gcc/reload.h

   1 /* Communication between reload.c and reload1.c.
   2    Copyright (C) 1987, 1991, 1992, 1993, 1994, 1995, 1997, 1998,
   3    1999, 2000, 2001, 2003, 2004 Free Software Foundation, Inc.
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 2, or (at your option) any later
  10 version.
  11
  12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING.  If not, write to the Free
  19 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
  20 02110-1301, USA.  */
  21
  22
  23 /* If secondary reloads are the same for inputs and outputs, define those
  24    macros here.  */
  25
  26 #ifdef SECONDARY_RELOAD_CLASS
  27 #define SECONDARY_INPUT_RELOAD_CLASS(CLASS, MODE, X) \
  28   SECONDARY_RELOAD_CLASS (CLASS, MODE, X)
  29 #define SECONDARY_OUTPUT_RELOAD_CLASS(CLASS, MODE, X) \
  30   SECONDARY_RELOAD_CLASS (CLASS, MODE, X)
  31 #endif
  32
  33 /* If MEMORY_MOVE_COST isn't defined, give it a default here.  */
  34 #ifndef MEMORY_MOVE_COST
  35 #define MEMORY_MOVE_COST(MODE,CLASS,IN) \
  36   (4 + memory_move_secondary_cost ((MODE), (CLASS), (IN)))
  37 #endif
  38 extern int memory_move_secondary_cost (enum machine_mode, enum reg_class, int);
  39
  40 /* Maximum number of reloads we can need.  */
  41 #define MAX_RELOADS (2 * MAX_RECOG_OPERANDS * (MAX_REGS_PER_ADDRESS + 1))
  42
  43 /* Encode the usage of a reload.  The following codes are supported:
  44
  45    RELOAD_FOR_INPUT             reload of an input operand
  46    RELOAD_FOR_OUTPUT            likewise, for output
  47    RELOAD_FOR_INSN              a reload that must not conflict with anything
  48                                 used in the insn, but may conflict with
  49                                 something used before or after the insn
  50    RELOAD_FOR_INPUT_ADDRESS     reload for parts of the address of an object
  51                                 that is an input reload
  52    RELOAD_FOR_INPADDR_ADDRESS   reload needed for RELOAD_FOR_INPUT_ADDRESS
  53    RELOAD_FOR_OUTPUT_ADDRESS    like RELOAD_FOR INPUT_ADDRESS, for output
  54    RELOAD_FOR_OUTADDR_ADDRESS   reload needed for RELOAD_FOR_OUTPUT_ADDRESS
  55    RELOAD_FOR_OPERAND_ADDRESS   reload for the address of a non-reloaded
  56                                 operand; these don't conflict with
  57                                 any other addresses.
  58    RELOAD_FOR_OPADDR_ADDR       reload needed for RELOAD_FOR_OPERAND_ADDRESS
  59                                 reloads; usually secondary reloads
  60    RELOAD_OTHER                 none of the above, usually multiple uses
  61    RELOAD_FOR_OTHER_ADDRESS     reload for part of the address of an input
  62                                 that is marked RELOAD_OTHER.
  63
  64    This used to be "enum reload_when_needed" but some debuggers have trouble
  65    with an enum tag and variable of the same name.  */
  66
  67 enum reload_type
  68 {
  69   RELOAD_FOR_INPUT, RELOAD_FOR_OUTPUT, RELOAD_FOR_INSN,
  70   RELOAD_FOR_INPUT_ADDRESS, RELOAD_FOR_INPADDR_ADDRESS,
  71   RELOAD_FOR_OUTPUT_ADDRESS, RELOAD_FOR_OUTADDR_ADDRESS,
  72   RELOAD_FOR_OPERAND_ADDRESS, RELOAD_FOR_OPADDR_ADDR,
  73   RELOAD_OTHER, RELOAD_FOR_OTHER_ADDRESS
  74 };
  75
  76 #ifdef GCC_INSN_CODES_H
  77 /* Each reload is recorded with a structure like this.  */
  78 struct reload
  79 {
  80   /* The value to reload from */
  81   rtx in;
  82   /* Where to store reload-reg afterward if nec (often the same as
  83      reload_in)  */
  84   rtx out;
  85
  86   /* The class of registers to reload into.  */
  87   enum reg_class class;
  88
  89   /* The mode this operand should have when reloaded, on input.  */
  90   enum machine_mode inmode;
  91   /* The mode this operand should have when reloaded, on output.  */
  92   enum machine_mode outmode;
  93
  94   /* The mode of the reload register.  */
  95   enum machine_mode mode;
  96
  97   /* the largest number of registers this reload will require.  */
  98   unsigned int nregs;
  99
 100   /* Positive amount to increment or decrement by if
 101      reload_in is a PRE_DEC, PRE_INC, POST_DEC, POST_INC.
 102      Ignored otherwise (don't assume it is zero).  */
 103   int inc;
 104   /* A reg for which reload_in is the equivalent.
 105      If reload_in is a symbol_ref which came from
 106      reg_equiv_constant, then this is the pseudo
 107      which has that symbol_ref as equivalent.  */
 108   rtx in_reg;
 109   rtx out_reg;
 110
 111   /* Used in find_reload_regs to record the allocated register.  */
 112   int regno;
 113   /* This is the register to reload into.  If it is zero when `find_reloads'
 114      returns, you must find a suitable register in the class specified by
 115      reload_reg_class, and store here an rtx for that register with mode from
 116      reload_inmode or reload_outmode.  */
 117   rtx reg_rtx;
 118   /* The operand number being reloaded.  This is used to group related reloads
 119      and need not always be equal to the actual operand number in the insn,
 120      though it current will be; for in-out operands, it is one of the two
 121      operand numbers.  */
 122   int opnum;
 123
 124   /* Gives the reload number of a secondary input reload, when needed;
 125      otherwise -1.  */
 126   int secondary_in_reload;
 127   /* Gives the reload number of a secondary output reload, when needed;
 128      otherwise -1.  */
 129   int secondary_out_reload;
 130   /* If a secondary input reload is required, gives the INSN_CODE that uses the
 131      secondary reload as a scratch register, or CODE_FOR_nothing if the
 132      secondary reload register is to be an intermediate register.  */
 133   enum insn_code secondary_in_icode;
 134   /* Likewise, for a secondary output reload.  */
 135   enum insn_code secondary_out_icode;
 136
 137   /* Classifies reload as needed either for addressing an input reload,
 138      addressing an output, for addressing a non-reloaded mem ref, or for
 139      unspecified purposes (i.e., more than one of the above).  */
 140   enum reload_type when_needed;
 141
 142   /* Nonzero for an optional reload.  Optional reloads are ignored unless the
 143      value is already sitting in a register.  */
 144   unsigned int optional:1;
 145   /* nonzero if this reload shouldn't be combined with another reload.  */
 146   unsigned int nocombine:1;
 147   /* Nonzero if this is a secondary register for one or more reloads.  */
 148   unsigned int secondary_p:1;
 149   /* Nonzero if this reload must use a register not already allocated to a
 150      group.  */
 151   unsigned int nongroup:1;
 152 };
 153
 154 extern struct reload rld[MAX_RELOADS];
 155 extern int n_reloads;
 156 #endif
 157
 158 extern GTY (()) VEC(rtx,gc) *reg_equiv_memory_loc_vec;
 159 extern rtx *reg_equiv_constant;
 160 extern rtx *reg_equiv_invariant;
 161 extern rtx *reg_equiv_memory_loc;
 162 extern rtx *reg_equiv_address;
 163 extern rtx *reg_equiv_mem;
 164 extern rtx *reg_equiv_alt_mem_list;
 165
 166 /* Element N is the list of insns that initialized reg N from its equivalent
 167    constant or memory slot.  */
 168 extern GTY((length("reg_equiv_init_size"))) rtx *reg_equiv_init;
 169
 170 /* The size of the previous array, for GC purposes.  */
 171 extern GTY(()) int reg_equiv_init_size;
 172
 173 /* All the "earlyclobber" operands of the current insn
 174    are recorded here.  */
 175 extern int n_earlyclobbers;
 176 extern rtx reload_earlyclobbers[MAX_RECOG_OPERANDS];
 177
 178 /* Save the number of operands.  */
 179 extern int reload_n_operands;
 180
 181 /* First uid used by insns created by reload in this function.
 182    Used in find_equiv_reg.  */
 183 extern int reload_first_uid;
 184
 185 /* Nonzero if indirect addressing is supported when the innermost MEM is
 186    of the form (MEM (SYMBOL_REF sym)).  It is assumed that the level to
 187    which these are valid is the same as spill_indirect_levels, above.  */
 188
 189 extern char indirect_symref_ok;
 190
 191 /* Nonzero if an address (plus (reg frame_pointer) (reg ...)) is valid.  */
 192 extern char double_reg_address_ok;
 193
 194 extern int num_not_at_initial_offset;
 195
 196 #if defined SET_HARD_REG_BIT && defined CLEAR_REG_SET
 197 /* This structure describes instructions which are relevant for reload.
 198    Apart from all regular insns, this also includes CODE_LABELs, since they
 199    must be examined for register elimination.  */
 200 struct insn_chain
 201 {
 202   /* Links to the neighbor instructions.  */
 203   struct insn_chain *next, *prev;
 204
 205   /* Link through a chains set up by calculate_needs_all_insns, containing
 206      all insns that need reloading.  */
 207   struct insn_chain *next_need_reload;
 208
 209   /* The basic block this insn is in.  */
 210   int block;
 211   /* The rtx of the insn.  */
 212   rtx insn;
 213   /* Register life information: record all live hard registers, and all
 214      live pseudos that have a hard register.  */
 215   regset_head live_throughout;
 216   regset_head dead_or_set;
 217
 218   /* Copies of the global variables computed by find_reloads.  */
 219   struct reload *rld;
 220   int n_reloads;
 221
 222   /* Indicates which registers have already been used for spills.  */
 223   HARD_REG_SET used_spill_regs;
 224
 225   /* Nonzero if find_reloads said the insn requires reloading.  */
 226   unsigned int need_reload:1;
 227   /* Nonzero if find_reloads needs to be run during reload_as_needed to
 228      perform modifications on any operands.  */
 229   unsigned int need_operand_change:1;
 230   /* Nonzero if eliminate_regs_in_insn said it requires eliminations.  */
 231   unsigned int need_elim:1;
 232   /* Nonzero if this insn was inserted by perform_caller_saves.  */
 233   unsigned int is_caller_save_insn:1;
 234 };
 235
 236 /* A chain of insn_chain structures to describe all non-note insns in
 237    a function.  */
 238 extern struct insn_chain *reload_insn_chain;
 239
 240 /* Allocate a new insn_chain structure.  */
 241 extern struct insn_chain *new_insn_chain (void);
 242
 243 extern void compute_use_by_pseudos (HARD_REG_SET *, regset);
 244 #endif
 245
 246 /* Functions from reload.c:  */
 247
 248 extern enum reg_class secondary_reload_class (bool, enum reg_class,
 249                                               enum machine_mode, rtx);
 250
 251 #ifdef GCC_INSN_CODES_H
 252 extern enum reg_class scratch_reload_class (enum insn_code);
 253 #endif
 254
 255 /* Return a memory location that will be used to copy X in mode MODE.
 256    If we haven't already made a location for this mode in this insn,
 257    call find_reloads_address on the location being returned.  */
 258 extern rtx get_secondary_mem (rtx, enum machine_mode, int, enum reload_type);
 259
 260 /* Clear any secondary memory locations we've made.  */
 261 extern void clear_secondary_mem (void);
 262
 263 /* Transfer all replacements that used to be in reload FROM to be in
 264    reload TO.  */
 265 extern void transfer_replacements (int, int);
 266
 267 /* IN_RTX is the value loaded by a reload that we now decided to inherit,
 268    or a subpart of it.  If we have any replacements registered for IN_RTX,
 269    cancel the reloads that were supposed to load them.
 270    Return nonzero if we canceled any reloads.  */
 271 extern int remove_address_replacements (rtx in_rtx);
 272
 273 /* Like rtx_equal_p except that it allows a REG and a SUBREG to match
 274    if they are the same hard reg, and has special hacks for
 275    autoincrement and autodecrement.  */
 276 extern int operands_match_p (rtx, rtx);
 277
 278 /* Return 1 if altering OP will not modify the value of CLOBBER.  */
 279 extern int safe_from_earlyclobber (rtx, rtx);
 280
 281 /* Search the body of INSN for values that need reloading and record them
 282    with push_reload.  REPLACE nonzero means record also where the values occur
 283    so that subst_reloads can be used.  */
 284 extern int find_reloads (rtx, int, int, int, short *);
 285
 286 /* Compute the sum of X and Y, making canonicalizations assumed in an
 287    address, namely: sum constant integers, surround the sum of two
 288    constants with a CONST, put the constant as the second operand, and
 289    group the constant on the outermost sum.  */
 290 extern rtx form_sum (rtx, rtx);
 291
 292 /* Substitute into the current INSN the registers into which we have reloaded
 293    the things that need reloading.  */
 294 extern void subst_reloads (rtx);
 295
 296 /* Make a copy of any replacements being done into X and move those copies
 297    to locations in Y, a copy of X.  We only look at the highest level of
 298    the RTL.  */
 299 extern void copy_replacements (rtx, rtx);
 300
 301 /* Change any replacements being done to *X to be done to *Y */
 302 extern void move_replacements (rtx *x, rtx *y);
 303
 304 /* If LOC was scheduled to be replaced by something, return the replacement.
 305    Otherwise, return *LOC.  */
 306 extern rtx find_replacement (rtx *);
 307
 308 /* Nonzero if modifying X will affect IN.  */
 309 extern int reg_overlap_mentioned_for_reload_p (rtx, rtx);
 310
 311 /* Check the insns before INSN to see if there is a suitable register
 312    containing the same value as GOAL.  */
 313 extern rtx find_equiv_reg (rtx, rtx, enum reg_class, int, short *,
 314                            int, enum machine_mode);
 315
 316 /* Return 1 if register REGNO is the subject of a clobber in insn INSN.  */
 317 extern int regno_clobbered_p (unsigned int, rtx, enum machine_mode, int);
 318
 319 /* Return 1 if X is an operand of an insn that is being earlyclobbered.  */
 320 extern int earlyclobber_operand_p (rtx);
 321
 322 /* Record one reload that needs to be performed.  */
 323 extern int push_reload (rtx, rtx, rtx *, rtx *, enum reg_class,
 324                         enum machine_mode, enum machine_mode,
 325                         int, int, int, enum reload_type);
 326
 327 /* Functions in postreload.c:  */
 328 extern void reload_cse_regs (rtx);
 329
 330 /* Functions in reload1.c:  */
 331
 332 /* Initialize the reload pass once per compilation.  */
 333 extern void init_reload (void);
 334
 335 /* The reload pass itself.  */
 336 extern int reload (rtx, int);
 337
 338 /* Mark the slots in regs_ever_live for the hard regs
 339    used by pseudo-reg number REGNO.  */
 340 extern void mark_home_live (int);
 341
 342 /* Scan X and replace any eliminable registers (such as fp) with a
 343    replacement (such as sp), plus an offset.  */
 344 extern rtx eliminate_regs (rtx, enum machine_mode, rtx);
 345
 346 /* Deallocate the reload register used by reload number R.  */
 347 extern void deallocate_reload_reg (int r);
 348
 349 /* Functions in caller-save.c:  */
 350
 351 /* Initialize for caller-save.  */
 352 extern void init_caller_save (void);
 353
 354 /* Initialize save areas by showing that we haven't allocated any yet.  */
 355 extern void init_save_areas (void);
 356
 357 /* Allocate save areas for any hard registers that might need saving.  */
 358 extern void setup_save_areas (void);
 359
 360 /* Find the places where hard regs are live across calls and save them.  */
 361 extern void save_call_clobbered_regs (void);
 362
 363 /* Replace (subreg (reg)) with the appropriate (reg) for any operands.  */
 364 extern void cleanup_subreg_operands (rtx);
 365
 366 /* Debugging support.  */
 367 extern void debug_reload_to_stream (FILE *);
 368 extern void debug_reload (void);
 369
 370 /* Compute the actual register we should reload to, in case we're
 371    reloading to/from a register that is wider than a word.  */
 372 extern rtx reload_adjust_reg_for_mode (rtx, enum machine_mode);