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 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, 59 Temple Place - Suite 330, Boston, MA
  20 02111-1307, 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 PARAMS ((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 rtx *reg_equiv_constant;
 168 extern rtx *reg_equiv_memory_loc;
 169 extern rtx *reg_equiv_address;
 170 extern rtx *reg_equiv_mem;
 171
 172 /* All the "earlyclobber" operands of the current insn
 173    are recorded here.  */
 174 extern int n_earlyclobbers;
 175 extern rtx reload_earlyclobbers[MAX_RECOG_OPERANDS];
 176
 177 /* Save the number of operands.  */
 178 extern int reload_n_operands;
 179
 180 /* First uid used by insns created by reload in this function.
 181    Used in find_equiv_reg.  */
 182 extern int reload_first_uid;
 183
 184 /* Nonzero if indirect addressing is supported when the innermost MEM is
 185    of the form (MEM (SYMBOL_REF sym)).  It is assumed that the level to
 186    which these are valid is the same as spill_indirect_levels, above.  */
 187
 188 extern char indirect_symref_ok;
 189
 190 /* Nonzero if an address (plus (reg frame_pointer) (reg ...)) is valid.  */
 191 extern char double_reg_address_ok;
 192
 193 extern int num_not_at_initial_offset;
 194
 195 struct needs
 196 {
 197   /* [0] is normal, [1] is nongroup.  */
 198   short regs[2][N_REG_CLASSES];
 199   short groups[N_REG_CLASSES];
 200 };
 201
 202 #if defined SET_HARD_REG_BIT && defined CLEAR_REG_SET
 203 /* This structure describes instructions which are relevant for reload.
 204    Apart from all regular insns, this also includes CODE_LABELs, since they
 205    must be examined for register elimination.  */
 206 struct insn_chain
 207 {
 208   /* Links to the neighbour instructions.  */
 209   struct insn_chain *next, *prev;
 210
 211   /* Link through a chains set up by calculate_needs_all_insns, containing
 212      all insns that need reloading.  */
 213   struct insn_chain *next_need_reload;
 214
 215   /* The basic block this insn is in.  */
 216   int block;
 217   /* The rtx of the insn.  */
 218   rtx insn;
 219   /* Register life information: record all live hard registers, and all
 220      live pseudos that have a hard register.  */
 221   regset_head live_throughout;
 222   regset_head dead_or_set;
 223
 224   /* Copies of the global variables computed by find_reloads.  */
 225   struct reload *rld;
 226   int n_reloads;
 227
 228   /* Indicates which registers have already been used for spills.  */
 229   HARD_REG_SET used_spill_regs;
 230
 231   /* Describe the needs for reload registers of this insn.  */
 232   struct needs need;
 233
 234   /* Nonzero if find_reloads said the insn requires reloading.  */
 235   unsigned int need_reload:1;
 236   /* Nonzero if find_reloads needs to be run during reload_as_needed to
 237      perform modifications on any operands.  */
 238   unsigned int need_operand_change:1;
 239   /* Nonzero if eliminate_regs_in_insn said it requires eliminations.  */
 240   unsigned int need_elim:1;
 241   /* Nonzero if this insn was inserted by perform_caller_saves.  */
 242   unsigned int is_caller_save_insn:1;
 243 };
 244
 245 /* A chain of insn_chain structures to describe all non-note insns in
 246    a function.  */
 247 extern struct insn_chain *reload_insn_chain;
 248
 249 /* Allocate a new insn_chain structure.  */
 250 extern struct insn_chain *new_insn_chain        PARAMS ((void));
 251
 252 extern void compute_use_by_pseudos              PARAMS ((HARD_REG_SET *, regset));
 253 #endif
 254
 255 /* Functions from reload.c:  */
 256
 257 /* Return a memory location that will be used to copy X in mode MODE.
 258    If we haven't already made a location for this mode in this insn,
 259    call find_reloads_address on the location being returned.  */
 260 extern rtx get_secondary_mem PARAMS ((rtx, enum machine_mode,
 261                                     int, enum reload_type));
 262
 263 /* Clear any secondary memory locations we've made.  */
 264 extern void clear_secondary_mem PARAMS ((void));
 265
 266 /* Transfer all replacements that used to be in reload FROM to be in
 267    reload TO.  */
 268 extern void transfer_replacements PARAMS ((int, int));
 269
 270 /* IN_RTX is the value loaded by a reload that we now decided to inherit,
 271    or a subpart of it.  If we have any replacements registered for IN_RTX,
 272    chancel the reloads that were supposed to load them.
 273    Return non-zero if we chanceled any reloads.  */
 274 extern int remove_address_replacements PARAMS ((rtx in_rtx));
 275
 276 /* Like rtx_equal_p except that it allows a REG and a SUBREG to match
 277    if they are the same hard reg, and has special hacks for
 278    autoincrement and autodecrement.  */
 279 extern int operands_match_p PARAMS ((rtx, rtx));
 280
 281 /* Return 1 if altering OP will not modify the value of CLOBBER.  */
 282 extern int safe_from_earlyclobber PARAMS ((rtx, rtx));
 283
 284 /* Search the body of INSN for values that need reloading and record them
 285    with push_reload.  REPLACE nonzero means record also where the values occur
 286    so that subst_reloads can be used.  */
 287 extern int find_reloads PARAMS ((rtx, int, int, int, short *));
 288
 289 /* Compute the sum of X and Y, making canonicalizations assumed in an
 290    address, namely: sum constant integers, surround the sum of two
 291    constants with a CONST, put the constant as the second operand, and
 292    group the constant on the outermost sum.  */
 293 extern rtx form_sum PARAMS ((rtx, rtx));
 294
 295 /* Substitute into the current INSN the registers into which we have reloaded
 296    the things that need reloading.  */
 297 extern void subst_reloads PARAMS ((rtx));
 298
 299 /* Make a copy of any replacements being done into X and move those copies
 300    to locations in Y, a copy of X.  We only look at the highest level of
 301    the RTL.  */
 302 extern void copy_replacements PARAMS ((rtx, rtx));
 303
 304 /* Change any replacements being done to *X to be done to *Y */
 305 extern void move_replacements PARAMS ((rtx *x, rtx *y));
 306
 307 /* If LOC was scheduled to be replaced by something, return the replacement.
 308    Otherwise, return *LOC.  */
 309 extern rtx find_replacement PARAMS ((rtx *));
 310
 311 /* Return nonzero if register in range [REGNO, ENDREGNO)
 312    appears either explicitly or implicitly in X
 313    other than being stored into.  */
 314 extern int refers_to_regno_for_reload_p PARAMS ((unsigned int, unsigned int,
 315                                                  rtx, rtx *));
 316
 317 /* Nonzero if modifying X will affect IN.  */
 318 extern int reg_overlap_mentioned_for_reload_p PARAMS ((rtx, rtx));
 319
 320 /* Return nonzero if anything in X contains a MEM.  Look also for pseudo
 321    registers.  */
 322 extern int refers_to_mem_for_reload_p PARAMS ((rtx));
 323
 324 /* Check the insns before INSN to see if there is a suitable register
 325    containing the same value as GOAL.  */
 326 extern rtx find_equiv_reg PARAMS ((rtx, rtx, enum reg_class, int, short *,
 327                                  int, enum machine_mode));
 328
 329 /* Return 1 if register REGNO is the subject of a clobber in insn INSN.  */
 330 extern int regno_clobbered_p PARAMS ((unsigned int, rtx, enum machine_mode,
 331                                       int));
 332
 333 /* Return 1 if X is an operand of an insn that is being earlyclobbered.  */
 334 extern int earlyclobber_operand_p PARAMS ((rtx));
 335
 336 /* Record one reload that needs to be performed.  */
 337 extern int push_reload PARAMS ((rtx, rtx, rtx *, rtx *, enum reg_class,
 338                                 enum machine_mode, enum machine_mode,
 339                                 int, int, int, enum reload_type));
 340
 341 /* Functions in reload1.c:  */
 342
 343 extern void reload_cse_regs             PARAMS ((rtx));
 344 extern int reloads_conflict             PARAMS ((int, int));
 345
 346 /* Initialize the reload pass once per compilation.  */
 347 extern void init_reload PARAMS ((void));
 348
 349 /* The reload pass itself.  */
 350 extern int reload PARAMS ((rtx, int));
 351
 352 /* Mark the slots in regs_ever_live for the hard regs
 353    used by pseudo-reg number REGNO.  */
 354 extern void mark_home_live PARAMS ((int));
 355
 356 /* Scan X and replace any eliminable registers (such as fp) with a
 357    replacement (such as sp), plus an offset.  */
 358 extern rtx eliminate_regs PARAMS ((rtx, enum machine_mode, rtx));
 359
 360 /* Emit code to perform a reload from IN (which may be a reload register) to
 361    OUT (which may also be a reload register).  IN or OUT is from operand
 362    OPNUM with reload type TYPE.  */
 363 extern rtx gen_reload PARAMS ((rtx, rtx, int, enum reload_type));
 364
 365 /* Deallocate the reload register used by reload number R.  */
 366 extern void deallocate_reload_reg PARAMS ((int r));
 367
 368 /* Functions in caller-save.c:  */
 369
 370 /* Initialize for caller-save.  */
 371 extern void init_caller_save PARAMS ((void));
 372
 373 /* Initialize save areas by showing that we haven't allocated any yet.  */
 374 extern void init_save_areas PARAMS ((void));
 375
 376 /* Allocate save areas for any hard registers that might need saving.  */
 377 extern void setup_save_areas PARAMS ((void));
 378
 379 /* Find the places where hard regs are live across calls and save them.  */
 380 extern void save_call_clobbered_regs PARAMS ((void));
 381
 382 /* Replace (subreg (reg)) with the appropriate (reg) for any operands.  */
 383 extern void cleanup_subreg_operands PARAMS ((rtx));
 384
 385 /* Debugging support.  */
 386 extern void debug_reload_to_stream PARAMS ((FILE *));
 387 extern void debug_reload PARAMS ((void));