gcc/reload.h

   1 /* Communication between reload.c and reload1.c.
   2    Copyright (C) 1987, 91-95, 97, 1998 Free Software Foundation, Inc.
   3
   4 This file is part of GNU CC.
   5
   6 GNU CC is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU CC is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 GNU General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU CC; see the file COPYING.  If not, write to
  18 the Free Software Foundation, 59 Temple Place - Suite 330,
  19 Boston, MA 02111-1307, USA.  */
  20
  21
  22 /* If secondary reloads are the same for inputs and outputs, define those
  23    macros here.  */
  24
  25 #ifdef SECONDARY_RELOAD_CLASS
  26 #define SECONDARY_INPUT_RELOAD_CLASS(CLASS, MODE, X) \
  27   SECONDARY_RELOAD_CLASS (CLASS, MODE, X)
  28 #define SECONDARY_OUTPUT_RELOAD_CLASS(CLASS, MODE, X) \
  29   SECONDARY_RELOAD_CLASS (CLASS, MODE, X)
  30 #endif
  31
  32 /* If either macro is defined, show that we need secondary reloads.  */
  33 #if defined(SECONDARY_INPUT_RELOAD_CLASS) || defined(SECONDARY_OUTPUT_RELOAD_CLASS)
  34 #define HAVE_SECONDARY_RELOADS
  35 #endif
  36
  37 /* If MEMORY_MOVE_COST isn't defined, give it a default here.  */
  38 #ifndef MEMORY_MOVE_COST
  39 #ifdef HAVE_SECONDARY_RELOADS
  40 #define MEMORY_MOVE_COST(MODE,CLASS,IN) \
  41   (4 + memory_move_secondary_cost ((MODE), (CLASS), (IN)))
  42 #else
  43 #define MEMORY_MOVE_COST(MODE,CLASS,IN) 4
  44 #endif
  45 #endif
  46 extern int memory_move_secondary_cost PROTO ((enum machine_mode, enum reg_class, int));
  47
  48 /* Maximum number of reloads we can need.  */
  49 #define MAX_RELOADS (2 * MAX_RECOG_OPERANDS * (MAX_REGS_PER_ADDRESS + 1))
  50
  51 /* Encode the usage of a reload.  The following codes are supported:
  52
  53    RELOAD_FOR_INPUT             reload of an input operand
  54    RELOAD_FOR_OUTPUT            likewise, for output
  55    RELOAD_FOR_INSN              a reload that must not conflict with anything
  56                                 used in the insn, but may conflict with
  57                                 something used before or after the insn
  58    RELOAD_FOR_INPUT_ADDRESS     reload for parts of the address of an object
  59                                 that is an input reload
  60    RELOAD_FOR_INPADDR_ADDRESS   reload needed for RELOAD_FOR_INPUT_ADDRESS
  61    RELOAD_FOR_OUTPUT_ADDRESS    like RELOAD_FOR INPUT_ADDRESS, for output
  62    RELOAD_FOR_OUTADDR_ADDRESS   reload needed for RELOAD_FOR_OUTPUT_ADDRESS
  63    RELOAD_FOR_OPERAND_ADDRESS   reload for the address of a non-reloaded
  64                                 operand; these don't conflict with
  65                                 any other addresses.
  66    RELOAD_FOR_OPADDR_ADDR       reload needed for RELOAD_FOR_OPERAND_ADDRESS
  67                                 reloads; usually secondary reloads
  68    RELOAD_OTHER                 none of the above, usually multiple uses
  69    RELOAD_FOR_OTHER_ADDRESS     reload for part of the address of an input
  70                                 that is marked RELOAD_OTHER.
  71
  72    This used to be "enum reload_when_needed" but some debuggers have trouble
  73    with an enum tag and variable of the same name.  */
  74
  75 enum reload_type
  76 {
  77   RELOAD_FOR_INPUT, RELOAD_FOR_OUTPUT, RELOAD_FOR_INSN,
  78   RELOAD_FOR_INPUT_ADDRESS, RELOAD_FOR_INPADDR_ADDRESS,
  79   RELOAD_FOR_OUTPUT_ADDRESS, RELOAD_FOR_OUTADDR_ADDRESS,
  80   RELOAD_FOR_OPERAND_ADDRESS, RELOAD_FOR_OPADDR_ADDR,
  81   RELOAD_OTHER, RELOAD_FOR_OTHER_ADDRESS
  82 };
  83
  84 #ifdef MAX_INSN_CODE
  85 /* Each reload is recorded with a structure like this.  */
  86 struct reload
  87 {
  88   /* The value to reload from */
  89   rtx in;
  90   /* Where to store reload-reg afterward if nec (often the same as
  91      reload_in)  */
  92   rtx out;
  93
  94   /* The class of registers to reload into.  */
  95   enum reg_class class;
  96
  97   /* The mode this operand should have when reloaded, on input.  */
  98   enum machine_mode inmode;
  99   /* The mode this operand should have when reloaded, on output.  */
 100   enum machine_mode outmode;
 101
 102   /* The mode of the reload register.  */
 103   enum machine_mode mode;
 104
 105   /* the largest number of registers this reload will require.  */
 106   int nregs;
 107
 108   /* Positive amount to increment or decrement by if
 109      reload_in is a PRE_DEC, PRE_INC, POST_DEC, POST_INC.
 110      Ignored otherwise (don't assume it is zero).  */
 111   int inc;
 112   /* A reg for which reload_in is the equivalent.
 113      If reload_in is a symbol_ref which came from
 114      reg_equiv_constant, then this is the pseudo
 115      which has that symbol_ref as equivalent.  */
 116   rtx in_reg;
 117   rtx out_reg;
 118
 119   /* Used in find_reload_regs to record the allocated register.  */
 120   int regno;
 121   /* This is the register to reload into.  If it is zero when `find_reloads'
 122      returns, you must find a suitable register in the class specified by
 123      reload_reg_class, and store here an rtx for that register with mode from
 124      reload_inmode or reload_outmode.  */
 125   rtx reg_rtx;
 126   /* The operand number being reloaded.  This is used to group related reloads
 127      and need not always be equal to the actual operand number in the insn,
 128      though it current will be; for in-out operands, it is one of the two
 129      operand numbers.  */
 130   int opnum;
 131
 132   /* Gives the reload number of a secondary input reload, when needed;
 133      otherwise -1.  */
 134   int secondary_in_reload;
 135   /* Gives the reload number of a secondary output reload, when needed;
 136      otherwise -1.  */
 137   int secondary_out_reload;
 138   /* If a secondary input reload is required, gives the INSN_CODE that uses the
 139      secondary reload as a scratch register, or CODE_FOR_nothing if the
 140      secondary reload register is to be an intermediate register.  */
 141   enum insn_code secondary_in_icode;
 142   /* Likewise, for a secondary output reload.  */
 143   enum insn_code secondary_out_icode;
 144
 145   /* Classifies reload as needed either for addressing an input reload,
 146      addressing an output, for addressing a non-reloaded mem ref, or for
 147      unspecified purposes (i.e., more than one of the above).  */
 148   enum reload_type when_needed;
 149
 150   /* Nonzero for an optional reload.  Optional reloads are ignored unless the
 151      value is already sitting in a register.  */
 152   unsigned int optional:1;
 153   /* nonzero if this reload shouldn't be combined with another reload.  */
 154   unsigned int nocombine:1;
 155   /* Nonzero if this is a secondary register for one or more reloads.  */
 156   unsigned int secondary_p:1;
 157   /* Nonzero if this reload must use a register not already allocated to a
 158      group.  */
 159   unsigned int nongroup:1;
 160 };
 161
 162 extern struct reload rld[MAX_RELOADS];
 163 extern int n_reloads;
 164 #endif
 165
 166 extern rtx *reg_equiv_constant;
 167 extern rtx *reg_equiv_memory_loc;
 168 extern rtx *reg_equiv_address;
 169 extern rtx *reg_equiv_mem;
 170
 171 /* All the "earlyclobber" operands of the current insn
 172    are recorded here.  */
 173 extern int n_earlyclobbers;
 174 extern rtx reload_earlyclobbers[MAX_RECOG_OPERANDS];
 175
 176 /* Save the number of operands.  */
 177 extern int reload_n_operands;
 178
 179 /* First uid used by insns created by reload in this function.
 180    Used in find_equiv_reg.  */
 181 extern int reload_first_uid;
 182
 183 /* Nonzero if indirect addressing is supported when the innermost MEM is
 184    of the form (MEM (SYMBOL_REF sym)).  It is assumed that the level to
 185    which these are valid is the same as spill_indirect_levels, above.   */
 186
 187 extern char indirect_symref_ok;
 188
 189 /* Nonzero if an address (plus (reg frame_pointer) (reg ...)) is valid.  */
 190 extern char double_reg_address_ok;
 191
 192 extern int num_not_at_initial_offset;
 193
 194 #ifdef MAX_INSN_CODE
 195 /* These arrays record the insn_code of insns that may be needed to
 196    perform input and output reloads of special objects.  They provide a
 197    place to pass a scratch register.  */
 198 extern enum insn_code reload_in_optab[];
 199 extern enum insn_code reload_out_optab[];
 200 #endif
 201
 202 struct needs
 203 {
 204   /* [0] is normal, [1] is nongroup.  */
 205   short regs[2][N_REG_CLASSES];
 206   short groups[N_REG_CLASSES];
 207 };
 208
 209 #if defined SET_HARD_REG_BIT && defined CLEAR_REG_SET
 210 /* This structure describes instructions which are relevant for reload.
 211    Apart from all regular insns, this also includes CODE_LABELs, since they
 212    must be examined for register elimination.  */
 213 struct insn_chain
 214 {
 215   /* Links to the neighbour instructions.  */
 216   struct insn_chain *next, *prev;
 217
 218   /* Link through a chains set up by calculate_needs_all_insns, containing
 219      all insns that need reloading.  */
 220   struct insn_chain *next_need_reload;
 221
 222   /* The basic block this insn is in.  */
 223   int block;
 224   /* The rtx of the insn.  */
 225   rtx insn;
 226   /* Register life information: record all live hard registers, and all
 227      live pseudos that have a hard register.
 228      This information is recorded for the point immediately before the insn
 229      (in live_before), and for the point within the insn at which all
 230      outputs have just been written to (in live_after).  */
 231   regset live_before;
 232   regset live_after;
 233
 234   /* For each class, size of group of consecutive regs
 235      that is needed for the reloads of this class.  */
 236   char group_size[N_REG_CLASSES];
 237   /* For each class, the machine mode which requires consecutive
 238      groups of regs of that class.
 239      If two different modes ever require groups of one class,
 240      they must be the same size and equally restrictive for that class,
 241      otherwise we can't handle the complexity.  */
 242   enum machine_mode group_mode[N_REG_CLASSES];
 243
 244   /* Indicates if a register was counted against the need for
 245      groups.  0 means it can count against max_nongroup instead.  */
 246   HARD_REG_SET counted_for_groups;
 247
 248   /* Indicates if a register was counted against the need for
 249      non-groups.  0 means it can become part of a new group.
 250      During choose_reload_regs, 1 here means don't use this reg
 251      as part of a group, even if it seems to be otherwise ok.  */
 252   HARD_REG_SET counted_for_nongroups;
 253
 254   /* Indicates which registers have already been used for spills.  */
 255   HARD_REG_SET used_spill_regs;
 256
 257   /* Describe the needs for reload registers of this insn.  */
 258   struct needs need;
 259
 260   /* Nonzero if find_reloads said the insn requires reloading.  */
 261   unsigned int need_reload:1;
 262   /* Nonzero if find_reloads needs to be run during reload_as_needed to
 263      perform modifications on any operands.  */
 264   unsigned int need_operand_change:1;
 265   /* Nonzero if eliminate_regs_in_insn said it requires eliminations.  */
 266   unsigned int need_elim:1;
 267   /* Nonzero if this insn was inserted by perform_caller_saves.  */
 268   unsigned int is_caller_save_insn:1;
 269 };
 270
 271 /* A chain of insn_chain structures to describe all non-note insns in
 272    a function.  */
 273 extern struct insn_chain *reload_insn_chain;
 274
 275 /* Allocate a new insn_chain structure.  */
 276 extern struct insn_chain *new_insn_chain        PROTO((void));
 277
 278 extern void compute_use_by_pseudos              PROTO((HARD_REG_SET *, regset));
 279 #endif
 280
 281 /* Functions from reload.c:  */
 282
 283 /* Return a memory location that will be used to copy X in mode MODE.
 284    If we haven't already made a location for this mode in this insn,
 285    call find_reloads_address on the location being returned.  */
 286 extern rtx get_secondary_mem PROTO((rtx, enum machine_mode,
 287                                     int, enum reload_type));
 288
 289 /* Clear any secondary memory locations we've made.  */
 290 extern void clear_secondary_mem PROTO((void));
 291
 292 /* Transfer all replacements that used to be in reload FROM to be in
 293    reload TO.  */
 294 extern void transfer_replacements PROTO((int, int));
 295
 296 /* IN_RTX is the value loaded by a reload that we now decided to inherit,
 297    or a subpart of it.  If we have any replacements registered for IN_RTX,
 298    chancel the reloads that were supposed to load them.
 299    Return non-zero if we chanceled any reloads.  */
 300 extern int remove_address_replacements PROTO((rtx in_rtx));
 301
 302 /* Like rtx_equal_p except that it allows a REG and a SUBREG to match
 303    if they are the same hard reg, and has special hacks for
 304    autoincrement and autodecrement.  */
 305 extern int operands_match_p PROTO((rtx, rtx));
 306
 307 /* Return 1 if altering OP will not modify the value of CLOBBER. */
 308 extern int safe_from_earlyclobber PROTO((rtx, rtx));
 309
 310 /* Search the body of INSN for values that need reloading and record them
 311    with push_reload.  REPLACE nonzero means record also where the values occur
 312    so that subst_reloads can be used.  */
 313 extern int find_reloads PROTO((rtx, int, int, int, short *));
 314
 315 /* Compute the sum of X and Y, making canonicalizations assumed in an
 316    address, namely: sum constant integers, surround the sum of two
 317    constants with a CONST, put the constant as the second operand, and
 318    group the constant on the outermost sum.  */
 319 extern rtx form_sum PROTO((rtx, rtx));
 320
 321 /* Substitute into the current INSN the registers into which we have reloaded
 322    the things that need reloading.  */
 323 extern void subst_reloads PROTO((void));
 324
 325 /* Make a copy of any replacements being done into X and move those copies
 326    to locations in Y, a copy of X.  We only look at the highest level of
 327    the RTL.  */
 328 extern void copy_replacements PROTO((rtx, rtx));
 329
 330 /* Change any replacements being done to *X to be done to *Y */
 331 extern void move_replacements PROTO((rtx *x, rtx *y));
 332
 333 /* If LOC was scheduled to be replaced by something, return the replacement.
 334    Otherwise, return *LOC.  */
 335 extern rtx find_replacement PROTO((rtx *));
 336
 337 /* Return nonzero if register in range [REGNO, ENDREGNO)
 338    appears either explicitly or implicitly in X
 339    other than being stored into.  */
 340 extern int refers_to_regno_for_reload_p PROTO((int, int, rtx, rtx *));
 341
 342 /* Nonzero if modifying X will affect IN.  */
 343 extern int reg_overlap_mentioned_for_reload_p PROTO((rtx, rtx));
 344
 345 /* Return nonzero if anything in X contains a MEM.  Look also for pseudo
 346    registers.  */
 347 extern int refers_to_mem_for_reload_p PROTO((rtx));
 348
 349 /* Check the insns before INSN to see if there is a suitable register
 350    containing the same value as GOAL.  */
 351 extern rtx find_equiv_reg PROTO((rtx, rtx, enum reg_class, int, short *,
 352                                  int, enum machine_mode));
 353
 354 /* Return 1 if register REGNO is the subject of a clobber in insn INSN.  */
 355 extern int regno_clobbered_p PROTO((int, rtx));
 356
 357 /* Return 1 if X is an operand of an insn that is being earlyclobbered.  */
 358 int earlyclobber_operand_p PROTO((rtx));
 359
 360 /* Functions in reload1.c:  */
 361
 362 extern int reloads_conflict             PROTO ((int, int));
 363
 364 int count_occurrences            PROTO((rtx, rtx));
 365
 366 /* Initialize the reload pass once per compilation.  */
 367 extern void init_reload PROTO((void));
 368
 369 /* The reload pass itself.  */
 370 extern int reload PROTO((rtx, int, FILE *));
 371
 372 /* Mark the slots in regs_ever_live for the hard regs
 373    used by pseudo-reg number REGNO.  */
 374 extern void mark_home_live PROTO((int));
 375
 376 /* Scan X and replace any eliminable registers (such as fp) with a
 377    replacement (such as sp), plus an offset.  */
 378 extern rtx eliminate_regs PROTO((rtx, enum machine_mode, rtx));
 379
 380 /* Emit code to perform a reload from IN (which may be a reload register) to
 381    OUT (which may also be a reload register).  IN or OUT is from operand
 382    OPNUM with reload type TYPE.  */
 383 extern rtx gen_reload PROTO((rtx, rtx, int, enum reload_type));
 384
 385 /* Deallocate the reload register used by reload number R.  */
 386 extern void deallocate_reload_reg PROTO((int r));
 387
 388 /* Functions in caller-save.c:  */
 389
 390 /* Initialize for caller-save.  */
 391 extern void init_caller_save PROTO((void));
 392
 393 /* Initialize save areas by showing that we haven't allocated any yet.  */
 394 extern void init_save_areas PROTO((void));
 395
 396 /* Allocate save areas for any hard registers that might need saving.  */
 397 extern void setup_save_areas PROTO((void));
 398
 399 /* Find the places where hard regs are live across calls and save them.  */
 400 extern void save_call_clobbered_regs PROTO((void));
 401
 402 /* Replace (subreg (reg)) with the appropriate (reg) for any operands.  */
 403 extern void cleanup_subreg_operands PROTO ((rtx));