK->global_live_at_start, which might still
              contain registers that have not actually been allocated
              since they have an equivalence.  */
           if (! reload_completed)
             abort ();
         }
       else
         {
           nregs = HARD_REGNO_NREGS (r, PSEUDO_REGNO_MODE (regno));
           while (nregs-- > 0)
             SET_HARD_REG_BIT (*to, r + nregs);
         }
     });
}
\f
/* Global variables used by reload and its subroutines.  */

/* Set during calculate_needs if an insn needs register elimination.  */
static int something_needs_elimination;
/* Set during calculate_needs if an insn needs an operand changed.  */
int something_needs_operands_changed;

/* Nonzero means we couldn't get enough spill regs.  */
static int failure;

/* Main entry point for the reload pass.

   FIRST is the first insn of the function being compiled.

   GLOBAL nonzero means we were called from global_alloc
   and should attempt to reallocate any pseudoregs that we
   displace from hard regs we will use for reloads.
   If GLOBAL is zero, we do not have enough information to do that,
   so any pseudo reg that is spilled must go to the stack.

   DUMPFILE is the global-reg debugging dump file stream, or 0.
   If it is nonzero, messages are written to it to describe
   which registers are seized as reload regs, which pseudo regs
   are spilled from them, and where the pseudo regs are reallocated to.

   Return value is nonzero if reload failed
   and we must not do any more for this function.  */

int
reload (first, global, dumpfile)
     rtx first;
     int global;
     FILE *dumpfile;
{
  register int i;
  register rtx insn;
  register struct elim_table *ep;

  /* The two pointers used to track the true location of the memory used
     for label offsets.  */
  char *real_known_ptr = NULL_PTR;
  int (*real_at_ptr)[NUM_ELIMINABLE_REGS];

  /* Make sure even insns with volatile mem refs are recognizable.  */
  init_recog ();

  failure = 0;

  reload_firstobj = (char *) obstack_alloc (&reload_obstack, 0);

  /* Make sure that the last insn in the chain
     is not something that needs reloading.  */
  emit_note (NULL_PTR, NOTE_INSN_DELETED);

  /* Enable find_equiv_reg to distinguish insns made by reload.  */
  reload_first_uid = get_max_uid ();

#ifdef SECONDARY_MEMORY_NEEDED
  /* Initialize the secondary memory table.  */
  clear_secondary_mem ();
#endif

  /* We don't have a stack slot for any spill reg yet.  */
  bzero ((char *) spill_stack_slot, sizeof spill_stack_slot);
  bzero ((char *) spill_stack_slot_width, sizeof spill_stack_slot_width);

  /* Initialize the save area information for caller-save, in case some
     are needed.  */
  init_save_areas ();

  /* Compute which hard registers are now in use
     as homes for pseudo registers.
     This is done here rather than (eg) in global_alloc
     because this point is reached even if not optimizing.  */
  for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
    mark_home_live (i);

  /* A function that receives a nonlocal goto must save all call-saved
     registers.  */
  if (current_function_has_nonlocal_label)
    for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
      {
        if (! call_used_regs[i] && ! fixed_regs[i])
          regs_ever_live[i] = 1;
      }

  /* Find all the pseudo registers that didn't get hard regs
     but do have known equivalent constants or memory slots.
     These include parameters (known equivalent to parameter slots)
     and cse'd or loop-moved constant memory addresses.

     Record constant equivalents in reg_equiv_constant
     so they will be substituted by find_reloads.
     Record memory equivalents in reg_mem_equiv so they can
     be substituted eventually by altering the REG-rtx's.  */

  reg_equiv_constant = (rtx *) xcalloc (max_regno, sizeof (rtx));
  reg_equiv_memory_loc = (rtx *) xcalloc (max_regno, sizeof (rtx));
  reg_equiv_mem = (rtx *) xcalloc (max_regno, sizeof (rtx));
  reg_equiv_init = (rtx *) xcalloc (max_regno, sizeof (rtx));
  reg_equiv_address = (rtx *) xcalloc (max_regno, sizeof (rtx));
  reg_max_ref_width = (unsigned int *) xcalloc (max_regno, sizeof (int));
  reg_old_renumber = (short *) xcalloc (max_regno, sizeof (short));
  bcopy ((PTR) reg_renumber, (PTR) reg_old_renumber, max_regno * sizeof (short));
  pseudo_forbidden_regs
    = (HARD_REG_SET *) xmalloc (max_regno * sizeof (HARD_REG_SET));
  pseudo_previous_regs
    = (HARD_REG_SET *) xcalloc (max_regno, sizeof (HARD_REG_SET));

  CLEAR_HARD_REG_SET (bad_spill_regs_global);

  /* Look for REG_EQUIV notes; record what each pseudo is equivalent to.
     Also find all paradoxical subregs and find largest such for each pseudo.
     On machines with small register classes, record hard registers that
     are used for user variables.  These can never be used for spills.
     Also look for a "constant" NOTE_INSN_SETJMP.  This means that all
     caller-saved registers must be marked live.  */

  num_eliminable_invariants = 0;
  for (insn = first; insn; insn = NEXT_INSN (insn))
    {
      rtx set = single_set (insn);

      if (GET_CODE (insn) == NOTE && CONST_CALL_P (insn)
          && NOTE_LINE_NUMBER (insn) == NOTE_INSN_SETJMP)
        for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
          if (! call_used_regs[i])
            regs_ever_live[i] = 1;

      if (set != 0 && GET_CODE (SET_DEST (set)) == REG)
        {
          rtx note = find_reg_note (insn, REG_EQUIV, NULL_RTX);
          if (note
#ifdef LEGITIMATE_PIC_OPERAND_P
              && (! function_invariant_p (XEXP (note, 0))
                  || ! flag_pic
                  || LEGITIMATE_PIC_OPERAND_P (XEXP (note, 0)))
#endif
              )
            {
              rtx x = XEXP (note, 0);
              i = REGNO (SET_DEST (set));
              if (i > LAST_VIRTUAL_REGISTER)
                {
                  if (GET_CODE (x) == MEM)
                    {
                      /* If the operand is a PLUS, the MEM may be shared,
                         so make sure we have an unshared copy here.  */
                      if (GET_CODE (XEXP (x, 0)) == PLUS)
                        x = copy_rtx (x);

                      reg_equiv_memory_loc[i] = x;
                    }
                  else if (function_invariant_p (x))
                    {
                      if (GET_CODE (x) == PLUS)
                        {
                          /* This is PLUS of frame pointer and a constant,
                             and might be shared.  Unshare it.  */
                          reg_equiv_constant[i] = copy_rtx (x);
                          num_eliminable_invariants++;
                        }
                      else if (x == frame_pointer_rtx
                               || x == arg_pointer_rtx)
                        {
                          reg_equiv_constant[i] = x;
                          num_eliminable_invariants++;
                        }
                      else if (LEGITIMATE_CONSTANT_P (x))
                        reg_equiv_constant[i] = x;
                      else
                        reg_equiv_memory_loc[i]
                          = force_const_mem (GET_MODE (SET_DEST (set)), x);
                    }
                  else
                    continue;

                  /* If this register is being made equivalent to a MEM
                     and the MEM is not SET_SRC, the equivalencing insn
                     is one with the MEM as a SET_DEST and it occurs later.
                     So don't mark this insn now.  */
                  if (GET_CODE (x) != MEM
                      || rtx_equal_p (SET_SRC (set), x))
                    reg_equiv_init[i]
                      = gen_rtx_INSN_LIST (VOIDmode, insn, reg_equiv_init[i]);
                }
            }
        }

      /* If this insn is setting a MEM from a register equivalent to it,
         this is the equivalencing insn.  */
      else if (set && GET_CODE (SET_DEST (set)) == MEM
               && GET_CODE (SET_SRC (set)) == REG
               && reg_equiv_memory_loc[REGNO (SET_SRC (set))]
               && rtx_equal_p (SET_DEST (set),
                               reg_equiv_memory_loc[REGNO (SET_SRC (set))]))
        reg_equiv_init[REGNO (SET_SRC (set))]
          = gen_rtx_INSN_LIST (VOIDmode, insn,
                               reg_equiv_init[REGNO (SET_SRC (set))]);

      if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
        scan_paradoxical_subregs (PATTERN (insn));
    }

  init_elim_table ();

  num_labels = max_label_num () - get_first_label_num ();

  /* Allocate the tables used to store offset information at labels.  */
  /* We used to use alloca here, but the size of what it would try to
     allocate would occasionally cause it to exceed the stack limit and
     cause a core dump.  */
  real_known_ptr = xmalloc (num_labels);
  real_at_ptr
    = (int (*)[NUM_ELIMINABLE_REGS])
    xmalloc (num_labels * NUM_ELIMINABLE_REGS * sizeof (int));

  offsets_known_at = real_known_ptr - get_first_label_num ();
  offsets_at
    = (int (*)[NUM_ELIMINABLE_REGS]) (real_at_ptr - get_first_label_num ());

  /* Alter each pseudo-reg rtx to contain its hard reg number.
     Assign stack slots to the pseudos that lack hard regs or equivalents.
     Do not touch virtual registers.  */

  for (i = LAST_VIRTUAL_REGISTER + 1; i < max_regno; i++)
    alter_reg (i, -1);

  /* If we have some registers we think can be eliminated, scan all insns to
     see if there is an insn that sets one of these registers to something
     other than itself plus a constant.  If so, the register cannot be
     eliminated.  Doing this scan here eliminates an extra pass through the
     main reload loop in the most common case where register elimination
     cannot be done.  */
  for (insn = first; insn && num_eliminable; insn = NEXT_INSN (insn))
    if (GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN
        || GET_CODE (insn) == CALL_INSN)
      note_stores (PATTERN (insn), mark_not_eliminable, NULL);

  maybe_fix_stack_asms ();

  insns_need_reload = 0;
  something_needs_elimination = 0;

  /* Initialize to -1, which means take the first spill register.  */
  last_spill_reg = -1;

  /* Spill any hard regs that we know we can't eliminate.  */
  CLEAR_HARD_REG_SET (used_spill_regs);
  for (ep = reg_eliminate; ep < &reg_eliminate[NUM_ELIMINABLE_REGS]; ep++)
    if (! ep->can_eliminate)
      spill_hard_reg (ep->from, dumpfile, 1);

#if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM
  if (frame_pointer_needed)
    spill_hard_reg (HARD_FRAME_POINTER_REGNUM, dumpfile, 1);
#endif
  finish_spills (global, dumpfile);

  /* From now on, we may need to generate moves differently.  We may also
     allow modifications of insns which cause them to not be recognized.
     Any such modifications will be cleaned up during reload itself.  */
  reload_in_progress = 1;

  /* This loop scans the entire function each go-round
     and repeats until one repetition spills no additional hard regs.  */
  for (;;)
    {
      int something_changed;
      int did_spill;

      HOST_WIDE_INT starting_frame_size;

      /* Round size of stack frame to stack_alignment_needed.  This must be done
         here because the stack size may be a part of the offset computation
         for register elimination, and there might have been new stack slots
         created in the last iteration of this loop.   */
      if (cfun->stack_alignment_needed)
        assign_stack_local (BLKmode, 0, cfun->stack_alignment_needed);

      starting_frame_size = get_frame_size ();

      set_initial_elim_offsets ();
      set_initial_label_offsets ();

      /* For each pseudo register that has an equivalent location defined,
         try to eliminate any eliminable registers (such as the frame pointer)
         assuming initial offsets for the replacement register, which
         is the normal case.

         If the resulting location is directly addressable, substitute
         the MEM we just got directly for the old REG.

         If it is not addressable but is a constant or the sum of a hard reg
         and constant, it is probably not addressable because the constant is
         out of range, in that case record the address; we will generate
         hairy code to compute the address in a register each time it is
         needed.  Similarly if it is a hard register, but one that is not
         valid as an address register.

         If the location is not addressable, but does not have one of the
         above forms, assign a stack slot.  We have to do this to avoid the
         potential of producing lots of reloads if, e.g., a location involves
         a pseudo that didn't get a hard register and has an equivalent memory
         location that also involves a pseudo that didn't get a hard register.

         Perhaps at some point we will improve reload_when_needed handling
         so this problem goes away.  But that's very hairy.  */

      for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
        if (reg_renumber[i] < 0 && reg_equiv_memory_loc[i])
          {
            rtx x = eliminate_regs (reg_equiv_memory_loc[i], 0, NULL_RTX);

            if (strict_memory_address_p (GET_MODE (regno_reg_rtx[i]),
                                         XEXP (x, 0)))
              reg_equiv_mem[i] = x, reg_equiv_address[i] = 0;
            else if (CONSTANT_P (XEXP (x, 0))
                     || (GET_CODE (XEXP (x, 0)) == REG
                         && REGNO (XEXP (x, 0)) < FIRST_PSEUDO_REGISTER)
                     || (GET_CODE (XEXP (x, 0)) == PLUS
                         && GET_CODE (XEXP (XEXP (x, 0), 0)) == REG
                         && (REGNO (XEXP (XEXP (x, 0), 0))
                             < FIRST_PSEUDO_REGISTER)
                         && CONSTANT_P (XEXP (XEXP (x, 0), 1))))
              reg_equiv_address[i] = XEXP (x, 0), reg_equiv_mem[i] = 0;
            else
              {
                /* Make a new stack slot.  Then indicate that something
                   changed so we go back and recompute offsets for
                   eliminable registers because the allocation of memory
                   below might change some offset.  reg_equiv_{mem,address}
                   will be set up for this pseudo on the next pass around
                   the loop.  */
                reg_equiv_memory_loc[i] = 0;
                reg_equiv_init[i] = 0;
                alter_reg (i, -1);
              }
          }

      if (caller_save_needed)
        setup_save_areas ();

      /* If we allocated another stack slot, redo elimination bookkeeping.  */
      if (starting_frame_size != get_frame_size ())
        continue;

      if (caller_save_needed)
        {
          save_call_clobbered_regs ();
          /* That might have allocated new insn_chain structures.  */
          reload_firstobj = (char *) obstack_alloc (&reload_obstack, 0);
        }

      calculate_needs_all_insns (global);

      CLEAR_REG_SET (&spilled_pseudos);
      did_spill = 0;

      something_changed = 0;

      /* If we allocated any new memory locations, make another pass
         since it might have changed elimination offsets.  */
      if (starting_frame_size != get_frame_size ())
        something_changed = 1;

      {
        HARD_REG_SET to_spill;
        CLEAR_HARD_REG_SET (to_spill);
        update_eliminables (&to_spill);
        for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
          if (TEST_HARD_REG_BIT (to_spill, i))
            {
              spill_hard_reg (i, dumpfile, 1);
              did_spill = 1;

              /* Regardless of the state of spills, if we previously had
                 a register that we thought we could eliminate, but no can
                 not eliminate, we must run another pass.

                 Consider pseudos which have an entry in reg_equiv_* which
                 reference an eliminable register.  We must make another pass
                 to update reg_equiv_* so that we do not substitute in the
                 old value from when we thought the elimination could be
                 performed.  */
              something_changed = 1;
            }
      }

      select_reload_regs (dumpfile);
      if (failure)
        goto failed;

      if (insns_need_reload != 0 || did_spill)
        something_changed |= finish_spills (global, dumpfile);

      if (! something_changed)
        break;

      if (caller_save_needed)
        delete_caller_save_insns ();

      obstack_free (&reload_obstack, reload_firstobj);
    }

  /* If global-alloc was run, notify it of any register eliminations we have
     done.  */
  if (global)
    for (ep = reg_eliminate; ep < &reg_eliminate[NUM_ELIMINABLE_REGS]; ep++)
      if (ep->can_eliminate)
        mark_elimination (ep->from, ep->to);

  /* If a pseudo has no hard reg, delete the insns that made the equivalence.
     If that insn didn't set the register (i.e., it copied the register to
     memory), just delete that insn instead of the equivalencing insn plus
     anything now dead.  If we call delete_dead_insn on that insn, we may
     delete the insn that actually sets the register if the register dies
     there and that is incorrect.  */

  for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
    {
      if (reg_renumber[i] < 0 && reg_equiv_init[i] != 0)
        {
          rtx list;
          for (list = reg_equiv_init[i]; list; list = XEXP (list, 1))
            {
              rtx equiv_insn = XEXP (list, 0);
              if (GET_CODE (equiv_insn) == NOTE)
                continue;
              if (reg_set_p (regno_reg_rtx[i], PATTERN (equiv_insn)))
                delete_dead_insn (equiv_insn);
              else
                {
                  PUT_CODE (equiv_insn, NOTE);
                  NOTE_SOURCE_FILE (equiv_insn) = 0;
                  NOTE_LINE_NUMBER (equiv_insn) = NOTE_INSN_DELETED;
                }
            }
        }
    }

  /* Use the reload registers where necessary
     by generating move instructions to move the must-be-register
     values into or out of the reload registers.  */

  if (insns_need_reload != 0 || something_needs_elimination
      || something_needs_operands_changed)
    {
      int old_frame_size = get_frame_size ();

      reload_as_needed (global);

      if (old_frame_size != get_frame_size ())
        abort ();

      if (num_eliminable)
        verify_initial_elim_offsets ();
    }

  /* If we were able to eliminate the frame pointer, show that it is no
     longer live at the start of any basic block.  If it ls live by
     virtue of being in a pseudo, that pseudo will be marked live
     and hence the frame pointer will be known to be live via that
     pseudo.  */

  if (! frame_pointer_needed)
    for (i = 0; i < n_basic_blocks; i++)
      CLEAR_REGNO_REG_SET (BASIC_BLOCK (i)->global_live_at_start,
                           HARD_FRAME_POINTER_REGNUM);

  /* Come here (with failure set nonzero) if we can't get enough spill regs
     and we decide not to abort about it.  */
 failed:

  CLEAR_REG_SET (&spilled_pseudos);
  reload_in_progress = 0;

  /* Now eliminate all pseudo regs by modifying them into
     their equivalent memory references.
     The REG-rtx's for the pseudos are modified in place,
     so all insns that used to refer to them now refer to memory.

     For a reg that has a reg_equiv_address, all those insns
     were changed by reloading so that no insns refer to it any longer;
     but the DECL_RTL of a variable decl may refer to it,
     and if so this causes the debugging info to mention the variable.  */

  for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
    {
      rtx addr = 0;
      int in_struct = 0;
      int is_scalar = 0;
      int is_readonly = 0;

      if (reg_equiv_memory_loc[i])
        {
          in_struct = MEM_IN_STRUCT_P (reg_equiv_memory_loc[i]);
          is_scalar = MEM_SCALAR_P (reg_equiv_memory_loc[i]);
          is_readonly = RTX_UNCHANGING_P (reg_equiv_memory_loc[i]);
        }

      if (reg_equiv_mem[i])
        addr = XEXP (reg_equiv_mem[i], 0);

      if (reg_equiv_address[i])
        addr = reg_equiv_address[i];

      if (addr)
        {
          if (reg_renumber[i] < 0)
            {
              rtx reg = regno_reg_rtx[i];
              PUT_CODE (reg, MEM);
              XEXP (reg, 0) = addr;
              REG_USERVAR_P (reg) = 0;
              RTX_UNCHANGING_P (reg) = is_readonly;
              MEM_IN_STRUCT_P (reg) = in_struct;
              MEM_SCALAR_P (reg) = is_scalar;
              /* We have no alias information about this newly created
                 MEM.  */
              MEM_ALIAS_SET (reg) = 0;
            }
          else if (reg_equiv_mem[i])
            XEXP (reg_equiv_mem[i], 0) = addr;
        }
    }

  /* We must set reload_completed now since the cleanup_subreg_operands call
     below will re-recognize each insn and reload may have generated insns
     which are only valid during and after reload.  */
  reload_completed = 1;

  /* Make a pass over all the insns and delete all USEs which we inserted
     only to tag a REG_EQUAL note on them.  Remove all REG_DEAD and REG_UNUSED
     notes.  Delete all CLOBBER insns that don't refer to the return value
     and simplify (subreg (reg)) operands.  Also remove all REG_RETVAL and
     REG_LIBCALL notes since they are no longer useful or accurate.  Strip
     and regenerate REG_INC notes that may have been moved around.  */

  for (insn = first; insn; insn = NEXT_INSN (insn))
    if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
      {
        rtx *pnote;

        if ((GET_CODE (PATTERN (insn)) == USE
             && find_reg_note (insn, REG_EQUAL, NULL_RTX))
            || (GET_CODE (PATTERN (insn)) == CLOBBER
                && (GET_CODE (XEXP (PATTERN (insn), 0)) != REG
                    || ! REG_FUNCTION_VALUE_P (XEXP (PATTERN (insn), 0)))))
          {
            PUT_CODE (insn, NOTE);
            NOTE_SOURCE_FILE (insn) = 0;
            NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
            continue;
          }

        pnote = &REG_NOTES (insn);
        while (*pnote != 0)
          {
            if (REG_NOTE_KIND (*pnote) == REG_DEAD
                || REG_NOTE_KIND (*pnote) == REG_UNUSED
                || REG_NOTE_KIND (*pnote) == REG_INC
                || REG_NOTE_KIND (*pnote) == REG_RETVAL
                || REG_NOTE_KIND (*pnote) == REG_LIBCALL)
              *pnote = XEXP (*pnote, 1);
            else
              pnote = &XEXP (*pnote, 1);
          }

#ifdef AUTO_INC_DEC
        add_auto_inc_notes (insn, PATTERN (insn));
#endif

        /* And simplify (subreg (reg)) if it appears as an operand.  */
        cleanup_subreg_operands (insn);
      }

  /* If we are doing stack checking, give a warning if this function's
     frame size is larger than we expect.  */
  if (flag_stack_check && ! STACK_CHECK_BUILTIN)
    {
      HOST_WIDE_INT size = get_frame_size () + STACK_CHECK_FIXED_FRAME_SIZE;
      static int verbose_warned = 0;

      for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
        if (regs_ever_live[i] && ! fixed_regs[i] && call_used_regs[i])
          size += UNITS_PER_WORD;

      if (size > STACK_CHECK_MAX_FRAME_SIZE)
        {
          warning ("frame size too large for reliable stack checking");
          if (! verbose_warned)
            {
              warning ("try reducing the number of local variables");
              verbose_warned = 1;
            }
        }
    }

  /* Indicate that we no longer have known memory locations or constants.  */
  if (reg_equiv_constant)
    free (reg_equiv_constant);
  reg_equiv_constant = 0;
  if (reg_equiv_memory_loc)
    free (reg_equiv_memory_loc);
  reg_equiv_memory_loc = 0;

  if (real_known_ptr)
    free (real_known_ptr);
  if (real_at_ptr)
    free (real_at_ptr);

  free (reg_equiv_mem);
  free (reg_equiv_init);
  free (reg_equiv_address);
  free (reg_max_ref_width);
  free (reg_old_renumber);
  free (pseudo_previous_regs);
  free (pseudo_forbidden_regs);

  CLEAR_HARD_REG_SET (used_spill_regs);
  for (i = 0; i < n_spills; i++)
    SET_HARD_REG_BIT (used_spill_regs, spill_regs[i]);

  /* Free all the insn_chain structures at once.  */
  obstack_free (&reload_obstack, reload_startobj);
  unused_insn_chains = 0;

  return failure;
}

/* Yet another special case.  Unfortunately, reg-stack forces people to
   write incorrect clobbers in asm statements.  These clobbers must not
   cause the register to appear in bad_spill_regs, otherwise we'll call
   fatal_insn later.  We clear the corresponding regnos in the live
   register sets to avoid this.
   The whole thing is rather sick, I'm afraid.  */
static void
maybe_fix_stack_asms ()
{
#ifdef STACK_REGS
  const char *constraints[MAX_RECOG_OPERANDS];
  enum machine_mode operand_mode[MAX_RECOG_OPERANDS];
  struct insn_chain *chain;

  for (chain = reload_insn_chain; chain != 0; chain = chain->next)
    {
      int i, noperands;
      HARD_REG_SET clobbered, allowed;
      rtx pat;

      if (GET_RTX_CLASS (GET_CODE (chain->insn)) != 'i'
          || (noperands = asm_noperands (PATTERN (chain->insn))) < 0)
        continue;
      pat = PATTERN (chain->insn);
      if (GET_CODE (pat) != PARALLEL)
        continue;

      CLEAR_HARD_REG_SET (clobbered);
      CLEAR_HARD_REG_SET (allowed);

      /* First, make a mask of all stack regs that are clobbered.  */
      for (i = 0; i < XVECLEN (pat, 0); i++)
        {
          rtx t = XVECEXP (pat, 0, i);
          if (GET_CODE (t) == CLOBBER && STACK_REG_P (XEXP (t, 0)))
            SET_HARD_REG_BIT (clobbered, REGNO (XEXP (t, 0)));
        }

      /* Get the operand values and constraints out of the insn.  */
      decode_asm_operands (pat, recog_data.operand, recog_data.operand_loc,
                           constraints, operand_mode);

      /* For every operand, see what registers are allowed.  */
      for (i = 0; i < noperands; i++)
        {
          const char *p = constraints[i];
          /* For every alternative, we compute the class of registers allowed
             for reloading in CLS, and merge its contents into the reg set
             ALLOWED.  */
          int cls = (int) NO_REGS;

          for (;;)
            {
              char c = *p++;

              if (c == '\0' || c == ',' || c == '#')
                {
                  /* End of one alternative - mark the regs in the current
                     class, and reset the class.  */
                  IOR_HARD_REG_SET (allowed, reg_class_contents[cls]);
                  cls = NO_REGS;
                  if (c == '#')
                    do {
                      c = *p++;
                    } while (c != '\0' && c != ',');
                  if (c == '\0')
                    break;
                  continue;
                }

              switch (c)
                {
                case '=': case '+': case '*': case '%': case '?': case '!':
                case '0': case '1': case '2': case '3': case '4': case 'm':
                case '<': case '>': case 'V': case 'o': case '&': case 'E':
                case 'F': case 's': case 'i': case 'n': case 'X': case 'I':
                case 'J': case 'K': case 'L': case 'M': case 'N': case 'O':
                case 'P':
#ifdef EXTRA_CONSTRAINT
                case 'Q': case 'R': case 'S': case 'T': case 'U':
#endif
                  break;

                case 'p':
                  cls = (int) reg_class_subunion[cls][(int) BASE_REG_CLASS];
                  break;

                case 'g':
                case 'r':
                  cls = (int) reg_class_subunion[cls][(int) GENERAL_REGS];
                  break;

                default:
                  cls = (int) reg_class_subunion[cls][(int) REG_CLASS_FROM_LETTER (c)];

                }
            }
        }
      /* Those of the registers which are clobbered, but allowed by the
         constraints, must be usable as reload registers.  So clear them
         out of the life information.  */
      AND_HARD_REG_SET (allowed, clobbered);
      for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
        if (TEST_HARD_REG_BIT (allowed, i))
          {
            CLEAR_REGNO_REG_SET (&chain->live_throughout, i);
            CLEAR_REGNO_REG_SET (&chain->dead_or_set, i);
          }
    }

#endif
}
\f
/* Copy the global variables n_reloads and rld into the corresponding elts
   of CHAIN.  */
static void
copy_reloads (chain)
     struct insn_chain *chain;
{
  chain->n_reloads = n_reloads;
  chain->rld
    = (struct reload *) obstack_alloc (&reload_obstack,
                                       n_reloads * sizeof (struct reload));
  memcpy (chain->rld, rld, n_reloads * sizeof (struct reload));
  reload_insn_firstobj = (char *) obstack_alloc (&reload_obstack, 0);
}

/* Walk the chain of insns, and determine for each whether it needs reloads
   and/or eliminations.  Build the corresponding insns_need_reload list, and
   set something_needs_elimination as appropriate.  */
static void
calculate_needs_all_insns (global)
     int global;
{
  struct insn_chain **pprev_reload = &insns_need_reload;
  struct insn_chain *chain;

  something_needs_elimination = 0;

  reload_insn_firstobj = (char *) obstack_alloc (&reload_obstack, 0);
  for (chain = reload_insn_chain; chain != 0; chain = chain->next)
    {
      rtx insn = chain->insn;

      /* Clear out the shortcuts.  */
      chain->n_reloads = 0;
      chain->need_elim = 0;
      chain->need_reload = 0;
      chain->need_operand_change = 0;

      /* If this is a label, a JUMP_INSN, or has REG_NOTES (which might
         include REG_LABEL), we need to see what effects this has on the
         known offsets at labels.  */

      if (GET_CODE (insn) == CODE_LABEL || GET_CODE (insn) == JUMP_INSN
          || (GET_RTX_CLASS (GET_CODE (insn)) == 'i'
              && REG_NOTES (insn) != 0))
        set_label_offsets (insn, insn, 0);

      if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
        {
          rtx old_body = PATTERN (insn);
          int old_code = INSN_CODE (insn);
          rtx old_notes = REG_NOTES (insn);
          int did_elimination = 0;
          int operands_changed = 0;
          rtx set = single_set (insn);

          /* Skip insns that only set an equivalence.  */
          if (set && GET_CODE (SET_DEST (set)) == REG
              && reg_renumber[REGNO (SET_DEST (set))] < 0
              && reg_equiv_constant[REGNO (SET_DEST (set))])
            continue;

          /* If needed, eliminate any eliminable registers.  */
          if (num_eliminable || num_eliminable_invariants)
            did_elimination = eliminate_regs_in_insn (insn, 0);

          /* Analyze the instruction.  */
          operands_changed = find_reloads (insn, 0, spill_indirect_levels,
                                           global, spill_reg_order);

          /* If a no-op set needs more than one reload, this is likely
             to be something that needs input address reloads.  We
             can't get rid of this cleanly later, and it is of no use
             anyway, so discard it now.
             We only do this when expensive_optimizations is enabled,
             since this complements reload inheritance / output
             reload deletion, and it can make debugging harder.  */
          if (flag_expensive_optimizations && n_reloads > 1)
            {
              rtx set = single_set (insn);
              if (set
                  && SET_SRC (set) == SET_DEST (set)
                  && GET_CODE (SET_SRC (set)) == REG
                  && REGNO (SET_SRC (set)) >= FIRST_PSEUDO_REGISTER)
                {
                  PUT_CODE (insn, NOTE);
                  NOTE_SOURCE_FILE (insn) = 0;
                  NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
                  continue;
                }
            }
          if (num_eliminable)
            update_eliminable_offsets ();

          /* Remember for later shortcuts which insns had any reloads or
             register eliminations.  */
          chain->need_elim = did_elimination;
          chain->need_reload = n_reloads > 0;
          chain->need_operand_change = operands_changed;

          /* Discard any register replacements done.  */
          if (did_elimination)
            {
              obstack_free (&reload_obstack, reload_insn_firstobj);
              PATTERN (insn) = old_body;
              INSN_CODE (insn) = old_code;
              REG_NOTES (insn) = old_notes;
              something_needs_elimination = 1;
            }

          something_needs_operands_changed |= operands_changed;

          if (n_reloads != 0)
            {
              copy_reloads (chain);
              *pprev_reload = chain;
              pprev_reload = &chain->next_need_reload;
            }
        }
    }
  *pprev_reload = 0;
}
\f
/* Comparison function for qsort to decide which of two reloads
   should be handled first.  *P1 and *P2 are the reload numbers.  */

static int
reload_reg_class_lower (r1p, r2p)
     const PTR r1p;
     const PTR r2p;
{
  register int r1 = *(const short *)r1p, r2 = *(const short *)r2p;
  register int t;

  /* Consider required reloads before optional ones.  */
  t = rld[r1].optional - rld[r2].optional;
  if (t != 0)
    return t;

  /* Count all solitary classes before non-solitary ones.  */
  t = ((reg_class_size[(int) rld[r2].class] == 1)
       - (reg_class_size[(int) rld[r1].class] == 1));
  if (t != 0)
    return t;

  /* Aside from solitaires, consider all multi-reg groups first.  */
  t = rld[r2].nregs - rld[r1].nregs;
  if (t != 0)
    return t;

  /* Consider reloads in order of increasing reg-class number.  */
  t = (int) rld[r1].class - (int) rld[r2].class;
  if (t != 0)
    return t;

  /* If reloads are equally urgent, sort by reload number,
     so that the results of qsort leave nothing to chance.  */
  return r1 - r2;
}
\f
/* The cost of spilling each hard reg.  */
static int spill_cost[FIRST_PSEUDO_REGISTER];

/* When spilling multiple hard registers, we use SPILL_COST for the first
   spilled hard reg and SPILL_ADD_COST for subsequent regs.  SPILL_ADD_COST
   only the first hard reg for a multi-reg pseudo.  */
static int spill_add_cost[FIRST_PSEUDO_REGISTER];

/* Update the spill cost arrays, considering that pseudo REG is live.  */

static void
count_pseudo (reg)
     int reg;
{
  int n_refs = REG_N_REFS (reg);
  int r = reg_renumber[reg];
  int nregs;

  if (REGNO_REG_SET_P (&pseudos_counted, reg)
      || REGNO_REG_SET_P (&spilled_pseudos, reg))
    return;

  SET_REGNO_REG_SET (&pseudos_counted, reg);

  if (r < 0)
    abort ();
  
  spill_add_cost[r] += n_refs;

  nregs = HARD_REGNO_NREGS (r, PSEUDO_REGNO_MODE (reg));
  while (nregs-- > 0)
    spill_cost[r + nregs] += n_refs;
}

/* Calculate the SPILL_COST and SPILL_ADD_COST arrays and determine the
   contents of BAD_SPILL_REGS for the insn described by CHAIN.  */
static void
order_regs_for_reload (chain)
     struct insn_chain *chain;
{
  register int i, j;

  COPY_HARD_REG_SET (bad_spill_regs, bad_spill_regs_global);

  memset (spill_cost, 0, sizeof spill_cost);
  memset (spill_add_cost, 0, sizeof spill_add_cost);

  /* Count number of uses of each hard reg by pseudo regs allocated to it
     and then order them by decreasing use.  */

  for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
    {
      /* Test the various reasons why we can't use a register for
         spilling in this insn.  */
      if (fixed_regs[i]
          || REGNO_REG_SET_P (&chain->live_throughout, i)
          || REGNO_REG_SET_P (&chain->dead_or_set, i))
        SET_HARD_REG_BIT (bad_spill_regs, i);
    }
  /* Now find out which pseudos are allocated to it, and update
     hard_reg_n_uses.  */
  CLEAR_REG_SET (&pseudos_counted);

  EXECUTE_IF_SET_IN_REG_SET
    (&chain->live_throughout, FIRST_PSEUDO_REGISTER, j,
     {
       count_pseudo (j);
     });
  EXECUTE_IF_SET_IN_REG_SET
    (&chain->dead_or_set, FIRST_PSEUDO_REGISTER, j,
     {
       count_pseudo (j);
     });
  CLEAR_REG_SET (&pseudos_counted);
}
\f
/* Vector of reload-numbers showing the order in which the reloads should
   be processed.  */
static short reload_order[MAX_RELOADS];

/* This is used to keep track of the spill regs used in one insn.  */
static HARD_REG_SET used_spill_regs_local;

/* We decided to spill hard register SPILLED, which has a size of
   SPILLED_NREGS.  Determine how pseudo REG, which is live during the insn,
   is affected.  We will add it to SPILLED_PSEUDOS if necessary, and we will
   update SPILL_COST/SPILL_ADD_COST.  */

static void
count_spilled_pseudo (spilled, spilled_nregs, reg)
     int spilled, spilled_nregs, reg;
{
  int r = reg_renumber[reg];
  int nregs = HARD_REGNO_NREGS (r, PSEUDO_REGNO_MODE (reg));

  if (REGNO_REG_SET_P (&spilled_pseudos, reg)
      || spilled + spilled_nregs <= r || r + nregs <= spilled)
    return;

  SET_REGNO_REG_SET (&spilled_pseudos, reg);

  spill_add_cost[r] -= REG_N_REFS (reg);
  while (nregs-- > 0)
    spill_cost[r + nregs] -= REG_N_REFS (reg);
}

/* Find reload register to use for reload number ORDER.  */

static int
find_reg (chain, order, dumpfile)
     struct insn_chain *chain;
     int order;
     FILE *dumpfile;
{
  int rnum = reload_order[order];
  struct reload *rl = rld + rnum;
  int best_cost = INT_MAX;
  int best_reg = -1;
  unsigned int i, j;
  int k;
  HARD_REG_SET not_usable;
  HARD_REG_SET used_by_other_reload;

  COPY_HARD_REG_SET (not_usable, bad_spill_regs);
  IOR_HARD_REG_SET (not_usable, bad_spill_regs_global);
  IOR_COMPL_HARD_REG_SET (not_usable, reg_class_contents[rl->class]);

  CLEAR_HARD_REG_SET (used_by_other_reload);
  for (k = 0; k < order; k++)
    {
      int other = reload_order[k];

      if (rld[other].regno >= 0 && reloads_conflict (other, rnum))
        for (j = 0; j < rld[other].nregs; j++)
          SET_HARD_REG_BIT (used_by_other_reload, rld[other].regno + j);
    }

  for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
    {
      unsigned int regno = i;

      if (! TEST_HARD_REG_BIT (not_usable, regno)
          && ! TEST_HARD_REG_BIT (used_by_other_reload, regno)
          && HARD_REGNO_MODE_OK (regno, rl->mode))
        {
          int this_cost = spill_cost[regno];
          int ok = 1;
          unsigned int this_nregs = HARD_REGNO_NREGS (regno, rl->mode);

          for (j = 1; j < this_nregs; j++)
            {
              this_cost += spill_add_cost[regno + j];
              if ((TEST_HARD_REG_BIT (not_usable, regno + j))
                  || TEST_HARD_REG_BIT (used_by_other_reload, regno + j))
                ok = 0;
            }
          if (! ok)
            continue;
          if (rl->in && GET_CODE (rl->in) == REG && REGNO (rl->in) == regno)
            this_cost--;
          if (rl->out && GET_CODE (rl->out) == REG && REGNO (rl->out) == regno)
            this_cost--;
          if (this_cost < best_cost
              /* Among registers with equal cost, prefer caller-saved ones, or
                 use REG_ALLOC_ORDER if it is defined.  */
              || (this_cost == best_cost
#ifdef REG_ALLOC_ORDER
                  && (inv_reg_alloc_order[regno]
                      < inv_reg_alloc_order[best_reg])
#else
                  && call_used_regs[regno]
                  && ! call_used_regs[best_reg]
#endif
                  ))
            {
              best_reg = regno;
              best_cost = this_cost;
            }
        }
    }
  if (best_reg == -1)
    return 0;

  if (dumpfile)
    fprintf (dumpfile, "Using reg %d for reload %d\n", best_reg, rnum);

  rl->nregs = HARD_REGNO_NREGS (best_reg, rl->mode);
  rl->regno = best_reg;

  EXECUTE_IF_SET_IN_REG_SET
    (&chain->live_throughout, FIRST_PSEUDO_REGISTER, j,
     {
       count_spilled_pseudo (best_reg, rl->nregs, j);
     });

  EXECUTE_IF_SET_IN_REG_SET
    (&chain->dead_or_set, FIRST_PSEUDO_REGISTER, j,
     {
       count_spilled_pseudo (best_reg, rl->nregs, j);
     });

  for (i = 0; i < rl->nregs; i++)
    {
      if (spill_cost[best_reg + i] != 0
          || spill_add_cost[best_reg + i] != 0)
        abort ();
      SET_HARD_REG_BIT (used_spill_regs_local, best_reg + i);
    }
  return 1;
}

/* Find more reload regs to satisfy the remaining need of an insn, which
   is given by CHAIN.
   Do it by ascending class number, since otherwise a reg
   might be spilled for a big class and might fail to count
   for a smaller class even though it belongs to that class.  */

static void
find_reload_regs (chain, dumpfile)
     struct insn_chain *chain;
     FILE *dumpfile;
{
  int i;

  /* In order to be certain of getting the registers we need,
     we must sort the reloads into order of increasing register class.
     Then our grabbing of reload registers will parallel the process
     that provided the reload registers.  */
  for (i = 0; i < chain->n_reloads; i++)
    {
      /* Show whether this reload already has a hard reg.  */
      if (chain->rld[i].reg_rtx)
        {
          int regno = REGNO (chain->rld[i].reg_rtx);
          chain->rld[i].regno = regno;
          chain->rld[i].nregs
            = HARD_REGNO_NREGS (regno, GET_MODE (chain->rld[i].reg_rtx));
        }
      else
        chain->rld[i].regno = -1;
      reload_order[i] = i;
    }

  n_reloads = chain->n_reloads;
  memcpy (rld, chain->rld, n_reloads * sizeof (struct reload));

  CLEAR_HARD_REG_SET (used_spill_regs_local);

  if (dumpfile)
    fprintf (dumpfile, "Spilling for insn %d.\n", INSN_UID (chain->insn));

  qsort (reload_order, n_reloads, sizeof (short), reload_reg_class_lower);

  /* Compute the order of preference for hard registers to spill.  */

  order_regs_for_reload (chain);

  for (i = 0; i < n_reloads; i++)
    {
      int r = reload_order[i];

      /* Ignore reloads that got marked inoperative.  */
      if ((rld[r].out != 0 || rld[r].in != 0 || rld[r].secondary_p)
          && ! rld[r].optional
          && rld[r].regno == -1)
        if (! find_reg (chain, i, dumpfile))
          {
            spill_failure (chain->insn, rld[r].class);
            failure = 1;
            return;
          }
    }

  COPY_HARD_REG_SET (chain->used_spill_regs, used_spill_regs_local);
  IOR_HARD_REG_SET (used_spill_regs, used_spill_regs_local);

  memcpy (chain->rld, rld, n_reloads * sizeof (struct reload));
}

static void
select_reload_regs (dumpfile)
     FILE *dumpfile;
{
  struct insn_chain *chain;

  /* Try to satisfy the needs for each insn.  */
  for (chain = insns_need_reload; chain != 0;
       chain = chain->next_need_reload)
    find_reload_regs (chain, dumpfile);
}
\f
/* Delete all insns that were inserted by emit_caller_save_insns during
   this iteration.  */
static void
delete_caller_save_insns ()
{
  struct insn_chain *c = reload_insn_chain;

  while (c != 0)
    {
      while (c != 0 && c->is_caller_save_insn)
        {
          struct insn_chain *next = c->next;
          rtx insn = c->insn;

          if (insn == BLOCK_HEAD (c->block))
            BLOCK_HEAD (c->block) = NEXT_INSN (insn);
          if (insn == BLOCK_END (c->block))
            BLOCK_END (c->block) = PREV_INSN (insn);
          if (c == reload_insn_chain)
            reload_insn_chain = next;

          if (NEXT_INSN (insn) != 0)
            PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn);
          if (PREV_INSN (insn) != 0)
            NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn);

          if (next)
            next->prev = c->prev;
          if (c->prev)
            c->prev->next = next;
          c->next = unused_insn_chains;
          unused_insn_chains = c;
          c = next;
        }
      if (c != 0)
        c = c->next;
    }
}
\f
/* Handle the failure to find a register to spill.
   INSN should be one of the insns which needed this particular spill reg.  */

static void
spill_failure (insn, class)
     rtx insn;
     enum reg_class class;
{
  static const char *const reg_class_names[] = REG_CLASS_NAMES;
  if (asm_noperands (PATTERN (insn)) >= 0)
    error_for_asm (insn, "Can't find a register in class `%s' while reloading `asm'.",
                   reg_class_names[class]);
  else
    {
      error ("Unable to find a register to spill in class `%s'.",
             reg_class_names[class]);
      fatal_insn ("This is the insn:", insn);
    }
}
\f
/* Delete an unneeded INSN and any previous insns who sole purpose is loading
   data that is dead in INSN.  */

static void
delete_dead_insn (insn)
     rtx insn;
{
  rtx prev = prev_real_insn (insn);
  rtx prev_dest;

  /* If the previous insn sets a register that dies in our insn, delete it
     too.  */
  if (prev && GET_CODE (PATTERN (prev)) == SET
      && (prev_dest = SET_DEST (PATTERN (prev)), GET_CODE (prev_dest) == REG)
      && reg_mentioned_p (prev_dest, PATTERN (insn))
      && find_regno_note (insn, REG_DEAD, REGNO (prev_dest))
      && ! side_effects_p (SET_SRC (PATTERN (prev))))
    delete_dead_insn (prev);

  PUT_CODE (insn, NOTE);
  NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
  NOTE_SOURCE_FILE (insn) = 0;
}

/* Modify the home of pseudo-reg I.
   The new home is present in reg_renumber[I].

   FROM_REG may be the hard reg that the pseudo-reg is being spilled from;
   or it may be -1, meaning there is none or it is not relevant.
   This is used so that all pseudos spilled from a given hard reg
   can share one stack slot.  */

static void
alter_reg (i, from_reg)
     register int i;
     int from_reg;
{
  /* When outputting an inline function, this can happen
     for a reg that isn't actually used.  */
  if (regno_reg_rtx[i] == 0)
    return;

  /* If the reg got changed to a MEM at rtl-generation time,
     ignore it.  */
  if (GET_CODE (regno_reg_rtx[i]) != REG)
    return;

  /* Modify the reg-rtx to contain the new hard reg
     number or else to contain its pseudo reg number.  */
  REGNO (regno_reg_rtx[i])
    = reg_renumber[i] >= 0 ? reg_renumber[i] : i;

  /* If we have a pseudo that is needed but has no hard reg or equivalent,
     allocate a stack slot for it.  */

  if (reg_renumber[i] < 0
      && REG_N_REFS (i) > 0
      && reg_equiv_constant[i] == 0
      && reg_equiv_memory_loc[i] == 0)
    {
      register rtx x;
      unsigned int inherent_size = PSEUDO_REGNO_BYTES (i);
      unsigned int total_size = MAX (inherent_size, reg_max_ref_width[i]);
      int adjust = 0;

      /* Each pseudo reg has an inherent size which comes from its own mode,
         and a total size which provides room for paradoxical subregs
         which refer to the pseudo reg in wider modes.

         We can use a slot already allocated if it provides both
         enough inherent space and enough total space.
         Otherwise, we allocate a new slot, making sure that it has no less
         inherent space, and no less total space, then the previous slot.  */
      if (from_reg == -1)
        {
          /* No known place to spill from => no slot to reuse.  */
          x = assign_stack_local (GET_MODE (regno_reg_rtx[i]), total_size,
                                  inherent_size == total_size ? 0 : -1);
          if (BYTES_BIG_ENDIAN)
            /* Cancel the  big-endian correction done in assign_stack_local.
               Get the address of the beginning of the slot.
               This is so we can do a big-endian correction unconditionally
               below.  */
            adjust = inherent_size - total_size;

          RTX_UNCHANGING_P (x) = RTX_UNCHANGING_P (regno_reg_rtx[i]);
        }
      /* Reuse a stack slot if possible.  */
      else if (spill_stack_slot[from_reg] != 0
               && spill_stack_slot_width[from_reg] >= total_size
               && (GET_MODE_SIZE (GET_MODE (spill_stack_slot[from_reg]))
                   >= inherent_size))
        x = spill_stack_slot[from_reg];
      /* Allocate a bigger slot.  */
      else
        {
          /* Compute maximum size needed, both for inherent size
             and for total size.  */
          enum machine_mode mode = GET_MODE (regno_reg_rtx[i]);
          rtx stack_slot;
          if (spill_stack_slot[from_reg])
            {
              if (GET_MODE_SIZE (GET_MODE (spill_stack_slot[from_reg]))
                  > inherent_size)
                mode = GET_MODE (spill_stack_slot[from_reg]);
              if (spill_stack_slot_width[from_reg] > total_size)
                total_size = spill_stack_slot_width[from_reg];
            }
          /* Make a slot with that size.  */
          x = assign_stack_local (mode, total_size,
                                  inherent_size == total_size ? 0 : -1);
          stack_slot = x;
          if (BYTES_BIG_ENDIAN)
            {
              /* Cancel the  big-endian correction done in assign_stack_local.
                 Get the address of the beginning of the slot.
                 This is so we can do a big-endian correction unconditionally
                 below.  */
              adjust = GET_MODE_SIZE (mode) - total_size;
              if (adjust)
                stack_slot = gen_rtx_MEM (mode_for_size (total_size
                                                         * BITS_PER_UNIT,
                                                         MODE_INT, 1),
                                          plus_constant (XEXP (x, 0), adjust));
            }
          spill_stack_slot[from_reg] = stack_slot;
          spill_stack_slot_width[from_reg] = total_size;
        }

      /* On a big endian machine, the "address" of the slot
         is the address of the low part that fits its inherent mode.  */
      if (BYTES_BIG_ENDIAN && inherent_size < total_size)
        adjust += (total_size - inherent_size);

      /* If we have any adjustment to make, or if the stack slot is the
         wrong mode, make a new stack slot.  */
      if (adjust != 0 || GET_MODE (x) != GET_MODE (regno_reg_rtx[i]))
        {
          x = gen_rtx_MEM (GET_MODE (regno_reg_rtx[i]),
                           plus_constant (XEXP (x, 0), adjust));

          /* If this was shared among registers, must ensure we never
             set it readonly since that can cause scheduling
             problems.  Note we would only have in this adjustment
             case in any event, since the code above doesn't set it.  */

          if (from_reg == -1)
            RTX_UNCHANGING_P (x) = RTX_UNCHANGING_P (regno_reg_rtx[i]);
        }

      /* Save the stack slot for later.   */
      reg_equiv_memory_loc[i] = x;
    }
}

/* Mark the slots in regs_ever_live for the hard regs
   used by pseudo-reg number REGNO.  */

void
mark_home_live (regno)
     int regno;
{
  register int i, lim;

  i = reg_renumber[regno];
  if (i < 0)
    return;
  lim = i + HARD_REGNO_NREGS (i, PSEUDO_REGNO_MODE (regno));
  while (i < lim)
    regs_ever_live[i++] = 1;
}
\f
/* This function handles the tracking of elimination offsets around branches.

   X is a piece of RTL being scanned.

   INSN is the insn that it came from, if any.

   INITIAL_P is non-zero if we are to set the offset to be the initial
   offset and zero if we are setting the offset of the label to be the
   current offset.  */

static void
set_label_offsets (x, insn, initial_p)
     rtx x;
     rtx insn;
     int initial_p;
{
  enum rtx_code code = GET_CODE (x);
  rtx tem;
  unsigned int i;
  struct elim_table *p;

  switch (code)
    {
    case LABEL_REF:
      if (LABEL_REF_NONLOCAL_P (x))
        return;

      x = XEXP (x, 0);

      /* ... fall through ...  */

    case CODE_LABEL:
      /* If we know nothing about this label, set the desired offsets.  Note
         that this sets the offset at a label to be the offset before a label
         if we don't know anything about the label.  This is not correct for
         the label after a BARRIER, but is the best guess we can make.  If
         we guessed wrong, we will suppress an elimination that might have
         been possible had we been able to guess correctly.  */

      if (! offsets_known_at[CODE_LABEL_NUMBER (x)])
        {
          for (i = 0; i < NUM_ELIMINABLE_REGS; i++)
            offsets_at[CODE_LABEL_NUMBER (x)][i]
              = (initial_p ? reg_eliminate[i].initial_offset
                 : reg_eliminate[i].offset);
          offsets_known_at[CODE_LABEL_NUMBER (x)] = 1;
        }

      /* Otherwise, if this is the definition of a label and it is
         preceded by a BARRIER, set our offsets to the known offset of
         that label.  */

      else if (x == insn
               && (tem = prev_nonnote_insn (insn)) != 0
               && GET_CODE (tem) == BARRIER)
        set_offsets_for_label (insn);
      else
        /* If neither of the above cases is true, compare each offset
           with those previously recorded and suppress any eliminations
           where the offsets disagree.  */

        for (i = 0; i < NUM_ELIMINABLE_REGS; i++)
          if (offsets_at[CODE_LABEL_NUMBER (x)][i]
              != (initial_p ? reg_eliminate[i].initial_offset
                  : reg_eliminate[i].offset))
            reg_eliminate[i].can_eliminate = 0;

      return;

    case JUMP_INSN:
      set_label_offsets (PATTERN (insn), insn, initial_p);

      /* ... fall through ...  */

    case INSN:
    case CALL_INSN:
      /* Any labels mentioned in REG_LABEL notes can be branched to indirectly
         and hence must have all eliminations at their initial offsets.  */
      for (tem = REG_NOTES (x); tem; tem = XEXP (tem, 1))
        if (REG_NOTE_KIND (tem) == REG_LABEL)
          set_label_offsets (XEXP (tem, 0), insn, 1);
      return;

    case ADDR_VEC:
    case ADDR_DIFF_VEC:
      /* Each of the labels in the address vector must be at their initial
         offsets.  We want the first field for ADDR_VEC and the second
         field for ADDR_DIFF_VEC.  */

      for (i = 0; i < (unsigned) XVECLEN (x, code == ADDR_DIFF_VEC); i++)
        set_label_offsets (XVECEXP (x, code == ADDR_DIFF_VEC, i),
                           insn, initial_p);
      return;

    case SET:
      /* We only care about setting PC.  If the source is not RETURN,
         IF_THEN_ELSE, or a label, disable any eliminations not at
         their initial offsets.  Similarly if any arm of the IF_THEN_ELSE
         isn't one of those possibilities.  For branches to a label,
         call ourselves recursively.

         Note that this can disable elimination unnecessarily when we have
         a non-local goto since it will look like a non-constant jump to
         someplace in the current function.  This isn't a significant
         problem since such jumps will normally be when all elimination
         pairs are back to their initial offsets.  */

      if (SET_DEST (x) != pc_rtx)
        return;

      switch (GET_CODE (SET_SRC (x)))
        {
        case PC:
        case RETURN:
          return;

        case LABEL_REF:
          set_label_offsets (XEXP (SET_SRC (x), 0), insn, initial_p);
          return;

        case IF_THEN_ELSE:
          tem = XEXP (SET_SRC (x), 1);
          if (GET_CODE (tem) == LABEL_REF)
            set_label_offsets (XEXP (tem, 0), insn, initial_p);
          else if (GET_CODE (tem) != PC && GET_CODE (tem) != RETURN)
            break;

          tem = XEXP (SET_SRC (x), 2);
          if (GET_CODE (tem) == LABEL_REF)
            set_label_offsets (XEXP (tem, 0), insn, initial_p);
          else if (GET_CODE (tem) != PC && GET_CODE (tem) != RETURN)
            break;
          return;

        default:
          break;
        }

      /* If we reach here, all eliminations must be at their initial
         offset because we are doing a jump to a variable address.  */
      for (p = reg_eliminate; p < &reg_eliminate[NUM_ELIMINABLE_REGS]; p++)
        if (p->offset != p->initial_offset)
          p->can_eliminate = 0;
      break;

    default:
      break;
    }
}
\f
/* Scan X and replace any eliminable registers (such as fp) with a
   replacement (such as sp), plus an offset.

   MEM_MODE is the mode of an enclosing MEM.  We need this to know how
   much to adjust a register for, e.g., PRE_DEC.  Also, if we are inside a
   MEM, we are allowed to replace a sum of a register and the constant zero
   with the register, which we cannot do outside a MEM.  In addition, we need
   to record the fact that a register is referenced outside a MEM.

   If INSN is an insn, it is the insn containing X.  If we replace a REG
   in a SET_DEST with an equivalent MEM and INSN is non-zero, write a
   CLOBBER of the pseudo after INSN so find_equiv_regs will know that
   the REG is being modified.

   Alternatively, INSN may be a note (an EXPR_LIST or INSN_LIST).
   That's used when we eliminate in expressions stored in notes.
   This means, do not set ref_outside_mem even if the reference
   is outside of MEMs.

   REG_EQUIV_MEM and REG_EQUIV_ADDRESS contain address that have had
   replacements done assuming all offsets are at their initial values.  If
   they are not, or if REG_EQUIV_ADDRESS is nonzero for a pseudo we
   encounter, return the actual location so that find_reloads will do
   the proper thing.  */

rtx
eliminate_regs (x, mem_mode, insn)
     rtx x;
     enum machine_mode mem_mode;
     rtx insn;
{
  enum rtx_code code = GET_CODE (x);
  struct elim_table *ep;
  int regno;
  rtx new;
  int i, j;
  const char *fmt;
  int copied = 0;

  if (! current_function_decl)
    return x;

  switch (code)
    {
    case CONST_INT:
    case CONST_DOUBLE:
    case CONST:
    case SYMBOL_REF:
    case CODE_LABEL:
    case PC:
    case CC0:
    case ASM_INPUT:
    case ADDR_VEC:
    case ADDR_DIFF_VEC:
    case RETURN:
      return x;

    case ADDRESSOF:
      /* This is only for the benefit of the debugging backends, which call
         eliminate_regs on DECL_RTL; any ADDRESSOFs in the actual insns are
         removed after CSE.  */
      new = eliminate_regs (XEXP (x, 0), 0, insn);
      if (GET_CODE (new) == MEM)
        return XEXP (new, 0);
      return x;

    case REG:
      regno = REGNO (x);

      /* First handle the case where we encounter a bare register that
         is eliminable.  Replace it with a PLUS.  */
      if (regno < FIRST_PSEUDO_REGISTER)
        {
          for (ep = reg_eliminate; ep < &reg_eliminate[NUM_ELIMINABLE_REGS];
               ep++)
            if (ep->from_rtx == x && ep->can_eliminate)
              return plus_constant (ep->to_rtx, ep->previous_offset);

        }
      else if (reg_renumber[regno] < 0 && reg_equiv_constant
               && reg_equiv_constant[regno]
               && ! CONSTANT_P (reg_equiv_constant[regno]))
        return eliminate_regs (copy_rtx (reg_equiv_constant[regno]),
                               mem_mode, insn);
      return x;

    /* You might think handling MINUS in a manner similar to PLUS is a
       good idea.  It is not.  It has been tried multiple times and every
       time the change has had to have been reverted.

       Other parts of reload know a PLUS is special (gen_reload for example)
       and require special code to handle code a reloaded PLUS operand.

       Also consider backends where the flags register is clobbered by a
       MINUS, but we can emit a PLUS that does not clobber flags (ia32,
       lea instruction comes to mind).  If we try to reload a MINUS, we
       may kill the flags register that was holding a useful value.

       So, please before trying to handle MINUS, consider reload as a
       whole instead of this little section as well as the backend issues.  */
    case PLUS:
      /* If this is the sum of an eliminable register and a constant, rework
         the sum.   */
      if (GET_CODE (XEXP (x, 0)) == REG
          && REGNO (XEXP (x, 0)) < FIRST_PSEUDO_REGISTER
          && CONSTANT_P (XEXP (x, 1)))
        {
          for (ep = reg_eliminate; ep < &reg_eliminate[NUM_ELIMINABLE_REGS];
               ep++)
            if (ep->from_rtx == XEXP (x, 0) && ep->can_eliminate)
              {
                /* The only time we want to replace a PLUS with a REG (this
                   occurs when the constant operand of the PLUS is the negative
                   of the offset) is when we are inside a MEM.  We won't want
                   to do so at other times because that would change the
                   structure of the insn in a way that reload can't handle.
                   We special-case the commonest situation in
                   eliminate_regs_in_insn, so just replace a PLUS with a
                   PLUS here, unless inside a MEM.  */
                if (mem_mode != 0 && GET_CODE (XEXP (x, 1)) == CONST_INT
                    && INTVAL (XEXP (x, 1)) == - ep->previous_offset)
                  return ep->to_rtx;
                else
                  return gen_rtx_PLUS (Pmode, ep->to_rtx,
                                       plus_constant (XEXP (x, 1),
                                                      ep->previous_offset));
              }

          /* If the register is not eliminable, we are done since the other
             operand is a constant.  */
          return x;
        }

      /* If this is part of an address, we want to bring any constant to the
         outermost PLUS.  We will do this by doing register replacement in
         our operands and seeing if a constant shows up in one of them.

         Note that there is no risk of modifying the structure of the insn,
         since we only get called for its operands, thus we are either
         modifying the address inside a MEM, or something like an address
         operand of a load-address insn.  */

      {
        rtx new0 = eliminate_regs (XEXP (x, 0), mem_mode, insn);
        rtx new1 = eliminate_regs (XEXP (x, 1), mem_mode, insn);

        if (new0 != XEXP (x, 0) || new1 != XEXP (x, 1))
          {
            /* If one side is a PLUS and the other side is a pseudo that
               didn't get a hard register but has a reg_equiv_constant,
               we must replace the constant here since it may no longer
               be in the position of any operand.  */
            if (GET_CODE (new0) == PLUS && GET_CODE (new1) == REG
                && REGNO (new1) >= FIRST_PSEUDO_REGISTER
                && reg_renumber[REGNO (new1)] < 0
                && reg_equiv_constant != 0
                && reg_equiv_constant[REGNO (new1)] != 0)
              new1 = reg_equiv_constant[REGNO (new1)];
            else if (GET_CODE (new1) == PLUS && GET_CODE (new0) == REG
                     && REGNO (new0) >= FIRST_PSEUDO_REGISTER
                     && reg_renumber[REGNO (new0)] < 0
                     && reg_equiv_constant[REGNO (new0)] != 0)
              new0 = reg_equiv_constant[REGNO (new0)];

            new = form_sum (new0, new1);

            /* As above, if we are not inside a MEM we do not want to
               turn a PLUS into something else.  We might try to do so here
               for an addition of 0 if we aren't optimizing.  */
            if (! mem_mode && GET_CODE (new) != PLUS)
              return gen_rtx_PLUS (GET_MODE (x), new, const0_rtx);
            else
              return new;
          }
      }
      return x;

    case MULT:
      /* If this is the product of an eliminable register and a
         constant, apply the distribute law and move the constant out
         so that we have (plus (mult ..) ..).  This is needed in order
         to keep load-address insns valid.   This case is pathological.
         We ignore the possibility of overflow here.  */
      if (GET_CODE (XEXP (x, 0)) == REG
          && REGNO (XEXP (x, 0)) < FIRST_PSEUDO_REGISTER
          && GET_CODE (XEXP (x, 1)) == CONST_INT)
        for (ep = reg_eliminate; ep < &reg_eliminate[NUM_ELIMINABLE_REGS];
             ep++)
          if (ep->from_rtx == XEXP (x, 0) && ep->can_eliminate)
            {
              if (! mem_mode
                  /* Refs inside notes don't count for this purpose.  */
                  && ! (insn != 0 && (GET_CODE (insn) == EXPR_LIST
                                      || GET_CODE (insn) == INSN_LIST)))
                ep->ref_outside_mem = 1;

              return
                plus_constant (gen_rtx_MULT (Pmode, ep->to_rtx, XEXP (x, 1)),
                               ep->previous_offset * INTVAL (XEXP (x, 1)));
            }

      /* ... fall through ...  */

    case CALL:
    case COMPARE:
    /* See comments before PLUS about handling MINUS.  */
    case MINUS:
    case DIV:      case UDIV:
    case MOD:      case UMOD:
    case AND:      case IOR:      case XOR:
    case ROTATERT: case ROTATE:
    case ASHIFTRT: case LSHIFTRT: case ASHIFT:
    case NE:       case EQ:
    case GE:       case GT:       case GEU:    case GTU:
    case LE:       case LT:       case LEU:    case LTU:
      {
        rtx new0 = eliminate_regs (XEXP (x, 0), mem_mode, insn);
        rtx new1
          = XEXP (x, 1) ? eliminate_regs (XEXP (x, 1), mem_mode, insn) : 0;

        if (new0 != XEXP (x, 0) || new1 != XEXP (x, 1))
          return gen_rtx_fmt_ee (code, GET_MODE (x), new0, new1);
      }
      return x;

    case EXPR_LIST:
      /* If we have something in XEXP (x, 0), the usual case, eliminate it.  */
      if (XEXP (x, 0))
        {
          new = eliminate_regs (XEXP (x, 0), mem_mode, insn);
          if (new != XEXP (x, 0))
            {
              /* If this is a REG_DEAD note, it is not valid anymore.
                 Using the eliminated version could result in creating a
                 REG_DEAD note for the stack or frame pointer.  */
              if (GET_MODE (x) == REG_DEAD)
                return (XEXP (x, 1)
                        ? eliminate_regs (XEXP (x, 1), mem_mode, insn)
                        : NULL_RTX);

              x = gen_rtx_EXPR_LIST (REG_NOTE_KIND (x), new, XEXP (x, 1));
            }
        }

      /* ... fall through ...  */

    case INSN_LIST:
      /* Now do eliminations in the rest of the chain.  If this was
         an EXPR_LIST, this might result in allocating more memory than is
         strictly needed, but it simplifies the code.  */
      if (XEXP (x, 1))
        {
          new = eliminate_regs (XEXP (x, 1), mem_mode, insn);
          if (new != XEXP (x, 1))
            return gen_rtx_fmt_ee (GET_CODE (x), GET_MODE (x), XEXP (x, 0), new);
        }
      return x;

    case PRE_INC:
    case POST_INC:
    case PRE_DEC:
    case POST_DEC:
    case STRICT_LOW_PART:
    case NEG:          case NOT:
    case SIGN_EXTEND:  case ZERO_EXTEND:
    case TRUNCATE:     case FLOAT_EXTEND: case FLOAT_TRUNCATE:
    case FLOAT:        case FIX:
    case UNSIGNED_FIX: case UNSIGNED_FLOAT:
    case ABS:
    case SQRT:
    case FFS:
      new = eliminate_regs (XEXP (x, 0), mem_mode, insn);
      if (new != XEXP (x, 0))
        return gen_rtx_fmt_e (code, GET_MODE (x), new);
      return x;

    case SUBREG:
      /* Similar to above processing, but preserve SUBREG_WORD.
         Convert (subreg (mem)) to (mem) if not paradoxical.
         Also, if we have a non-paradoxical (subreg (pseudo)) and the
         pseudo didn't get a hard reg, we must replace this with the
         eliminated version of the memory location because push_reloads
         may do the replacement in certain circumstances.  */
      if (GET_CODE (SUBREG_REG (x)) == REG
          && (GET_MODE_SIZE (GET_MODE (x))
              <= GET_MODE_SIZE (GET_MODE (SUBREG_REG (x))))
          && reg_equiv_memory_loc != 0
          && reg_equiv_memory_loc[REGNO (SUBREG_REG (x))] != 0)
        {
          new = SUBREG_REG (x);
        }
      else
        new = eliminate_regs (SUBREG_REG (x), mem_mode, insn);

      if (new != XEXP (x, 0))
        {
          int x_size = GET_MODE_SIZE (GET_MODE (x));
          int new_size = GET_MODE_SIZE (GET_MODE (new));

          if (GET_CODE (new) == MEM
              && ((x_size < new_size
#ifdef WORD_REGISTER_OPERATIONS
                   /* On these machines, combine can create rtl of the form
                      (set (subreg:m1 (reg:m2 R) 0) ...)
                      where m1 < m2, and expects something interesting to
                      happen to the entire word.  Moreover, it will use the
                      (reg:m2 R) later, expecting all bits to be preserved.
                      So if the number of words is the same, preserve the
                      subreg so that push_reloads can see it.  */
                   && ! ((x_size-1)/UNITS_PER_WORD == (new_size-1)/UNITS_PER_WORD)
#endif
                   )
                  || (x_size == new_size))
              )
            {
              int offset = SUBREG_WORD (x) * UNITS_PER_WORD;
              enum machine_mode mode = GET_MODE (x);

              if (BYTES_BIG_ENDIAN)
                offset += (MIN (UNITS_PER_WORD,
                                GET_MODE_SIZE (GET_MODE (new)))
                           - MIN (UNITS_PER_WORD, GET_MODE_SIZE (mode)));

              PUT_MODE (new, mode);
              XEXP (new, 0) = plus_constant (XEXP (new, 0), offset);
              return new;
            }
          else
            return gen_rtx_SUBREG (GET_MODE (x), new, SUBREG_WORD (x));
        }

      return x;

    case MEM:
      /* This is only for the benefit of the debugging backends, which call
         eliminate_regs on DECL_RTL; any ADDRESSOFs in the actual insns are
         removed after CSE.  */
      if (GET_CODE (XEXP (x, 0)) == ADDRESSOF)
        return eliminate_regs (XEXP (XEXP (x, 0), 0), 0, insn);

      /* Our only special processing is to pass the mode of the MEM to our
         recursive call and copy the flags.  While we are here, handle this
         case more efficiently.  */
      new = eliminate_regs (XEXP (x, 0), GET_MODE (x), insn);
      if (new != XEXP (x, 0))
        {
          new = gen_rtx_MEM (GET_MODE (x), new);
          new->volatil = x->volatil;
          new->unchanging = x->unchanging;
          new->in_struct = x->in_struct;
          return new;
        }
      else
        return x;

    case USE:
    case CLOBBER:
    case ASM_OPERANDS:
    case SET:
      abort ();

    default:
      break;
    }

  /* Process each of our operands recursively.  If any have changed, make a
     copy of the rtx.  */
  fmt = GET_RTX_FORMAT (code);
  for (i = 0; i < GET_RTX_LENGTH (code); i++, fmt++)
    {
      if (*fmt == 'e')
        {
          new = eliminate_regs (XEXP (x, i), mem_mode, insn);
          if (new != XEXP (x, i) && ! copied)
            {
              rtx new_x = rtx_alloc (code);
              bcopy ((char *) x, (char *) new_x,
                     (sizeof (*new_x) - sizeof (new_x->fld)
                      + sizeof (new_x->fld[0]) * GET_RTX_LENGTH (code)));
              x = new_x;
              copied = 1;
            }
          XEXP (x, i) = new;
        }
      else if (*fmt == 'E')
        {
          int copied_vec = 0;
          for (j = 0; j < XVECLEN (x, i); j++)
            {
              new = eliminate_regs (XVECEXP (x, i, j), mem_mode, insn);
              if (new != XVECEXP (x, i, j) && ! copied_vec)
                {
                  rtvec new_v = gen_rtvec_v (XVECLEN (x, i),
                                             XVEC (x, i)->elem);
                  if (! copied)
                    {
                      rtx new_x = rtx_alloc (code);
                      bcopy ((char *) x, (char *) new_x,
                             (sizeof (*new_x) - sizeof (new_x->fld)
                              + (sizeof (new_x->fld[0])
                                 * GET_RTX_LENGTH (code))));
                      x = new_x;
                      copied = 1;
                    }
                  XVEC (x, i) = new_v;
                  copied_vec = 1;
                }
              XVECEXP (x, i, j) = new;
            }
        }
    }

  return x;
}

/* Scan rtx X for modifications of elimination target registers.  Update
   the table of eliminables to reflect the changed state.  MEM_MODE is
   the mode of an enclosing MEM rtx, or VOIDmode if not within a MEM.  */

static void
elimination_effects (x, mem_mode)
     rtx x;
     enum machine_mode mem_mode;

{
  enum rtx_code code = GET_CODE (x);
  struct elim_table *ep;
  int regno;
  int i, j;
  const char *fmt;

  switch (code)
    {
    case CONST_INT:
    case CONST_DOUBLE:
    case CONST:
    case SYMBOL_REF:
    case CODE_LABEL:
    case PC:
    case CC0:
    case ASM_INPUT:
    case ADDR_VEC:
    case ADDR_DIFF_VEC:
    case RETURN:
      return;

    case ADDRESSOF:
      abort ();

    case REG:
      regno = REGNO (x);

      /* First handle the case where we encounter a bare register that
         is eliminable.  Replace it with a PLUS.  */
      if (regno < FIRST_PSEUDO_REGISTER)
        {
          for (ep = reg_eliminate; ep < &reg_eliminate[NUM_ELIMINABLE_REGS];
               ep++)
            if (ep->from_rtx == x && ep->can_eliminate)
              {
                if (! mem_mode)
                  ep->ref_outside_mem = 1;
                return;
              }

        }
      else if (reg_renumber[regno] < 0 && reg_equiv_constant
               && reg_equiv_constant[regno]
               && ! CONSTANT_P (reg_equiv_constant[regno]))
        elimination_effects (reg_equiv_constant[regno], mem_mode);
      return;

    case PRE_INC:
    case POST_INC:
    case PRE_DEC:
    case POST_DEC:
      for (ep = reg_eliminate; ep < &reg_eliminate[NUM_ELIMINABLE_REGS]; ep++)
        if (ep->to_rtx == XEXP (x, 0))
          {
            int size = GET_MODE_SIZE (mem_mode);

            /* If more bytes than MEM_MODE are pushed, account for them.  */
#ifdef PUSH_ROUNDING
            if (ep->to_rtx == stack_pointer_rtx)
              size = PUSH_ROUNDING (size);
#endif
            if (code == PRE_DEC || code == POST_DEC)
              ep->offset += size;
            else
              ep->offset -= size;
          }

      /* Fall through to generic unary operation case.  */
    case STRICT_LOW_PART:
    case NEG:          case NOT:
    case SIGN_EXTEND:  case ZERO_EXTEND:
    case TRUNCATE:     case FLOAT_EXTEND: case FLOAT_TRUNCATE:
    case FLOAT:        case FIX:
    case UNSIGNED_FIX: case UNSIGNED_FLOAT:
    case ABS:
    case SQRT:
    case FFS:
      elimination_effects (XEXP (x, 0), mem_mode);
      return;

    case SUBREG:
      if (GET_CODE (SUBREG_REG (x)) == REG
          && (GET_MODE_SIZE (GET_MODE (x))
              <= GET_MODE_SIZE (GET_MODE (SUBREG_REG (x))))
          && reg_equiv_memory_loc != 0
          && reg_equiv_memory_loc[REGNO (SUBREG_REG (x))] != 0)
        return;

      elimination_effects (SUBREG_REG (x), mem_mode);
      return;

    case USE:
      /* If using a register that is the source of an eliminate we still
         think can be performed, note it cannot be performed since we don't
         know how this register is used.  */
      for (ep = reg_eliminate; ep < &reg_eliminate[NUM_ELIMINABLE_REGS]; ep++)
        if (ep->from_rtx == XEXP (x, 0))
          ep->can_eliminate = 0;

      elimination_effects (XEXP (x, 0), mem_mode);
      return;

    case CLOBBER:
      /* If clobbering a register that is the replacement register for an
         elimination we still think can be performed, note that it cannot
         be performed.  Otherwise, we need not be concerned about it.  */
      for (ep = reg_eliminate; ep < &reg_eliminate[NUM_ELIMINABLE_REGS]; ep++)
        if (ep->to_rtx == XEXP (x, 0))
          ep->can_eliminate = 0;

      elimination_effects (XEXP (x, 0), mem_mode);
      return;

    case SET:
      /* Check for setting a register that we know about.  */
      if (GET_CODE (SET_DEST (x)) == REG)
        {
          /* See if this is setting the replacement register for an
             elimination.

             If DEST is the hard frame pointer, we do nothing because we
             assume that all assignments to the frame pointer are for
             non-local gotos and are being done at a time when they are valid
             and do not disturb anything else.  Some machines want to
             eliminate a fake argument pointer (or even a fake frame pointer)
             with either the real frame or the stack pointer.  Assignments to
             the hard frame pointer must not prevent this elimination.  */

          for (ep = reg_eliminate; ep < &reg_eliminate[NUM_ELIMINABLE_REGS];
               ep++)
            if (ep->to_rtx == SET_DEST (x)
                && SET_DEST (x) != hard_frame_pointer_rtx)
              {
                /* If it is being incremented, adjust the offset.  Otherwise,
                   this elimination can't be done.  */
                rtx src = SET_SRC (x);

                if (GET_CODE (src) == PLUS
                    && XEXP (src, 0) == SET_DEST (x)
                    && GET_CODE (XEXP (src, 1)) == CONST_INT)
                  ep->offset -= INTVAL (XEXP (src, 1));
                else
                  ep->can_eliminate = 0;
              }
        }

      elimination_effects (SET_DEST (x), 0);
      elimination_effects (SET_SRC (x), 0);
      return;

    case MEM:
      if (GET_CODE (XEXP (x, 0)) == ADDRESSOF)
        abort ();

      /* Our only special processing is to pass the mode of the MEM to our
         recursive call.  */
      elimination_effects (XEXP (x, 0), GET_MODE (x));
      return;

    default:
      break;
    }

  fmt = GET_RTX_FORMAT (code);
  for (i = 0; i < GET_RTX_LENGTH (code); i++, fmt++)
    {
      if (*fmt == 'e')
        elimination_effects (XEXP (x, i), mem_mode);
      else if (*fmt == 'E')
        for (j = 0; j < XVECLEN (x, i); j++)
          elimination_effects (XVECEXP (x, i, j), mem_mode);
    }
}

/* Descend through rtx X and verify that no references to eliminable registers
   remain.  If any do remain, mark the involved register as not
   eliminable.  */

static void
check_eliminable_occurrences (x)
     rtx x;
{
  const char *fmt;
  int i;
  enum rtx_code code;

  if (x == 0)
    return;
  
  code = GET_CODE (x);

  if (code == REG && REGNO (x) < FIRST_PSEUDO_REGISTER)
    {
      struct elim_table *ep;

      for (ep = reg_eliminate; ep < &reg_eliminate[NUM_ELIMINABLE_REGS]; ep++)
        if (ep->from_rtx == x && ep->can_eliminate)
          ep->can_eliminate = 0;
      return;
    }
  
  fmt = GET_RTX_FORMAT (code);
  for (i = 0; i < GET_RTX_LENGTH (code); i++, fmt++)
    {
      if (*fmt == 'e')
        check_eliminable_occurrences (XEXP (x, i));
      else if (*fmt == 'E')
        {
          int j;
          for (j = 0; j < XVECLEN (x, i); j++)
            check_eliminable_occurrences (XVECEXP (x, i, j));
        }
    }
}
\f
/* Scan INSN and eliminate all eliminable registers in it.

   If REPLACE is nonzero, do the replacement destructively.  Also
   delete the insn as dead it if it is setting an eliminable register.

   If REPLACE is zero, do all our allocations in reload_obstack.

   If no eliminations were done and this insn doesn't require any elimination
   processing (these are not identical conditions: it might be updating sp,
   but not referencing fp; this needs to be seen during reload_as_needed so
   that the offset between fp and sp can be taken into consideration), zero
   is returned.  Otherwise, 1 is returned.  */

static int
eliminate_regs_in_insn (insn, replace)
     rtx insn;
     int replace;
{
  int icode = recog_memoized (insn);
  rtx old_body = PATTERN (insn);
  int insn_is_asm = asm_noperands (old_body) >= 0;
  rtx old_set = single_set (insn);
  rtx new_body;
  int val = 0;
  int i, any_changes;
  rtx substed_operand[MAX_RECOG_OPERANDS];
  rtx orig_operand[MAX_RECOG_OPERANDS];
  struct elim_table *ep;

  if (! insn_is_asm && icode < 0)
    {
      if (GET_CODE (PATTERN (insn)) == USE
          || GET_CODE (PATTERN (insn)) == CLOBBER
          || GET_CODE (PATTERN (insn)) == ADDR_VEC
          || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC
          || GET_CODE (PATTERN (insn)) == ASM_INPUT)
        return 0;
      abort ();
    }

  if (! replace)
    push_obstacks (&reload_obstack, &reload_obstack);

  if (old_set != 0 && GET_CODE (SET_DEST (old_set)) == REG
      && REGNO (SET_DEST (old_set)) < FIRST_PSEUDO_REGISTER)
    {
      /* Check for setting an eliminable register.  */
      for (ep = reg_eliminate; ep < &reg_eliminate[NUM_ELIMINABLE_REGS]; ep++)
        if (ep->from_rtx == SET_DEST (old_set) && ep->can_eliminate)
          {
#if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM
            /* If this is setting the frame pointer register to the
               hardware frame pointer register and this is an elimination
               that will be done (tested above), this insn is really
               adjusting the frame pointer downward to compensate for
               the adjustment done before a nonlocal goto.  */
            if (ep->from == FRAME_POINTER_REGNUM
                && ep->to == HARD_FRAME_POINTER_REGNUM)
              {
                rtx src = SET_SRC (old_set);
                int offset = 0, ok = 0;
                rtx prev_insn, prev_set;

                if (src == ep->to_rtx)
                  offset = 0, ok = 1;
                else if (GET_CODE (src) == PLUS
                         && GET_CODE (XEXP (src, 0)) == CONST_INT
                         && XEXP (src, 1) == ep->to_rtx)
                  offset = INTVAL (XEXP (src, 0)), ok = 1;
                else if (GET_CODE (src) == PLUS
                         && GET_CODE (XEXP (src, 1)) == CONST_INT
                         && XEXP (src, 0) == ep->to_rtx)
                  offset = INTVAL (XEXP (src, 1)), ok = 1;
                else if ((prev_insn = prev_nonnote_insn (insn)) != 0
                         && (prev_set = single_set (prev_insn)) != 0
                         && rtx_equal_p (SET_DEST (prev_set), src))
                  {
                    src = SET_SRC (prev_set);
                    if (src == ep->to_rtx)
                      offset = 0, ok = 1;
                    else if (GET_CODE (src) == PLUS
                             && GET_CODE (XEXP (src, 0)) == CONST_INT
                             && XEXP (src, 1) == ep->to_rtx)
                      offset = INTVAL (XEXP (src, 0)), ok = 1;
                    else if (GET_CODE (src) == PLUS
                             && GET_CODE (XEXP (src, 1)) == CONST_INT
                             && XEXP (src, 0) == ep->to_rtx)
                      offset = INTVAL (XEXP (src, 1)), ok = 1;
                  }

                if (ok)
                  {
                    if (replace)
                      {
                        rtx src
                          = plus_constant (ep->to_rtx, offset - ep->offset);

                        /* First see if this insn remains valid when we
                           make the change.  If not, keep the INSN_CODE
                           the same and let reload fit it up.  */
                        validate_change (insn, &SET_SRC (old_set), src, 1);
                        validate_change (insn, &SET_DEST (old_set),
                                         ep->to_rtx, 1);
                        if (! apply_change_group ())
                          {
                            SET_SRC (old_set) = src;
                            SET_DEST (old_set) = ep->to_rtx;
                          }
                      }

                    val = 1;
                    goto done;
                  }
              }
#endif

            /* In this case this insn isn't serving a useful purpose.  We
               will delete it in reload_as_needed once we know that this
               elimination is, in fact, being done.

               If REPLACE isn't set, we can't delete this insn, but needn't
               process it since it won't be used unless something changes.  */
            if (replace)
              {
                delete_dead_insn (insn);
                return 1;
              }
            val = 1;
            goto done;
          }
    }

  /* We allow one special case which happens to work on all machines we
     currently support: a single set with the source being a PLUS of an
     eliminable register and a constant.  */
  if (old_set
      && GET_CODE (SET_SRC (old_set)) == PLUS
      && GET_CODE (XEXP (SET_SRC (old_set), 0)) == REG
      && GET_CODE (XEXP (SET_SRC (old_set), 1)) == CONST_INT
      && REGNO (XEXP (SET_SRC (old_set), 0)) < FIRST_PSEUDO_REGISTER)
    {
      rtx reg = XEXP (SET_SRC (old_set), 0);
      int offset = INTVAL (XEXP (SET_SRC (old_set), 1));

      for (ep = reg_eliminate; ep < &reg_eliminate[NUM_ELIMINABLE_REGS]; ep++)
        if (ep->from_rtx == reg && ep->can_eliminate)
          {
            offset += ep->offset;

            if (offset == 0)
              {
                /* We assume here that we don't need a PARALLEL of
                   any CLOBBERs for this assignment.  There's not
                   much we can do if we do need it.  */
                PATTERN (insn) = gen_rtx_SET (VOIDmode,
                                              SET_DEST (old_set),
                                              ep->to_rtx);
                INSN_CODE (insn) = recog (PATTERN (insn), insn, 0);
                if (INSN_CODE (insn) < 0)
                  abort ();
              }
            else
              {
                new_body = old_body;
                if (! replace)
                  {
                    new_body = copy_insn (old_body);
                    if (REG_NOTES (insn))
                      REG_NOTES (insn) = copy_insn_1 (REG_NOTES (insn));
                  }
                PATTERN (insn) = new_body;
                old_set = single_set (insn);

                XEXP (SET_SRC (old_set), 0) = ep->to_rtx;
                XEXP (SET_SRC (old_set), 1) = GEN_INT (offset);
              }
            val = 1;
            /* This can't have an effect on elimination offsets, so skip right
               to the end.  */
            goto done;
          }
    }

  /* Determine the effects of this insn on elimination offsets.  */
  elimination_effects (old_body, 0);

  /* Eliminate all eliminable registers occurring in operands that
     can be handled by reload.  */
  extract_insn (insn);
  any_changes = 0;
  for (i = 0; i < recog_data.n_operands; i++)
    {
      orig_operand[i] = recog_data.operand[i];
      substed_operand[i] = recog_data.operand[i];

      /* For an asm statement, every operand is eliminable.  */
      if (insn_is_asm || insn_data[icode].operand[i].eliminable)
        {
          /* Check for setting a register that we know about.  */
          if (recog_data.operand_type[i] != OP_IN
              && GET_CODE (orig_operand[i]) == REG)
            {
              /* If we are assigning to a register that can be eliminated, it
                 must be as part of a PARALLEL, since the code above handles
                 single SETs.  We must indicate that we can no longer
                 eliminate this reg.  */
              for (ep = reg_eliminate; ep < &reg_eliminate[NUM_ELIMINABLE_REGS];
                   ep++)
                if (ep->from_rtx == orig_operand[i] && ep->can_eliminate)
                  ep->can_eliminate = 0;
            }

          substed_operand[i] = eliminate_regs (recog_data.operand[i], 0,
                                               replace ? insn : NULL_RTX);
          if (substed_operand[i] != orig_operand[i])
            val = any_changes = 1;
          /* Terminate the search in check_eliminable_occurrences at
             this point.  */
          *recog_data.operand_loc[i] = 0;

        /* If an output operand changed from a REG to a MEM and INSN is an
           insn, write a CLOBBER insn.  */
          if (recog_data.operand_type[i] != OP_IN
              && GET_CODE (orig_operand[i]) == REG
              && GET_CODE (substed_operand[i]) == MEM
              && replace)
            emit_insn_after (gen_rtx_CLOBBER (VOIDmode, orig_operand[i]),
                             insn);
        }
    }

  for (i = 0; i < recog_data.n_dups; i++)
    *recog_data.dup_loc[i]
      = *recog_data.operand_loc[(int)recog_data.dup_num[i]];

  /* If any eliminable remain, they aren't eliminable anymore.  */
  check_eliminable_occurrences (old_body);

  /* Substitute the operands; the new values are in the substed_operand
     array.  */
  for (i = 0; i < recog_data.n_operands; i++)
    *recog_data.operand_loc[i] = substed_operand[i];
  for (i = 0; i < recog_data.n_dups; i++)
    *recog_data.dup_loc[i] = substed_operand[(int)recog_data.dup_num[i]];

  /* If we are replacing a body that was a (set X (plus Y Z)), try to
     re-recognize the insn.  We do this in case we had a simple addition
     but now can do this as a load-address.  This saves an insn in this
     common case.
     If re-recognition fails, the old insn code number will still be used,
     and some register operands may have changed into PLUS expressions.
     These will be handled by find_reloads by loading them into a register
     again.*/

  if (val)
    {
      /* If we aren't replacing things permanently and we changed something,
         make another copy to ensure that all the RTL is new.  Otherwise
         things can go wrong if find_reload swaps commutative operands
         and one is inside RTL that has been copied while the other is not.  */
      new_body = old_body;
      if (! replace)
        {
          new_body = copy_insn (old_body);
          if (REG_NOTES (insn))
            REG_NOTES (insn) = copy_insn_1 (REG_NOTES (insn));
        }
      PATTERN (insn) = new_body;

      /* If we had a move insn but now we don't, rerecognize it.  This will
         cause spurious re-recognition if the old move had a PARALLEL since
         the new one still will, but we can't call single_set without
         having put NEW_BODY into the insn and the re-recognition won't
         hurt in this rare case.  */
      /* ??? Why this huge if statement - why don't we just rerecognize the
         thing always?  */
      if (! insn_is_asm
          && old_set != 0
          && ((GET_CODE (SET_SRC (old_set)) == REG
               && (GET_CODE (new_body) != SET
                   || GET_CODE (SET_SRC (new_body)) != REG))
              /* If this was a load from or store to memory, compare
                 the MEM in recog_data.operand to the one in the insn.
                 If they are not equal, then rerecognize the insn.  */
              || (old_set != 0
                  && ((GET_CODE (SET_SRC (old_set)) == MEM
                       && SET_SRC (old_set) != recog_data.operand[1])
                      || (GET_CODE (SET_DEST (old_set)) == MEM
                          && SET_DEST (old_set) != recog_data.operand[0])))
              /* If this was an add insn before, rerecognize.  */
              || GET_CODE (SET_SRC (old_set)) == PLUS))
        {
          int new_icode = recog (PATTERN (insn), insn, 0);
          if (new_icode < 0)
            INSN_CODE (insn) = icode;
        }
    }

  /* Restore the old body.  If there were any changes to it, we made a copy
     of it while the changes were still in place, so we'll correctly return
     a modified insn below.  */
  if (! replace)
    {
      /* Restore the old body.  */
      for (i = 0; i < recog_data.n_operands; i++)
        *recog_data.operand_loc[i] = orig_operand[i];
      for (i = 0; i < recog_data.n_dups; i++)
        *recog_data.dup_loc[i] = orig_operand[(int)recog_data.dup_num[i]];
    }

  /* Update all elimination pairs to reflect the status after the current
     insn.  The changes we make were determined by the earlier call to
     elimination_effects.

     We also detect a cases where register elimination cannot be done,
     namely, if a register would be both changed and referenced outside a MEM
     in the resulting insn since such an insn is often undefined and, even if
     not, we cannot know what meaning will be given to it.  Note that it is
     valid to have a register used in an address in an insn that changes it
     (presumably with a pre- or post-increment or decrement).

     If anything changes, return nonzero.  */

  for (ep = reg_eliminate; ep < &reg_eliminate[NUM_ELIMINABLE_REGS]; ep++)
    {
      if (ep->previous_offset != ep->offset && ep->ref_outside_mem)
        ep->can_eliminate = 0;

      ep->ref_outside_mem = 0;

      if (ep->previous_offset != ep->offset)
        val = 1;
    }

 done:
  /* If we changed something, perform elimination in REG_NOTES.  This is
     needed even when REPLACE is zero because a REG_DEAD note might refer
     to a register that we eliminate and could cause a different number
     of spill registers to be needed in the final reload pass than in
     the pre-passes.  */
  if (val && REG_NOTES (insn) != 0)
    REG_NOTES (insn) = eliminate_regs (REG_NOTES (insn), 0, REG_NOTES (insn));

  if (! replace)
    pop_obstacks ();

  return val;
}

/* Loop through all elimination pairs.
   Recalculate the number not at initial offset.

   Compute the maximum offset (minimum offset if the stack does not
   grow downward) for each elimination pair.  */

static void
update_eliminable_offsets ()
{
  struct elim_table *ep;

  num_not_at_initial_offset = 0;
  for (ep = reg_eliminate; ep < &reg_eliminate[NUM_ELIMINABLE_REGS]; ep++)
    {
      ep->previous_offset = ep->offset;
      if (ep->can_eliminate && ep->offset != ep->initial_offset)
        num_not_at_initial_offset++;
    }
}

/* Given X, a SET or CLOBBER of DEST, if DEST is the target of a register
   replacement we currently believe is valid, mark it as not eliminable if X
   modifies DEST in any way other than by adding a constant integer to it.

   If DEST is the frame pointer, we do nothing because we assume that
   all assignments to the hard frame pointer are nonlocal gotos and are being
   done at a time when they are valid and do not disturb anything else.
   Some machines want to eliminate a fake argument pointer with either the
   frame or stack pointer.  Assignments to the hard frame pointer must not
   prevent this elimination.

   Called via note_stores from reload before starting its passes to scan
   the insns of the function.  */

static void
mark_not_eliminable (dest, x, data)
     rtx dest;
     rtx x;
     void *data ATTRIBUTE_UNUSED;
{
  register unsigned int i;

  /* A SUBREG of a hard register here is just changing its mode.  We should
     not see a SUBREG of an eliminable hard register, but check just in
     case.  */
  if (GET_CODE (dest) == SUBREG)
    dest = SUBREG_REG (dest);

  if (dest == hard_frame_pointer_rtx)
    return;

  for (i = 0; i < NUM_ELIMINABLE_REGS; i++)
    if (reg_eliminate[i].can_eliminate && dest == reg_eliminate[i].to_rtx
        && (GET_CODE (x) != SET
            || GET_CODE (SET_SRC (x)) != PLUS
            || XEXP (SET_SRC (x), 0) != dest
            || GET_CODE (XEXP (SET_SRC (x), 1)) != CONST_INT))
      {
        reg_eliminate[i].can_eliminate_previous
          = reg_eliminate[i].can_eliminate = 0;
        num_eliminable--;
      }
}

/* Verify that the initial elimination offsets did not change since the
   last call to set_initial_elim_offsets.  This is used to catch cases
   where something illegal happened during reload_as_needed that could
   cause incorrect code to be generated if we did not check for it.  */

static void
verify_initial_elim_offsets ()
{
  int t;

#ifdef ELIMINABLE_REGS
  struct elim_table *ep;

  for (ep = reg_eliminate; ep < &reg_eliminate[NUM_ELIMINABLE_REGS]; ep++)
    {
      INITIAL_ELIMINATION_OFFSET (ep->from, ep->to, t);
      if (t != ep->initial_offset)
        abort ();
    }
#else
  INITIAL_FRAME_POINTER_OFFSET (t);
  if (t != reg_eliminate[0].initial_offset)
    abort ();
#endif
}

/* Reset all offsets on eliminable registers to their initial values.  */

static void
set_initial_elim_offsets ()
{
  struct elim_table *ep = reg_eliminate;

#ifdef ELIMINABLE_REGS
  for (; ep < &reg_eliminate[NUM_ELIMINABLE_REGS]; ep++)
    {
      INITIAL_ELIMINATION_OFFSET (ep->from, ep->to, ep->initial_offset);
      ep->previous_offset = ep->offset = ep->initial_offset;
    }
#else
  INITIAL_FRAME_POINTER_OFFSET (ep->initial_offset);
  ep->previous_offset = ep->offset = ep->initial_offset;
#endif

  num_not_at_initial_offset = 0;
}

/* Initialize the known label offsets.
   Set a known offset for each forced label to be at the initial offset
   of each elimination.  We do this because we assume that all
   computed jumps occur from a location where each elimination is
   at its initial offset.
   For all other labels, show that we don't know the offsets.  */

static void
set_initial_label_offsets ()
{
  rtx x;
  bzero ((char *) &offsets_known_at[get_first_label_num ()], num_labels);

  for (x = forced_labels; x; x = XEXP (x, 1))
    if (XEXP (x, 0))
      set_label_offsets (XEXP (x, 0), NULL_RTX, 1);
}

/* Set all elimination offsets to the known values for the code label given
   by INSN.  */

static void
set_offsets_for_label (insn)
     rtx insn;
{
  unsigned int i;
  int label_nr = CODE_LABEL_NUMBER (insn);
  struct elim_table *ep;

  num_not_at_initial_offset = 0;
  for (i = 0, ep = reg_eliminate; i < NUM_ELIMINABLE_REGS; ep++, i++)
    {
      ep->offset = ep->previous_offset = offsets_at[label_nr][i];
      if (ep->can_eliminate && ep->offset != ep->initial_offset)
        num_not_at_initial_offset++;
    }
}

/* See if anything that happened changes which eliminations are valid.
   For example, on the Sparc, whether or not the frame pointer can
   be eliminated can depend on what registers have been used.  We need
   not check some conditions again (such as flag_omit_frame_pointer)
   since they can't have changed.  */

static void
update_eliminables (pset)
     HARD_REG_SET *pset;
{
#if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM
  int previous_frame_pointer_needed = frame_pointer_needed;
#endif
  struct elim_table *ep;

  for (ep = reg_eliminate; ep < &reg_eliminate[NUM_ELIMINABLE_REGS]; ep++)
    if ((ep->from == HARD_FRAME_POINTER_REGNUM && FRAME_POINTER_REQUIRED)
#ifdef ELIMINABLE_REGS
        || ! CAN_ELIMINATE (ep->from, ep->to)
#endif
        )
      ep->can_eliminate = 0;

  /* Look for the case where we have discovered that we can't replace
     register A with register B and that means that we will now be
     trying to replace register A with register C.  This means we can
     no longer replace register C with register B and we need to disable
     such an elimination, if it exists.  This occurs often with A == ap,
     B == sp, and C == fp.  */

  for (ep = reg_eliminate; ep < &reg_eliminate[NUM_ELIMINABLE_REGS]; ep++)
    {
      struct elim_table *op;
      register int new_to = -1;

      if (! ep->can_eliminate && ep->can_eliminate_previous)
        {
          /* Find the current elimination for ep->from, if there is a
             new one.  */
          for (op = reg_eliminate;
               op < &reg_eliminate[NUM_ELIMINABLE_REGS]; op++)
            if (op->from == ep->from && op->can_eliminate)
              {
                new_to = op->to;
                break;
              }

          /* See if there is an elimination of NEW_TO -> EP->TO.  If so,
             disable it.  */
          for (op = reg_eliminate;
               op < &reg_eliminate[NUM_ELIMINABLE_REGS]; op++)
            if (op->from == new_to && op->to == ep->to)
              op->can_eliminate = 0;
        }
    }

  /* See if any registers that we thought we could eliminate the previous
     time are no longer eliminable.  If so, something has changed and we
     must spill the register.  Also, recompute the number of eliminable
     registers and see if the frame pointer is needed; it is if there is
     no elimination of the frame pointer that we can perform.  */

  frame_pointer_needed = 1;
  for (ep = reg_eliminate; ep < &reg_eliminate[NUM_ELIMINABLE_REGS]; ep++)
    {
      if (ep->can_eliminate && ep->from == FRAME_POINTER_REGNUM
          && ep->to != HARD_FRAME_POINTER_REGNUM)
        frame_pointer_needed = 0;

      if (! ep->can_eliminate && ep->can_eliminate_previous)
        {
          ep->can_eliminate_previous = 0;
          SET_HARD_REG_BIT (*pset, ep->from);
          num_eliminable--;
        }
    }

#if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM
  /* If we didn't need a frame pointer last time, but we do now, spill
     the hard frame pointer.  */
  if (frame_pointer_needed && ! previous_frame_pointer_needed)
    SET_HARD_REG_BIT (*pset, HARD_FRAME_POINTER_REGNUM);
#endif
}

/* Initialize the table of registers to eliminate.  */

static void
init_elim_table ()
{
  struct elim_table *ep;
#ifdef ELIMINABLE_REGS
  struct elim_table_1 *ep1;
#endif

  if (!reg_eliminate)
    reg_eliminate = (struct elim_table *)
      xcalloc(sizeof(struct elim_table), NUM_ELIMINABLE_REGS);

  /* Does this function require a frame pointer?  */

  frame_pointer_needed = (! flag_omit_frame_pointer
#ifdef EXIT_IGNORE_STACK
                          /* ?? If EXIT_IGNORE_STACK is set, we will not save
                             and restore sp for alloca.  So we can't eliminate
                             the frame pointer in that case.  At some point,
                             we should improve this by emitting the
                             sp-adjusting insns for this case.  */
                          || (current_function_calls_alloca
                              && EXIT_IGNORE_STACK)
#endif
                          || FRAME_POINTER_REQUIRED);

  num_eliminable = 0;

#ifdef ELIMINABLE_REGS
  for (ep = reg_eliminate, ep1 = reg_eliminate_1;
       ep < &reg_eliminate[NUM_ELIMINABLE_REGS]; ep++, ep1++)
    {
      ep->from = ep1->from;
      ep->to = ep1->to;
      ep->can_eliminate = ep->can_eliminate_previous
        = (CAN_ELIMINATE (ep->from, ep->to)
           && ! (ep->to == STACK_POINTER_REGNUM && frame_pointer_needed));
    }
#else
  reg_eliminate[0].from = reg_eliminate_1[0].from;
  reg_eliminate[0].to = reg_eliminate_1[0].to;
  reg_eliminate[0].can_eliminate = reg_eliminate[0].can_eliminate_previous
    = ! frame_pointer_needed;
#endif

  /* Count the number of eliminable registers and build the FROM and TO
     REG rtx's.  Note that code in gen_rtx will cause, e.g.,
     gen_rtx (REG, Pmode, STACK_POINTER_REGNUM) to equal stack_pointer_rtx.
     We depend on this.  */
  for (ep = reg_eliminate; ep < &reg_eliminate[NUM_ELIMINABLE_REGS]; ep++)
    {
      num_eliminable += ep->can_eliminate;
      ep->from_rtx = gen_rtx_REG (Pmode, ep->from);
      ep->to_rtx = gen_rtx_REG (Pmode, ep->to);
    }
}
\f
/* Kick all pseudos out of hard register REGNO.
   If DUMPFILE is nonzero, log actions taken on that file.

   If CANT_ELIMINATE is nonzero, it means that we are doing this spill
   because we found we can't eliminate some register.  In the case, no pseudos
   are allowed to be in the register, even if they are only in a block that
   doesn't require spill registers, unlike the case when we are spilling this
   hard reg to produce another spill register.

   Return nonzero if any pseudos needed to be kicked out.  */

static void
spill_hard_reg (regno, dumpfile, cant_eliminate)
     unsigned int regno;
     FILE *dumpfile ATTRIBUTE_UNUSED;
     int cant_eliminate;
{
  register int i;

  if (cant_eliminate)
    {
      SET_HARD_REG_BIT (bad_spill_regs_global, regno);
      regs_ever_live[regno] = 1;
    }

  /* Spill every pseudo reg that was allocated to this reg
     or to something that overlaps this reg.  */

  for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
    if (reg_renumber[i] >= 0
        && (unsigned int) reg_renumber[i] <= regno
        && ((unsigned int) reg_renumber[i]
            + HARD_REGNO_NREGS ((unsigned int) reg_renumber[i],
                                PSEUDO_REGNO_MODE (i))
            > regno))
      SET_REGNO_REG_SET (&spilled_pseudos, i);
}

/* I'm getting weird preprocessor errors if I use IOR_HARD_REG_SET
   from within EXECUTE_IF_SET_IN_REG_SET.  Hence this awkwardness.  */

static void
ior_hard_reg_set (set1, set2)
     HARD_REG_SET *set1, *set2;
{
  IOR_HARD_REG_SET (*set1, *set2);
}

/* After find_reload_regs has been run for all insn that need reloads,
   and/or spill_hard_regs was called, this function is used to actually
   spill pseudo registers and try to reallocate them.  It also sets up the
   spill_regs array for use by choose_reload_regs.  */

static int
finish_spills (global, dumpfile)
     int global;
     FILE *dumpfile;
{
  struct insn_chain *chain;
  int something_changed = 0;
  int i;

  /* Build the spill_regs array for the function.  */
  /* If there are some registers still to eliminate and one of the spill regs
     wasn't ever used before, additional stack space may have to be
     allocated to store this register.  Thus, we may have changed the offset
     between the stack and frame pointers, so mark that something has changed.

     One might think that we need only set VAL to 1 if this is a call-used
     register.  However, the set of registers that must be saved by the
     prologue is not identical to the call-used set.  For example, the
     register used by the call insn for the return PC is a call-used register,
     but must be saved by the prologue.  */

  n_spills = 0;
  for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
    if (TEST_HARD_REG_BIT (used_spill_regs, i))
      {
        spill_reg_order[i] = n_spills;
        spill_regs[n_spills++] = i;
        if (num_eliminable && ! regs_ever_live[i])
          something_changed = 1;
        regs_ever_live[i] = 1;
      }
    else
      spill_reg_order[i] = -1;

  for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
    if (REGNO_REG_SET_P (&spilled_pseudos, i))
      {
        /* Record the current hard register the pseudo is allocated to in
           pseudo_previous_regs so we avoid reallocating it to the same
           hard reg in a later pass.  */
        if (reg_renumber[i] < 0)
          abort ();
        SET_HARD_REG_BIT (pseudo_previous_regs[i], reg_renumber[i]);
        /* Mark it as no longer having a hard register home.  */
        reg_renumber[i] = -1;
        /* We will need to scan everything again.  */
        something_changed = 1;
      }

  /* Retry global register allocation if possible.  */
  if (global)
    {
      bzero ((char *) pseudo_forbidden_regs, max_regno * sizeof (HARD_REG_SET));
      /* For every insn that needs reloads, set the registers used as spill
         regs in pseudo_forbidden_regs for every pseudo live across the
         insn.  */
      for (chain = insns_need_reload; chain; chain = chain->next_need_reload)
        {
          EXECUTE_IF_SET_IN_REG_SET
            (&chain->live_throughout, FIRST_PSEUDO_REGISTER, i,
             {
               ior_hard_reg_set (pseudo_forbidden_regs + i,
                                 &chain->used_spill_regs);
             });
          EXECUTE_IF_SET_IN_REG_SET
            (&chain->dead_or_set, FIRST_PSEUDO_REGISTER, i,
             {
               ior_hard_reg_set (pseudo_forbidden_regs + i,
                                 &chain->used_spill_regs);
             });
        }

      /* Retry allocating the spilled pseudos.  For each reg, merge the
         various reg sets that indicate which hard regs can't be used,
         and call retry_global_alloc.
         We change spill_pseudos here to only contain pseudos that did not
         get a new hard register.  */
      for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
        if (reg_old_renumber[i] != reg_renumber[i])
          {
            HARD_REG_SET forbidden;
            COPY_HARD_REG_SET (forbidden, bad_spill_regs_global);
            IOR_HARD_REG_SET (forbidden, pseudo_forbidden_regs[i]);
            IOR_HARD_REG_SET (forbidden, pseudo_previous_regs[i]);
            retry_global_alloc (i, forbidden);
            if (reg_renumber[i] >= 0)
              CLEAR_REGNO_REG_SET (&spilled_pseudos, i);
          }
    }

  /* Fix up the register information in the insn chain.
     This involves deleting those of the spilled pseudos which did not get
     a new hard register home from the live_{before,after} sets.  */
  for (chain = reload_insn_chain; chain; chain = chain->next)
    {
      HARD_REG_SET used_by_pseudos;
      HARD_REG_SET used_by_pseudos2;

      AND_COMPL_REG_SET (&chain->live_throughout, &spilled_pseudos);
      AND_COMPL_REG_SET (&chain->dead_or_set, &spilled_pseudos);

      /* Mark any unallocated hard regs as available for spills.  That
         makes inheritance work somewhat better.  */
      if (chain->need_reload)
        {
          REG_SET_TO_HARD_REG_SET (used_by_pseudos, &chain->live_throughout);
          REG_SET_TO_HARD_REG_SET (used_by_pseudos2, &chain->dead_or_set);
          IOR_HARD_REG_SET (used_by_pseudos, used_by_pseudos2);

          /* Save the old value for the sanity test below.  */
          COPY_HARD_REG_SET (used_by_pseudos2, chain->used_spill_regs);

          compute_use_by_pseudos (&used_by_pseudos, &chain->live_throughout);
          compute_use_by_pseudos (&used_by_pseudos, &chain->dead_or_set);
          COMPL_HARD_REG_SET (chain->used_spill_regs, used_by_pseudos);
          AND_HARD_REG_SET (chain->used_spill_regs, used_spill_regs);

          /* Make sure we only enlarge the set.  */
          GO_IF_HARD_REG_SUBSET (used_by_pseudos2, chain->used_spill_regs, ok);
          abort ();
        ok:;
        }
    }

  /* Let alter_reg modify the reg rtx's for the modified pseudos.  */
  for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
    {
      int regno = reg_renumber[i];
      if (reg_old_renumber[i] == regno)
        continue;

      alter_reg (i, reg_old_renumber[i]);
      reg_old_renumber[i] = regno;
      if (dumpfile)
        {
          if (regno == -1)
            fprintf (dumpfile, " Register %d now on stack.\n\n", i);
          else
            fprintf (dumpfile, " Register %d now in %d.\n\n",
                     i, reg_renumber[i]);
        }
    }

  return something_changed;
}
\f
/* Find all paradoxical subregs within X and update reg_max_ref_width.
   Also mark any hard registers used to store user variables as
   forbidden from being used for spill registers.  */

static void
scan_paradoxical_subregs (x)
     register rtx x;
{
  register int i;
  register const char *fmt;
  register enum rtx_code code = GET_CODE (x);

  switch (code)
    {
    case REG:
#if 0
      if (SMALL_REGISTER_CLASSES && REGNO (x) < FIRST_PSEUDO_REGISTER
          && REG_USERVAR_P (x))
        SET_HARD_REG_BIT (bad_spill_regs_global, REGNO (x));
#endif
      return;

    case CONST_INT:
    case CONST:
    case SYMBOL_REF:
    case LABEL_REF:
    case CONST_DOUBLE:
    case CC0:
    case PC:
    case USE:
    case CLOBBER:
      return;

    case SUBREG:
      if (GET_CODE (SUBREG_REG (x)) == REG
          && GET_MODE_SIZE (GET_MODE (x)) > GET_MODE_SIZE (GET_MODE (SUBREG_REG (x))))
        reg_max_ref_width[REGNO (SUBREG_REG (x))]
          = GET_MODE_SIZE (GET_MODE (x));
      return;

    default:
      break;
    }

  fmt = GET_RTX_FORMAT (code);
  for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
    {
      if (fmt[i] == 'e')
        scan_paradoxical_subregs (XEXP (x, i));
      else if (fmt[i] == 'E')
        {
          register int j;
          for (j = XVECLEN (x, i) - 1; j >=0; j--)
            scan_paradoxical_subregs (XVECEXP (x, i, j));
        }
    }
}
\f
/* Reload pseudo-registers into hard regs around each insn as needed.
   Additional register load insns are output before the insn that needs it
   and perhaps store insns after insns that modify the reloaded pseudo reg.

   reg_last_reload_reg and reg_reloaded_contents keep track of
   which registers are already available in reload registers.
   We update these for the reloads that we perform,
   as the insns are scanned.  */

static void
reload_as_needed (live_known)
     int live_known;
{
  struct insn_chain *chain;
#if defined (AUTO_INC_DEC)
  register int i;
#endif
  rtx x;

  bzero ((char *) spill_reg_rtx, sizeof spill_reg_rtx);
  bzero ((char *) spill_reg_store, sizeof spill_reg_store);
  reg_last_reload_reg = (rtx *) xcalloc (max_regno, sizeof (rtx));
  reg_has_output_reload = (char *) xmalloc (max_regno);
  CLEAR_HARD_REG_SET (reg_reloaded_valid);

  set_initial_elim_offsets ();

  for (chain = reload_insn_chain; chain; chain = chain->next)
    {
      rtx prev;
      rtx insn = chain->insn;
      rtx old_next = NEXT_INSN (insn);

      /* If we pass a label, copy the offsets from the label information
         into the current offsets of each elimination.  */
      if (GET_CODE (insn) == CODE_LABEL)
        set_offsets_for_label (insn);

      else if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
        {
          rtx oldpat = PATTERN (insn);

          /* If this is a USE and CLOBBER of a MEM, ensure that any
             references to eliminable registers have been removed.  */

          if ((GET_CODE (PATTERN (insn)) == USE
               || GET_CODE (PATTERN (insn)) == CLOBBER)
              && GET_CODE (XEXP (PATTERN (insn), 0)) == MEM)
            XEXP (XEXP (PATTERN (insn), 0), 0)
              = eliminate_regs (XEXP (XEXP (PATTERN (insn), 0), 0),
                                GET_MODE (XEXP (PATTERN (insn), 0)),
                                NULL_RTX);

          /* If we need to do register elimination processing, do so.
             This might delete the insn, in which case we are done.  */
          if ((num_eliminable || num_eliminable_invariants) && chain->need_elim)
            {
              eliminate_regs_in_insn (insn, 1);
              if (GET_CODE (insn) == NOTE)
                {
                  update_eliminable_offsets ();
                  continue;
                }
            }

          /* If need_elim is nonzero but need_reload is zero, one might think
             that we could simply set n_reloads to 0.  However, find_reloads
             could have done some manipulation of the insn (such as swapping
             commutative operands), and these manipulations are lost during
             the first pass for every insn that needs register elimination.
             So the actions of find_reloads must be redone here.  */

          if (! chain->need_elim && ! chain->need_reload
              && ! chain->need_operand_change)
            n_reloads = 0;
          /* First find the pseudo regs that must be reloaded for this insn.
             This info is returned in the tables reload_... (see reload.h).
             Also modify the body of INSN by substituting RELOAD
             rtx's for those pseudo regs.  */
          else
            {
              bzero (reg_has_output_reload, max_regno);
              CLEAR_HARD_REG_SET (reg_is_output_reload);

              find_reloads (insn, 1, spill_indirect_levels, live_known,
                            spill_reg_order);
            }

          if (num_eliminable && chain->need_elim)
            update_eliminable_offsets ();

          if (n_reloads > 0)
            {
              rtx next = NEXT_INSN (insn);
              rtx p;

              prev = PREV_INSN (insn);

              /* Now compute which reload regs to reload them into.  Perhaps
                 reusing reload regs from previous insns, or else output
                 load insns to reload them.  Maybe output store insns too.
                 Record the choices of reload reg in reload_reg_rtx.  */
              choose_reload_regs (chain);

              /* Merge any reloads that we didn't combine for fear of
                 increasing the number of spill registers needed but now
                 discover can be safely merged.  */
              if (SMALL_REGISTER_CLASSES)
                merge_assigned_reloads (insn);

              /* Generate the insns to reload operands into or out of
                 their reload regs.  */
              emit_reload_insns (chain);

              /* Substitute the chosen reload regs from reload_reg_rtx
                 into the insn's body (or perhaps into the bodies of other
                 load and store insn that we just made for reloading
                 and that we moved the structure into).  */
              subst_reloads ();

              /* If this was an ASM, make sure that all the reload insns
                 we have generated are valid.  If not, give an error
                 and delete them.  */

              if (asm_noperands (PATTERN (insn)) >= 0)
                for (p = NEXT_INSN (prev); p != next; p = NEXT_INSN (p))
                  if (p != insn && GET_RTX_CLASS (GET_CODE (p)) == 'i'
                      && (recog_memoized (p) < 0
                          || (extract_insn (p), ! constrain_operands (1))))
                    {
                      error_for_asm (insn,
                                     "`asm' operand requires impossible reload");
                      PUT_CODE (p, NOTE);
                      NOTE_SOURCE_FILE (p) = 0;
                      NOTE_LINE_NUMBER (p) = NOTE_INSN_DELETED;
                    }
            }
          /* Any previously reloaded spilled pseudo reg, stored in this insn,
             is no longer validly lying around to save a future reload.
             Note that this does not detect pseudos that were reloaded
             for this insn in order to be stored in
             (obeying register constraints).  That is correct; such reload
             registers ARE still valid.  */
          note_stores (oldpat, forget_old_reloads_1, NULL);

          /* There may have been CLOBBER insns placed after INSN.  So scan
             between INSN and NEXT and use them to forget old reloads.  */
          for (x = NEXT_INSN (insn); x != old_next; x = NEXT_INSN (x))
            if (GET_CODE (x) == INSN && GET_CODE (PATTERN (x)) == CLOBBER)
              note_stores (PATTERN (x), forget_old_reloads_1, NULL);

#ifdef AUTO_INC_DEC
          /* Likewise for regs altered by auto-increment in this insn.
             REG_INC notes have been changed by reloading:
             find_reloads_address_1 records substitutions for them,
             which have been performed by subst_reloads above.  */
          for (i = n_reloads - 1; i >= 0; i--)
            {
              rtx in_reg = rld[i].in_reg;
              if (in_reg)
                {
                  enum rtx_code code = GET_CODE (in_reg);
                  /* PRE_INC / PRE_DEC will have the reload register ending up
                     with the same value as the stack slot, but that doesn't
                     hold true for POST_INC / POST_DEC.  Either we have to
                     convert the memory access to a true POST_INC / POST_DEC,
                     or we can't use the reload register for inheritance.  */
                  if ((code == POST_INC || code == POST_DEC)
                      && TEST_HARD_REG_BIT (reg_reloaded_valid,
                                            REGNO (rld[i].reg_rtx))
                      /* Make sure it is the inc/dec pseudo, and not
                         some other (e.g. output operand) pseudo.  */
                      && (reg_reloaded_contents[REGNO (rld[i].reg_rtx)]
                          == REGNO (XEXP (in_reg, 0))))

                    {
                      rtx reload_reg = rld[i].reg_rtx;
                      enum machine_mode mode = GET_MODE (reload_reg);
                      int n = 0;
                      rtx p;

                      for (p = PREV_INSN (old_next); p != prev; p = PREV_INSN (p))
                        {
                          /* We really want to ignore REG_INC notes here, so
                             use PATTERN (p) as argument to reg_set_p .  */
                          if (reg_set_p (reload_reg, PATTERN (p)))
                            break;
                          n = count_occurrences (PATTERN (p), reload_reg);
                          if (! n)
                            continue;
                          if (n == 1)
                            {
                              n = validate_replace_rtx (reload_reg,
                                                        gen_rtx (code, mode,
                                                                 reload_reg),
                                                        p);

                              /* We must also verify that the constraints
                                 are met after the replacement.  */
                              extract_insn (p);
                              if (n)
                                n = constrain_operands (1);
                              else
                                break;

                              /* If the constraints were not met, then
                                 undo the replacement.  */
                              if (!n)
                                {
                                  validate_replace_rtx (gen_rtx (code, mode,
                                                                 reload_reg),
                                                        reload_reg, p);
                                  break;
                                }

                            }
                          break;
                        }
                      if (n == 1)
                        {
                          REG_NOTES (p)
                            = gen_rtx_EXPR_LIST (REG_INC, reload_reg,
                                                 REG_NOTES (p));
                          /* Mark this as having an output reload so that the
                             REG_INC processing code below won't invalidate
                             the reload for inheritance.  */
                          SET_HARD_REG_BIT (reg_is_output_reload,
                                            REGNO (reload_reg));
                          reg_has_output_reload[REGNO (XEXP (in_reg, 0))] = 1;
                        }
                      else
                        forget_old_reloads_1 (XEXP (in_reg, 0), NULL_RTX, 
                                              NULL);
                    }
                  else if ((code == PRE_INC || code == PRE_DEC)
                           && TEST_HARD_REG_BIT (reg_reloaded_valid,
                                                 REGNO (rld[i].reg_rtx))
                           /* Make sure it is the inc/dec pseudo, and not
                              some other (e.g. output operand) pseudo.  */
                           && (reg_reloaded_contents[REGNO (rld[i].reg_rtx)]
                               == REGNO (XEXP (in_reg, 0))))
                    {
                      SET_HARD_REG_BIT (reg_is_output_reload,
                                        REGNO (rld[i].reg_rtx));
                      reg_has_output_reload[REGNO (XEXP (in_reg, 0))] = 1;
                    }
                }
            }
          /* If a pseudo that got a hard register is auto-incremented,
             we must purge records of copying it into pseudos without
             hard registers.  */
          for (x = REG_NOTES (insn); x; x = XEXP (x, 1))
            if (REG_NOTE_KIND (x) == REG_INC)
              {
                /* See if this pseudo reg was reloaded in this insn.
                   If so, its last-reload info is still valid
                   because it is based on this insn's reload.  */
                for (i = 0; i < n_reloads; i++)
                  if (rld[i].out == XEXP (x, 0))
                    break;

                if (i == n_reloads)
                  forget_old_reloads_1 (XEXP (x, 0), NULL_RTX, NULL);
              }
#endif
        }
      /* A reload reg's contents are unknown after a label.  */
      if (GET_CODE (insn) == CODE_LABEL)
        CLEAR_HARD_REG_SET (reg_reloaded_valid);

      /* Don't assume a reload reg is still good after a call insn
         if it is a call-used reg.  */
      else if (GET_CODE (insn) == CALL_INSN)
        AND_COMPL_HARD_REG_SET(reg_reloaded_valid, call_used_reg_set);
    }

  /* Clean up.  */
  free (reg_last_reload_reg);
  free (reg_has_output_reload);
}

/* Discard all record of any value reloaded from X,
   or reloaded in X from someplace else;
   unless X is an output reload reg of the current insn.

   X may be a hard reg (the reload reg)
   or it may be a pseudo reg that was reloaded from.  */

static void
forget_old_reloads_1 (x, ignored, data)
     rtx x;
     rtx ignored ATTRIBUTE_UNUSED;
     void *data ATTRIBUTE_UNUSED;
{
  unsigned int regno;
  unsigned int nr;
  int offset = 0;

  /* note_stores does give us subregs of hard regs.  */
  while (GET_CODE (x) == SUBREG)
    {
      offset += SUBREG_WORD (x);
      x = SUBREG_REG (x);
    }

  if (GET_CODE (x) != REG)
    return;

  regno = REGNO (x) + offset;

  if (regno >= FIRST_PSEUDO_REGISTER)
    nr = 1;
  else
    {
      unsigned int i;

      nr = HARD_REGNO_NREGS (regno, GET_MODE (x));
      /* Storing into a spilled-reg invalidates its contents.
         This can happen if a block-local pseudo is allocated to that reg
         and it wasn't spilled because this block's total need is 0.
         Then some insn might have an optional reload and use this reg.  */
      for (i = 0; i < nr; i++)
        /* But don't do this if the reg actually serves as an output
           reload reg in the current instruction.  */
        if (n_reloads == 0
            || ! TEST_HARD_REG_BIT (reg_is_output_reload, regno + i))
          CLEAR_HARD_REG_BIT (reg_reloaded_valid, regno + i);
    }

  /* Since value of X has changed,
     forget any value previously copied from it.  */

  while (nr-- > 0)
    /* But don't forget a copy if this is the output reload
       that establishes the copy's validity.  */
    if (n_reloads == 0 || reg_has_output_reload[regno + nr] == 0)
      reg_last_reload_reg[regno + nr] = 0;
}
\f
/* The following HARD_REG_SETs indicate when each hard register is
   used for a reload of various parts of the current insn.  */

/* If reg is unavailable for all reloads.  */
static HARD_REG_SET reload_reg_unavailable;
/* If reg is in use as a reload reg for a RELOAD_OTHER reload.  */
static HARD_REG_SET reload_reg_used;
/* If reg is in use for a RELOAD_FOR_INPUT_ADDRESS reload for operand I.  */
static HARD_REG_SET reload_reg_used_in_input_addr[MAX_RECOG_OPERANDS];
/* If reg is in use for a RELOAD_FOR_INPADDR_ADDRESS reload for operand I.  */
static HARD_REG_SET reload_reg_used_in_inpaddr_addr[MAX_RECOG_OPERANDS];
/* If reg is in use for a RELOAD_FOR_OUTPUT_ADDRESS reload for operand I.  */
static HARD_REG_SET reload_reg_used_in_output_addr[MAX_RECOG_OPERANDS];
/* If reg is in use for a RELOAD_FOR_OUTADDR_ADDRESS reload for operand I.  */
static HARD_REG_SET reload_reg_used_in_outaddr_addr[MAX_RECOG_OPERANDS];
/* If reg is in use for a RELOAD_FOR_INPUT reload for operand I.  */
static HARD_REG_SET reload_reg_used_in_input[MAX_RECOG_OPERANDS];
/* If reg is in use for a RELOAD_FOR_OUTPUT reload for operand I.  */
static HARD_REG_SET reload_reg_used_in_output[MAX_RECOG_OPERANDS];
/* If reg is in use for a RELOAD_FOR_OPERAND_ADDRESS reload.  */
static HARD_REG_SET reload_reg_used_in_op_addr;
/* If reg is in use for a RELOAD_FOR_OPADDR_ADDR reload.  */
static HARD_REG_SET reload_reg_used_in_op_addr_reload;
/* If reg is in use for a RELOAD_FOR_INSN reload.  */
static HARD_REG_SET reload_reg_used_in_insn;
/* If reg is in use for a RELOAD_FOR_OTHER_ADDRESS reload.  */
static HARD_REG_SET reload_reg_used_in_other_addr;

/* If reg is in use as a reload reg for any sort of reload.  */
static HARD_REG_SET reload_reg_used_at_all;

/* If reg is use as an inherited reload.  We just mark the first register
   in the group.  */
static HARD_REG_SET reload_reg_used_for_inherit;

/* Records which hard regs are used in any way, either as explicit use or
   by being allocated to a pseudo during any point of the current insn.  */
static HARD_REG_SET reg_used_in_insn;

/* Mark reg REGNO as in use for a reload of the sort spec'd by OPNUM and
   TYPE. MODE is used to indicate how many consecutive regs are
   actually used.  */

static void
mark_reload_reg_in_use (regno, opnum, type, mode)
     unsigned int regno;
     int opnum;
     enum reload_type type;
     enum machine_mode mode;
{
  unsigned int nregs = HARD_REGNO_NREGS (regno, mode);
  unsigned int i;

  for (i = regno; i < nregs + regno; i++)
    {
      switch (type)
        {
        case RELOAD_OTHER:
          SET_HARD_REG_BIT (reload_reg_used, i);
          break;

        case RELOAD_FOR_INPUT_ADDRESS:
          SET_HARD_REG_BIT (reload_reg_used_in_input_addr[opnum], i);
          break;

        case RELOAD_FOR_INPADDR_ADDRESS:
          SET_HARD_REG_BIT (reload_reg_used_in_inpaddr_addr[opnum], i);
          break;

        case RELOAD_FOR_OUTPUT_ADDRESS:
          SET_HARD_REG_BIT (reload_reg_used_in_output_addr[opnum], i);
          break;

        case RELOAD_FOR_OUTADDR_ADDRESS:
          SET_HARD_REG_BIT (reload_reg_used_in_outaddr_addr[opnum], i);
          break;

        case RELOAD_FOR_OPERAND_ADDRESS:
          SET_HARD_REG_BIT (reload_reg_used_in_op_addr, i);
          break;

        case RELOAD_FOR_OPADDR_ADDR:
          SET_HARD_REG_BIT (reload_reg_used_in_op_addr_reload, i);
          break;

        case RELOAD_FOR_OTHER_ADDRESS:
          SET_HARD_REG_BIT (reload_reg_used_in_other_addr, i);
          break;

        case RELOAD_FOR_INPUT:
          SET_HARD_REG_BIT (reload_reg_used_in_input[opnum], i);
          break;

        case RELOAD_FOR_OUTPUT:
          SET_HARD_REG_BIT (reload_reg_used_in_output[opnum], i);
          break;

        case RELOAD_FOR_INSN:
          SET_HARD_REG_BIT (reload_reg_used_in_insn, i);
          break;
        }

      SET_HARD_REG_BIT (reload_reg_used_at_all, i);
    }
}

/* Similarly, but show REGNO is no longer in use for a reload.  */

static void
clear_reload_reg_in_use (regno, opnum, type, mode)
     unsigned int regno;
     int opnum;
     enum reload_type type;
     enum machine_mode mode;
{
  unsigned int nregs = HARD_REGNO_NREGS (regno, mode);
  unsigned int start_regno, end_regno, r;
  int i;
  /* A complication is that for some reload types, inheritance might
     allow multiple reloads of the same types to share a reload register.
     We set check_opnum if we have to check only reloads with the same
     operand number, and check_any if we have to check all reloads.  */
  int check_opnum = 0;
  int check_any = 0;
  HARD_REG_SET *used_in_set;

  switch (type)
    {
    case RELOAD_OTHER:
      used_in_set = &reload_reg_used;
      break;

    case RELOAD_FOR_INPUT_ADDRESS:
      used_in_set = &reload_reg_used_in_input_addr[opnum];
      break;

    case RELOAD_FOR_INPADDR_ADDRESS:
      check_opnum = 1;
      used_in_set = &reload_reg_used_in_inpaddr_addr[opnum];
      break;

    case RELOAD_FOR_OUTPUT_ADDRESS:
      used_in_set = &reload_reg_used_in_output_addr[opnum];
      break;

    case RELOAD_FOR_OUTADDR_ADDRESS:
      check_opnum = 1;
      used_in_set = &reload_reg_used_in_outaddr_addr[opnum];
      break;

    case RELOAD_FOR_OPERAND_ADDRESS:
      used_in_set = &reload_reg_used_in_op_addr;
      break;

    case RELOAD_FOR_OPADDR_ADDR:
      check_any = 1;
      used_in_set = &reload_reg_used_in_op_addr_reload;
      break;

    case RELOAD_FOR_OTHER_ADDRESS:
      used_in_set = &reload_reg_used_in_other_addr;
      check_any = 1;
      break;

    case RELOAD_FOR_INPUT:
      used_in_set = &reload_reg_used_in_input[opnum];
      break;

    case RELOAD_FOR_OUTPUT:
      used_in_set = &reload_reg_used_in_output[opnum];
      break;

    case RELOAD_FOR_INSN:
      used_in_set = &reload_reg_used_in_insn;
      break;
    default:
      abort ();
    }
  /* We resolve conflicts with remaining reloads of the same type by
     excluding the intervals of of reload registers by them from the
     interval of freed reload registers.  Since we only keep track of
     one set of interval bounds, we might have to exclude somewhat
     more then what would be necessary if we used a HARD_REG_SET here.
     But this should only happen very infrequently, so there should
     be no reason to worry about it.  */

  start_regno = regno;
  end_regno = regno + nregs;
  if (check_opnum || check_any)
    {
      for (i = n_reloads - 1; i >= 0; i--)
        {
          if (rld[i].when_needed == type
              && (check_any || rld[i].opnum == opnum)
              && rld[i].reg_rtx)
            {
              unsigned int conflict_start = true_regnum (rld[i].reg_rtx);
              unsigned int conflict_end
                = (conflict_start
                   + HARD_REGNO_NREGS (conflict_start, rld[i].mode));

              /* If there is an overlap with the first to-be-freed register,
                 adjust the interval start.  */
              if (conflict_start <= start_regno && conflict_end > start_regno)
                start_regno = conflict_end;
              /* Otherwise, if there is a conflict with one of the other
                 to-be-freed registers, adjust the interval end.  */
              if (conflict_start > start_regno && conflict_start < end_regno)
                end_regno = conflict_start;
            }
        }
    }

  for (r = start_regno; r < end_regno; r++)
    CLEAR_HARD_REG_BIT (*used_in_set, r);
}

/* 1 if reg REGNO is free as a reload reg for a reload of the sort
   specified by OPNUM and TYPE.  */

static int
reload_reg_free_p (regno, opnum, type)
     unsigned int regno;
     int opnum;
     enum reload_type type;
{
  int i;

  /* In use for a RELOAD_OTHER means it's not available for anything.  */
  if (TEST_HARD_REG_BIT (reload_reg_used, regno)
      || TEST_HARD_REG_BIT (reload_reg_unavailable, regno))
    return 0;

  switch (type)
    {
    case RELOAD_OTHER:
      /* In use for anything means we can't use it for RELOAD_OTHER.  */
      if (TEST_HARD_REG_BIT (reload_reg_used_in_other_addr, regno)
          || TEST_HARD_REG_BIT (reload_reg_used_in_op_addr, regno)
          || TEST_HARD_REG_BIT (reload_reg_used_in_insn, regno))
        return 0;

      for (i = 0; i < reload_n_operands; i++)
        if (TEST_HARD_REG_BIT (reload_reg_used_in_input_addr[i], regno)
            || TEST_HARD_REG_BIT (reload_reg_used_in_inpaddr_addr[i], regno)
            || TEST_HARD_REG_BIT (reload_reg_used_in_output_addr[i], regno)
            || TEST_HARD_REG_BIT (reload_reg_used_in_outaddr_addr[i], regno)
            || TEST_HARD_REG_BIT (reload_reg_used_in_input[i], regno)
            || TEST_HARD_REG_BIT (reload_reg_used_in_output[i], regno))
          return 0;

      return 1;

    case RELOAD_FOR_INPUT:
      if (TEST_HARD_REG_BIT (reload_reg_used_in_insn, regno)
          || TEST_HARD_REG_BIT (reload_reg_used_in_op_addr, regno))
        return 0;

      if (TEST_HARD_REG_BIT (reload_reg_used_in_op_addr_reload, regno))
        return 0;

      /* If it is used for some other input, can't use it.  */
      for (i = 0; i < reload_n_operands; i++)
        if (TEST_HARD_REG_BIT (reload_reg_used_in_input[i], regno))
          return 0;

      /* If it is used in a later operand's address, can't use it.  */
      for (i = opnum + 1; i < reload_n_operands; i++)
        if (TEST_HARD_REG_BIT (reload_reg_used_in_input_addr[i], regno)
            || TEST_HARD_REG_BIT (reload_reg_used_in_inpaddr_addr[i], regno))
          return 0;

      return 1;

    case RELOAD_FOR_INPUT_ADDRESS:
      /* Can't use a register if it is used for an input address for this
         operand or used as an input in an earlier one.  */
      if (TEST_HARD_REG_BIT (reload_reg_used_in_input_addr[opnum], regno)
          || TEST_HARD_REG_BIT (reload_reg_used_in_inpaddr_addr[opnum], regno))
        return 0;

      for (i = 0; i < opnum; i++)
        if (TEST_HARD_REG_BIT (reload_reg_used_in_input[i], regno))
          return 0;

      return 1;

    case RELOAD_FOR_INPADDR_ADDRESS:
      /* Can't use a register if it is used for an input address
         for this operand or used as an input in an earlier
         one.  */
      if (TEST_HARD_REG_BIT (reload_reg_used_in_inpaddr_addr[opnum], regno))
        return 0;

      for (i = 0; i < opnum; i++)
        if (TEST_HARD_REG_BIT (reload_reg_used_in_input[i], regno))
          return 0;

      return 1;

    case RELOAD_FOR_OUTPUT_ADDRESS:
      /* Can't use a register if it is used for an output address for this
         operand or used as an output in this or a later operand.  */
      if (TEST_HARD_REG_BIT (reload_reg_used_in_output_addr[opnum], regno))
        return 0;

      for (i = opnum; i < reload_n_operands; i++)
        if (TEST_HARD_REG_BIT (reload_reg_used_in_output[i], regno))
          return 0;

      return 1;

    case RELOAD_FOR_OUTADDR_ADDRESS:
      /* Can't use a register if it is used for an output address
         for this operand or used as an output in this or a
         later operand.  */
      if (TEST_HARD_REG_BIT (reload_reg_used_in_outaddr_addr[opnum], regno))
        return 0;

      for (i = opnum; i < reload_n_operands; i++)
        if (TEST_HARD_REG_BIT (reload_reg_used_in_output[i], regno))
          return 0;

      return 1;

    case RELOAD_FOR_OPERAND_ADDRESS:
      for (i = 0; i < reload_n_operands; i++)
        if (TEST_HARD_REG_BIT (reload_reg_used_in_input[i], regno))
          return 0;

      return (! TEST_HARD_REG_BIT (reload_reg_used_in_insn, regno)
              && ! TEST_HARD_REG_BIT (reload_reg_used_in_op_addr, regno));

    case RELOAD_FOR_OPADDR_ADDR:
      for (i = 0; i < reload_n_operands; i++)
        if (TEST_HARD_REG_BIT (reload_reg_used_in_input[i], regno))
          return 0;

      return (!TEST_HARD_REG_BIT (reload_reg_used_in_op_addr_reload, regno));

    case RELOAD_FOR_OUTPUT:
      /* This cannot share a register with RELOAD_FOR_INSN reloads, other
         outputs, or an operand address for this or an earlier output.  */
      if (TEST_HARD_REG_BIT (reload_reg_used_in_insn, regno))
        return 0;

      for (i = 0; i < reload_n_operands; i++)
        if (TEST_HARD_REG_BIT (reload_reg_used_in_output[i], regno))
          return 0;

      for (i = 0; i <= opnum; i++)
        if (TEST_HARD_REG_BIT (reload_reg_used_in_output_addr[i], regno)
            || TEST_HARD_REG_BIT (reload_reg_used_in_outaddr_addr[i], regno))
          return 0;

      return 1;

    case RELOAD_FOR_INSN:
      for (i = 0; i < reload_n_operands; i++)
        if (TEST_HARD_REG_BIT (reload_reg_used_in_input[i], regno)
            || TEST_HARD_REG_BIT (reload_reg_used_in_output[i], regno))
          return 0;

      return (! TEST_HARD_REG_BIT (reload_reg_used_in_insn, regno)
              && ! TEST_HARD_REG_BIT (reload_reg_used_in_op_addr, regno));

    case RELOAD_FOR_OTHER_ADDRESS:
      return ! TEST_HARD_REG_BIT (reload_reg_used_in_other_addr, regno);
    }
  abort ();
}

/* Return 1 if the value in reload reg REGNO, as used by a reload
   needed for the part of the insn specified by OPNUM and TYPE,
   is still available in REGNO at the end of the insn.

   We can assume that the reload reg was already tested for availability
   at the time it is needed, and we should not check this again,
   in case the reg has already been marked in use.  */

static int
reload_reg_reaches_end_p (regno, opnum, type)
     unsigned int regno;
     int opnum;
     enum reload_type type;
{
  int i;

  switch (type)
    {
    case RELOAD_OTHER:
      /* Since a RELOAD_OTHER reload claims the reg for the entire insn,
         its value must reach the end.  */
      return 1;

      /* If this use is for part of the insn,
         its value reaches if no subsequent part uses the same register.
         Just like the above function, don't try to do this with lots
         of fallthroughs.  */

    case RELOAD_FOR_OTHER_ADDRESS:
      /* Here we check for everything else, since these don't conflict
         with anything else and everything comes later.  */

      for (i = 0; i < reload_n_operands; i++)
        if (TEST_HARD_REG_BIT (reload_reg_used_in_output_addr[i], regno)
            || TEST_HARD_REG_BIT (reload_reg_used_in_outaddr_addr[i], regno)
            || TEST_HARD_REG_BIT (reload_reg_used_in_output[i], regno)
            || TEST_HARD_REG_BIT (reload_reg_used_in_input_addr[i], regno)
            || TEST_HARD_REG_BIT (reload_reg_used_in_inpaddr_addr[i], regno)
            || TEST_HARD_REG_BIT (reload_reg_used_in_input[i], regno))
          return 0;

      return (! TEST_HARD_REG_BIT (reload_reg_used_in_op_addr, regno)
              && ! TEST_HARD_REG_BIT (reload_reg_used_in_insn, regno)
              && ! TEST_HARD_REG_BIT (reload_reg_used, regno));

    case RELOAD_FOR_INPUT_ADDRESS:
    case RELOAD_FOR_INPADDR_ADDRESS:
      /* Similar, except that we check only for this and subsequent inputs
         and the address of only subsequent inputs and we do not need
         to check for RELOAD_OTHER objects since they are known not to
         conflict.  */

      for (i = opnum; i < reload_n_operands; i++)
        if (TEST_HARD_REG_BIT (reload_reg_used_in_input[i], regno))
          return 0;

      for (i = opnum + 1; i < reload_n_operands; i++)
        if (TEST_HARD_REG_BIT (reload_reg_used_in_input_addr[i], regno)
            || TEST_HARD_REG_BIT (reload_reg_used_in_inpaddr_addr[i], regno))
          return 0;

      for (i = 0; i < reload_n_operands; i++)
        if (TEST_HARD_REG_BIT (reload_reg_used_in_output_addr[i], regno)
            || TEST_HARD_REG_BIT (reload_reg_used_in_outaddr_addr[i], regno)
            || TEST_HARD_REG_BIT (reload_reg_used_in_output[i], regno))
          return 0;

      if (TEST_HARD_REG_BIT (reload_reg_used_in_op_addr_reload, regno))
        return 0;

      return (! TEST_HARD_REG_BIT (reload_reg_used_in_op_addr, regno)
              && ! TEST_HARD_REG_BIT (reload_reg_used_in_insn, regno));

    case RELOAD_FOR_INPUT:
      /* Similar to input address, except we start at the next operand for
         both input and input address and we do not check for
         RELOAD_FOR_OPERAND_ADDRESS and RELOAD_FOR_INSN since these
         would conflict.  */

      for (i = opnum + 1; i < reload_n_operands; i++)
        if (TEST_HARD_REG_BIT (reload_reg_used_in_input_addr[i], regno)
            || TEST_HARD_REG_BIT (reload_reg_used_in_inpaddr_addr[i], regno)
            || TEST_HARD_REG_BIT (reload_reg_used_in_input[i], regno))
          return 0;

      /* ... fall through ...  */

    case RELOAD_FOR_OPERAND_ADDRESS:
      /* Check outputs and their addresses.  */

      for (i = 0; i < reload_n_operands; i++)
        if (TEST_HARD_REG_BIT (reload_reg_used_in_output_addr[i], regno)
            || TEST_HARD_REG_BIT (reload_reg_used_in_outaddr_addr[i], regno)
            || TEST_HARD_REG_BIT (reload_reg_used_in_output[i], regno))
          return 0;

      return 1;

    case RELOAD_FOR_OPADDR_ADDR:
      for (i = 0; i < reload_n_operands; i++)
        if (TEST_HARD_REG_BIT (reload_reg_used_in_output_addr[i], regno)
            || TEST_HARD_REG_BIT (reload_reg_used_in_outaddr_addr[i], regno)
            || TEST_HARD_REG_BIT (reload_reg_used_in_output[i], regno))
          return 0;

      return (! TEST_HARD_REG_BIT (reload_reg_used_in_op_addr, regno)
              && !TEST_HARD_REG_BIT (reload_reg_used_in_insn, regno));

    case RELOAD_FOR_INSN:
      /* These conflict with other outputs with RELOAD_OTHER.  So
         we need only check for output addresses.  */

      opnum = -1;

      /* ... fall through ...  */

    case RELOAD_FOR_OUTPUT:
    case RELOAD_FOR_OUTPUT_ADDRESS:
    case RELOAD_FOR_OUTADDR_ADDRESS:
      /* We already know these can't conflict with a later output.  So the
         only thing to check are later output addresses.  */
      for (i = opnum + 1; i < reload_n_operands; i++)
        if (TEST_HARD_REG_BIT (reload_reg_used_in_output_addr[i], regno)
            || TEST_HARD_REG_BIT (reload_reg_used_in_outaddr_addr[i], regno))
          return 0;

      return 1;
    }

  abort ();
}
\f
/* Return 1 if the reloads denoted by R1 and R2 cannot share a register.
   Return 0 otherwise.

   This function uses the same algorithm as reload_reg_free_p above.  */

int
reloads_conflict (r1, r2)
     int r1, r2;
{
  enum reload_type r1_type = rld[r1].when_needed;
  enum reload_type r2_type = rld[r2].when_needed;
  int r1_opnum = rld[r1].opnum;
  int r2_opnum = rld[r2].opnum;

  /* RELOAD_OTHER conflicts with everything.  */
  if (r2_type == RELOAD_OTHER)
    return 1;

  /* Otherwise, check conflicts differently for each type.  */

  switch (r1_type)
    {
    case RELOAD_FOR_INPUT:
      return (r2_type == RELOAD_FOR_INSN
              || r2_type == RELOAD_FOR_OPERAND_ADDRESS
              || r2_type == RELOAD_FOR_OPADDR_ADDR
              || r2_type == RELOAD_FOR_INPUT
              || ((r2_type == RELOAD_FOR_INPUT_ADDRESS
                   || r2_type == RELOAD_FOR_INPADDR_ADDRESS)
                  && r2_opnum > r1_opnum));

    case RELOAD_FOR_INPUT_ADDRESS:
      return ((r2_type == RELOAD_FOR_INPUT_ADDRESS && r1_opnum == r2_opnum)
              || (r2_type == RELOAD_FOR_INPUT && r2_opnum < r1_opnum));

    case RELOAD_FOR_INPADDR_ADDRESS:
      return ((r2_type == RELOAD_FOR_INPADDR_ADDRESS && r1_opnum == r2_opnum)
              || (r2_type == RELOAD_FOR_INPUT && r2_opnum < r1_opnum));

    case RELOAD_FOR_OUTPUT_ADDRESS:
      return ((r2_type == RELOAD_FOR_OUTPUT_ADDRESS && r2_opnum == r1_opnum)
              || (r2_type == RELOAD_FOR_OUTPUT && r2_opnum >= r1_opnum));

    case RELOAD_FOR_OUTADDR_ADDRESS:
      return ((r2_type == RELOAD_FOR_OUTADDR_ADDRESS && r2_opnum == r1_opnum)
              || (r2_type == RELOAD_FOR_OUTPUT && r2_opnum >= r1_opnum));

    case RELOAD_FOR_OPERAND_ADDRESS:
      return (r2_type == RELOAD_FOR_INPUT || r2_type == RELOAD_FOR_INSN
              || r2_type == RELOAD_FOR_OPERAND_ADDRESS);

    case RELOAD_FOR_OPADDR_ADDR:
      return (r2_type == RELOAD_FOR_INPUT
              || r2_type == RELOAD_FOR_OPADDR_ADDR);

    case RELOAD_FOR_OUTPUT:
      return (r2_type == RELOAD_FOR_INSN || r2_type == RELOAD_FOR_OUTPUT
              || ((r2_type == RELOAD_FOR_OUTPUT_ADDRESS
                   || r2_type == RELOAD_FOR_OUTADDR_ADDRESS)
                  && r2_opnum <= r1_opnum));

    case RELOAD_FOR_INSN:
      return (r2_type == RELOAD_FOR_INPUT || r2_type == RELOAD_FOR_OUTPUT
              || r2_type == RELOAD_FOR_INSN
              || r2_type == RELOAD_FOR_OPERAND_ADDRESS);

    case RELOAD_FOR_OTHER_ADDRESS:
      return r2_type == RELOAD_FOR_OTHER_ADDRESS;

    case RELOAD_OTHER:
      return 1;

    default:
      abort ();
    }
}
\f
/* Indexed by reload number, 1 if incoming value
   inherited from previous insns.  */
char reload_inherited[MAX_RELOADS];

/* For an inherited reload, this is the insn the reload was inherited from,
   if we know it.  Otherwise, this is 0.  */
rtx reload_inheritance_insn[MAX_RELOADS];

/* If non-zero, this is a place to get the value of the reload,
   rather than using reload_in.  */
rtx reload_override_in[MAX_RELOADS];

/* For each reload, the hard register number of the register used,
   or -1 if we did not need a register for this reload.  */
int reload_spill_index[MAX_RELOADS];

/* Return 1 if the value in reload reg REGNO, as used by a reload
   needed for the part of the insn specified by OPNUM and TYPE,
   may be used to load VALUE into it.

   Other read-only reloads with the same value do not conflict
   unless OUT is non-zero and these other reloads have to live while
   output reloads live.
   If OUT is CONST0_RTX, this is a special case: it means that the
   test should not be for using register REGNO as reload register, but
   for copying from register REGNO into the reload register.

   RELOADNUM is the number of the reload we want to load this value for;
   a reload does not conflict with itself.

   When IGNORE_ADDRESS_RELOADS is set, we can not have conflicts with
   reloads that load an address for the very reload we are considering.

   The caller has to make sure that there is no conflict with the return
   register.  */
static int
reload_reg_free_for_value_p (regno, opnum, type, value, out, reloadnum,
                             ignore_address_reloads)
     int regno;
     int opnum;
     enum reload_type type;
     rtx value, out;
     int reloadnum;
     int ignore_address_reloads;
{
  int time1;
  /* Set if we see an input reload that must not share its reload register
     with any new earlyclobber, but might otherwise share the reload
     register with an output or input-output reload.  */
  int check_earlyclobber = 0;
  int i;
  int copy = 0;

  if (TEST_HARD_REG_BIT (reload_reg_unavailable, regno))
    return 0;

  if (out == const0_rtx)
    {
      copy = 1;
      out = NULL_RTX;
    }

  /* We use some pseudo 'time' value to check if the lifetimes of the
     new register use would overlap with the one of a previous reload
     that is not read-only or uses a different value.
     The 'time' used doesn't have to be linear in any shape or form, just
     monotonic.
     Some reload types use different 'buckets' for each operand.
     So there are MAX_RECOG_OPERANDS different time values for each
     such reload type.
     We compute TIME1 as the time when the register for the prospective
     new reload ceases to be live, and TIME2 for each existing
     reload as the time when that the reload register of that reload
     becomes live.
     Where there is little to be gained by exact lifetime calculations,
     we just make conservative assumptions, i.e. a longer lifetime;
     this is done in the 'default:' cases.  */
  switch (type)
    {
    case RELOAD_FOR_OTHER_ADDRESS:
      /* RELOAD_FOR_OTHER_ADDRESS conflicts with RELOAD_OTHER reloads.  */
      time1 = copy ? 0 : 1;
      break;
    case RELOAD_OTHER:
      time1 = copy ? 1 : MAX_RECOG_OPERANDS * 5 + 5;
      break;
      /* For each input, we may have a sequence of RELOAD_FOR_INPADDR_ADDRESS,
         RELOAD_FOR_INPUT_ADDRESS and RELOAD_FOR_INPUT.  By adding 0 / 1 / 2 ,
         respectively, to the time values for these, we get distinct time
         values.  To get distinct time values for each operand, we have to
         multiply opnum by at least three.  We round that up to four because
         multiply by four is often cheaper.  */
    case RELOAD_FOR_INPADDR_ADDRESS:
      time1 = opnum * 4 + 2;
      break;
    case RELOAD_FOR_INPUT_ADDRESS:
      time1 = opnum * 4 + 3;
      break;
    case RELOAD_FOR_INPUT:
      /* All RELOAD_FOR_INPUT reloads remain live till the instruction
         executes (inclusive).  */
      time1 = copy ? opnum * 4 + 4 : MAX_RECOG_OPERANDS * 4 + 3;
      break;
    case RELOAD_FOR_OPADDR_ADDR:
      /* opnum * 4 + 4
         <= (MAX_RECOG_OPERANDS - 1) * 4 + 4 == MAX_RECOG_OPERANDS * 4 */
      time1 = MAX_RECOG_OPERANDS * 4 + 1;
      break;
    case RELOAD_FOR_OPERAND_ADDRESS:
      /* RELOAD_FOR_OPERAND_ADDRESS reloads are live even while the insn
         is executed.  */
      time1 = copy ? MAX_RECOG_OPERANDS * 4 + 2 : MAX_RECOG_OPERANDS * 4 + 3;
      break;
    case RELOAD_FOR_OUTADDR_ADDRESS:
      time1 = MAX_RECOG_OPERANDS * 4 + 4 + opnum;
      break;
    case RELOAD_FOR_OUTPUT_ADDRESS:
      time1 = MAX_RECOG_OPERANDS * 4 + 5 + opnum;
      break;
    default:
      time1 = MAX_RECOG_OPERANDS * 5 + 5;
    }

  for (i = 0; i < n_reloads; i++)
    {
      rtx reg = rld[i].reg_rtx;
      if (reg && GET_CODE (reg) == REG
          && ((unsigned) regno - true_regnum (reg)
              <= HARD_REGNO_NREGS (REGNO (reg), GET_MODE (reg)) - (unsigned)1)
          && i != reloadnum)
        {
          if (! rld[i].in || ! rtx_equal_p (rld[i].in, value)
              || rld[i].out || out)
            {
              int time2;
              switch (rld[i].when_needed)
                {
                case RELOAD_FOR_OTHER_ADDRESS:
                  time2 = 0;
                  break;
                case RELOAD_FOR_INPADDR_ADDRESS:
                  /* find_reloads makes sure that a
                     RELOAD_FOR_{INP,OP,OUT}ADDR_ADDRESS reload is only used
                     by at most one - the first -
                     RELOAD_FOR_{INPUT,OPERAND,OUTPUT}_ADDRESS .  If the
                     address reload is inherited, the address address reload
                     goes away, so we can ignore this conflict.  */
                  if (type == RELOAD_FOR_INPUT_ADDRESS && reloadnum == i + 1
                      && ignore_address_reloads
                      /* Unless the RELOAD_FOR_INPUT is an auto_inc expression.
                         Then the address address is still needed to store
                         back the new address.  */
                      && ! rld[reloadnum].out)
                    continue;
                  /* Likewise, if a RELOAD_FOR_INPUT can inherit a value, its
                     RELOAD_FOR_INPUT_ADDRESS / RELOAD_FOR_INPADDR_ADDRESS
                     reloads go away.  */
                  if (type == RELOAD_FOR_INPUT && opnum == rld[i].opnum
                      && ignore_address_reloads
                      /* Unless we are reloading an auto_inc expression.  */
                      && ! rld[reloadnum].out)
                    continue;
                  time2 = rld[i].opnum * 4 + 2;
                  break;
                case RELOAD_FOR_INPUT_ADDRESS:
                  if (type == RELOAD_FOR_INPUT && opnum == rld[i].opnum
                      && ignore_address_reloads
                      && ! rld[reloadnum].out)
                    continue;
                  time2 = rld[i].opnum * 4 + 3;
                  break;
                case RELOAD_FOR_INPUT:
                  time2 = rld[i].opnum * 4 + 4;
                  check_earlyclobber = 1;
                  break;
                  /* rld[i].opnum * 4 + 4 <= (MAX_RECOG_OPERAND - 1) * 4 + 4
                     == MAX_RECOG_OPERAND * 4  */
                case RELOAD_FOR_OPADDR_ADDR:
                  if (type == RELOAD_FOR_OPERAND_ADDRESS && reloadnum == i + 1
                      && ignore_address_reloads
                      && ! rld[reloadnum].out)
                    continue;
                  time2 = MAX_RECOG_OPERANDS * 4 + 1;
                  break;
                case RELOAD_FOR_OPERAND_ADDRESS:
                  time2 = MAX_RECOG_OPERANDS * 4 + 2;
                  check_earlyclobber = 1;
                  break;
                case RELOAD_FOR_INSN:
                  time2 = MAX_RECOG_OPERANDS * 4 + 3;
                  break;
                case RELOAD_FOR_OUTPUT:
                  /* All RELOAD_FOR_OUTPUT reloads become live just after the
                     instruction is executed.  */
                  time2 = MAX_RECOG_OPERANDS * 4 + 4;
                  break;
                  /* The first RELOAD_FOR_OUTADDR_ADDRESS reload conflicts with
                     the RELOAD_FOR_OUTPUT reloads, so assign it the same time
                     value.  */
                case RELOAD_FOR_OUTADDR_ADDRESS:
                  if (type == RELOAD_FOR_OUTPUT_ADDRESS && reloadnum == i + 1
                      && ignore_address_reloads
                      && ! rld[reloadnum].out)
                    continue;
                  time2 = MAX_RECOG_OPERANDS * 4 + 4 + rld[i].opnum;
                  break;
                case RELOAD_FOR_OUTPUT_ADDRESS:
                  time2 = MAX_RECOG_OPERANDS * 4 + 5 + rld[i].opnum;
                  break;
                case RELOAD_OTHER:
                  /* If there is no conflict in the input part, handle this
                     like an output reload.  */
                  if (! rld[i].in || rtx_equal_p (rld[i].in, value))
                    {
                      time2 = MAX_RECOG_OPERANDS * 4 + 4;
                      /* Earlyclobbered outputs must conflict with inputs.  */
                      if (earlyclobber_operand_p (rld[i].out))
                        time2 = MAX_RECOG_OPERANDS * 4 + 3;
                          
                      break;
                    }
                  time2 = 1;
                  /* RELOAD_OTHER might be live beyond instruction execution,
                     but this is not obvious when we set time2 = 1.  So check
                     here if there might be a problem with the new reload
                     clobbering the register used by the RELOAD_OTHER.  */
                  if (out)
                    return 0;
                  break;
                default:
                  return 0;
                }
              if ((time1 >= time2
                   && (! rld[i].in || rld[i].out
                       || ! rtx_equal_p (rld[i].in, value)))
                  || (out && rld[reloadnum].out_reg
                      && time2 >= MAX_RECOG_OPERANDS * 4 + 3))
                return 0;
            }
        }
    }

  /* Earlyclobbered outputs must conflict with inputs.  */
  if (check_earlyclobber && out && earlyclobber_operand_p (out))
    return 0;

  return 1;
}

/* Give an error message saying we failed to find a reload for INSN,
   and clear out reload R.  */
static void
failed_reload (insn, r)
     rtx insn;
     int r;
{
  if (asm_noperands (PATTERN (insn)) < 0)
    /* It's the compiler's fault.  */
    fatal_insn ("Could not find a spill register", insn);

  /* It's the user's fault; the operand's mode and constraint
     don't match.  Disable this reload so we don't crash in final.  */
  error_for_asm (insn,
                 "`asm' operand constraint incompatible with operand size");
  rld[r].in = 0;
  rld[r].out = 0;
  rld[r].reg_rtx = 0;
  rld[r].optional = 1;
  rld[r].secondary_p = 1;
}

/* I is the index in SPILL_REG_RTX of the reload register we are to allocate
   for reload R.  If it's valid, get an rtx for it.  Return nonzero if
   successful.  */
static int
set_reload_reg (i, r)
     int i, r;
{
  int regno;
  rtx reg = spill_reg_rtx[i];

  if (reg == 0 || GET_MODE (reg) != rld[r].mode)
    spill_reg_rtx[i] = reg
      = gen_rtx_REG (rld[r].mode, spill_regs[i]);

  regno = true_regnum (reg);

  /* Detect when the reload reg can't hold the reload mode.
     This used to be one `if', but Sequent compiler can't handle that.  */
  if (HARD_REGNO_MODE_OK (regno, rld[r].mode))
    {
      enum machine_mode test_mode = VOIDmode;
      if (rld[r].in)
        test_mode = GET_MODE (rld[r].in);
      /* If rld[r].in has VOIDmode, it means we will load it
         in whatever mode the reload reg has: to wit, rld[r].mode.
         We have already tested that for validity.  */
      /* Aside from that, we need to test that the expressions
         to reload from or into have modes which are valid for this
         reload register.  Otherwise the reload insns would be invalid.  */
      if (! (rld[r].in != 0 && test_mode != VOIDmode
             && ! HARD_REGNO_MODE_OK (regno, test_mode)))
        if (! (rld[r].out != 0
               && ! HARD_REGNO_MODE_OK (regno, GET_MODE (rld[r].out))))
          {
            /* The reg is OK.  */
            last_spill_reg = i;

            /* Mark as in use for this insn the reload regs we use
               for this.  */
            mark_reload_reg_in_use (spill_regs[i], rld[r].opnum,
                                    rld[r].when_needed, rld[r].mode);

            rld[r].reg_rtx = reg;
            reload_spill_index[r] = spill_regs[i];
            return 1;
          }
    }
  return 0;
}

/* Find a spill register to use as a reload register for reload R.
   LAST_RELOAD is non-zero if this is the last reload for the insn being
   processed.

   Set rld[R].reg_rtx to the register allocated.

   We return 1 if successful, or 0 if we couldn't find a spill reg and
   we didn't change anything.  */

static int
allocate_reload_reg (chain, r, last_reload)
     struct insn_chain *chain ATTRIBUTE_UNUSED;
     int r;
     int last_reload;
{
  int i, pass, count;

  /* If we put this reload ahead, thinking it is a group,
     then insist on finding a group.  Otherwise we can grab a
     reg that some other reload needs.
     (That can happen when we have a 68000 DATA_OR_FP_REG
     which is a group of data regs or one fp reg.)
     We need not be so restrictive if there are no more reloads
     for this insn.

     ??? Really it would be nicer to have smarter handling
     for that kind of reg class, where a problem like this is normal.
     Perhaps those classes should be avoided for reloading
     by use of more alternatives.  */

  int force_group = rld[r].nregs > 1 && ! last_reload;

  /* If we want a single register and haven't yet found one,
     take any reg in the right class and not in use.
     If we want a consecutive group, here is where we look for it.

     We use two passes so we can first look for reload regs to
     reuse, which are already in use for other reloads in this insn,
     and only then use additional registers.
     I think that maximizing reuse is needed to make sure we don't
     run out of reload regs.  Suppose we have three reloads, and
     reloads A and B can share regs.  These need two regs.
     Suppose A and B are given different regs.
     That leaves none for C.  */
  for (pass = 0; pass < 2; pass++)
    {
      /* I is the index in spill_regs.
         We advance it round-robin between insns to use all spill regs
         equally, so that inherited reloads have a chance
         of leapfrogging each other.  */

      i = last_spill_reg;

      for (count = 0; count < n_spills; count++)
        {
          int class = (int) rld[r].class;
          int regnum;

          i++;
          if (i >= n_spills)
            i -= n_spills;
          regnum = spill_regs[i];

          if ((reload_reg_free_p (regnum, rld[r].opnum,
                                  rld[r].when_needed)
               || (rld[r].in
                   /* We check reload_reg_used to make sure we
                      don't clobber the return register.  */
                   && ! TEST_HARD_REG_BIT (reload_reg_used, regnum)
                   && reload_reg_free_for_value_p (regnum,
                                                   rld[r].opnum,
                                                   rld[r].when_needed,
                                                   rld[r].in,
                                                   rld[r].out, r, 1)))
              && TEST_HARD_REG_BIT (reg_class_contents[class], regnum)
              && HARD_REGNO_MODE_OK (regnum, rld[r].mode)
              /* Look first for regs to share, then for unshared.  But
                 don't share regs used for inherited reloads; they are
                 the ones we want to preserve.  */
              && (pass
                  || (TEST_HARD_REG_BIT (reload_reg_used_at_all,
                                         regnum)
                      && ! TEST_HARD_REG_BIT (reload_reg_used_for_inherit,
                                              regnum))))
            {
              int nr = HARD_REGNO_NREGS (regnum, rld[r].mode);
              /* Avoid the problem where spilling a GENERAL_OR_FP_REG
                 (on 68000) got us two FP regs.  If NR is 1,
                 we would reject both of them.  */
              if (force_group)
                nr = rld[r].nregs;
              /* If we need only one reg, we have already won.  */
              if (nr == 1)
                {
                  /* But reject a single reg if we demand a group.  */
                  if (force_group)
                    continue;
                  break;
                }
              /* Otherwise check that as many consecutive regs as we need
                 are available here.  */
              while (nr > 1)
                {
                  int regno = regnum + nr - 1;
                  if (!(TEST_HARD_REG_BIT (reg_class_contents[class], regno)
                        && spill_reg_order[regno] >= 0
                        && reload_reg_free_p (regno, rld[r].opnum,
                                              rld[r].when_needed)))
                    break;
                  nr--;
                }
              if (nr == 1)
                break;
            }
        }

      /* If we found something on pass 1, omit pass 2.  */
      if (count < n_spills)
        break;
    }
    
  /* We should have found a spill register by now.  */
  if (count >= n_spills)
    return 0;

  /* I is the index in SPILL_REG_RTX of the reload register we are to
     allocate.  Get an rtx for it and find its register number.  */

  return set_reload_reg (i, r);
}
\f
/* Initialize all the tables needed to allocate reload registers.
   CHAIN is the insn currently being processed; SAVE_RELOAD_REG_RTX
   is the array we use to restore the reg_rtx field for every reload.  */
static void
choose_reload_regs_init (chain, save_reload_reg_rtx)
     struct insn_chain *chain;
     rtx *save_reload_reg_rtx;
{
  int i;

  for (i = 0; i < n_reloads; i++)
    rld[i].reg_rtx = save_reload_reg_rtx[i];

  bzero (reload_inherited, MAX_RELOADS);
  bzero ((char *) reload_inheritance_insn, MAX_RELOADS * sizeof (rtx));
  bzero ((char *) reload_override_in, MAX_RELOADS * sizeof (rtx));

  CLEAR_HARD_REG_SET (reload_reg_used);
  CLEAR_HARD_REG_SET (reload_reg_used_at_all);
  CLEAR_HARD_REG_SET (reload_reg_used_in_op_addr);
  CLEAR_HARD_REG_SET (reload_reg_used_in_op_addr_reload);
  CLEAR_HARD_REG_SET (reload_reg_used_in_insn);
  CLEAR_HARD_REG_SET (reload_reg_used_in_other_addr);

  CLEAR_HARD_REG_SET (reg_used_in_insn);
  {
    HARD_REG_SET tmp;
    REG_SET_TO_HARD_REG_SET (tmp, &chain->live_throughout);
    IOR_HARD_REG_SET (reg_used_in_insn, tmp);
    REG_SET_TO_HARD_REG_SET (tmp, &chain->dead_or_set);
    IOR_HARD_REG_SET (reg_used_in_insn, tmp);
    compute_use_by_pseudos (&reg_used_in_insn, &chain->live_throughout);
    compute_use_by_pseudos (&reg_used_in_insn, &chain->dead_or_set);
  }
  for (i = 0; i < reload_n_operands; i++)
    {
      CLEAR_HARD_REG_SET (reload_reg_used_in_output[i]);
      CLEAR_HARD_REG_SET (reload_reg_used_in_input[i]);
      CLEAR_HARD_REG_SET (reload_reg_used_in_input_addr[i]);
      CLEAR_HARD_REG_SET (reload_reg_used_in_inpaddr_addr[i]);
      CLEAR_HARD_REG_SET (reload_reg_used_in_output_addr[i]);
      CLEAR_HARD_REG_SET (reload_reg_used_in_outaddr_addr[i]);
    }

  COMPL_HARD_REG_SET (reload_reg_unavailable, chain->used_spill_regs);

  CLEAR_HARD_REG_SET (reload_reg_used_for_inherit);

  for (i = 0; i < n_reloads; i++)
    /* If we have already decided to use a certain register,
       don't use it in another way.  */
    if (rld[i].reg_rtx)
      mark_reload_reg_in_use (REGNO (rld[i].reg_rtx), rld[i].opnum,
                              rld[i].when_needed, rld[i].mode);
}

/* Assign hard reg targets for the pseudo-registers we must reload
   into hard regs for this insn.
   Also output the instructions to copy them in and out of the hard regs.

   For machines with register classes, we are responsible for
   finding a reload reg in the proper class.  */

static void
choose_reload_regs (chain)
     struct insn_chain *chain;
{
  rtx insn = chain->insn;
  register int i, j;
  unsigned int max_group_size = 1;
  enum reg_class group_class = NO_REGS;
  int pass, win, inheritance;

  rtx save_reload_reg_rtx[MAX_RELOADS];

  /* In order to be certain of getting the registers we need,
     we must sort the reloads into order of increasing register class.
     Then our grabbing of reload registers will parallel the process
     that provided the reload registers.

     Also note whether any of the reloads wants a consecutive group of regs.
     If so, record the maximum size of the group desired and what
     register class contains all the groups needed by this insn.  */

  for (j = 0; j < n_reloads; j++)
    {
      reload_order[j] = j;
      reload_spill_index[j] = -1;

      if (rld[j].nregs > 1)
        {
          max_group_size = MAX (rld[j].nregs, max_group_size);
          group_class
            = reg_class_superunion[(int)rld[j].class][(int)group_class];
        }

      save_reload_reg_rtx[j] = rld[j].reg_rtx;
    }

  if (n_reloads > 1)
    qsort (reload_order, n_reloads, sizeof (short), reload_reg_class_lower);

  /* If -O, try first with inheritance, then turning it off.
     If not -O, don't do inheritance.
     Using inheritance when not optimizing leads to paradoxes
     with fp on the 68k: fp numbers (not NaNs) fail to be equal to themselves
     because one side of the comparison might be inherited.  */
  win = 0;
  for (inheritance = optimize > 0; inheritance >= 0; inheritance--)
    {
      choose_reload_regs_init (chain, save_reload_reg_rtx);

      /* Process the reloads in order of preference just found.
         Beyond this point, subregs can be found in reload_reg_rtx.

         This used to look for an existing reloaded home for all of the
         reloads, and only then perform any new reloads.  But that could lose
         if the reloads were done out of reg-class order because a later
         reload with a looser constraint might have an old home in a register
         needed by an earlier reload with a tighter constraint.

         To solve this, we make two passes over the reloads, in the order
         described above.  In the first pass we try to inherit a reload
         from a previous insn.  If there is a later reload that needs a
         class that is a proper subset of the class being processed, we must
         also allocate a spill register during the first pass.

         Then make a second pass over the reloads to allocate any reloads
         that haven't been given registers yet.  */

      for (j = 0; j < n_reloads; j++)
        {
          register int r = reload_order[j];
          rtx search_equiv = NULL_RTX;

          /* Ignore reloads that got marked inoperative.  */
          if (rld[r].out == 0 && rld[r].in == 0
              && ! rld[r].secondary_p)
            continue;

          /* If find_reloads chose to use reload_in or reload_out as a reload
             register, we don't need to chose one.  Otherwise, try even if it
             found one since we might save an insn if we find the value lying
             around.
             Try also when reload_in is a pseudo without a hard reg.  */
          if (rld[r].in != 0 && rld[r].reg_rtx != 0
              && (rtx_equal_p (rld[r].in, rld[r].reg_rtx)
                  || (rtx_equal_p (rld[r].out, rld[r].reg_rtx)
                      && GET_CODE (rld[r].in) != MEM
                      && true_regnum (rld[r].in) < FIRST_PSEUDO_REGISTER)))
            continue;

#if 0 /* No longer needed for correct operation.
         It might give better code, or might not; worth an experiment?  */
          /* If this is an optional reload, we can't inherit from earlier insns
             until we are sure that any non-optional reloads have been allocated.
             The following code takes advantage of the fact that optional reloads
             are at the end of reload_order.  */
          if (rld[r].optional != 0)
            for (i = 0; i < j; i++)
              if ((rld[reload_order[i]].out != 0
                   || rld[reload_order[i]].in != 0
                   || rld[reload_order[i]].secondary_p)
                  && ! rld[reload_order[i]].optional
                  && rld[reload_order[i]].reg_rtx == 0)
                allocate_reload_reg (chain, reload_order[i], 0);
#endif

          /* First see if this pseudo is already available as reloaded
             for a previous insn.  We cannot try to inherit for reloads
             that are smaller than the maximum number of registers needed
             for groups unless the register we would allocate cannot be used
             for the groups.

             We could check here to see if this is a secondary reload for
             an object that is already in a register of the desired class.
             This would avoid the need for the secondary reload register.
             But this is complex because we can't easily determine what
             objects might want to be loaded via this reload.  So let a
             register be allocated here.  In `emit_reload_insns' we suppress
             one of the loads in the case described above.  */

          if (inheritance)
            {
              int word = 0;
              register int regno = -1;
              enum machine_mode mode = VOIDmode;

              if (rld[r].in == 0)
                ;
              else if (GET_CODE (rld[r].in) == REG)
                {
                  regno = REGNO (rld[r].in);
                  mode = GET_MODE (rld[r].in);
                }
              else if (GET_CODE (rld[r].in_reg) == REG)
                {
                  regno = REGNO (rld[r].in_reg);
                  mode = GET_MODE (rld[r].in_reg);
                }
              else if (GET_CODE (rld[r].in_reg) == SUBREG
                       && GET_CODE (SUBREG_REG (rld[r].in_reg)) == REG)
                {
                  word = SUBREG_WORD (rld[r].in_reg);
                  regno = REGNO (SUBREG_REG (rld[r].in_reg));
                  if (regno < FIRST_PSEUDO_REGISTER)
                    regno += word;
                  mode = GET_MODE (rld[r].in_reg);
                }
#ifdef AUTO_INC_DEC
              else if ((GET_CODE (rld[r].in_reg) == PRE_INC
                        || GET_CODE (rld[r].in_reg) == PRE_DEC
                        || GET_CODE (rld[r].in_reg) == POST_INC
                        || GET_CODE (rld[r].in_reg) == POST_DEC)
                       && GET_CODE (XEXP (rld[r].in_reg, 0)) == REG)
                {
                  regno = REGNO (XEXP (rld[r].in_reg, 0));
                  mode = GET_MODE (XEXP (rld[r].in_reg, 0));
                  rld[r].out = rld[r].in;
                }
#endif
#if 0
              /* This won't work, since REGNO can be a pseudo reg number.
                 Also, it takes much more hair to keep track of all the things
                 that can invalidate an inherited reload of part of a pseudoreg.  */
              else if (GET_CODE (rld[r].in) == SUBREG
                       && GET_CODE (SUBREG_REG (rld[r].in)) == REG)
                regno = REGNO (SUBREG_REG (rld[r].in)) + SUBREG_WORD (rld[r].in);
#endif

              if (regno >= 0 && reg_last_reload_reg[regno] != 0)
                {
                  enum reg_class class = rld[r].class, last_class;
                  rtx last_reg = reg_last_reload_reg[regno];

                  i = REGNO (last_reg) + word;
                  last_class = REGNO_REG_CLASS (i);
                  if ((GET_MODE_SIZE (GET_MODE (last_reg))
                       >= GET_MODE_SIZE (mode) + word * UNITS_PER_WORD)
                      && reg_reloaded_contents[i] == regno
                      && TEST_HARD_REG_BIT (reg_reloaded_valid, i)
                      && HARD_REGNO_MODE_OK (i, rld[r].mode)
                      && (TEST_HARD_REG_BIT (reg_class_contents[(int) class], i)
                          /* Even if we can't use this register as a reload
                             register, we might use it for reload_override_in,
                             if copying it to the desired class is cheap
                             enough.  */
                          || ((REGISTER_MOVE_COST (last_class, class)
                               < MEMORY_MOVE_COST (mode, class, 1))
#ifdef SECONDARY_INPUT_RELOAD_CLASS
                              && (SECONDARY_INPUT_RELOAD_CLASS (class, mode,
                                                                last_reg)
                                  == NO_REGS)
#endif
#ifdef SECONDARY_MEMORY_NEEDED
                              && ! SECONDARY_MEMORY_NEEDED (last_class, class,
                                                            mode)
#endif
                              ))

                      && (rld[r].nregs == max_group_size
                          || ! TEST_HARD_REG_BIT (reg_class_contents[(int) group_class],
                                                  i))
                      && reload_reg_free_for_value_p (i, rld[r].opnum,
                                                      rld[r].when_needed,
                                                      rld[r].in,
                                                      const0_rtx, r, 1))
                    {
                      /* If a group is needed, verify that all the subsequent
                         registers still have their values intact.  */
                      int nr
                        = HARD_REGNO_NREGS (i, rld[r].mode);
                      int k;

                      for (k = 1; k < nr; k++)
                        if (reg_reloaded_contents[i + k] != regno
                            || ! TEST_HARD_REG_BIT (reg_reloaded_valid, i + k))
                          break;

                      if (k == nr)
                        {
                          int i1;

                          last_reg = (GET_MODE (last_reg) == mode
                                      ? last_reg : gen_rtx_REG (mode, i));

                          /* We found a register that contains the
                             value we need.  If this register is the
                             same as an `earlyclobber' operand of the
                             current insn, just mark it as a place to
                             reload from since we can't use it as the
                             reload register itself.  */

                          for (i1 = 0; i1 < n_earlyclobbers; i1++)
                            if (reg_overlap_mentioned_for_reload_p
                                (reg_last_reload_reg[regno],
                                 reload_earlyclobbers[i1]))
                              break;

                          if (i1 != n_earlyclobbers
                              || ! (reload_reg_free_for_value_p
                                    (i, rld[r].opnum, rld[r].when_needed,
                                     rld[r].in, rld[r].out, r, 1))
                              /* Don't use it if we'd clobber a pseudo reg.  */
                              || (TEST_HARD_REG_BIT (reg_used_in_insn, i)
                                  && rld[r].out
                                  && ! TEST_HARD_REG_BIT (reg_reloaded_dead, i))
                              /* Don't clobber the frame pointer.  */
                              || (i == HARD_FRAME_POINTER_REGNUM && rld[r].out)
                              /* Don't really use the inherited spill reg
                                 if we need it wider than we've got it.  */
                              || (GET_MODE_SIZE (rld[r].mode)
                                  > GET_MODE_SIZE (mode))
                              || ! TEST_HARD_REG_BIT (reg_class_contents[(int) rld[r].class],
                                                      i)

                              /* If find_reloads chose reload_out as reload
                                 register, stay with it - that leaves the
                                 inherited register for subsequent reloads.  */
                              || (rld[r].out && rld[r].reg_rtx
                                  && rtx_equal_p (rld[r].out, rld[r].reg_rtx)))
                            {
                              reload_override_in[r] = last_reg;
                              reload_inheritance_insn[r]
                                = reg_reloaded_insn[i];
                            }
                          else
                            {
                              int k;
                              /* We can use this as a reload reg.  */
                              /* Mark the register as in use for this part of
                                 the insn.  */
                              mark_reload_reg_in_use (i,
                                                      rld[r].opnum,
                                                      rld[r].when_needed,
                                                      rld[r].mode);
                              rld[r].reg_rtx = last_reg;
                              reload_inherited[r] = 1;
                              reload_inheritance_insn[r]
                                = reg_reloaded_insn[i];
                              reload_spill_index[r] = i;
                              for (k = 0; k < nr; k++)
                                SET_HARD_REG_BIT (reload_reg_used_for_inherit,
                                                  i + k);
                            }
                        }
                    }
                }
            }

          /* Here's another way to see if the value is already lying around.  */
          if (inheritance
              && rld[r].in != 0
              && ! reload_inherited[r]
              && rld[r].out == 0
              && (CONSTANT_P (rld[r].in)
                  || GET_CODE (rld[r].in) == PLUS
                  || GET_CODE (rld[r].in) == REG
                  || GET_CODE (rld[r].in) == MEM)
              && (rld[r].nregs == max_group_size
                  || ! reg_classes_intersect_p (rld[r].class, group_class)))
            search_equiv = rld[r].in;
          /* If this is an output reload from a simple move insn, look
             if an equivalence for the input is available.  */
          else if (inheritance && rld[r].in == 0 && rld[r].out != 0)
            {
              rtx set = single_set (insn);

              if (set
                  && rtx_equal_p (rld[r].out, SET_DEST (set))
                  && CONSTANT_P (SET_SRC (set)))
                search_equiv = SET_SRC (set);
            }

          if (search_equiv)
            {
              register rtx equiv
                = find_equiv_reg (search_equiv, insn, rld[r].class,
                                  -1, NULL_PTR, 0, rld[r].mode);
              int regno = 0;

              if (equiv != 0)
                {
                  if (GET_CODE (equiv) == REG)
                    regno = REGNO (equiv);
                  else if (GET_CODE (equiv) == SUBREG)
                    {
                      /* This must be a SUBREG of a hard register.
                         Make a new REG since this might be used in an
                         address and not all machines support SUBREGs
                         there.  */
                      regno = REGNO (SUBREG_REG (equiv)) + SUBREG_WORD (equiv);
                      equiv = gen_rtx_REG (rld[r].mode, regno);
                    }
                  else
                    abort ();
                }

              /* If we found a spill reg, reject it unless it is free
                 and of the desired class.  */
              if (equiv != 0
                  && ((TEST_HARD_REG_BIT (reload_reg_used_at_all, regno)
                       && ! reload_reg_free_for_value_p (regno, rld[r].opnum,
                                                         rld[r].when_needed,
                                                         rld[r].in,
                                                         rld[r].out, r, 1))
                      || ! TEST_HARD_REG_BIT (reg_class_contents[(int) rld[r].class],
                                              regno)))
                equiv = 0;

              if (equiv != 0 && ! HARD_REGNO_MODE_OK (regno, rld[r].mode))
                equiv = 0;

              /* We found a register that contains the value we need.
                 If this register is the same as an `earlyclobber' operand
                 of the current insn, just mark it as a place to reload from
                 since we can't use it as the reload register itself.  */

              if (equiv != 0)
                for (i = 0; i < n_earlyclobbers; i++)
                  if (reg_overlap_mentioned_for_reload_p (equiv,
                                                          reload_earlyclobbers[i]))
                    {
                      reload_override_in[r] = equiv;
                      equiv = 0;
                      break;
                    }

              /* If the equiv register we have found is explicitly clobbered
                 in the current insn, it depends on the reload type if we
                 can use it, use it for reload_override_in, or not at all.
                 In particular, we then can't use EQUIV for a
                 RELOAD_FOR_OUTPUT_ADDRESS reload.  */

              if (equiv != 0 && regno_clobbered_p (regno, insn))
                {
                  switch (rld[r].when_needed)
                    {
                    case RELOAD_FOR_OTHER_ADDRESS:
                    case RELOAD_FOR_INPADDR_ADDRESS:
                    case RELOAD_FOR_INPUT_ADDRESS:
                    case RELOAD_FOR_OPADDR_ADDR:
                      break;
                    case RELOAD_OTHER:
                    case RELOAD_FOR_INPUT:
                    case RELOAD_FOR_OPERAND_ADDRESS:
                      reload_override_in[r] = equiv;
                      /* Fall through. */
                    default:
                      equiv = 0;
                      break;
                    }
                }

              /* If we found an equivalent reg, say no code need be generated
                 to load it, and use it as our reload reg.  */
              if (equiv != 0 && regno != HARD_FRAME_POINTER_REGNUM)
                {
                  int nr = HARD_REGNO_NREGS (regno, rld[r].mode);
                  int k;
                  rld[r].reg_rtx = equiv;
                  reload_inherited[r] = 1;

                  /* If reg_reloaded_valid is not set for this register,
                     there might be a stale spill_reg_store lying around.
                     We must clear it, since otherwise emit_reload_insns
                     might delete the store.  */
                  if (! TEST_HARD_REG_BIT (reg_reloaded_valid, regno))
                    spill_reg_store[regno] = NULL_RTX;
                  /* If any of the hard registers in EQUIV are spill
                     registers, mark them as in use for this insn.  */
                  for (k = 0; k < nr; k++)
                    {
                      i = spill_reg_order[regno + k];
                      if (i >= 0)
                        {
                          mark_reload_reg_in_use (regno, rld[r].opnum,
                                                  rld[r].when_needed,
                                                  rld[r].mode);
                          SET_HARD_REG_BIT (reload_reg_used_for_inherit,
                                            regno + k);
                        }
                    }
                }
            }

          /* If we found a register to use already, or if this is an optional
             reload, we are done.  */
          if (rld[r].reg_rtx != 0 || rld[r].optional != 0)
            continue;

#if 0 /* No longer needed for correct operation.  Might or might not
         give better code on the average.  Want to experiment?  */

          /* See if there is a later reload that has a class different from our
             class that intersects our class or that requires less register
             than our reload.  If so, we must allocate a register to this
             reload now, since that reload might inherit a previous reload
             and take the only available register in our class.  Don't do this
             for optional reloads since they will force all previous reloads
             to be allocated.  Also don't do this for reloads that have been
             turned off.  */

          for (i = j + 1; i < n_reloads; i++)
            {
              int s = reload_order[i];

              if ((rld[s].in == 0 && rld[s].out == 0
                   && ! rld[s].secondary_p)
                  || rld[s].optional)
                continue;

              if ((rld[s].class != rld[r].class
                   && reg_classes_intersect_p (rld[r].class,
                                               rld[s].class))
                  || rld[s].nregs < rld[r].nregs)
                break;
            }

          if (i == n_reloads)
            continue;

          allocate_reload_reg (chain, r, j == n_reloads - 1);
#endif
        }

      /* Now allocate reload registers for anything non-optional that
         didn't get one yet.  */
      for (j = 0; j < n_reloads; j++)
        {
          register int r = reload_order[j];

          /* Ignore reloads that got marked inoperative.  */
          if (rld[r].out == 0 && rld[r].in == 0 && ! rld[r].secondary_p)
            continue;

          /* Skip reloads that already have a register allocated or are
             optional.  */
          if (rld[r].reg_rtx != 0 || rld[r].optional)
            continue;

          if (! allocate_reload_reg (chain, r, j == n_reloads - 1))
            break;
        }

      /* If that loop got all the way, we have won.  */
      if (j == n_reloads)
        {
          win = 1;
          break;
        }

      /* Loop around and try without any inheritance.  */
    }

  if (! win)
    {
      /* First undo everything done by the failed attempt
         to allocate with inheritance.  */
      choose_reload_regs_init (chain, save_reload_reg_rtx);

      /* Some sanity tests to verify that the reloads found in the first
         pass are identical to the ones we have now.  */
      if (chain->n_reloads != n_reloads)
        abort ();

      for (i = 0; i < n_reloads; i++)
        {
          if (chain->rld[i].regno < 0 || chain->rld[i].reg_rtx != 0)
            continue;
          if (chain->rld[i].when_needed != rld[i].when_needed)
            abort ();
          for (j = 0; j < n_spills; j++)
            if (spill_regs[j] == chain->rld[i].regno)
              if (! set_reload_reg (j, i))
                failed_reload (chain->insn, i);
        }
    }

  /* If we thought we could inherit a reload, because it seemed that
     nothing else wanted the same reload register earlier in the insn,
     verify that assumption, now that all reloads have been assigned.
     Likewise for reloads where reload_override_in has been set.  */

  /* If doing expensive optimizations, do one preliminary pass that doesn't
     cancel any inheritance, but removes reloads that have been needed only
     for reloads that we know can be inherited.  */
  for (pass = flag_expensive_optimizations; pass >= 0; pass--)
    {
      for (j = 0; j < n_reloads; j++)
        {
          register int r = reload_order[j];
          rtx check_reg;
          if (reload_inherited[r] && rld[r].reg_rtx)
            check_reg = rld[r].reg_rtx;
          else if (reload_override_in[r]
                   && (GET_CODE (reload_override_in[r]) == REG
                       || GET_CODE (reload_override_in[r]) == SUBREG))
            check_reg = reload_override_in[r];
          else
            continue;
          if (! reload_reg_free_for_value_p (true_regnum (check_reg),
                                             rld[r].opnum,
                                             rld[r].when_needed,
                                             rld[r].in,
                                             (reload_inherited[r]
                                              ? rld[r].out : const0_rtx),
                                             r, 1))
            {
              if (pass)
                continue;
              reload_inherited[r] = 0;
              reload_override_in[r] = 0;
            }
          /* If we can inherit a RELOAD_FOR_INPUT, or can use a
             reload_override_in, then we do not need its related
             RELOAD_FOR_INPUT_ADDRESS / RELOAD_FOR_INPADDR_ADDRESS reloads;
             likewise for other reload types.
             We handle this by removing a reload when its only replacement
             is mentioned in reload_in of the reload we are going to inherit.
             A special case are auto_inc expressions; even if the input is
             inherited, we still need the address for the output.  We can
             recognize them because they have RELOAD_OUT set to RELOAD_IN.
             If we suceeded removing some reload and we are doing a preliminary
             pass just to remove such reloads, make another pass, since the
             removal of one reload might allow us to inherit another one.  */
          else if (rld[r].in
                   && rld[r].out != rld[r].in
                   && remove_address_replacements (rld[r].in) && pass)
            pass = 2;
        }
    }

  /* Now that reload_override_in is known valid,
     actually override reload_in.  */
  for (j = 0; j < n_reloads; j++)
    if (reload_override_in[j])
      rld[j].in = reload_override_in[j];

  /* If this reload won't be done because it has been cancelled or is
     optional and not inherited, clear reload_reg_rtx so other
     routines (such as subst_reloads) don't get confused.  */
  for (j = 0; j < n_reloads; j++)
    if (rld[j].reg_rtx != 0
        && ((rld[j].optional && ! reload_inherited[j])
            || (rld[j].in == 0 && rld[j].out == 0
                && ! rld[j].secondary_p)))
      {
        int regno = true_regnum (rld[j].reg_rtx);

        if (spill_reg_order[regno] >= 0)
          clear_reload_reg_in_use (regno, rld[j].opnum,
                                   rld[j].when_needed, rld[j].mode);
        rld[j].reg_rtx = 0;
        reload_spill_index[j] = -1;
      }

  /* Record which pseudos and which spill regs have output reloads.  */
  for (j = 0; j < n_reloads; j++)
    {
      register int r = reload_order[j];

      i = reload_spill_index[r];

      /* I is nonneg if this reload uses a register.
         If rld[r].reg_rtx is 0, this is an optional reload
         that we opted to ignore.  */
      if (rld[r].out_reg != 0 && GET_CODE (rld[r].out_reg) == REG
          && rld[r].reg_rtx != 0)
        {
          register int nregno = REGNO (rld[r].out_reg);
          int nr = 1;

          if (nregno < FIRST_PSEUDO_REGISTER)
            nr = HARD_REGNO_NREGS (nregno, rld[r].mode);

          while (--nr >= 0)
            reg_has_output_reload[nregno + nr] = 1;

          if (i >= 0)
            {
              nr = HARD_REGNO_NREGS (i, rld[r].mode);
              while (--nr >= 0)
                SET_HARD_REG_BIT (reg_is_output_reload, i + nr);
            }

          if (rld[r].when_needed != RELOAD_OTHER
              && rld[r].when_needed != RELOAD_FOR_OUTPUT
              && rld[r].when_needed != RELOAD_FOR_INSN)
            abort ();
        }
    }
}

/* Deallocate the reload register for reload R.  This is called from
   remove_address_replacements.  */

void
deallocate_reload_reg (r)
     int r;
{
  int regno;

  if (! rld[r].reg_rtx)
    return;
  regno = true_regnum (rld[r].reg_rtx);
  rld[r].reg_rtx = 0;
  if (spill_reg_order[regno] >= 0)
    clear_reload_reg_in_use (regno, rld[r].opnum, rld[r].when_needed,
                             rld[r].mode);
  reload_spill_index[r] = -1;
}
\f
/* If SMALL_REGISTER_CLASSES is non-zero, we may not have merged two
   reloads of the same item for fear that we might not have enough reload
   registers. However, normally they will get the same reload register
   and hence actually need not be loaded twice.

   Here we check for the most common case of this phenomenon: when we have
   a number of reloads for the same object, each of which were allocated
   the same reload_reg_rtx, that reload_reg_rtx is not used for any other
   reload, and is not modified in the insn itself.  If we find such,
   merge all the reloads and set the resulting reload to RELOAD_OTHER.
   This will not increase the number of spill registers needed and will
   prevent redundant code.  */

static void
merge_assigned_reloads (insn)
     rtx insn;
{
  int i, j;

  /* Scan all the reloads looking for ones that only load values and
     are not already RELOAD_OTHER and ones whose reload_reg_rtx are
     assigned and not modified by INSN.  */

  for (i = 0; i < n_reloads; i++)
    {
      int conflicting_input = 0;
      int max_input_address_opnum = -1;
      int min_conflicting_input_opnum = MAX_RECOG_OPERANDS;

      if (rld[i].in == 0 || rld[i].when_needed == RELOAD_OTHER
          || rld[i].out != 0 || rld[i].reg_rtx == 0
          || reg_set_p (rld[i].reg_rtx, insn))
        continue;

      /* Look at all other reloads.  Ensure that the only use of this
         reload_reg_rtx is in a reload that just loads the same value
         as we do.  Note that any secondary reloads must be of the identical
         class since the values, modes, and result registers are the
         same, so we need not do anything with any secondary reloads.  */

      for (j = 0; j < n_reloads; j++)
        {
          if (i == j || rld[j].reg_rtx == 0
              || ! reg_overlap_mentioned_p (rld[j].reg_rtx,
                                            rld[i].reg_rtx))
            continue;

          if (rld[j].when_needed == RELOAD_FOR_INPUT_ADDRESS
              && rld[j].opnum > max_input_address_opnum)
            max_input_address_opnum = rld[j].opnum;

          /* If the reload regs aren't exactly the same (e.g, different modes)
             or if the values are different, we can't merge this reload.
             But if it is an input reload, we might still merge
             RELOAD_FOR_INPUT_ADDRESS and RELOAD_FOR_OTHER_ADDRESS reloads.  */

          if (! rtx_equal_p (rld[i].reg_rtx, rld[j].reg_rtx)
              || rld[j].out != 0 || rld[j].in == 0
              || ! rtx_equal_p (rld[i].in, rld[j].in))
            {
              if (rld[j].when_needed != RELOAD_FOR_INPUT
                  || ((rld[i].when_needed != RELOAD_FOR_INPUT_ADDRESS
                       || rld[i].opnum > rld[j].opnum)
                      && rld[i].when_needed != RELOAD_FOR_OTHER_ADDRESS))
                break;
              conflicting_input = 1;
              if (min_conflicting_input_opnum > rld[j].opnum)
                min_conflicting_input_opnum = rld[j].opnum;
            }
        }

      /* If all is OK, merge the reloads.  Only set this to RELOAD_OTHER if
         we, in fact, found any matching reloads.  */

      if (j == n_reloads
          && max_input_address_opnum <= min_conflicting_input_opnum)
        {
          for (j = 0; j < n_reloads; j++)
            if (i != j && rld[j].reg_rtx != 0
                && rtx_equal_p (rld[i].reg_rtx, rld[j].reg_rtx)
                && (! conflicting_input
                    || rld[j].when_needed == RELOAD_FOR_INPUT_ADDRESS
                    || rld[j].when_needed == RELOAD_FOR_OTHER_ADDRESS))
              {
                rld[i].when_needed = RELOAD_OTHER;
                rld[j].in = 0;
                reload_spill_index[j] = -1;
                transfer_replacements (i, j);
              }

          /* If this is now RELOAD_OTHER, look for any reloads that load
             parts of this operand and set them to RELOAD_FOR_OTHER_ADDRESS
             if they were for inputs, RELOAD_OTHER for outputs.  Note that
             this test is equivalent to looking for reloads for this operand
             number.  */

          if (rld[i].when_needed == RELOAD_OTHER)
            for (j = 0; j < n_reloads; j++)
              if (rld[j].in != 0
                  && rld[i].when_needed != RELOAD_OTHER
                  && reg_overlap_mentioned_for_reload_p (rld[j].in,
                                                         rld[i].in))
                rld[j].when_needed
                  = ((rld[i].when_needed == RELOAD_FOR_INPUT_ADDRESS
                      || rld[i].when_needed == RELOAD_FOR_INPADDR_ADDRESS)
                     ? RELOAD_FOR_OTHER_ADDRESS : RELOAD_OTHER);
        }
    }
}

\f
/* These arrays are filled by emit_reload_insns and its subroutines.  */
static rtx input_reload_insns[MAX_RECOG_OPERANDS];
static rtx other_input_address_reload_insns = 0;
static rtx other_input_reload_insns = 0;
static rtx input_address_reload_insns[MAX_RECOG_OPERANDS];
static rtx inpaddr_address_reload_insns[MAX_RECOG_OPERANDS];
static rtx output_reload_insns[MAX_RECOG_OPERANDS];
static rtx output_address_reload_insns[MAX_RECOG_OPERANDS];
static rtx outaddr_address_reload_insns[MAX_RECOG_OPERANDS];
static rtx operand_reload_insns = 0;
static rtx other_operand_reload_insns = 0;
static rtx other_output_reload_insns[MAX_RECOG_OPERANDS];

/* Values to be put in spill_reg_store are put here first.  */
static rtx new_spill_reg_store[FIRST_PSEUDO_REGISTER];
static HARD_REG_SET reg_reloaded_died;

/* Generate insns to perform reload RL, which is for the insn in CHAIN and
   has the number J.  OLD contains the value to be used as input.  */

static void
emit_input_reload_insns (chain, rl, old, j)
     struct insn_chain *chain;
     struct reload *rl;
     rtx old;
     int j;
{
  rtx insn = chain->insn;
  register rtx reloadreg = rl->reg_rtx;
  rtx oldequiv_reg = 0;
  rtx oldequiv = 0;
  int special = 0;
  enum machine_mode mode;
  rtx *where;

  /* Determine the mode to reload in.
     This is very tricky because we have three to choose from.
     There is the mode the insn operand wants (rl->inmode).
     There is the mode of the reload register RELOADREG.
     There is the intrinsic mode of the operand, which we could find
     by stripping some SUBREGs.
     It turns out that RELOADREG's mode is irrelevant:
     we can change that arbitrarily.

     Consider (SUBREG:SI foo:QI) as an operand that must be SImode;
     then the reload reg may not support QImode moves, so use SImode.
     If foo is in memory due to spilling a pseudo reg, this is safe,
     because the QImode value is in the least significant part of a
     slot big enough for a SImode.  If foo is some other sort of
     memory reference, then it is impossible to reload this case,
     so previous passes had better make sure this never happens.

     Then consider a one-word union which has SImode and one of its
     members is a float, being fetched as (SUBREG:SF union:SI).
     We must fetch that as SFmode because we could be loading into
     a float-only register.  In this case OLD's mode is correct.

     Consider an immediate integer: it has VOIDmode.  Here we need
     to get a mode from something else.

     In some cases, there is a fourth mode, the operand's
     containing mode.  If the insn specifies a containing mode for
     this operand, it overrides all others.

     I am not sure whether the algorithm here is always right,
     but it does the right things in those cases.  */

  mode = GET_MODE (old);
  if (mode == VOIDmode)
    mode = rl->inmode;

#ifdef SECONDARY_INPUT_RELOAD_CLASS
  /* If we need a secondary register for this operation, see if
     the value is already in a register in that class.  Don't
     do this if the secondary register will be used as a scratch
     register.  */

  if (rl->secondary_in_reload >= 0
      && rl->secondary_in_icode == CODE_FOR_nothing
      && optimize)
    oldequiv
      = find_equiv_reg (old, insn,
                        rld[rl->secondary_in_reload].class,
                        -1, NULL_PTR, 0, mode);
#endif

  /* If reloading from memory, see if there is a register
     that already holds the same value.  If so, reload from there.
     We can pass 0 as the reload_reg_p argument because
     any other reload has either already been emitted,
     in which case find_equiv_reg will see the reload-insn,
     or has yet to be emitted, in which case it doesn't matter
     because we will use this equiv reg right away.  */

  if (oldequiv == 0 && optimize
      && (GET_CODE (old) == MEM
          || (GET_CODE (old) == REG
              && REGNO (old) >= FIRST_PSEUDO_REGISTER
              && reg_renumber[REGNO (old)] < 0)))
    oldequiv = find_equiv_reg (old, insn, ALL_REGS,
                               -1, NULL_PTR, 0, mode);

  if (oldequiv)
    {
      unsigned int regno = true_regnum (oldequiv);

      /* Don't use OLDEQUIV if any other reload changes it at an
         earlier stage of this insn or at this stage.  */
      if (! reload_reg_free_for_value_p (regno, rl->opnum,
                                         rl->when_needed,
                                         rl->in, const0_rtx, j,
                                         0))
        oldequiv = 0;

      /* If it is no cheaper to copy from OLDEQUIV into the
         reload register than it would be to move from memory,
         don't use it. Likewise, if we need a secondary register
         or memory.   */

      if (oldequiv != 0
          && ((REGNO_REG_CLASS (regno) != rl->class
               && (REGISTER_MOVE_COST (REGNO_REG_CLASS (regno),
                                       rl->class)
                   >= MEMORY_MOVE_COST (mode, rl->class, 1)))
#ifdef SECONDARY_INPUT_RELOAD_CLASS
              || (SECONDARY_INPUT_RELOAD_CLASS (rl->class,
                                                mode, oldequiv)
                  != NO_REGS)
#endif
#ifdef SECONDARY_MEMORY_NEEDED
              || SECONDARY_MEMORY_NEEDED (REGNO_REG_CLASS (regno),
                                          rl->class,
                                          mode)
#endif
              ))
        oldequiv = 0;
    }

  /* delete_output_reload is only invoked properly if old contains
     the original pseudo register.  Since this is replaced with a
     hard reg when RELOAD_OVERRIDE_IN is set, see if we can
     find the pseudo in RELOAD_IN_REG.  */
  if (oldequiv == 0
      && reload_override_in[j]
      && GET_CODE (rl->in_reg) == REG)
    {
      oldequiv = old;
      old = rl->in_reg;
    }
  if (oldequiv == 0)
    oldequiv = old;
  else if (GET_CODE (oldequiv) == REG)
    oldequiv_reg = oldequiv;
  else if (GET_CODE (oldequiv) == SUBREG)
    oldequiv_reg = SUBREG_REG (oldequiv);

  /* If we are reloading from a register that was recently stored in
     with an output-reload, see if we can prove there was
     actually no need to store the old value in it.  */

  if (optimize && GET_CODE (oldequiv) == REG
      && REGNO (oldequiv) < FIRST_PSEUDO_REGISTER
      && spill_reg_store[REGNO (oldequiv)]
      && GET_CODE (old) == REG
      && (dead_or_set_p (insn, spill_reg_stored_to[REGNO (oldequiv)])
          || rtx_equal_p (spill_reg_stored_to[REGNO (oldequiv)],
                          rl->out_reg)))
    delete_output_reload (insn, j, REGNO (oldequiv));

  /* Encapsulate both RELOADREG and OLDEQUIV into that mode,
     then load RELOADREG from OLDEQUIV.  Note that we cannot use
     gen_lowpart_common since it can do the wrong thing when
     RELOADREG has a multi-word mode.  Note that RELOADREG
     must always be a REG here.  */

  if (GET_MODE (reloadreg) != mode)
    reloadreg = gen_rtx_REG (mode, REGNO (reloadreg));
  while (GET_CODE (oldequiv) == SUBREG && GET_MODE (oldequiv) != mode)
    oldequiv = SUBREG_REG (oldequiv);
  if (GET_MODE (oldequiv) != VOIDmode
      && mode != GET_MODE (oldequiv))
    oldequiv = gen_rtx_SUBREG (mode, oldequiv, 0);

  /* Switch to the right place to emit the reload insns.  */
  switch (rl->when_needed)
    {
    case RELOAD_OTHER:
      where = &other_input_reload_insns;
      break;
    case RELOAD_FOR_INPUT:
      where = &input_reload_insns[rl->opnum];
      break;
    case RELOAD_FOR_INPUT_ADDRESS:
      where = &input_address_reload_insns[rl->opnum];
      break;
    case RELOAD_FOR_INPADDR_ADDRESS:
      where = &inpaddr_address_reload_insns[rl->opnum];
      break;
    case RELOAD_FOR_OUTPUT_ADDRESS:
      where = &output_address_reload_insns[rl->opnum];
      break;
    case RELOAD_FOR_OUTADDR_ADDRESS:
      where = &outaddr_address_reload_insns[rl->opnum];
      break;
    case RELOAD_FOR_OPERAND_ADDRESS:
      where = &operand_reload_insns;
      break;
    case RELOAD_FOR_OPADDR_ADDR:
      where = &other_operand_reload_insns;
      break;
    case RELOAD_FOR_OTHER_ADDRESS:
      where = &other_input_address_reload_insns;
      break;
    default:
      abort ();
    }

  push_to_sequence (*where);

  /* Auto-increment addresses must be reloaded in a special way.  */
  if (rl->out && ! rl->out_reg)
    {
      /* We are not going to bother supporting the case where a
         incremented register can't be copied directly from
         OLDEQUIV since this seems highly unlikely.  */
      if (rl->secondary_in_reload >= 0)
        abort ();

      if (reload_inherited[j])
        oldequiv = reloadreg;

      old = XEXP (rl->in_reg, 0);

      if (optimize && GET_CODE (oldequiv) == REG
          && REGNO (oldequiv) < FIRST_PSEUDO_REGISTER
          && spill_reg_store[REGNO (oldequiv)]
          && GET_CODE (old) == REG
          && (dead_or_set_p (insn,
                             spill_reg_stored_to[REGNO (oldequiv)])
              || rtx_equal_p (spill_reg_stored_to[REGNO (oldequiv)],
                              old)))
        delete_output_reload (insn, j, REGNO (oldequiv));

      /* Prevent normal processing of this reload.  */
      special = 1;
      /* Output a special code sequence for this case.  */
      new_spill_reg_store[REGNO (reloadreg)]
        = inc_for_reload (reloadreg, oldequiv, rl->out,
                          rl->inc);
    }

  /* If we are reloading a pseudo-register that was set by the previous
     insn, see if we can get rid of that pseudo-register entirely
     by redirecting the previous insn into our reload register.  */

  else if (optimize && GET_CODE (old) == REG
           && REGNO (old) >= FIRST_PSEUDO_REGISTER
           && dead_or_set_p (insn, old)
           /* This is unsafe if some other reload
              uses the same reg first.  */
           && reload_reg_free_for_value_p (REGNO (reloadreg),
                                           rl->opnum,
                                           rl->when_needed,
                                           old, rl->out,
                                           j, 0))
    {
      rtx temp = PREV_INSN (insn);
      while (temp && GET_CODE (temp) == NOTE)
        temp = PREV_INSN (temp);
      if (temp
          && GET_CODE (temp) == INSN
          && GET_CODE (PATTERN (temp)) == SET
          && SET_DEST (PATTERN (temp)) == old
          /* Make sure we can access insn_operand_constraint.  */
          && asm_noperands (PATTERN (temp)) < 0
          /* This is unsafe if prev insn rejects our reload reg.  */
          && constraint_accepts_reg_p (insn_data[recog_memoized (temp)].operand[0].constraint,
                                       reloadreg)
          /* This is unsafe if operand occurs more than once in current
             insn.  Perhaps some occurrences aren't reloaded.  */
          && count_occurrences (PATTERN (insn), old) == 1
          /* Don't risk splitting a matching pair of operands.  */
          && ! reg_mentioned_p (old, SET_SRC (PATTERN (temp))))
        {
          /* Store into the reload register instead of the pseudo.  */
          SET_DEST (PATTERN (temp)) = reloadreg;

          /* If the previous insn is an output reload, the source is
             a reload register, and its spill_reg_store entry will
             contain the previous destination.  This is now
             invalid.  */
          if (GET_CODE (SET_SRC (PATTERN (temp))) == REG
              && REGNO (SET_SRC (PATTERN (temp))) < FIRST_PSEUDO_REGISTER)
            {
              spill_reg_store[REGNO (SET_SRC (PATTERN (temp)))] = 0;
              spill_reg_stored_to[REGNO (SET_SRC (PATTERN (temp)))] = 0;
            }

          /* If these are the only uses of the pseudo reg,
             pretend for GDB it lives in the reload reg we used.  */
          if (REG_N_DEATHS (REGNO (old)) == 1
              && REG_N_SETS (REGNO (old)) == 1)
            {
              reg_renumber[REGNO (old)] = REGNO (rl->reg_rtx);
              alter_reg (REGNO (old), -1);
            }
          special = 1;
        }
    }

  /* We can't do that, so output an insn to load RELOADREG.  */

#ifdef SECONDARY_INPUT_RELOAD_CLASS
  /* If we have a secondary reload, pick up the secondary register
     and icode, if any.  If OLDEQUIV and OLD are different or
     if this is an in-out reload, recompute whether or not we
     still need a secondary register and what the icode should
     be.  If we still need a secondary register and the class or
     icode is different, go back to reloading from OLD if using
     OLDEQUIV means that we got the wrong type of register.  We
     cannot have different class or icode due to an in-out reload
     because we don't make such reloads when both the input and
     output need secondary reload registers.  */

  if (! special && rl->secondary_in_reload >= 0)
    {
      rtx second_reload_reg = 0;
      int secondary_reload = rl->secondary_in_reload;
      rtx real_oldequiv = oldequiv;
      rtx real_old = old;
      rtx tmp;
      enum insn_code icode;

      /* If OLDEQUIV is a pseudo with a MEM, get the real MEM
         and similarly for OLD.
         See comments in get_secondary_reload in reload.c.  */
      /* If it is a pseudo that cannot be replaced with its
         equivalent MEM, we must fall back to reload_in, which
         will have all the necessary substitutions registered.
         Likewise for a pseudo that can't be replaced with its
         equivalent constant.

         Take extra care for subregs of such pseudos.  Note that
         we cannot use reg_equiv_mem in this case because it is
         not in the right mode.  */

      tmp = oldequiv;
      if (GET_CODE (tmp) == SUBREG)
        tmp = SUBREG_REG (tmp);
      if (GET_CODE (tmp) == REG
          && REGNO (tmp) >= FIRST_PSEUDO_REGISTER
          && (reg_equiv_memory_loc[REGNO (tmp)] != 0
              || reg_equiv_constant[REGNO (tmp)] != 0))
        {
          if (! reg_equiv_mem[REGNO (tmp)]
              || num_not_at_initial_offset
              || GET_CODE (oldequiv) == SUBREG)
            real_oldequiv = rl->in;
          else
            real_oldequiv = reg_equiv_mem[REGNO (tmp)];
        }

      tmp = old;
      if (GET_CODE (tmp) == SUBREG)
        tmp = SUBREG_REG (tmp);
      if (GET_CODE (tmp) == REG
          && REGNO (tmp) >= FIRST_PSEUDO_REGISTER
          && (reg_equiv_memory_loc[REGNO (tmp)] != 0
              || reg_equiv_constant[REGNO (tmp)] != 0))
        {
          if (! reg_equiv_mem[REGNO (tmp)]
              || num_not_at_initial_offset
              || GET_CODE (old) == SUBREG)
            real_old = rl->in;
          else
            real_old = reg_equiv_mem[REGNO (tmp)];
        }

      second_reload_reg = rld[secondary_reload].reg_rtx;
      icode = rl->secondary_in_icode;

      if ((old != oldequiv && ! rtx_equal_p (old, oldequiv))
          || (rl->in != 0 && rl->out != 0))
        {
          enum reg_class new_class
            = SECONDARY_INPUT_RELOAD_CLASS (rl->class,
                                            mode, real_oldequiv);

          if (new_class == NO_REGS)
            second_reload_reg = 0;
          else
            {
              enum insn_code new_icode;
              enum machine_mode new_mode;

              if (! TEST_HARD_REG_BIT (reg_class_contents[(int) new_class],
                                       REGNO (second_reload_reg)))
                oldequiv = old, real_oldequiv = real_old;
              else
                {
                  new_icode = reload_in_optab[(int) mode];
                  if (new_icode != CODE_FOR_nothing
                      && ((insn_data[(int) new_icode].operand[0].predicate
                           && ! ((*insn_data[(int) new_icode].operand[0].predicate)
                                 (reloadreg, mode)))
                          || (insn_data[(int) new_icode].operand[1].predicate
                              && ! ((*insn_data[(int) new_icode].operand[1].predicate)
                                    (real_oldequiv, mode)))))
                    new_icode = CODE_FOR_nothing;

                  if (new_icode == CODE_FOR_nothing)
                    new_mode = mode;
                  else
                    new_mode = insn_data[(int) new_icode].operand[2].mode;

                  if (GET_MODE (second_reload_reg) != new_mode)
                    {
                      if (!HARD_REGNO_MODE_OK (REGNO (second_reload_reg),
                                               new_mode))
                        oldequiv = old, real_oldequiv = real_old;
                      else
                        second_reload_reg
                          = gen_rtx_REG (new_mode,
                                         REGNO (second_reload_reg));
                    }
                }
            }
        }

      /* If we still need a secondary reload register, check
         to see if it is being used as a scratch or intermediate
         register and generate code appropriately.  If we need
         a scratch register, use REAL_OLDEQUIV since the form of
         the insn may depend on the actual address if it is
         a MEM.  */

      if (second_reload_reg)
        {
          if (icode != CODE_FOR_nothing)
            {
              emit_insn (GEN_FCN (icode) (reloadreg, real_oldequiv,
                                          second_reload_reg));
              special = 1;
            }
          else
            {
              /* See if we need a scratch register to load the
                 intermediate register (a tertiary reload).  */
              enum insn_code tertiary_icode
                = rld[secondary_reload].secondary_in_icode;

              if (tertiary_icode != CODE_FOR_nothing)
                {
                  rtx third_reload_reg
                    = rld[rld[secondary_reload].secondary_in_reload].reg_rtx;

                  emit_insn ((GEN_FCN (tertiary_icode)
                              (second_reload_reg, real_oldequiv,
                               third_reload_reg)));
                }
              else
                gen_reload (second_reload_reg, real_oldequiv,
                            rl->opnum,
                            rl->when_needed);

              oldequiv = second_reload_reg;
            }
        }
    }
#endif

  if (! special && ! rtx_equal_p (reloadreg, oldequiv))
    {
      rtx real_oldequiv = oldequiv;

      if ((GET_CODE (oldequiv) == REG
           && REGNO (oldequiv) >= FIRST_PSEUDO_REGISTER
           && (reg_equiv_memory_loc[REGNO (oldequiv)] != 0
               || reg_equiv_constant[REGNO (oldequiv)] != 0))
          || (GET_CODE (oldequiv) == SUBREG
              && GET_CODE (SUBREG_REG (oldequiv)) == REG
              && (REGNO (SUBREG_REG (oldequiv))
                  >= FIRST_PSEUDO_REGISTER)
              && ((reg_equiv_memory_loc
                   [REGNO (SUBREG_REG (oldequiv))] != 0)
                  || (reg_equiv_constant
                      [REGNO (SUBREG_REG (oldequiv))] != 0))))
        real_oldequiv = rl->in;
      gen_reload (reloadreg, real_oldequiv, rl->opnum,
                  rl->when_needed);
    }

  /* End this sequence.  */
  *where = get_insns ();
  end_sequence ();

  /* Update reload_override_in so that delete_address_reloads_1
     can see the actual register usage.  */
  if (oldequiv_reg)
    reload_override_in[j] = oldequiv;
}

/* Generate insns to for the output reload RL, which is for the insn described
   by CHAIN and has the number J.  */
static void
emit_output_reload_insns (chain, rl, j)
     struct insn_chain *chain;
     struct reload *rl;
     int j;
{
  rtx reloadreg = rl->reg_rtx;
  rtx insn = chain->insn;
  int special = 0;
  rtx old = rl->out;
  enum machine_mode mode = GET_MODE (old);
  rtx p;

  if (rl->when_needed == RELOAD_OTHER)
    start_sequence ();
  else
    push_to_sequence (output_reload_insns[rl->opnum]);

  /* Determine the mode to reload in.
     See comments above (for input reloading).  */

  if (mode == VOIDmode)
    {
      /* VOIDmode should never happen for an output.  */
      if (asm_noperands (PATTERN (insn)) < 0)
        /* It's the compiler's fault.  */
        fatal_insn ("VOIDmode on an output", insn);
      error_for_asm (insn, "output operand is constant in `asm'");
      /* Prevent crash--use something we know is valid.  */
      mode = word_mode;
      old = gen_rtx_REG (mode, REGNO (reloadreg));
    }

  if (GET_MODE (reloadreg) != mode)
    reloadreg = gen_rtx_REG (mode, REGNO (reloadreg));

#ifdef SECONDARY_OUTPUT_RELOAD_CLASS

  /* If we need two reload regs, set RELOADREG to the intermediate
     one, since it will be stored into OLD.  We might need a secondary
     register only for an input reload, so check again here.  */

  if (rl->secondary_out_reload >= 0)
    {
      rtx real_old = old;

      if (GET_CODE (old) == REG && REGNO (old) >= FIRST_PSEUDO_REGISTER
          && reg_equiv_mem[REGNO (old)] != 0)
        real_old = reg_equiv_mem[REGNO (old)];

      if ((SECONDARY_OUTPUT_RELOAD_CLASS (rl->class,
                                          mode, real_old)
           != NO_REGS))
        {
          rtx second_reloadreg = reloadreg;
          reloadreg = rld[rl->secondary_out_reload].reg_rtx;

          /* See if RELOADREG is to be used as a scratch register
             or as an intermediate register.  */
          if (rl->secondary_out_icode != CODE_FOR_nothing)
            {
              emit_insn ((GEN_FCN (rl->secondary_out_icode)
                          (real_old, second_reloadreg, reloadreg)));
              special = 1;
            }
          else
            {
              /* See if we need both a scratch and intermediate reload
                 register.  */

              int secondary_reload = rl->secondary_out_reload;
              enum insn_code tertiary_icode
                = rld[secondary_reload].secondary_out_icode;

              if (GET_MODE (reloadreg) != mode)
                reloadreg = gen_rtx_REG (mode, REGNO (reloadreg));

              if (tertiary_icode != CODE_FOR_nothing)
                {
                  rtx third_reloadreg
                    = rld[rld[secondary_reload].secondary_out_reload].reg_rtx;
                  rtx tem;

                  /* Copy primary reload reg to secondary reload reg.
                     (Note that these have been swapped above, then
                     secondary reload reg to OLD using our insn.  */

                  /* If REAL_OLD is a paradoxical SUBREG, remove it
                     and try to put the opposite SUBREG on
                     RELOADREG.  */
                  if (GET_CODE (real_old) == SUBREG
                      && (GET_MODE_SIZE (GET_MODE (real_old))
                          > GET_MODE_SIZE (GET_MODE (SUBREG_REG (real_old))))
                      && 0 != (tem = gen_lowpart_common
                               (GET_MODE (SUBREG_REG (real_old)),
                                reloadreg)))
                    real_old = SUBREG_REG (real_old), reloadreg = tem;

                  gen_reload (reloadreg, second_reloadreg,
                              rl->opnum, rl->when_needed);
                  emit_insn ((GEN_FCN (tertiary_icode)
                              (real_old, reloadreg, third_reloadreg)));
                  special = 1;
                }

              else
                /* Copy between the reload regs here and then to
                   OUT later.  */

                gen_reload (reloadreg, second_reloadreg,
                            rl->opnum, rl->when_needed);
            }
        }
    }
#endif

  /* Output the last reload insn.  */
  if (! special)
    {
      rtx set;

      /* Don't output the last reload if OLD is not the dest of
         INSN and is in the src and is clobbered by INSN. */
      if (! flag_expensive_optimizations
          || GET_CODE (old) != REG
          || !(set = single_set (insn))
          || rtx_equal_p (old, SET_DEST (set))
          || !reg_mentioned_p (old, SET_SRC (set))
          || !regno_clobbered_p (REGNO (old), insn))
        gen_reload (old, reloadreg, rl->opnum,
                    rl->when_needed);
    }

  /* Look at all insns we emitted, just to be safe.  */
  for (p = get_insns (); p; p = NEXT_INSN (p))
    if (GET_RTX_CLASS (GET_CODE (p)) == 'i')
      {
        rtx pat = PATTERN (p);

        /* If this output reload doesn't come from a spill reg,
           clear any memory of reloaded copies of the pseudo reg.
           If this output reload comes from a spill reg,
           reg_has_output_reload will make this do nothing.  */
        note_stores (pat, forget_old_reloads_1, NULL);

        if (reg_mentioned_p (rl->reg_rtx, pat))
          {
            rtx set = single_set (insn);
            if (reload_spill_index[j] < 0
                && set
                && SET_SRC (set) == rl->reg_rtx)
              {
                int src = REGNO (SET_SRC (set));

                reload_spill_index[j] = src;
                SET_HARD_REG_BIT (reg_is_output_reload, src);
                if (find_regno_note (insn, REG_DEAD, src))
                  SET_HARD_REG_BIT (reg_reloaded_died, src);
              }
            if (REGNO (rl->reg_rtx) < FIRST_PSEUDO_REGISTER)
              {
                int s = rl->secondary_out_reload;
                set = single_set (p);
                /* If this reload copies only to the secondary reload
                   register, the secondary reload does the actual
                   store.  */
                if (s >= 0 && set == NULL_RTX)
                  ; /* We can't tell what function the secondary reload
                       has and where the actual store to the pseudo is
                       made; leave new_spill_reg_store alone.  */
                else if (s >= 0
                         && SET_SRC (set) == rl->reg_rtx
                         && SET_DEST (set) == rld[s].reg_rtx)
                  {
                    /* Usually the next instruction will be the
                       secondary reload insn;  if we can confirm
                       that it is, setting new_spill_reg_store to
                       that insn will allow an extra optimization.  */
                    rtx s_reg = rld[s].reg_rtx;
                    rtx next = NEXT_INSN (p);
                    rld[s].out = rl->out;
                    rld[s].out_reg = rl->out_reg;
                    set = single_set (next);
                    if (set && SET_SRC (set) == s_reg
                        && ! new_spill_reg_store[REGNO (s_reg)])
                      {
                        SET_HARD_REG_BIT (reg_is_output_reload,
                                          REGNO (s_reg));
                        new_spill_reg_store[REGNO (s_reg)] = next;
                      }
                  }
                else
                  new_spill_reg_store[REGNO (rl->reg_rtx)] = p;
              }
          }
      }

  if (rl->when_needed == RELOAD_OTHER)
    {
      emit_insns (other_output_reload_insns[rl->opnum]);
      other_output_reload_insns[rl->opnum] = get_insns ();
    }
  else
    output_reload_insns[rl->opnum] = get_insns ();

  end_sequence (); 
}

/* Do input reloading for reload RL, which is for the insn described by CHAIN
   and has the number J.  */
static void
do_input_reload (chain, rl, j)
     struct insn_chain *chain;
     struct reload *rl;
     int j;
{
  int expect_occurrences = 1;
  rtx insn = chain->insn;
  rtx old = (rl->in && GET_CODE (rl->in) == MEM
             ? rl->in_reg : rl->in);

  if (old != 0
      /* AUTO_INC reloads need to be handled even if inherited.  We got an
         AUTO_INC reload if reload_out is set but reload_out_reg isn't.  */
      && (! reload_inherited[j] || (rl->out && ! rl->out_reg))
      && ! rtx_equal_p (rl->reg_rtx, old)
      && rl->reg_rtx != 0)
    emit_input_reload_insns (chain, rld + j, old, j);

  /* When inheriting a wider reload, we have a MEM in rl->in,
     e.g. inheriting a SImode output reload for
     (mem:HI (plus:SI (reg:SI 14 fp) (const_int 10)))  */
  if (optimize && reload_inherited[j] && rl->in
      && GET_CODE (rl->in) == MEM
      && GET_CODE (rl->in_reg) == MEM
      && reload_spill_index[j] >= 0
      && TEST_HARD_REG_BIT (reg_reloaded_valid, reload_spill_index[j]))
    {
      expect_occurrences
        = count_occurrences (PATTERN (insn), rl->in) == 1 ? 0 : -1;
      rl->in
        = regno_reg_rtx[reg_reloaded_contents[reload_spill_index[j]]];
    }

  /* If we are reloading a register that was recently stored in with an
     output-reload, see if we can prove there was
     actually no need to store the old value in it.  */

  if (optimize
      && (reload_inherited[j] || reload_override_in[j])
      && rl->reg_rtx
      && GET_CODE (rl->reg_rtx) == REG
      && spill_reg_store[REGNO (rl->reg_rtx)] != 0
#if 0
      /* There doesn't seem to be any reason to restrict this to pseudos
         and doing so loses in the case where we are copying from a
         register of the wrong class.  */
      && (REGNO (spill_reg_stored_to[REGNO (rl->reg_rtx)])
          >= FIRST_PSEUDO_REGISTER)
#endif
      /* The insn might have already some references to stackslots
         replaced by MEMs, while reload_out_reg still names the
         original pseudo.  */
      && (dead_or_set_p (insn,
                         spill_reg_stored_to[REGNO (rl->reg_rtx)])
          || rtx_equal_p (spill_reg_stored_to[REGNO (rl->reg_rtx)],
                          rl->out_reg)))
    delete_output_reload (insn, j, REGNO (rl->reg_rtx));
}

/* Do output reloading for reload RL, which is for the insn described by
   CHAIN and has the number J.
   ??? At some point we need to support handling output reloads of
   JUMP_INSNs or insns that set cc0.  */
static void
do_output_reload (chain, rl, j)
     struct insn_chain *chain;
     struct reload *rl;
     int j;
{
  rtx note, old;
  rtx insn = chain->insn;
  /* If this is an output reload that stores something that is
     not loaded in this same reload, see if we can eliminate a previous
     store.  */
  rtx pseudo = rl->out_reg;

  if (pseudo
      && GET_CODE (pseudo) == REG
      && ! rtx_equal_p (rl->in_reg, pseudo)
      && REGNO (pseudo) >= FIRST_PSEUDO_REGISTER
      && reg_last_reload_reg[REGNO (pseudo)])
    {
      int pseudo_no = REGNO (pseudo);
      int last_regno = REGNO (reg_last_reload_reg[pseudo_no]);

      /* We don't need to test full validity of last_regno for
         inherit here; we only want to know if the store actually
         matches the pseudo.  */
      if (TEST_HARD_REG_BIT (reg_reloaded_valid, last_regno)
          && reg_reloaded_contents[last_regno] == pseudo_no
          && spill_reg_store[last_regno]
          && rtx_equal_p (pseudo, spill_reg_stored_to[last_regno]))
        delete_output_reload (insn, j, last_regno);
    }

  old = rl->out_reg;
  if (old == 0
      || rl->reg_rtx == old
      || rl->reg_rtx == 0)
    return;

  /* An output operand that dies right away does need a reload,
     but need not be copied from it.  Show the new location in the
     REG_UNUSED note.  */
  if ((GET_CODE (old) == REG || GET_CODE (old) == SCRATCH)
      && (note = find_reg_note (insn, REG_UNUSED, old)) != 0)
    {
      XEXP (note, 0) = rl->reg_rtx;
      return;
    }
  /* Likewise for a SUBREG of an operand that dies.  */
  else if (GET_CODE (old) == SUBREG
           && GET_CODE (SUBREG_REG (old)) == REG
           && 0 != (note = find_reg_note (insn, REG_UNUSED,
                                          SUBREG_REG (old))))
    {
      XEXP (note, 0) = gen_lowpart_common (GET_MODE (old),
                                           rl->reg_rtx);
      return;
    }
  else if (GET_CODE (old) == SCRATCH)
    /* If we aren't optimizing, there won't be a REG_UNUSED note,
       but we don't want to make an output reload.  */
    return;

  /* If is a JUMP_INSN, we can't support output reloads yet.  */
  if (GET_CODE (insn) == JUMP_INSN)
    abort ();

  emit_output_reload_insns (chain, rld + j, j);
}

/* Output insns to reload values in and out of the chosen reload regs.  */

static void
emit_reload_insns (chain)
     struct insn_chain *chain;
{
  rtx insn = chain->insn;

  register int j;
  rtx following_insn = NEXT_INSN (insn);
  rtx before_insn = PREV_INSN (insn);

  CLEAR_HARD_REG_SET (reg_reloaded_died);

  for (j = 0; j < reload_n_operands; j++)
    input_reload_insns[j] = input_address_reload_insns[j]
      = inpaddr_address_reload_insns[j]
      = output_reload_insns[j] = output_address_reload_insns[j]
      = outaddr_address_reload_insns[j]
      = other_output_reload_insns[j] = 0;
  other_input_address_reload_insns = 0;
  other_input_reload_insns = 0;
  operand_reload_insns = 0;
  other_operand_reload_insns = 0;

  /* Now output the instructions to copy the data into and out of the
     reload registers.  Do these in the order that the reloads were reported,
     since reloads of base and index registers precede reloads of operands
     and the operands may need the base and index registers reloaded.  */

  for (j = 0; j < n_reloads; j++)
    {
      if (rld[j].reg_rtx
          && REGNO (rld[j].reg_rtx) < FIRST_PSEUDO_REGISTER)
        new_spill_reg_store[REGNO (rld[j].reg_rtx)] = 0;

      do_input_reload (chain, rld + j, j);
      do_output_reload (chain, rld + j, j);
    }

  /* Now write all the insns we made for reloads in the order expected by
     the allocation functions.  Prior to the insn being reloaded, we write
     the following reloads:

     RELOAD_FOR_OTHER_ADDRESS reloads for input addresses.

     RELOAD_OTHER reloads.

     For each operand, any RELOAD_FOR_INPADDR_ADDRESS reloads followed
     by any RELOAD_FOR_INPUT_ADDRESS reloads followed by the
     RELOAD_FOR_INPUT reload for the operand.

     RELOAD_FOR_OPADDR_ADDRS reloads.

     RELOAD_FOR_OPERAND_ADDRESS reloads.

     After the insn being reloaded, we write the following:

     For each operand, any RELOAD_FOR_OUTADDR_ADDRESS reloads followed
     by any RELOAD_FOR_OUTPUT_ADDRESS reload followed by the
     RELOAD_FOR_OUTPUT reload, followed by any RELOAD_OTHER output
     reloads for the operand.  The RELOAD_OTHER output reloads are
     output in descending order by reload number.  */

  emit_insns_before (other_input_address_reload_insns, insn);
  emit_insns_before (other_input_reload_insns, insn);

  for (j = 0; j < reload_n_operands; j++)
    {
      emit_insns_before (inpaddr_address_reload_insns[j], insn);
      emit_insns_before (input_address_reload_insns[j], insn);
      emit_insns_before (input_reload_insns[j], insn);
    }

  emit_insns_before (other_operand_reload_insns, insn);
  emit_insns_before (operand_reload_insns, insn);

  for (j = 0; j < reload_n_operands; j++)
    {
      emit_insns_before (outaddr_address_reload_insns[j], following_insn);
      emit_insns_before (output_address_reload_insns[j], following_insn);
      emit_insns_before (output_reload_insns[j], following_insn);
      emit_insns_before (other_output_reload_insns[j], following_insn);
    }

  /* Keep basic block info up to date.  */
  if (n_basic_blocks)
    {
      if (BLOCK_HEAD (chain->block) == insn)
        BLOCK_HEAD (chain->block) = NEXT_INSN (before_insn);
      if (BLOCK_END (chain->block) == insn)
        BLOCK_END (chain->block) = PREV_INSN (following_insn);
    }

  /* For all the spill regs newly reloaded in this instruction,
     record what they were reloaded from, so subsequent instructions
     can inherit the reloads.

     Update spill_reg_store for the reloads of this insn.
     Copy the elements that were updated in the loop above.  */

  for (j = 0; j < n_reloads; j++)
    {
      register int r = reload_order[j];
      register int i = reload_spill_index[r];

      /* If this is a non-inherited input reload from a pseudo, we must
         clear any memory of a previous store to the same pseudo.  Only do
         something if there will not be an output reload for the pseudo
         being reloaded.  */
      if (rld[r].in_reg != 0
          && ! (reload_inherited[r] || reload_override_in[r]))
        {
          rtx reg = rld[r].in_reg;

          if (GET_CODE (reg) == SUBREG)
            reg = SUBREG_REG (reg);

          if (GET_CODE (reg) == REG
              && REGNO (reg) >= FIRST_PSEUDO_REGISTER
              && ! reg_has_output_reload[REGNO (reg)])
            {
              int nregno = REGNO (reg);

              if (reg_last_reload_reg[nregno])
                {
                  int last_regno = REGNO (reg_last_reload_reg[nregno]);

                  if (reg_reloaded_contents[last_regno] == nregno)
                    spill_reg_store[last_regno] = 0;
                }
            }
        }

      /* I is nonneg if this reload used a register.
         If rld[r].reg_rtx is 0, this is an optional reload
         that we opted to ignore.  */

      if (i >= 0 && rld[r].reg_rtx != 0)
        {
          int nr
            = HARD_REGNO_NREGS (i, GET_MODE (rld[r].reg_rtx));
          int k;
          int part_reaches_end = 0;
          int all_reaches_end = 1;

          /* For a multi register reload, we need to check if all or part
             of the value lives to the end.  */
          for (k = 0; k < nr; k++)
            {
              if (reload_reg_reaches_end_p (i + k, rld[r].opnum,
                                            rld[r].when_needed))
                part_reaches_end = 1;
              else
                all_reaches_end = 0;
            }

          /* Ignore reloads that don't reach the end of the insn in
             entirety.  */
          if (all_reaches_end)
            {
              /* First, clear out memory of what used to be in this spill reg.
                 If consecutive registers are used, clear them all.  */

              for (k = 0; k < nr; k++)
                CLEAR_HARD_REG_BIT (reg_reloaded_valid, i + k);

              /* Maybe the spill reg contains a copy of reload_out.  */
              if (rld[r].out != 0
                  && (GET_CODE (rld[r].out) == REG
#ifdef AUTO_INC_DEC
                      || ! rld[r].out_reg
#endif
                      || GET_CODE (rld[r].out_reg) == REG))
                {
                  rtx out = (GET_CODE (rld[r].out) == REG
                             ? rld[r].out
                             : rld[r].out_reg
                             ? rld[r].out_reg
/* AUTO_INC */               : XEXP (rld[r].in_reg, 0));
                  register int nregno = REGNO (out);
                  int nnr = (nregno >= FIRST_PSEUDO_REGISTER ? 1
                             : HARD_REGNO_NREGS (nregno,
                                                 GET_MODE (rld[r].reg_rtx)));

                  spill_reg_store[i] = new_spill_reg_store[i];
                  spill_reg_stored_to[i] = out;
                  reg_last_reload_reg[nregno] = rld[r].reg_rtx;

                  /* If NREGNO is a hard register, it may occupy more than
                     one register.  If it does, say what is in the
                     rest of the registers assuming that both registers
                     agree on how many words the object takes.  If not,
                     invalidate the subsequent registers.  */

                  if (nregno < FIRST_PSEUDO_REGISTER)
                    for (k = 1; k < nnr; k++)
                      reg_last_reload_reg[nregno + k]
                        = (nr == nnr
                           ? gen_rtx_REG (reg_raw_mode[REGNO (rld[r].reg_rtx) + k],
                                          REGNO (rld[r].reg_rtx) + k)
                           : 0);

                  /* Now do the inverse operation.  */
                  for (k = 0; k < nr; k++)
                    {
                      CLEAR_HARD_REG_BIT (reg_reloaded_dead, i + k);
                      reg_reloaded_contents[i + k]
                        = (nregno >= FIRST_PSEUDO_REGISTER || nr != nnr
                           ? nregno
                           : nregno + k);
                      reg_reloaded_insn[i + k] = insn;
                      SET_HARD_REG_BIT (reg_reloaded_valid, i + k);
                    }
                }

              /* Maybe the spill reg contains a copy of reload_in.  Only do
                 something if there will not be an output reload for
                 the register being reloaded.  */
              else if (rld[r].out_reg == 0
                       && rld[r].in != 0
                       && ((GET_CODE (rld[r].in) == REG
                            && REGNO (rld[r].in) >= FIRST_PSEUDO_REGISTER
                            && ! reg_has_output_reload[REGNO (rld[r].in)])
                           || (GET_CODE (rld[r].in_reg) == REG
                               && ! reg_has_output_reload[REGNO (rld[r].in_reg)]))
                       && ! reg_set_p (rld[r].reg_rtx, PATTERN (insn)))
                {
                  register int nregno;
                  int nnr;

                  if (GET_CODE (rld[r].in) == REG
                      && REGNO (rld[r].in) >= FIRST_PSEUDO_REGISTER)
                    nregno = REGNO (rld[r].in);
                  else if (GET_CODE (rld[r].in_reg) == REG)
                    nregno = REGNO (rld[r].in_reg);
                  else
                    nregno = REGNO (XEXP (rld[r].in_reg, 0));

                  nnr = (nregno >= FIRST_PSEUDO_REGISTER ? 1
                         : HARD_REGNO_NREGS (nregno,
                                             GET_MODE (rld[r].reg_rtx)));

                  reg_last_reload_reg[nregno] = rld[r].reg_rtx;

                  if (nregno < FIRST_PSEUDO_REGISTER)
                    for (k = 1; k < nnr; k++)
                      reg_last_reload_reg[nregno + k]
                        = (nr == nnr
                           ? gen_rtx_REG (reg_raw_mode[REGNO (rld[r].reg_rtx) + k],
                                          REGNO (rld[r].reg_rtx) + k)
                           : 0);

                  /* Unless we inherited this reload, show we haven't
                     recently done a store.
                     Previous stores of inherited auto_inc expressions
                     also have to be discarded.  */
                  if (! reload_inherited[r]
                      || (rld[r].out && ! rld[r].out_reg))
                    spill_reg_store[i] = 0;

                  for (k = 0; k < nr; k++)
                    {
                      CLEAR_HARD_REG_BIT (reg_reloaded_dead, i + k);
                      reg_reloaded_contents[i + k]
                        = (nregno >= FIRST_PSEUDO_REGISTER || nr != nnr
                           ? nregno
                           : nregno + k);
                      reg_reloaded_insn[i + k] = insn;
                      SET_HARD_REG_BIT (reg_reloaded_valid, i + k);
                    }
                }
            }

          /* However, if part of the reload reaches the end, then we must
             invalidate the old info for the part that survives to the end.  */
          else if (part_reaches_end)
            {
              for (k = 0; k < nr; k++)
                if (reload_reg_reaches_end_p (i + k,
                                              rld[r].opnum,
                                              rld[r].when_needed))
                  CLEAR_HARD_REG_BIT (reg_reloaded_valid, i + k);
            }
        }

      /* The following if-statement was #if 0'd in 1.34 (or before...).
         It's reenabled in 1.35 because supposedly nothing else
         deals with this problem.  */

      /* If a register gets output-reloaded from a non-spill register,
         that invalidates any previous reloaded copy of it.
         But forget_old_reloads_1 won't get to see it, because
         it thinks only about the original insn.  So invalidate it here.  */
      if (i < 0 && rld[r].out != 0
          && (GET_CODE (rld[r].out) == REG
              || (GET_CODE (rld[r].out) == MEM
                  && GET_CODE (rld[r].out_reg) == REG)))
        {
          rtx out = (GET_CODE (rld[r].out) == REG
                     ? rld[r].out : rld[r].out_reg);
          register int nregno = REGNO (out);
          if (nregno >= FIRST_PSEUDO_REGISTER)
            {
              rtx src_reg, store_insn = NULL_RTX;

              reg_last_reload_reg[nregno] = 0;

              /* If we can find a hard register that is stored, record
                 the storing insn so that we may delete this insn with
                 delete_output_reload.  */
              src_reg = rld[r].reg_rtx;

              /* If this is an optional reload, try to find the source reg
                 from an input reload.  */
              if (! src_reg)
                {
                  rtx set = single_set (insn);
                  if (set && SET_DEST (set) == rld[r].out)
                    {
                      int k;

                      src_reg = SET_SRC (set);
                      store_insn = insn;
                      for (k = 0; k < n_reloads; k++)
                        {
                          if (rld[k].in == src_reg)
                            {
                              src_reg = rld[k].reg_rtx;
                              break;
                            }
                        }
                    }
                }
              else
                store_insn = new_spill_reg_store[REGNO (src_reg)];
              if (src_reg && GET_CODE (src_reg) == REG
                  && REGNO (src_reg) < FIRST_PSEUDO_REGISTER)
                {
                  int src_regno = REGNO (src_reg);
                  int nr = HARD_REGNO_NREGS (src_regno, rld[r].mode);
                  /* The place where to find a death note varies with
                     PRESERVE_DEATH_INFO_REGNO_P .  The condition is not
                     necessarily checked exactly in the code that moves
                     notes, so just check both locations.  */
                  rtx note = find_regno_note (insn, REG_DEAD, src_regno);
                  if (! note)
                    note = find_regno_note (store_insn, REG_DEAD, src_regno);
                  while (nr-- > 0)
                    {
                      spill_reg_store[src_regno + nr] = store_insn;
                      spill_reg_stored_to[src_regno + nr] = out;
                      reg_reloaded_contents[src_regno + nr] = nregno;
                      reg_reloaded_insn[src_regno + nr] = store_insn;
                      CLEAR_HARD_REG_BIT (reg_reloaded_dead, src_regno + nr);
                      SET_HARD_REG_BIT (reg_reloaded_valid, src_regno + nr);
                      SET_HARD_REG_BIT (reg_is_output_reload, src_regno + nr);
                      if (note)
                        SET_HARD_REG_BIT (reg_reloaded_died, src_regno);
                      else
                        CLEAR_HARD_REG_BIT (reg_reloaded_died, src_regno);
                    }
                  reg_last_reload_reg[nregno] = src_reg;
                }
            }
          else
            {
              int num_regs = HARD_REGNO_NREGS (nregno,GET_MODE (rld[r].out));

              while (num_regs-- > 0)
                reg_last_reload_reg[nregno + num_regs] = 0;
            }
        }
    }
  IOR_HARD_REG_SET (reg_reloaded_dead, reg_reloaded_died);
}
\f
/* Emit code to perform a reload from IN (which may be a reload register) to
   OUT (which may also be a reload register).  IN or OUT is from operand
   OPNUM with reload type TYPE.

   Returns first insn emitted.  */

rtx
gen_reload (out, in, opnum, type)
     rtx out;
     rtx in;
     int opnum;
     enum reload_type type;
{
  rtx last = get_last_insn ();
  rtx tem;

  /* If IN is a paradoxical SUBREG, remove it and try to put the
     opposite SUBREG on OUT.  Likewise for a paradoxical SUBREG on OUT.  */
  if (GET_CODE (in) == SUBREG
      && (GET_MODE_SIZE (GET_MODE (in))
          > GET_MODE_SIZE (GET_MODE (SUBREG_REG (in))))
      && (tem = gen_lowpart_common (GET_MODE (SUBREG_REG (in)), out)) != 0)
    in = SUBREG_REG (in), out = tem;
  else if (GET_CODE (out) == SUBREG
           && (GET_MODE_SIZE (GET_MODE (out))
               > GET_MODE_SIZE (GET_MODE (SUBREG_REG (out))))
           && (tem = gen_lowpart_common (GET_MODE (SUBREG_REG (out)), in)) != 0)
    out = SUBREG_REG (out), in = tem;

  /* How to do this reload can get quite tricky.  Normally, we are being
     asked to reload a simple operand, such as a MEM, a constant, or a pseudo
     register that didn't get a hard register.  In that case we can just
     call emit_move_insn.

     We can also be asked to reload a PLUS that adds a register or a MEM to
     another register, constant or MEM.  This can occur during frame pointer
     elimination and while reloading addresses.  This case is handled by
     trying to emit a single insn to perform the add.  If it is not valid,
     we use a two insn sequence.

     Finally, we could be called to handle an 'o' constraint by putting
     an address into a register.  In that case, we first try to do this
     with a named pattern of "reload_load_address".  If no such pattern
     exists, we just emit a SET insn and hope for the best (it will normally
     be valid on machines that use 'o').

     This entire process is made complex because reload will never
     process the insns we generate here and so we must ensure that
     they will fit their constraints and also by the fact that parts of
     IN might be being reloaded separately and replaced with spill registers.
     Because of this, we are, in some sense, just guessing the right approach
     here.  The one listed above seems to work.

     ??? At some point, this whole thing needs to be rethought.  */

  if (GET_CODE (in) == PLUS
      && (GET_CODE (XEXP (in, 0)) == REG
          || GET_CODE (XEXP (in, 0)) == SUBREG
          || GET_CODE (XEXP (in, 0)) == MEM)
      && (GET_CODE (XEXP (in, 1)) == REG
          || GET_CODE (XEXP (in, 1)) == SUBREG
          || CONSTANT_P (XEXP (in, 1))
          || GET_CODE (XEXP (in, 1)) == MEM))
    {
      /* We need to compute the sum of a register or a MEM and another
         register, constant, or MEM, and put it into the reload
         register.  The best possible way of doing this is if the machine
         has a three-operand ADD insn that accepts the required operands.

         The simplest approach is to try to generate such an insn and see if it
         is recognized and matches its constraints.  If so, it can be used.

         It might be better not to actually emit the insn unless it is valid,
         but we need to pass the insn as an operand to `recog' and
         `extract_insn' and it is simpler to emit and then delete the insn if
         not valid than to dummy things up.  */

      rtx op0, op1, tem, insn;
      int code;

      op0 = find_replacement (&XEXP (in, 0));
      op1 = find_replacement (&XEXP (in, 1));

      /* Since constraint checking is strict, commutativity won't be
         checked, so we need to do that here to avoid spurious failure
         if the add instruction is two-address and the second operand
         of the add is the same as the reload reg, which is frequently
         the case.  If the insn would be A = B + A, rearrange it so
         it will be A = A + B as constrain_operands expects.  */

      if (GET_CODE (XEXP (in, 1)) == REG
          && REGNO (out) == REGNO (XEXP (in, 1)))
        tem = op0, op0 = op1, op1 = tem;

      if (op0 != XEXP (in, 0) || op1 != XEXP (in, 1))
        in = gen_rtx_PLUS (GET_MODE (in), op0, op1);

      insn = emit_insn (gen_rtx_SET (VOIDmode, out, in));
      code = recog_memoized (insn);

      if (code >= 0)
        {
          extract_insn (insn);
          /* We want constrain operands to treat this insn strictly in
             its validity determination, i.e., the way it would after reload
             has completed.  */
          if (constrain_operands (1))
            return insn;
        }

      delete_insns_since (last);

      /* If that failed, we must use a conservative two-insn sequence.

         Use a move to copy one operand into the reload register.  Prefer
         to reload a constant, MEM or pseudo since the move patterns can
         handle an arbitrary operand.  If OP1 is not a constant, MEM or
         pseudo and OP1 is not a valid operand for an add instruction, then
         reload OP1.

         After reloading one of the operands into the reload register, add
         the reload register to the output register.

         If there is another way to do this for a specific machine, a
         DEFINE_PEEPHOLE should be specified that recognizes the sequence
         we emit below.  */

      code = (int) add_optab->handlers[(int) GET_MODE (out)].insn_code;

      if (CONSTANT_P (op1) || GET_CODE (op1) == MEM || GET_CODE (op1) == SUBREG
          || (GET_CODE (op1) == REG
              && REGNO (op1) >= FIRST_PSEUDO_REGISTER)
          || (code != CODE_FOR_nothing
              && ! ((*insn_data[code].operand[2].predicate)
                    (op1, insn_data[code].operand[2].mode))))
        tem = op0, op0 = op1, op1 = tem;

      gen_reload (out, op0, opnum, type);

      /* If OP0 and OP1 are the same, we can use OUT for OP1.
         This fixes a problem on the 32K where the stack pointer cannot
         be used as an operand of an add insn.  */

      if (rtx_equal_p (op0, op1))
        op1 = out;

      insn = emit_insn (gen_add2_insn (out, op1));

      /* If that failed, copy the address register to the reload register.
         Then add the constant to the reload register.  */

      code = recog_memoized (insn);

      if (code >= 0)
        {
          extract_insn (insn);
          /* We want constrain operands to treat this insn strictly in
             its validity determination, i.e., the way it would after reload
             has completed.  */
          if (constrain_operands (1))
            {
              /* Add a REG_EQUIV note so that find_equiv_reg can find it.  */
              REG_NOTES (insn)
                = gen_rtx_EXPR_LIST (REG_EQUIV, in, REG_NOTES (insn));
              return insn;
            }
        }

      delete_insns_since (last);

      gen_reload (out, op1, opnum, type);
      insn = emit_insn (gen_add2_insn (out, op0));
      REG_NOTES (insn) = gen_rtx_EXPR_LIST (REG_EQUIV, in, REG_NOTES (insn));
    }

#ifdef SECONDARY_MEMORY_NEEDED
  /* If we need a memory location to do the move, do it that way.  */
  else if (GET_CODE (in) == REG && REGNO (in) < FIRST_PSEUDO_REGISTER
           && GET_CODE (out) == REG && REGNO (out) < FIRST_PSEUDO_REGISTER
           && SECONDARY_MEMORY_NEEDED (REGNO_REG_CLASS (REGNO (in)),
                                       REGNO_REG_CLASS (REGNO (out)),
                                       GET_MODE (out)))
    {
      /* Get the memory to use and rewrite both registers to its mode.  */
      rtx loc = get_secondary_mem (in, GET_MODE (out), opnum, type);

      if (GET_MODE (loc) != GET_MODE (out))
        out = gen_rtx_REG (GET_MODE (loc), REGNO (out));

      if (GET_MODE (loc) != GET_MODE (in))
        in = gen_rtx_REG (GET_MODE (loc), REGNO (in));

      gen_reload (loc, in, opnum, type);
      gen_reload (out, loc, opnum, type);
    }
#endif

  /* If IN is a simple operand, use gen_move_insn.  */
  else if (GET_RTX_CLASS (GET_CODE (in)) == 'o' || GET_CODE (in) == SUBREG)
    emit_insn (gen_move_insn (out, in));

#ifdef HAVE_reload_load_address
  else if (HAVE_reload_load_address)
    emit_insn (gen_reload_load_address (out, in));
#endif

  /* Otherwise, just write (set OUT IN) and hope for the best.  */
  else
    emit_insn (gen_rtx_SET (VOIDmode, out, in));

  /* Return the first insn emitted.
     We can not just return get_last_insn, because there may have
     been multiple instructions emitted.  Also note that gen_move_insn may
     emit more than one insn itself, so we can not assume that there is one
     insn emitted per emit_insn_before call.  */

  return last ? NEXT_INSN (last) : get_insns ();
}
\f
/* Delete a previously made output-reload
   whose result we now believe is not needed.
   First we double-check.

   INSN is the insn now being processed.
   LAST_RELOAD_REG is the hard register number for which we want to delete
   the last output reload.
   J is the reload-number that originally used REG.  The caller has made
   certain that reload J doesn't use REG any longer for input.  */

static void
delete_output_reload (insn, j, last_reload_reg)
     rtx insn;
     int j;
     int last_reload_reg;
{
  rtx output_reload_insn = spill_reg_store[last_reload_reg];
  rtx reg = spill_reg_stored_to[last_reload_reg];
  int k;
  int n_occurrences;
  int n_inherited = 0;
  register rtx i1;
  rtx substed;

  /* Get the raw pseudo-register referred to.  */

  while (GET_CODE (reg) == SUBREG)
    reg = SUBREG_REG (reg);
  substed = reg_equiv_memory_loc[REGNO (reg)];

  /* This is unsafe if the operand occurs more often in the current
     insn than it is inherited.  */
  for (k = n_reloads - 1; k >= 0; k--)
    {
      rtx reg2 = rld[k].in;
      if (! reg2)
        continue;
      if (GET_CODE (reg2) == MEM || reload_override_in[k])
        reg2 = rld[k].in_reg;
#ifdef AUTO_INC_DEC
      if (rld[k].out && ! rld[k].out_reg)
        reg2 = XEXP (rld[k].in_reg, 0);
#endif
      while (GET_CODE (reg2) == SUBREG)
        reg2 = SUBREG_REG (reg2);
      if (rtx_equal_p (reg2, reg))
        {
          if (reload_inherited[k] || reload_override_in[k] || k == j)
            {
              n_inherited++;
              reg2 = rld[k].out_reg;
              if (! reg2)
                continue;
              while (GET_CODE (reg2) == SUBREG)
                reg2 = XEXP (reg2, 0);
              if (rtx_equal_p (reg2, reg))
                n_inherited++;
            }
          else
            return;
        }
    }
  n_occurrences = count_occurrences (PATTERN (insn), reg);
  if (substed)
    n_occurrences += count_occurrences (PATTERN (insn), substed);
  if (n_occurrences > n_inherited)
    return;

  /* If the pseudo-reg we are reloading is no longer referenced
     anywhere between the store into it and here,
     and no jumps or labels intervene, then the value can get
     here through the reload reg alone.
     Otherwise, give up--return.  */
  for (i1 = NEXT_INSN (output_reload_insn);
       i1 != insn; i1 = NEXT_INSN (i1))
    {
      if (GET_CODE (i1) == CODE_LABEL || GET_CODE (i1) == JUMP_INSN)
        return;
      if ((GET_CODE (i1) == INSN || GET_CODE (i1) == CALL_INSN)
          && reg_mentioned_p (reg, PATTERN (i1)))
        {
          /* If this is USE in front of INSN, we only have to check that
             there are no more references than accounted for by inheritance.  */
          while (GET_CODE (i1) == INSN && GET_CODE (PATTERN (i1)) == USE)
            {
              n_occurrences += rtx_equal_p (reg, XEXP (PATTERN (i1), 0)) != 0;
              i1 = NEXT_INSN (i1);
            }
          if (n_occurrences <= n_inherited && i1 == insn)
            break;
          return;
        }
    }

  /* The caller has already checked that REG dies or is set in INSN.
     It has also checked that we are optimizing, and thus some inaccurancies
     in the debugging information are acceptable.
     So we could just delete output_reload_insn.
     But in some cases we can improve the debugging information without
     sacrificing optimization - maybe even improving the code:
     See if the pseudo reg has been completely replaced
     with reload regs.  If so, delete the store insn
     and forget we had a stack slot for the pseudo.  */
  if (rld[j].out != rld[j].in
      && REG_N_DEATHS (REGNO (reg)) == 1
      && REG_N_SETS (REGNO (reg)) == 1
      && REG_BASIC_BLOCK (REGNO (reg)) >= 0
      && find_regno_note (insn, REG_DEAD, REGNO (reg)))
    {
      rtx i2;

      /* We know that it was used only between here
         and the beginning of the current basic block.
         (We also know that the last use before INSN was
         the output reload we are thinking of deleting, but never mind that.)
         Search that range; see if any ref remains.  */
      for (i2 = PREV_INSN (insn); i2; i2 = PREV_INSN (i2))
        {
          rtx set = single_set (i2);

          /* Uses which just store in the pseudo don't count,
             since if they are the only uses, they are dead.  */
          if (set != 0 && SET_DEST (set) == reg)
            continue;
          if (GET_CODE (i2) == CODE_LABEL
              || GET_CODE (i2) == JUMP_INSN)
            break;
          if ((GET_CODE (i2) == INSN || GET_CODE (i2) == CALL_INSN)
              && reg_mentioned_p (reg, PATTERN (i2)))
            {
              /* Some other ref remains; just delete the output reload we
                 know to be dead.  */
              delete_address_reloads (output_reload_insn, insn);
              PUT_CODE (output_reload_insn, NOTE);
              NOTE_SOURCE_FILE (output_reload_insn) = 0;
              NOTE_LINE_NUMBER (output_reload_insn) = NOTE_INSN_DELETED;
              return;
            }
        }

      /* Delete the now-dead stores into this pseudo.  */
      for (i2 = PREV_INSN (insn); i2; i2 = PREV_INSN (i2))
        {
          rtx set = single_set (i2);

          if (set != 0 && SET_DEST (set) == reg)
            {
              delete_address_reloads (i2, insn);
              /* This might be a basic block head,
                 thus don't use delete_insn.  */
              PUT_CODE (i2, NOTE);
              NOTE_SOURCE_FILE (i2) = 0;
              NOTE_LINE_NUMBER (i2) = NOTE_INSN_DELETED;
            }
          if (GET_CODE (i2) == CODE_LABEL
              || GET_CODE (i2) == JUMP_INSN)
            break;
        }

      /* For the debugging info,
         say the pseudo lives in this reload reg.  */
      reg_renumber[REGNO (reg)] = REGNO (rld[j].reg_rtx);
      alter_reg (REGNO (reg), -1);
    }
  delete_address_reloads (output_reload_insn, insn);
  PUT_CODE (output_reload_insn, NOTE);
  NOTE_SOURCE_FILE (output_reload_insn) = 0;
  NOTE_LINE_NUMBER (output_reload_insn) = NOTE_INSN_DELETED;

}

/* We are going to delete DEAD_INSN.  Recursively delete loads of
   reload registers used in DEAD_INSN that are not used till CURRENT_INSN.
   CURRENT_INSN is being reloaded, so we have to check its reloads too.  */
static void
delete_address_reloads (dead_insn, current_insn)
     rtx dead_insn, current_insn;
{
  rtx set = single_set (dead_insn);
  rtx set2, dst, prev, next;
  if (set)
    {
      rtx dst = SET_DEST (set);
      if (GET_CODE (dst) == MEM)
        delete_address_reloads_1 (dead_insn, XEXP (dst, 0), current_insn);
    }
  /* If we deleted the store from a reloaded post_{in,de}c expression,
     we can delete the matching adds.  */
  prev = PREV_INSN (dead_insn);
  next = NEXT_INSN (dead_insn);
  if (! prev || ! next)
    return;
  set = single_set (next);
  set2 = single_set (prev);
  if (! set || ! set2
      || GET_CODE (SET_SRC (set)) != PLUS || GET_CODE (SET_SRC (set2)) != PLUS
      || GET_CODE (XEXP (SET_SRC (set), 1)) != CONST_INT
      || GET_CODE (XEXP (SET_SRC (set2), 1)) != CONST_INT)
    return;
  dst = SET_DEST (set);
  if (! rtx_equal_p (dst, SET_DEST (set2))
      || ! rtx_equal_p (dst, XEXP (SET_SRC (set), 0))
      || ! rtx_equal_p (dst, XEXP (SET_SRC (set2), 0))
      || (INTVAL (XEXP (SET_SRC (set), 1))
          != - INTVAL (XEXP (SET_SRC (set2), 1))))
    return;
  delete_insn (prev);
  delete_insn (next);
}

/* Subfunction of delete_address_reloads: process registers found in X.  */
static void
delete_address_reloads_1 (dead_insn, x, current_insn)
     rtx dead_insn, x, current_insn;
{
  rtx prev, set, dst, i2;
  int i, j;
  enum rtx_code code = GET_CODE (x);

  if (code != REG)
    {
      const char *fmt= GET_RTX_FORMAT (code);
      for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
        {
          if (fmt[i] == 'e')
            delete_address_reloads_1 (dead_insn, XEXP (x, i), current_insn);
          else if (fmt[i] == 'E')
            {
              for (j = XVECLEN (x, i) - 1; j >=0; j--)
                delete_address_reloads_1 (dead_insn, XVECEXP (x, i, j),
                                          current_insn);
            }
        }
      return;
    }

  if (spill_reg_order[REGNO (x)] < 0)
    return;

  /* Scan backwards for the insn that sets x.  This might be a way back due
     to inheritance.  */
  for (prev = PREV_INSN (dead_insn); prev; prev = PREV_INSN (prev))
    {
      code = GET_CODE (prev);
      if (code == CODE_LABEL || code == JUMP_INSN)
        return;
      if (GET_RTX_CLASS (code) != 'i')
        continue;
      if (reg_set_p (x, PATTERN (prev)))
        break;
      if (reg_referenced_p (x, PATTERN (prev)))
        return;
    }
  if (! prev || INSN_UID (prev) < reload_first_uid)
    return;
  /* Check that PREV only sets the reload register.  */
  set = single_set (prev);
  if (! set)
    return;
  dst = SET_DEST (set);
  if (GET_CODE (dst) != REG
      || ! rtx_equal_p (dst, x))
    return;
  if (! reg_set_p (dst, PATTERN (dead_insn)))
    {
      /* Check if DST was used in a later insn -
         it might have been inherited.  */
      for (i2 = NEXT_INSN (dead_insn); i2; i2 = NEXT_INSN (i2))
        {
          if (GET_CODE (i2) == CODE_LABEL)
            break;
          if (GET_RTX_CLASS (GET_CODE (i2)) != 'i')
            continue;
          if (reg_referenced_p (dst, PATTERN (i2)))
            {
              /* If there is a reference to the register in the current insn,
                 it might be loaded in a non-inherited reload.  If no other
                 reload uses it, that means the register is set before
                 referenced.  */
              if (i2 == current_insn)
                {
                  for (j = n_reloads - 1; j >= 0; j--)
                    if ((rld[j].reg_rtx == dst && reload_inherited[j])
                        || reload_override_in[j] == dst)
                      return;
                  for (j = n_reloads - 1; j >= 0; j--)
                    if (rld[j].in && rld[j].reg_rtx == dst)
                      break;
                  if (j >= 0)
                    break;
                }
              return;
            }
          if (GET_CODE (i2) == JUMP_INSN)
            break;
          /* If DST is still live at CURRENT_INSN, check if it is used for
             any reload.  Note that even if CURRENT_INSN sets DST, we still
             have to check the reloads.  */
          if (i2 == current_insn)
            {
              for (j = n_reloads - 1; j >= 0; j--)
                if ((rld[j].reg_rtx == dst && reload_inherited[j])
                    || reload_override_in[j] == dst)
                  return;
              /* ??? We can't finish the loop here, because dst might be
                 allocated to a pseudo in this block if no reload in this
                 block needs any of the clsses containing DST - see
                 spill_hard_reg.  There is no easy way to tell this, so we
                 have to scan till the end of the basic block.  */
            }
          if (reg_set_p (dst, PATTERN (i2)))
            break;
        }
    }
  delete_address_reloads_1 (prev, SET_SRC (set), current_insn);
  reg_reloaded_contents[REGNO (dst)] = -1;
  /* Can't use delete_insn here because PREV might be a basic block head.  */
  PUT_CODE (prev, NOTE);
  NOTE_LINE_NUMBER (prev) = NOTE_INSN_DELETED;
  NOTE_SOURCE_FILE (prev) = 0;
}
\f
/* Output reload-insns to reload VALUE into RELOADREG.
   VALUE is an autoincrement or autodecrement RTX whose operand
   is a register or memory location;
   so reloading involves incrementing that location.
   IN is either identical to VALUE, or some cheaper place to reload from.

   INC_AMOUNT is the number to increment or decrement by (always positive).
   This cannot be deduced from VALUE.

   Return the instruction that stores into RELOADREG.  */

static rtx
inc_for_reload (reloadreg, in, value, inc_amount)
     rtx reloadreg;
     rtx in, value;
     int inc_amount;
{
  /* REG or MEM to be copied and incremented.  */
  rtx incloc = XEXP (value, 0);
  /* Nonzero if increment after copying.  */
  int post = (GET_CODE (value) == POST_DEC || GET_CODE (value) == POST_INC);
  rtx last;
  rtx inc;
  rtx add_insn;
  int code;
  rtx store;
  rtx real_in = in == value ? XEXP (in, 0) : in;

  /* No hard register is equivalent to this register after
     inc/dec operation.  If REG_LAST_RELOAD_REG were non-zero,
     we could inc/dec that register as well (maybe even using it for
     the source), but I'm not sure it's worth worrying about.  */
  if (GET_CODE (incloc) == REG)
    reg_last_reload_reg[REGNO (incloc)] = 0;

  if (GET_CODE (value) == PRE_DEC || GET_CODE (value) == POST_DEC)
    inc_amount = - inc_amount;

  inc = GEN_INT (inc_amount);

  /* If this is post-increment, first copy the location to the reload reg.  */
  if (post && real_in != reloadreg)
    emit_insn (gen_move_insn (reloadreg, real_in));

  if (in == value)
    {
      /* See if we can directly increment INCLOC.  Use a method similar to
         that in gen_reload.  */

      last = get_last_insn ();
      add_insn = emit_insn (gen_rtx_SET (VOIDmode, incloc,
                                         gen_rtx_PLUS (GET_MODE (incloc),
                                                       incloc, inc)));

      code = recog_memoized (add_insn);
      if (code >= 0)
        {
          extract_insn (add_insn);
          if (constrain_operands (1))
            {
              /* If this is a pre-increment and we have incremented the value
                 where it lives, copy the incremented value to RELOADREG to
                 be used as an address.  */

              if (! post)
                emit_insn (gen_move_insn (reloadreg, incloc));

              return add_insn;
            }
        }
      delete_insns_since (last);
    }

  /* If couldn't do the increment directly, must increment in RELOADREG.
     The way we do this depends on whether this is pre- or post-increment.
     For pre-increment, copy INCLOC to the reload register, increment it
     there, then save back.  */

  if (! post)
    {
      if (in != reloadreg)
        emit_insn (gen_move_insn (reloadreg, real_in));
      emit_insn (gen_add2_insn (reloadreg, inc));
      store = emit_insn (gen_move_insn (incloc, reloadreg));
    }
  else
    {
      /* Postincrement.
         Because this might be a jump insn or a compare, and because RELOADREG
         may not be available after the insn in an input reload, we must do
         the incrementation before the insn being reloaded for.

         We have already copied IN to RELOADREG.  Increment the copy in
         RELOADREG, save that back, then decrement RELOADREG so it has
         the original value.  */

      emit_insn (gen_add2_insn (reloadreg, inc));
      store = emit_insn (gen_move_insn (incloc, reloadreg));
      emit_insn (gen_add2_insn (reloadreg, GEN_INT (-inc_amount)));
    }

  return store;
}
\f
/* Return 1 if we are certain that the constraint-string STRING allows
   the hard register REG.  Return 0 if we can't be sure of this.  */

static int
constraint_accepts_reg_p (string, reg)
     const char *string;
     rtx reg;
{
  int value = 0;
  int regno = true_regnum (reg);
  int c;

  /* Initialize for first alternative.  */
  value = 0;
  /* Check that each alternative contains `g' or `r'.  */
  while (1)
    switch (c = *string++)
      {
      case 0:
        /* If an alternative lacks `g' or `r', we lose.  */
        return value;
      case ',':
        /* If an alternative lacks `g' or `r', we lose.  */
        if (value == 0)
          return 0;
        /* Initialize for next alternative.  */
        value = 0;
        break;
      case 'g':
      case 'r':
        /* Any general reg wins for this alternative.  */
        if (TEST_HARD_REG_BIT (reg_class_contents[(int) GENERAL_REGS], regno))
          value = 1;
        break;
      default:
        /* Any reg in specified class wins for this alternative.  */
        {
          enum reg_class class = REG_CLASS_FROM_LETTER (c);

          if (TEST_HARD_REG_BIT (reg_class_contents[(int) class], regno))
            value = 1;
        }
      }
}
\f
/* Return the number of places FIND appears within X, but don't count
   an occurrence if some SET_DEST is FIND.  */

int
count_occurrences (x, find)
     register rtx x, find;
{
  register int i, j;
  register enum rtx_code code;
  register const char *format_ptr;
  int count;

  if (x == find)
    return 1;
  if (x == 0)
    return 0;

  code = GET_CODE (x);

  switch (code)
    {
    case REG:
    case QUEUED:
    case CONST_INT:
    case CONST_DOUBLE:
    case SYMBOL_REF:
    case CODE_LABEL:
    case PC:
    case CC0:
      return 0;

    case MEM:
      if (GET_CODE (find) == MEM && rtx_equal_p (x, find))
        return 1;
      break;
    case SET:
      if (SET_DEST (x) == find)
        return count_occurrences (SET_SRC (x), find);
      break;

    default:
      break;
    }

  format_ptr = GET_RTX_FORMAT (code);
  count = 0;

  for (i = 0; i < GET_RTX_LENGTH (code); i++)
    {
      switch (*format_ptr++)
        {
        case 'e':
          count += count_occurrences (XEXP (x, i), find);
          break;

        case 'E':
          if (XVEC (x, i) != NULL)
            {
              for (j = 0; j < XVECLEN (x, i); j++)
                count += count_occurrences (XVECEXP (x, i, j), find);
            }
          break;
        }
    }
  return count;
}
\f
/* INSN is a no-op; delete it.
   If this sets the return value of the function, we must keep a USE around,
   in case this is in a different basic block than the final USE.  Otherwise,
   we could loose important register lifeness information on
   SMALL_REGISTER_CLASSES machines, where return registers might be used as
   spills:  subsequent passes assume that spill registers are dead at the end
   of a basic block.
   VALUE must be the return value in such a case, NULL otherwise.  */
static void
reload_cse_delete_noop_set (insn, value)
     rtx insn, value;
{
  if (value)
    {
      PATTERN (insn) = gen_rtx_USE (VOIDmode, value);
      INSN_CODE (insn) = -1;
      REG_NOTES (insn) = NULL_RTX;
    }
  else
    {
      PUT_CODE (insn, NOTE);
      NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
      NOTE_SOURCE_FILE (insn) = 0;
    }
}

/* See whether a single set SET is a noop.  */
static int
reload_cse_noop_set_p (set)
     rtx set;
{
  return rtx_equal_for_cselib_p (SET_DEST (set), SET_SRC (set));
}

/* Try to simplify INSN.  */
static void
reload_cse_simplify (insn)
     rtx insn;
{
  rtx body = PATTERN (insn);

  if (GET_CODE (body) == SET)
    {
      int count = 0;
      if (reload_cse_noop_set_p (body))
        {
          rtx value = SET_DEST (body);
          if (! REG_FUNCTION_VALUE_P (SET_DEST (body)))
            value = 0;
          reload_cse_delete_noop_set (insn, value);
          return;
        }

      /* It's not a no-op, but we can try to simplify it.  */
      count += reload_cse_simplify_set (body, insn);

      if (count > 0)
        apply_change_group ();
      else
        reload_cse_simplify_operands (insn);
    }
  else if (GET_CODE (body) == PARALLEL)
    {
      int i;
      int count = 0;
      rtx value = NULL_RTX;

      /* If every action in a PARALLEL is a noop, we can delete
         the entire PARALLEL.  */
      for (i = XVECLEN (body, 0) - 1; i >= 0; --i)
        {
          rtx part = XVECEXP (body, 0, i);
          if (GET_CODE (part) == SET)
            {
              if (! reload_cse_noop_set_p (part))
                break;
              if (REG_FUNCTION_VALUE_P (SET_DEST (part)))
                {
                  if (value)
                    break;
                  value = SET_DEST (part);
                }
            }
          else if (GET_CODE (part) != CLOBBER)
            break;
        }

      if (i < 0)
        {
          reload_cse_delete_noop_set (insn, value);
          /* We're done with this insn.  */
          return;
        }

      /* It's not a no-op, but we can try to simplify it.  */
      for (i = XVECLEN (body, 0) - 1; i >= 0; --i)
        if (GET_CODE (XVECEXP (body, 0, i)) == SET)
          count += reload_cse_simplify_set (XVECEXP (body, 0, i), insn);

      if (count > 0)
        apply_change_group ();
      else
        reload_cse_simplify_operands (insn);
    }
}

/* Do a very simple CSE pass over the hard registers.

   This function detects no-op moves where we happened to assign two
   different pseudo-registers to the same hard register, and then
   copied one to the other.  Reload will generate a useless
   instruction copying a register to itself.

   This function also detects cases where we load a value from memory
   into two different registers, and (if memory is more expensive than
   registers) changes it to simply copy the first register into the
   second register.

   Another optimization is performed that scans the operands of each
   instruction to see whether the value is already available in a
   hard register.  It then replaces the operand with the hard register
   if possible, much like an optional reload would.  */

static void
reload_cse_regs_1 (first)
     rtx first;
{
  rtx insn;

  cselib_init ();  
  init_alias_analysis ();

  for (insn = first; insn; insn = NEXT_INSN (insn))
    {
      if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
        reload_cse_simplify (insn);

      cselib_process_insn (insn);
    }

  /* Clean up.  */
  end_alias_analysis ();
  cselib_finish ();
}

/* Call cse / combine like post-reload optimization phases.
   FIRST is the first instruction.  */
void
reload_cse_regs (first)
     rtx first;
{
  reload_cse_regs_1 (first);
  reload_combine ();
  reload_cse_move2add (first);
  if (flag_expensive_optimizations)
    reload_cse_regs_1 (first);
}

/* Try to simplify a single SET instruction.  SET is the set pattern.
   INSN is the instruction it came from.
   This function only handles one case: if we set a register to a value
   which is not a register, we try to find that value in some other register
   and change the set into a register copy.  */

static int
reload_cse_simplify_set (set, insn)
     rtx set;
     rtx insn;
{
  int did_change = 0;
  int dreg;
  rtx src;
  enum reg_class dclass;
  int old_cost;
  cselib_val *val;
  struct elt_loc_list *l;

  dreg = true_regnum (SET_DEST (set));
  if (dreg < 0)
    return 0;

  src = SET_SRC (set);
  if (side_effects_p (src) || true_regnum (src) >= 0)
    return 0;

  dclass = REGNO_REG_CLASS (dreg);

  /* If memory loads are cheaper than register copies, don't change them.  */
  if (GET_CODE (src) == MEM)
    old_cost = MEMORY_MOVE_COST (GET_MODE (src), dclass, 1);
  else if (CONSTANT_P (src))
    old_cost = rtx_cost (src, SET);
  else if (GET_CODE (src) == REG)
    old_cost = REGISTER_MOVE_COST (REGNO_REG_CLASS (REGNO (src)), dclass);
  else
    /* ???   */
    old_cost = rtx_cost (src, SET);

  val = cselib_lookup (src, VOIDmode, 0);
  if (! val)
    return 0;
  for (l = val->locs; l; l = l->next)
    {
      int this_cost;
      if (CONSTANT_P (l->loc) && ! references_value_p (l->loc, 0))
        this_cost = rtx_cost (l->loc, SET);
      else if (GET_CODE (l->loc) == REG)
        this_cost = REGISTER_MOVE_COST (REGNO_REG_CLASS (REGNO (l->loc)),
                                        dclass);
      else
        continue;
      /* If equal costs, prefer registers over anything else.  That tends to
         lead to smaller instructions on some machines.  */
      if ((this_cost < old_cost
           || (this_cost == old_cost
               && GET_CODE (l->loc) == REG
               && GET_CODE (SET_SRC (set)) != REG))
          && validate_change (insn, &SET_SRC (set), copy_rtx (l->loc), 1))
        old_cost = this_cost, did_change = 1;
    }

  return did_change;
}

/* Try to replace operands in INSN with equivalent values that are already
   in registers.  This can be viewed as optional reloading.

   For each non-register operand in the insn, see if any hard regs are
   known to be equivalent to that operand.  Record the alternatives which
   can accept these hard registers.  Among all alternatives, select the
   ones which are better or equal to the one currently matching, where
   "better" is in terms of '?' and '!' constraints.  Among the remaining
   alternatives, select the one which replaces most operands with
   hard registers.  */

static int
reload_cse_simplify_operands (insn)
     rtx insn;
{
  int i,j;

  /* For each operand, all registers that are equivalent to it.  */
  HARD_REG_SET equiv_regs[MAX_RECOG_OPERANDS];

  const char *constraints[MAX_RECOG_OPERANDS];

  /* Vector recording how bad an alternative is.  */
  int *alternative_reject;
  /* Vector recording how many registers can be introduced by choosing
     this alternative.  */
  int *alternative_nregs;
  /* Array of vectors recording, for each operand and each alternative,
     which hard register to substitute, or -1 if the operand should be
     left as it is.  */
  int *op_alt_regno[MAX_RECOG_OPERANDS];
  /* Array of alternatives, sorted in order of decreasing desirability.  */
  int *alternative_order;
  rtx reg = gen_rtx_REG (VOIDmode, -1);

  extract_insn (insn);

  if (recog_data.n_alternatives == 0 || recog_data.n_operands == 0)
    return 0;

  /* Figure out which alternative currently matches.  */
  if (! constrain_operands (1))
    fatal_insn_not_found (insn);
  
  alternative_reject = (int *) alloca (recog_data.n_alternatives * sizeof (int));
  alternative_nregs = (int *) alloca (recog_data.n_alternatives * sizeof (int));
  alternative_order = (int *) alloca (recog_data.n_alternatives * sizeof (int));
  bzero ((char *)alternative_reject, recog_data.n_alternatives * sizeof (int));
  bzero ((char *)alternative_nregs, recog_data.n_alternatives * sizeof (int));

  /* For each operand, find out which regs are equivalent.  */
  for (i = 0; i < recog_data.n_operands; i++)
    {
      cselib_val *v;
      struct elt_loc_list *l;

      CLEAR_HARD_REG_SET (equiv_regs[i]);

      /* cselib blows up on CODE_LABELs.  Trying to fix that doesn't seem
         right, so avoid the problem here.  */
      if (GET_CODE (recog_data.operand[i]) == CODE_LABEL)
        continue;

      v = cselib_lookup (recog_data.operand[i], recog_data.operand_mode[i], 0);
      if (! v)
        continue;

      for (l = v->locs; l; l = l->next)
        if (GET_CODE (l->loc) == REG)
          SET_HARD_REG_BIT (equiv_regs[i], REGNO (l->loc));
    }

  for (i = 0; i < recog_data.n_operands; i++)
    {
      enum machine_mode mode;
      int regno;
      const char *p;

      op_alt_regno[i] = (int *) alloca (recog_data.n_alternatives * sizeof (int));
      for (j = 0; j < recog_data.n_alternatives; j++)
        op_alt_regno[i][j] = -1;

      p = constraints[i] = recog_data.constraints[i];
      mode = recog_data.operand_mode[i];

      /* Add the reject values for each alternative given by the constraints
         for this operand.  */
      j = 0;
      while (*p != '\0')
        {
          char c = *p++;
          if (c == ',')
            j++;
          else if (c == '?')
            alternative_reject[j] += 3;
          else if (c == '!')
            alternative_reject[j] += 300;
        }

      /* We won't change operands which are already registers.  We
         also don't want to modify output operands.  */
      regno = true_regnum (recog_data.operand[i]);
      if (regno >= 0
          || constraints[i][0] == '='
          || constraints[i][0] == '+')
        continue;

      for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
        {
          int class = (int) NO_REGS;

          if (! TEST_HARD_REG_BIT (equiv_regs[i], regno))
            continue;

          REGNO (reg) = regno;
          PUT_MODE (reg, mode);

          /* We found a register equal to this operand.  Now look for all
             alternatives that can accept this register and have not been
             assigned a register they can use yet.  */
          j = 0;
          p = constraints[i];
          for (;;)
            {
              char c = *p++;

              switch (c)
                {
                case '=':  case '+':  case '?':
                case '#':  case '&':  case '!':
                case '*':  case '%':
                case '0':  case '1':  case '2':  case '3':  case '4':
                case '5':  case '6':  case '7':  case '8':  case '9':
                case 'm':  case '<':  case '>':  case 'V':  case 'o':
                case 'E':  case 'F':  case 'G':  case 'H':
                case 's':  case 'i':  case 'n':
                case 'I':  case 'J':  case 'K':  case 'L':
                case 'M':  case 'N':  case 'O':  case 'P':
#ifdef EXTRA_CONSTRAINT
                case 'Q':  case 'R':  case 'S':  case 'T':  case 'U':
#endif
                case 'p': case 'X':
                  /* These don't say anything we care about.  */
                  break;

                case 'g': case 'r':
                  class = reg_class_subunion[(int) class][(int) GENERAL_REGS];
                  break;

                default:
                  class
                    = reg_class_subunion[(int) class][(int) REG_CLASS_FROM_LETTER ((unsigned char)c)];
                  break;

                case ',': case '\0':
                  /* See if REGNO fits this alternative, and set it up as the
                     replacement register if we don't have one for this
                     alternative yet and the operand being replaced is not
                     a cheap CONST_INT. */
                  if (op_alt_regno[i][j] == -1
                      && reg_fits_class_p (reg, class, 0, mode)
                      && (GET_CODE (recog_data.operand[i]) != CONST_INT
                          || (rtx_cost (recog_data.operand[i], SET)
                              > rtx_cost (reg, SET))))
                    {
                      alternative_nregs[j]++;
                      op_alt_regno[i][j] = regno;
                    }
                  j++;
                  break;
                }

              if (c == '\0')
                break;
            }
        }
    }

  /* Record all alternatives which are better or equal to the currently
     matching one in the alternative_order array.  */
  for (i = j = 0; i < recog_data.n_alternatives; i++)
    if (alternative_reject[i] <= alternative_reject[which_alternative])
      alternative_order[j++] = i;
  recog_data.n_alternatives = j;

  /* Sort it.  Given a small number of alternatives, a dumb algorithm
     won't hurt too much.  */
  for (i = 0; i < recog_data.n_alternatives - 1; i++)
    {
      int best = i;
      int best_reject = alternative_reject[alternative_order[i]];
      int best_nregs = alternative_nregs[alternative_order[i]];
      int tmp;

      for (j = i + 1; j < recog_data.n_alternatives; j++)
        {
          int this_reject = alternative_reject[alternative_order[j]];
          int this_nregs = alternative_nregs[alternative_order[j]];

          if (this_reject < best_reject
              || (this_reject == best_reject && this_nregs < best_nregs))
            {
              best = j;
              best_reject = this_reject;
              best_nregs = this_nregs;
            }
        }

      tmp = alternative_order[best];
      alternative_order[best] = alternative_order[i];
      alternative_order[i] = tmp;
    }

  /* Substitute the operands as determined by op_alt_regno for the best
     alternative.  */
  j = alternative_order[0];

  for (i = 0; i < recog_data.n_operands; i++)
    {
      enum machine_mode mode = recog_data.operand_mode[i];
      if (op_alt_regno[i][j] == -1)
        continue;

      validate_change (insn, recog_data.operand_loc[i],
                       gen_rtx_REG (mode, op_alt_regno[i][j]), 1);
    }

  for (i = recog_data.n_dups - 1; i >= 0; i--)
    {
      int op = recog_data.dup_num[i];
      enum machine_mode mode = recog_data.operand_mode[op];

      if (op_alt_regno[op][j] == -1)
        continue;

      validate_change (insn, recog_data.dup_loc[i],
                       gen_rtx_REG (mode, op_alt_regno[op][j]), 1);
    }

  return apply_change_group ();
}
\f
/* If reload couldn't use reg+reg+offset addressing, try to use reg+reg
   addressing now.
   This code might also be useful when reload gave up on reg+reg addresssing
   because of clashes between the return register and INDEX_REG_CLASS.  */

/* The maximum number of uses of a register we can keep track of to
   replace them with reg+reg addressing.  */
#define RELOAD_COMBINE_MAX_USES 6

/* INSN is the insn where a register has ben used, and USEP points to the
   location of the register within the rtl.  */
struct reg_use { rtx insn, *usep; };

/* If the register is used in some unknown fashion, USE_INDEX is negative.
   If it is dead, USE_INDEX is RELOAD_COMBINE_MAX_USES, and STORE_RUID
   indicates where it becomes live again.
   Otherwise, USE_INDEX is the index of the last encountered use of the
   register (which is first among these we have seen since we scan backwards),
   OFFSET contains the constant offset that is added to the register in
   all encountered uses, and USE_RUID indicates the first encountered, i.e.
   last, of these uses.
   STORE_RUID is always meaningful if we only want to use a value in a
   register in a different place: it denotes the next insn in the insn
   stream (i.e. the last ecountered) that sets or clobbers the register.  */
static struct
  {
    struct reg_use reg_use[RELOAD_COMBINE_MAX_USES];
    int use_index;
    rtx offset;
    int store_ruid;
    int use_ruid;
  } reg_state[FIRST_PSEUDO_REGISTER];

/* Reverse linear uid.  This is increased in reload_combine while scanning
   the instructions from last to first.  It is used to set last_label_ruid
   and the store_ruid / use_ruid fields in reg_state.  */
static int reload_combine_ruid;

#define LABEL_LIVE(LABEL) \
  (label_live[CODE_LABEL_NUMBER (LABEL) - min_labelno])

static void
reload_combine ()
{
  rtx insn, set;
  int first_index_reg = 1, last_index_reg = 0;
  int i;
  int last_label_ruid;
  int min_labelno, n_labels;
  HARD_REG_SET ever_live_at_start, *label_live;

  /* If reg+reg can be used in offsetable memory adresses, the main chunk of
     reload has already used it where appropriate, so there is no use in
     trying to generate it now.  */
  if (double_reg_address_ok && INDEX_REG_CLASS != NO_REGS)
    return;

  /* To avoid wasting too much time later searching for an index register,
     determine the minimum and maximum index register numbers.  */
  for (i = FIRST_PSEUDO_REGISTER - 1; i >= 0; --i)
    {
      if (TEST_HARD_REG_BIT (reg_class_contents[INDEX_REG_CLASS], i))
        {
          if (! last_index_reg)
            last_index_reg = i;
          first_index_reg = i;
        }
    }
  /* If no index register is available, we can quit now.  */
  if (first_index_reg > last_index_reg)
    return;

  /* Set up LABEL_LIVE and EVER_LIVE_AT_START.  The register lifetime
     information is a bit fuzzy immediately after reload, but it's
     still good enough to determine which registers are live at a jump
     destination.  */
  min_labelno = get_first_label_num ();
  n_labels = max_label_num () - min_labelno;
  label_live = (HARD_REG_SET *) xmalloc (n_labels * sizeof (HARD_REG_SET));
  CLEAR_HARD_REG_SET (ever_live_at_start);
  for (i = n_basic_blocks - 1; i >= 0; i--)
    {
      insn = BLOCK_HEAD (i);
      if (GET_CODE (insn) == CODE_LABEL)
        {
          HARD_REG_SET live;

          REG_SET_TO_HARD_REG_SET (live, BASIC_BLOCK (i)->global_live_at_start);
          compute_use_by_pseudos (&live, BASIC_BLOCK (i)->global_live_at_start);
          COPY_HARD_REG_SET (LABEL_LIVE (insn), live);
          IOR_HARD_REG_SET (ever_live_at_start, live);
        }
    }

  /* Initialize last_label_ruid, reload_combine_ruid and reg_state.  */
  last_label_ruid = reload_combine_ruid = 0;
  for (i = FIRST_PSEUDO_REGISTER - 1; i >= 0; --i)
    {
      reg_state[i].store_ruid = reload_combine_ruid;
      if (fixed_regs[i])
        reg_state[i].use_index = -1;
      else
        reg_state[i].use_index = RELOAD_COMBINE_MAX_USES;
    }

  for (insn = get_last_insn (); insn; insn = PREV_INSN (insn))
    {
      rtx note;

      /* We cannot do our optimization across labels.  Invalidating all the use
         information we have would be costly, so we just note where the label
         is and then later disable any optimization that would cross it.  */
      if (GET_CODE (insn) == CODE_LABEL)
        last_label_ruid = reload_combine_ruid;
      if (GET_CODE (insn) == BARRIER)
        {
          for (i = FIRST_PSEUDO_REGISTER - 1; i >= 0; --i)
            if (! fixed_regs[i])
              reg_state[i].use_index = RELOAD_COMBINE_MAX_USES;
        }
      if (GET_RTX_CLASS (GET_CODE (insn)) != 'i')
        continue;
      reload_combine_ruid++;

      /* Look for (set (REGX) (CONST_INT))
         (set (REGX) (PLUS (REGX) (REGY)))
         ...
         ... (MEM (REGX)) ...
         and convert it to
         (set (REGZ) (CONST_INT))
         ...
         ... (MEM (PLUS (REGZ) (REGY)))... .

         First, check that we have (set (REGX) (PLUS (REGX) (REGY)))
         and that we know all uses of REGX before it dies.  */
      set = single_set (insn);
      if (set != NULL_RTX
          && GET_CODE (SET_DEST (set)) == REG
          && (HARD_REGNO_NREGS (REGNO (SET_DEST (set)),
                                GET_MODE (SET_DEST (set)))
              == 1)
          && GET_CODE (SET_SRC (set)) == PLUS
          && GET_CODE (XEXP (SET_SRC (set), 1)) == REG
          && rtx_equal_p (XEXP (SET_SRC (set), 0), SET_DEST (set))
          && last_label_ruid < reg_state[REGNO (SET_DEST (set))].use_ruid)
        {
          rtx reg = SET_DEST (set);
          rtx plus = SET_SRC (set);
          rtx base = XEXP (plus, 1);
          rtx prev = prev_nonnote_insn (insn);
          rtx prev_set = prev ? single_set (prev) : NULL_RTX;
          int regno = REGNO (reg);
          rtx const_reg = NULL_RTX;
          rtx reg_sum = NULL_RTX;

          /* Now, we need an index register.
             We'll set index_reg to this index register, const_reg to the
             register that is to be loaded with the constant
             (denoted as REGZ in the substitution illustration above),
             and reg_sum to the register-register that we want to use to
             substitute uses of REG (typically in MEMs) with.
             First check REG and BASE for being index registers;
             we can use them even if they are not dead.  */
          if (TEST_HARD_REG_BIT (reg_class_contents[INDEX_REG_CLASS], regno)
              || TEST_HARD_REG_BIT (reg_class_contents[INDEX_REG_CLASS],
                                    REGNO (base)))
            {
              const_reg = reg;
              reg_sum = plus;
            }
          else
            {
              /* Otherwise, look for a free index register.  Since we have
                 checked above that neiter REG nor BASE are index registers,
                 if we find anything at all, it will be different from these
                 two registers.  */
              for (i = first_index_reg; i <= last_index_reg; i++)
                {
                  if (TEST_HARD_REG_BIT (reg_class_contents[INDEX_REG_CLASS], i)
                      && reg_state[i].use_index == RELOAD_COMBINE_MAX_USES
                      && reg_state[i].store_ruid <= reg_state[regno].use_ruid
                      && HARD_REGNO_NREGS (i, GET_MODE (reg)) == 1)
                    {
                      rtx index_reg = gen_rtx_REG (GET_MODE (reg), i);
                      const_reg = index_reg;
                      reg_sum = gen_rtx_PLUS (GET_MODE (reg), index_reg, base);
                      break;
                    }
                }
            }
          /* Check that PREV_SET is indeed (set (REGX) (CONST_INT)) and that
             (REGY), i.e. BASE, is not clobbered before the last use we'll
             create.  */
          if (prev_set
              && GET_CODE (SET_SRC (prev_set)) == CONST_INT
              && rtx_equal_p (SET_DEST (prev_set), reg)
              && reg_state[regno].use_index >= 0
              && reg_state[REGNO (base)].store_ruid <= reg_state[regno].use_ruid
              && reg_sum)
            {
              int i;

              /* Change destination register and - if necessary - the
                 constant value in PREV, the constant loading instruction.  */
              validate_change (prev, &SET_DEST (prev_set), const_reg, 1);
              if (reg_state[regno].offset != const0_rtx)
                validate_change (prev,
                                 &SET_SRC (prev_set),
                                 GEN_INT (INTVAL (SET_SRC (prev_set))
                                          + INTVAL (reg_state[regno].offset)),
                                 1);
              /* Now for every use of REG that we have recorded, replace REG
                 with REG_SUM.  */
              for (i = reg_state[regno].use_index;
                   i < RELOAD_COMBINE_MAX_USES; i++)
                validate_change (reg_state[regno].reg_use[i].insn,
                                 reg_state[regno].reg_use[i].usep,
                                 reg_sum, 1);

              if (apply_change_group ())
                {
                  rtx *np;

                  /* Delete the reg-reg addition.  */
                  PUT_CODE (insn, NOTE);
                  NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
                  NOTE_SOURCE_FILE (insn) = 0;

                  if (reg_state[regno].offset != const0_rtx)
                    {
                      /* Previous REG_EQUIV / REG_EQUAL notes for PREV
                         are now invalid.  */
                      for (np = &REG_NOTES (prev); *np; )
                        {
                          if (REG_NOTE_KIND (*np) == REG_EQUAL
                              || REG_NOTE_KIND (*np) == REG_EQUIV)
                            *np = XEXP (*np, 1);
                          else
                            np = &XEXP (*np, 1);
                        }
                    }
                  reg_state[regno].use_index = RELOAD_COMBINE_MAX_USES;
                  reg_state[REGNO (const_reg)].store_ruid = reload_combine_ruid;
                  continue;
                }
            }
        }
      note_stores (PATTERN (insn), reload_combine_note_store, NULL);
      if (GET_CODE (insn) == CALL_INSN)
        {
          rtx link;

          for (i = FIRST_PSEUDO_REGISTER - 1; i >= 0; --i)
            {
              if (call_used_regs[i])
                {
                  reg_state[i].use_index = RELOAD_COMBINE_MAX_USES;
                  reg_state[i].store_ruid = reload_combine_ruid;
                }
            }
          for (link = CALL_INSN_FUNCTION_USAGE (insn); link;
               link = XEXP (link, 1))
            {
              rtx use = XEXP (link, 0);
              int regno = REGNO (XEXP (use, 0));
              if (GET_CODE (use) == CLOBBER)
                {
                  reg_state[regno].use_index = RELOAD_COMBINE_MAX_USES;
                  reg_state[regno].store_ruid = reload_combine_ruid;
                }
              else
                reg_state[regno].use_index = -1;
            }
        }
      if (GET_CODE (insn) == JUMP_INSN && GET_CODE (PATTERN (insn)) != RETURN)
        {
          /* Non-spill registers might be used at the call destination in
             some unknown fashion, so we have to mark the unknown use.  */
          HARD_REG_SET *live;
          if ((condjump_p (insn) || condjump_in_parallel_p (insn))
              && JUMP_LABEL (insn))
            live = &LABEL_LIVE (JUMP_LABEL (insn));
          else
            live = &ever_live_at_start;
          for (i = FIRST_PSEUDO_REGISTER - 1; i >= 0; --i)
            {
              if (TEST_HARD_REG_BIT (*live, i))
                reg_state[i].use_index = -1;
            }
        }
      reload_combine_note_use (&PATTERN (insn), insn);
      for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
        {
          if (REG_NOTE_KIND (note) == REG_INC
              && GET_CODE (XEXP (note, 0)) == REG)
            {
              int regno = REGNO (XEXP (note, 0));

              reg_state[regno].store_ruid = reload_combine_ruid;
              reg_state[regno].use_index = -1;
            }
        }
    }
  free (label_live);
}

/* Check if DST is a register or a subreg of a register; if it is,
   update reg_state[regno].store_ruid and reg_state[regno].use_index
   accordingly.  Called via note_stores from reload_combine.  */
static void
reload_combine_note_store (dst, set, data)
     rtx dst, set;
     void *data ATTRIBUTE_UNUSED;
{
  int regno = 0;
  int i;
  enum machine_mode mode = GET_MODE (dst);

  if (GET_CODE (dst) == SUBREG)
    {
      regno = SUBREG_WORD (dst);
      dst = SUBREG_REG (dst);
    }
  if (GET_CODE (dst) != REG)
    return;
  regno += REGNO (dst);

  /* note_stores might have stripped a STRICT_LOW_PART, so we have to be
     careful with registers / register parts that are not full words.

     Similarly for ZERO_EXTRACT and SIGN_EXTRACT.  */
  if (GET_CODE (set) != SET
      || GET_CODE (SET_DEST (set)) == ZERO_EXTRACT
      || GET_CODE (SET_DEST (set)) == SIGN_EXTRACT
      || GET_CODE (SET_DEST (set)) == STRICT_LOW_PART)
    {
      for (i = HARD_REGNO_NREGS (regno, mode) - 1 + regno; i >= regno; i--)
        {
          reg_state[i].use_index = -1;
          reg_state[i].store_ruid = reload_combine_ruid;
        }
    }
  else
    {
      for (i = HARD_REGNO_NREGS (regno, mode) - 1 + regno; i >= regno; i--)
        {
          reg_state[i].store_ruid = reload_combine_ruid;
          reg_state[i].use_index = RELOAD_COMBINE_MAX_USES;
        }
    }
}

/* XP points to a piece of rtl that has to be checked for any uses of
   registers.
   *XP is the pattern of INSN, or a part of it.
   Called from reload_combine, and recursively by itself.  */
static void
reload_combine_note_use (xp, insn)
     rtx *xp, insn;
{
  rtx x = *xp;
  enum rtx_code code = x->code;
  const char *fmt;
  int i, j;
  rtx offset = const0_rtx; /* For the REG case below.  */

  switch (code)
    {
    case SET:
      if (GET_CODE (SET_DEST (x)) == REG)
        {
          reload_combine_note_use (&SET_SRC (x), insn);
          return;
        }
      break;

    case USE:
      /* If this is the USE of a return value, we can't change it.  */
      if (GET_CODE (XEXP (x, 0)) == REG && REG_FUNCTION_VALUE_P (XEXP (x, 0)))
        {
        /* Mark the return register as used in an unknown fashion.  */
          rtx reg = XEXP (x, 0);
          int regno = REGNO (reg);
          int nregs = HARD_REGNO_NREGS (regno, GET_MODE (reg));

          while (--nregs >= 0)
            reg_state[regno + nregs].use_index = -1;
          return;
        }
      break;

    case CLOBBER:
      if (GET_CODE (SET_DEST (x)) == REG)
        return;
      break;

    case PLUS:
      /* We are interested in (plus (reg) (const_int)) .  */
      if (GET_CODE (XEXP (x, 0)) != REG || GET_CODE (XEXP (x, 1)) != CONST_INT)
        break;
      offset = XEXP (x, 1);
      x = XEXP (x, 0);
      /* Fall through.  */
    case REG:
      {
        int regno = REGNO (x);
        int use_index;
        int nregs;

        /* Some spurious USEs of pseudo registers might remain.
           Just ignore them.  */
        if (regno >= FIRST_PSEUDO_REGISTER)
          return;

        nregs = HARD_REGNO_NREGS (regno, GET_MODE (x));

        /* We can't substitute into multi-hard-reg uses.  */
        if (nregs > 1)
          {
            while (--nregs >= 0)
              reg_state[regno + nregs].use_index = -1;
            return;
          }

        /* If this register is already used in some unknown fashion, we
           can't do anything.
           If we decrement the index from zero to -1, we can't store more
           uses, so this register becomes used in an unknown fashion.  */
        use_index = --reg_state[regno].use_index;
        if (use_index < 0)
          return;

        if (use_index != RELOAD_COMBINE_MAX_USES - 1)
          {
            /* We have found another use for a register that is already
               used later.  Check if the offsets match; if not, mark the
               register as used in an unknown fashion.  */
            if (! rtx_equal_p (offset, reg_state[regno].offset))
              {
                reg_state[regno].use_index = -1;
                return;
              }
          }
        else
          {
            /* This is the first use of this register we have seen since we
               marked it as dead.  */
            reg_state[regno].offset = offset;
            reg_state[regno].use_ruid = reload_combine_ruid;
          }
        reg_state[regno].reg_use[use_index].insn = insn;
        reg_state[regno].reg_use[use_index].usep = xp;
        return;
      }

    default:
      break;
    }

  /* Recursively process the components of X.  */
  fmt = GET_RTX_FORMAT (code);
  for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
    {
      if (fmt[i] == 'e')
        reload_combine_note_use (&XEXP (x, i), insn);
      else if (fmt[i] == 'E')
        {
          for (j = XVECLEN (x, i) - 1; j >= 0; j--)
            reload_combine_note_use (&XVECEXP (x, i, j), insn);
        }
    }
}
\f
/* See if we can reduce the cost of a constant by replacing a move with
   an add.  */
/* We cannot do our optimization across labels.  Invalidating all the
   information about register contents we have would be costly, so we
   use last_label_luid (local variable of reload_cse_move2add) to note
   where the label is and then later disable any optimization that would
   cross it.
   reg_offset[n] / reg_base_reg[n] / reg_mode[n] are only valid if
   reg_set_luid[n] is larger than last_label_luid[n] .  */
static int reg_set_luid[FIRST_PSEUDO_REGISTER];

/* reg_offset[n] has to be CONST_INT for it and reg_base_reg[n] /
   reg_mode[n] to be valid.
   If reg_offset[n] is a CONST_INT and reg_base_reg[n] is negative, register n
   has been set to reg_offset[n] in mode reg_mode[n] .
   If reg_offset[n] is a CONST_INT and reg_base_reg[n] is non-negative,
   register n has been set to the sum of reg_offset[n] and register
   reg_base_reg[n], calculated in mode reg_mode[n] .  */
static rtx reg_offset[FIRST_PSEUDO_REGISTER];
static int reg_base_reg[FIRST_PSEUDO_REGISTER];
static enum machine_mode reg_mode[FIRST_PSEUDO_REGISTER];

/* move2add_luid is linearily increased while scanning the instructions
   from first to last.  It is used to set reg_set_luid in
   reload_cse_move2add and move2add_note_store.  */
static int move2add_luid;

/* Generate a CONST_INT and force it in the range of MODE.  */

static rtx
gen_mode_int (mode, value)
     enum machine_mode mode;
     HOST_WIDE_INT value;
{
  HOST_WIDE_INT cval = value & GET_MODE_MASK (mode);
  int width = GET_MODE_BITSIZE (mode);

  /* If MODE is narrower than HOST_WIDE_INT and CVAL is a negative number,
     sign extend it.  */
  if (width > 0 && width < HOST_BITS_PER_WIDE_INT
      && (cval & ((HOST_WIDE_INT) 1 << (width - 1))) != 0)
    cval |= (HOST_WIDE_INT) -1 << width;

  return GEN_INT (cval);
}

static void
reload_cse_move2add (first)
     rtx first;
{
  int i;
  rtx insn;
  int last_label_luid;

  for (i = FIRST_PSEUDO_REGISTER-1; i >= 0; i--)
    reg_set_luid[i] = 0;

  last_label_luid = 0;
  move2add_luid = 1;
  for (insn = first; insn; insn = NEXT_INSN (insn), move2add_luid++)
    {
      rtx pat, note;

      if (GET_CODE (insn) == CODE_LABEL)
        last_label_luid = move2add_luid;
      if (GET_RTX_CLASS (GET_CODE (insn)) != 'i')
        continue;
      pat = PATTERN (insn);
      /* For simplicity, we only perform this optimization on
         straightforward SETs.  */
      if (GET_CODE (pat) == SET
          && GET_CODE (SET_DEST (pat)) == REG)
        {
          rtx reg = SET_DEST (pat);
          int regno = REGNO (reg);
          rtx src = SET_SRC (pat);

          /* Check if we have valid information on the contents of this
             register in the mode of REG.  */
          /* ??? We don't know how zero / sign extension is handled, hence
             we can't go from a narrower to a wider mode.  */
          if (reg_set_luid[regno] > last_label_luid
              && (GET_MODE_SIZE (GET_MODE (reg))
                  <= GET_MODE_SIZE (reg_mode[regno]))
              && GET_CODE (reg_offset[regno]) == CONST_INT)
            {
              /* Try to transform (set (REGX) (CONST_INT A))
                                  ...
                                  (set (REGX) (CONST_INT B))
                 to
                                  (set (REGX) (CONST_INT A))
                                  ...
                                  (set (REGX) (plus (REGX) (CONST_INT B-A)))  */

              if (GET_CODE (src) == CONST_INT && reg_base_reg[regno] < 0)
                {
                  int success = 0;
                  rtx new_src
                    = gen_mode_int (GET_MODE (reg),
                                    INTVAL (src) - INTVAL (reg_offset[regno]));
                  /* (set (reg) (plus (reg) (const_int 0))) is not canonical;
                     use (set (reg) (reg)) instead.
                     We don't delete this insn, nor do we convert it into a
                     note, to avoid losing register notes or the return
                     value flag.  jump2 already knowns how to get rid of
                     no-op moves.  */
                  if (new_src == const0_rtx)
                    success = validate_change (insn, &SET_SRC (pat), reg, 0);
                  else if (rtx_cost (new_src, PLUS) < rtx_cost (src, SET)
                           && have_add2_insn (GET_MODE (reg)))
                    success = validate_change (insn, &PATTERN (insn),
                                               gen_add2_insn (reg, new_src), 0);
                  reg_set_luid[regno] = move2add_luid;
                  reg_mode[regno] = GET_MODE (reg);
                  reg_offset[regno] = src;
                  continue;
                }

              /* Try to transform (set (REGX) (REGY))
                                  (set (REGX) (PLUS (REGX) (CONST_INT A)))
                                  ...
                                  (set (REGX) (REGY))
                                  (set (REGX) (PLUS (REGX) (CONST_INT B)))
                 to
                                  (REGX) (REGY))
                                  (set (REGX) (PLUS (REGX) (CONST_INT A)))
                                  ...
                                  (set (REGX) (plus (REGX) (CONST_INT B-A)))  */
              else if (GET_CODE (src) == REG
                       && reg_base_reg[regno] == (int) REGNO (src)
                       && reg_set_luid[regno] > reg_set_luid[REGNO (src)])
                {
                  rtx next = next_nonnote_insn (insn);
                  rtx set = NULL_RTX;
                  if (next)
                    set = single_set (next);
                  if (next
                      && set
                      && SET_DEST (set) == reg
                      && GET_CODE (SET_SRC (set)) == PLUS
                      && XEXP (SET_SRC (set), 0) == reg
                      && GET_CODE (XEXP (SET_SRC (set), 1)) == CONST_INT)
                    {
                      rtx src3 = XEXP (SET_SRC (set), 1);
                      rtx new_src
                        = gen_mode_int (GET_MODE (reg),
                                        INTVAL (src3)
                                        - INTVAL (reg_offset[regno]));
                      int success = 0;

                      if (new_src == const0_rtx)
                        /* See above why we create (set (reg) (reg)) here.  */
                        success
                          = validate_change (next, &SET_SRC (set), reg, 0);
                      else if ((rtx_cost (new_src, PLUS)
                                < 2 + rtx_cost (src3, SET))
                               && have_add2_insn (GET_MODE (reg)))
                        success
                          = validate_change (next, &PATTERN (next),
                                             gen_add2_insn (reg, new_src), 0);
                      if (success)
                        {
                          /* INSN might be the first insn in a basic block
                             if the preceding insn is a conditional jump
                             or a possible-throwing call.  */
                          PUT_CODE (insn, NOTE);
                          NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
                          NOTE_SOURCE_FILE (insn) = 0;
                        }
                      insn = next;
                      reg_set_luid[regno] = move2add_luid;
                      reg_mode[regno] = GET_MODE (reg);
                      reg_offset[regno] = src3;
                      continue;
                    }
                }
            }
        }

      for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
        {
          if (REG_NOTE_KIND (note) == REG_INC
              && GET_CODE (XEXP (note, 0)) == REG)
            {
              /* Indicate that this register has been recently written to,
                 but the exact contents are not available.  */
              int regno = REGNO (XEXP (note, 0));
              if (regno < FIRST_PSEUDO_REGISTER)
                {
                  reg_set_luid[regno] = move2add_luid;
                  reg_offset[regno] = note;
                }
            }
        }
      note_stores (PATTERN (insn), move2add_note_store, NULL);
      /* If this is a CALL_INSN, all call used registers are stored with
         unknown values.  */
      if (GET_CODE (insn) == CALL_INSN)
        {
          for (i = FIRST_PSEUDO_REGISTER-1; i >= 0; i--)
            {
              if (call_used_regs[i])
                {
                  reg_set_luid[i] = move2add_luid;
                  reg_offset[i] = insn; /* Invalidate contents.  */
                }
            }
        }
    }
}

/* SET is a SET or CLOBBER that sets DST.
   Update reg_set_luid, reg_offset and reg_base_reg accordingly.
   Called from reload_cse_move2add via note_stores.  */

static void
move2add_note_store (dst, set, data)
     rtx dst, set;
     void *data ATTRIBUTE_UNUSED;
{
  unsigned int regno = 0;
  unsigned int i;
  enum machine_mode mode = GET_MODE (dst);

  if (GET_CODE (dst) == SUBREG)
    {
      regno = SUBREG_WORD (dst);
      dst = SUBREG_REG (dst);
    }

  if (GET_CODE (dst) != REG)
    return;

  regno += REGNO (dst);

  if (HARD_REGNO_NREGS (regno, mode) == 1 && GET_CODE (set) == SET
      && GET_CODE (SET_DEST (set)) != ZERO_EXTRACT
      && GET_CODE (SET_DEST (set)) != SIGN_EXTRACT
      && GET_CODE (SET_DEST (set)) != STRICT_LOW_PART)
    {
      rtx src = SET_SRC (set);

      reg_mode[regno] = mode;
      switch (GET_CODE (src))
        {
        case PLUS:
          {
            rtx src0 = XEXP (src, 0);

            if (GET_CODE (src0) == REG)
              {
                if (REGNO (src0) != regno
                    || reg_offset[regno] != const0_rtx)
                  {
                    reg_base_reg[regno] = REGNO (src0);
                    reg_set_luid[regno] = move2add_luid;
                  }

                reg_offset[regno] = XEXP (src, 1);
                break;
              }

            reg_set_luid[regno] = move2add_luid;
            reg_offset[regno] = set;    /* Invalidate contents.  */
            break;
          }

        case REG:
          reg_base_reg[regno] = REGNO (SET_SRC (set));
          reg_offset[regno] = const0_rtx;
          reg_set_luid[regno] = move2add_luid;
          break;

        default:
          reg_base_reg[regno] = -1;
          reg_offset[regno] = SET_SRC (set);
          reg_set_luid[regno] = move2add_luid;
          break;
        }
    }
  else
    {
      unsigned int endregno = regno + HARD_REGNO_NREGS (regno, mode);

      for (i = regno; i < endregno; i++)
        {
          /* Indicate that this register has been recently written to,
             but the exact contents are not available.  */
          reg_set_luid[i] = move2add_luid;
          reg_offset[i] = dst;
        }
    }
}

#ifdef AUTO_INC_DEC
static void
add_auto_inc_notes (insn, x)
     rtx insn;
     rtx x;
{
  enum rtx_code code = GET_CODE (x);
  const char *fmt;
  int i, j;

  if (code == MEM && auto_inc_p (XEXP (x, 0)))
    {
      REG_NOTES (insn)
        = gen_rtx_EXPR_LIST (REG_INC, XEXP (XEXP (x, 0), 0), REG_NOTES (insn));
      return;
    }

  /* Scan all the operand sub-expressions.  */
  fmt = GET_RTX_FORMAT (code);
  for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
    {
      if (fmt[i] == 'e')
        add_auto_inc_notes (insn, XEXP (x, i));
      else if (fmt[i] == 'E')
        for (j = XVECLEN (x, i) - 1; j >= 0; j--)
          add_auto_inc_notes (insn, XVECEXP (x, i, j));
    }
}
#endif