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 either macro is defined, show that we need secondary reloads.  */
  34 #if defined(SECONDARY_INPUT_RELOAD_CLASS) || defined(SECONDARY_OUTPUT_RELOAD_CLASS)
  35 #define HAVE_SECONDARY_RELOADS
  36 #endif
  37
  38 /* If MEMORY_MOVE_COST isn't defined, give it a default here.  */
  39 #ifndef MEMORY_MOVE_COST
  40 #ifdef HAVE_SECONDARY_RELOADS
  41 #define MEMORY_MOVE_COST(MODE,CLASS,IN) \
  42   (4 + memory_move_secondary_cost ((MODE), (CLASS), (IN)))
  43 #else
  44 #define MEMORY_MOVE_COST(MODE,CLASS,IN) 4
  45 #endif
  46 #endif
  47 extern int memory_move_secondary_cost (enum machine_mode, enum reg_class, int);
  48
  49 /* Maximum number of reloads we can need.  */
  50 #define MAX_RELOADS (2 * MAX_RECOG_OPERANDS * (MAX_REGS_PER_ADDRESS + 1))
  51
  52 /* Encode the usage of a reload.  The following codes are supported:
  53
  54    RELOAD_FOR_INPUT             reload of an input operand
  55    RELOAD_FOR_OUTPUT            likewise, for output
  56    RELOAD_FOR_INSN              a reload that must not conflict with anything
  57                                 used in the insn, but may conflict with
  58                                 something used before or after the insn
  59    RELOAD_FOR_INPUT_ADDRESS     reload for parts of the address of an object
  60                                 that is an input reload
  61    RELOAD_FOR_INPADDR_ADDRESS   reload needed for RELOAD_FOR_INPUT_ADDRESS
  62    RELOAD_FOR_OUTPUT_ADDRESS    like RELOAD_FOR INPUT_ADDRESS, for output
  63    RELOAD_FOR_OUTADDR_ADDRESS   reload needed for RELOAD_FOR_OUTPUT_ADDRESS
  64    RELOAD_FOR_OPERAND_ADDRESS   reload for the address of a non-reloaded
  65                                 operand; these don't conflict with
  66                                 any other addresses.
  67    RELOAD_FOR_OPADDR_ADDR       reload needed for RELOAD_FOR_OPERAND_ADDRESS
  68                                 reloads; usually secondary reloads
  69    RELOAD_OTHER                 none of the above, usually multiple uses
  70    RELOAD_FOR_OTHER_ADDRESS     reload for part of the address of an input
  71                                 that is marked RELOAD_OTHER.
  72
  73    This used to be "enum reload_when_needed" but some debuggers have trouble
  74    with an enum tag and variable of the same name.  */
  75
  76 enum reload_type
  77 {
  78   RELOAD_FOR_INPUT, RELOAD_FOR_OUTPUT, RELOAD_FOR_INSN,
  79   RELOAD_FOR_INPUT_ADDRESS, RELOAD_FOR_INPADDR_ADDRESS,
  80   RELOAD_FOR_OUTPUT_ADDRESS, RELOAD_FOR_OUTADDR_ADDRESS,
  81   RELOAD_FOR_OPERAND_ADDRESS, RELOAD_FOR_OPADDR_ADDR,
  82   RELOAD_OTHER, RELOAD_FOR_OTHER_ADDRESS
  83 };
  84
  85 #ifdef GCC_INSN_CODES_H
  86 /* Each reload is recorded with a structure like this.  */
  87 struct reload
  88 {
  89   /* The value to reload from */
  90   rtx in;
  91   /* Where to store reload-reg afterward if nec (often the same as
  92      reload_in)  */
  93   rtx out;
  94
  95   /* The class of registers to reload into.  */
  96   enum reg_class class;
  97
  98   /* The mode this operand should have when reloaded, on input.  */
  99   enum machine_mode inmode;
 100   /* The mode this operand should have when reloaded, on output.  */
 101   enum machine_mode outmode;
 102
 103   /* The mode of the reload register.  */
 104   enum machine_mode mode;
 105
 106   /* the largest number of registers this reload will require.  */
 107   unsigned int nregs;
 108
 109   /* Positive amount to increment or decrement by if
 110      reload_in is a PRE_DEC, PRE_INC, POST_DEC, POST_INC.
 111      Ignored otherwise (don't assume it is zero).  */
 112   int inc;
 113   /* A reg for which reload_in is the equivalent.
 114      If reload_in is a symbol_ref which came from
 115      reg_equiv_constant, then this is the pseudo
 116      which has that symbol_ref as equivalent.  */
 117   rtx in_reg;
 118   rtx out_reg;
 119
 120   /* Used in find_reload_regs to record the allocated register.  */
 121   int regno;
 122   /* This is the register to reload into.  If it is zero when `find_reloads'
 123      returns, you must find a suitable register in the class specified by
 124      reload_reg_class, and store here an rtx for that register with mode from
 125      reload_inmode or reload_outmode.  */
 126   rtx reg_rtx;
 127   /* The operand number being reloaded.  This is used to group related reloads
 128      and need not always be equal to the actual operand number in the insn,
 129      though it current will be; for in-out operands, it is one of the two
 130      operand numbers.  */
 131   int opnum;
 132
 133   /* Gives the reload number of a secondary input reload, when needed;
 134      otherwise -1.  */
 135   int secondary_in_reload;
 136   /* Gives the reload number of a secondary output reload, when needed;
 137      otherwise -1.  */
 138   int secondary_out_reload;
 139   /* If a secondary input reload is required, gives the INSN_CODE that uses the
 140      secondary reload as a scratch register, or CODE_FOR_nothing if the
 141      secondary reload register is to be an intermediate register.  */
 142   enum insn_code secondary_in_icode;
 143   /* Likewise, for a secondary output reload.  */
 144   enum insn_code secondary_out_icode;
 145
 146   /* Classifies reload as needed either for addressing an input reload,
 147      addressing an output, for addressing a non-reloaded mem ref, or for
 148      unspecified purposes (i.e., more than one of the above).  */
 149   enum reload_type when_needed;
 150
 151   /* Nonzero for an optional reload.  Optional reloads are ignored unless the
 152      value is already sitting in a register.  */
 153   unsigned int optional:1;
 154   /* nonzero if this reload shouldn't be combined with another reload.  */
 155   unsigned int nocombine:1;
 156   /* Nonzero if this is a secondary register for one or more reloads.  */
 157   unsigned int secondary_p:1;
 158   /* Nonzero if this reload must use a register not already allocated to a
 159      group.  */
 160   unsigned int nongroup:1;
 161 };
 162
 163 extern struct reload rld[MAX_RELOADS];
 164 extern int n_reloads;
 165 #endif
 166
 167 extern GTY (()) struct varray_head_tag *reg_equiv_memory_loc_varray;
 168 extern rtx *reg_equiv_constant;
 169 extern rtx *reg_equiv_memory_loc;
 170 extern rtx *reg_equiv_address;
 171 extern rtx *reg_equiv_mem;
 172
 173 /* Element N is the list of insns that initialized reg N from its equivalent
 174    constant or memory slot.  */
 175 extern GTY((length("reg_equiv_init_size"))) rtx *reg_equiv_init;
 176
 177 /* The size of the previous array, for GC purposes.  */
 178 extern GTY(()) int reg_equiv_init_size;
 179
 180 /* All the "earlyclobber" operands of the current insn
 181    are recorded here.  */
 182 extern int n_earlyclobbers;
 183 extern rtx reload_earlyclobbers[MAX_RECOG_OPERANDS];
 184
 185 /* Save the number of operands.  */
 186 extern int reload_n_operands;
 187
 188 /* First uid used by insns created by reload in this function.
 189    Used in find_equiv_reg.  */
 190 extern int reload_first_uid;
 191
 192 /* Nonzero if indirect addressing is supported when the innermost MEM is
 193    of the form (MEM (SYMBOL_REF sym)).  It is assumed that the level to
 194    which these are valid is the same as spill_indirect_levels, above.  */
 195
 196 extern char indirect_symref_ok;
 197
 198 /* Nonzero if an address (plus (reg frame_pointer) (reg ...)) is valid.  */
 199 extern char double_reg_address_ok;
 200
 201 extern int num_not_at_initial_offset;
 202
 203 #if defined SET_HARD_REG_BIT && defined CLEAR_REG_SET
 204 /* This structure describes instructions which are relevant for reload.
 205    Apart from all regular insns, this also includes CODE_LABELs, since they
 206    must be examined for register elimination.  */
 207 struct insn_chain
 208 {
 209   /* Links to the neighbor instructions.  */
 210   struct insn_chain *next, *prev;
 211
 212   /* Link through a chains set up by calculate_needs_all_insns, containing
 213      all insns that need reloading.  */
 214   struct insn_chain *next_need_reload;
 215
 216   /* The basic block this insn is in.  */
 217   int block;
 218   /* The rtx of the insn.  */
 219   rtx insn;
 220   /* Register life information: record all live hard registers, and all
 221      live pseudos that have a hard register.  */
 222   regset_head live_throughout;
 223   regset_head dead_or_set;
 224
 225   /* Copies of the global variables computed by find_reloads.  */
 226   struct reload *rld;
 227   int n_reloads;
 228
 229   /* Indicates which registers have already been used for spills.  */
 230   HARD_REG_SET used_spill_regs;
 231
 232   /* Nonzero if find_reloads said the insn requires reloading.  */
 233   unsigned int need_reload:1;
 234   /* Nonzero if find_reloads needs to be run during reload_as_needed to
 235      perform modifications on any operands.  */
 236   unsigned int need_operand_change:1;
 237   /* Nonzero if eliminate_regs_in_insn said it requires eliminations.  */
 238   unsigned int need_elim:1;
 239   /* Nonzero if this insn was inserted by perform_caller_saves.  */
 240   unsigned int is_caller_save_insn:1;
 241 };
 242
 243 /* A chain of insn_chain structures to describe all non-note insns in
 244    a function.  */
 245 extern struct insn_chain *reload_insn_chain;
 246
 247 /* Allocate a new insn_chain structure.  */
 248 extern struct insn_chain *new_insn_chain (void);
 249
 250 extern void compute_use_by_pseudos (HARD_REG_SET *, regset);
 251 #endif
 252
 253 /* Functions from reload.c:  */
 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);