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 /* See reload.c and reload1.c for comments on these variables.  */
  49
  50 /* Maximum number of reloads we can need.  */
  51 #define MAX_RELOADS (2 * MAX_RECOG_OPERANDS * (MAX_REGS_PER_ADDRESS + 1))
  52
  53 extern enum reg_class reload_address_base_reg_class;
  54 extern enum reg_class reload_address_index_reg_class;
  55 extern rtx reload_in[MAX_RELOADS];
  56 extern rtx reload_out[MAX_RELOADS];
  57 extern rtx reload_in_reg[MAX_RELOADS];
  58 extern enum reg_class reload_reg_class[MAX_RELOADS];
  59 extern enum machine_mode reload_inmode[MAX_RELOADS];
  60 extern enum machine_mode reload_outmode[MAX_RELOADS];
  61 extern char reload_optional[MAX_RELOADS];
  62 extern char reload_nongroup[MAX_RELOADS];
  63 extern int reload_inc[MAX_RELOADS];
  64 extern int reload_opnum[MAX_RELOADS];
  65 extern int reload_secondary_p[MAX_RELOADS];
  66 extern int reload_secondary_in_reload[MAX_RELOADS];
  67 extern int reload_secondary_out_reload[MAX_RELOADS];
  68 #ifdef MAX_INSN_CODE
  69 extern enum insn_code reload_secondary_in_icode[MAX_RELOADS];
  70 extern enum insn_code reload_secondary_out_icode[MAX_RELOADS];
  71 #endif
  72 extern int n_reloads;
  73
  74 extern rtx reload_reg_rtx[MAX_RELOADS];
  75
  76 /* Encode the usage of a reload.  The following codes are supported:
  77
  78    RELOAD_FOR_INPUT             reload of an input operand
  79    RELOAD_FOR_OUTPUT            likewise, for output
  80    RELOAD_FOR_INSN              a reload that must not conflict with anything
  81                                 used in the insn, but may conflict with
  82                                 something used before or after the insn
  83    RELOAD_FOR_INPUT_ADDRESS     reload for parts of the address of an object
  84                                 that is an input reload
  85    RELOAD_FOR_INPADDR_ADDRESS   reload needed for RELOAD_FOR_INPUT_ADDRESS
  86    RELOAD_FOR_OUTPUT_ADDRESS    like RELOAD_FOR INPUT_ADDRESS, for output
  87    RELOAD_FOR_OUTADDR_ADDRESS   reload needed for RELOAD_FOR_OUTPUT_ADDRESS
  88    RELOAD_FOR_OPERAND_ADDRESS   reload for the address of a non-reloaded
  89                                 operand; these don't conflict with
  90                                 any other addresses.
  91    RELOAD_FOR_OPADDR_ADDR       reload needed for RELOAD_FOR_OPERAND_ADDRESS
  92                                 reloads; usually secondary reloads
  93    RELOAD_OTHER                 none of the above, usually multiple uses
  94    RELOAD_FOR_OTHER_ADDRESS     reload for part of the address of an input
  95                                 that is marked RELOAD_OTHER.
  96
  97    This used to be "enum reload_when_needed" but some debuggers have trouble
  98    with an enum tag and variable of the same name.  */
  99
 100 enum reload_type
 101 {
 102   RELOAD_FOR_INPUT, RELOAD_FOR_OUTPUT, RELOAD_FOR_INSN,
 103   RELOAD_FOR_INPUT_ADDRESS, RELOAD_FOR_INPADDR_ADDRESS,
 104   RELOAD_FOR_OUTPUT_ADDRESS, RELOAD_FOR_OUTADDR_ADDRESS,
 105   RELOAD_FOR_OPERAND_ADDRESS, RELOAD_FOR_OPADDR_ADDR,
 106   RELOAD_OTHER, RELOAD_FOR_OTHER_ADDRESS
 107 };
 108
 109 extern enum reload_type reload_when_needed[MAX_RELOADS];
 110
 111 extern rtx *reg_equiv_constant;
 112 extern rtx *reg_equiv_memory_loc;
 113 extern rtx *reg_equiv_address;
 114 extern rtx *reg_equiv_mem;
 115
 116 /* All the "earlyclobber" operands of the current insn
 117    are recorded here.  */
 118 extern int n_earlyclobbers;
 119 extern rtx reload_earlyclobbers[MAX_RECOG_OPERANDS];
 120
 121 /* Save the number of operands.  */
 122 extern int reload_n_operands;
 123
 124 /* First uid used by insns created by reload in this function.
 125    Used in find_equiv_reg.  */
 126 extern int reload_first_uid;
 127
 128 /* Nonzero if indirect addressing is supported when the innermost MEM is
 129    of the form (MEM (SYMBOL_REF sym)).  It is assumed that the level to
 130    which these are valid is the same as spill_indirect_levels, above.   */
 131
 132 extern char indirect_symref_ok;
 133
 134 /* Nonzero if an address (plus (reg frame_pointer) (reg ...)) is valid.  */
 135 extern char double_reg_address_ok;
 136
 137 #ifdef MAX_INSN_CODE
 138 /* These arrays record the insn_code of insns that may be needed to
 139    perform input and output reloads of special objects.  They provide a
 140    place to pass a scratch register.  */
 141 extern enum insn_code reload_in_optab[];
 142 extern enum insn_code reload_out_optab[];
 143 #endif
 144
 145 struct needs
 146 {
 147   /* [0] is normal, [1] is nongroup.  */
 148   short regs[2][N_REG_CLASSES];
 149   short groups[N_REG_CLASSES];
 150 };
 151
 152 #if defined SET_HARD_REG_BIT && defined CLEAR_REG_SET
 153 /* This structure describes instructions which are relevant for reload.
 154    Apart from all regular insns, this also includes CODE_LABELs, since they
 155    must be examined for register elimination.  */
 156 struct insn_chain
 157 {
 158   /* Links to the neighbour instructions.  */
 159   struct insn_chain *next, *prev;
 160
 161   /* Link through a chains set up by calculate_needs_all_insns, containing
 162      all insns that need reloading.  */
 163   struct insn_chain *next_need_reload;
 164
 165   /* The basic block this insn is in.  */
 166   int block;
 167   /* The rtx of the insn.  */
 168   rtx insn;
 169   /* Register life information: record all live hard registers, and all
 170      live pseudos that have a hard register.
 171      This information is recorded for the point immediately before the insn
 172      (in live_before), and for the point within the insn at which all
 173      outputs have just been written to (in live_after).  */
 174   regset live_before;
 175   regset live_after;
 176
 177   /* For each class, size of group of consecutive regs
 178      that is needed for the reloads of this class.  */
 179   char group_size[N_REG_CLASSES];
 180   /* For each class, the machine mode which requires consecutive
 181      groups of regs of that class.
 182      If two different modes ever require groups of one class,
 183      they must be the same size and equally restrictive for that class,
 184      otherwise we can't handle the complexity.  */
 185   enum machine_mode group_mode[N_REG_CLASSES];
 186
 187   /* Indicates if a register was counted against the need for
 188      groups.  0 means it can count against max_nongroup instead.  */
 189   HARD_REG_SET counted_for_groups;
 190
 191   /* Indicates if a register was counted against the need for
 192      non-groups.  0 means it can become part of a new group.
 193      During choose_reload_regs, 1 here means don't use this reg
 194      as part of a group, even if it seems to be otherwise ok.  */
 195   HARD_REG_SET counted_for_nongroups;
 196
 197   /* Indicates which registers have already been used for spills.  */
 198   HARD_REG_SET used_spill_regs;
 199
 200   /* Describe the needs for reload registers of this insn.  */
 201   struct needs need;
 202
 203   /* Nonzero if find_reloads said the insn requires reloading.  */
 204   unsigned int need_reload:1;
 205   /* Nonzero if eliminate_regs_in_insn said it requires eliminations.  */
 206   unsigned int need_elim:1;
 207   /* Nonzero if this insn was inserted by perform_caller_saves.  */
 208   unsigned int is_caller_save_insn:1;
 209 };
 210
 211 /* A chain of insn_chain structures to describe all non-note insns in
 212    a function.  */
 213 extern struct insn_chain *reload_insn_chain;
 214
 215 /* Allocate a new insn_chain structure.  */
 216 extern struct insn_chain *new_insn_chain        PROTO((void));
 217
 218 extern void compute_use_by_pseudos              PROTO((HARD_REG_SET *, regset));
 219 #endif
 220
 221 /* Functions from reload.c:  */
 222
 223 /* Return a memory location that will be used to copy X in mode MODE.
 224    If we haven't already made a location for this mode in this insn,
 225    call find_reloads_address on the location being returned.  */
 226 extern rtx get_secondary_mem PROTO((rtx, enum machine_mode,
 227                                     int, enum reload_type));
 228
 229 /* Clear any secondary memory locations we've made.  */
 230 extern void clear_secondary_mem PROTO((void));
 231
 232 /* Transfer all replacements that used to be in reload FROM to be in
 233    reload TO.  */
 234 extern void transfer_replacements PROTO((int, int));
 235
 236 /* Remove all replacements in reload FROM.  */
 237 extern void remove_replacements PROTO((int));
 238
 239 /* Like rtx_equal_p except that it allows a REG and a SUBREG to match
 240    if they are the same hard reg, and has special hacks for
 241    autoincrement and autodecrement.  */
 242 extern int operands_match_p PROTO((rtx, rtx));
 243
 244 /* Return the number of times character C occurs in string S.  */
 245 extern int n_occurrences PROTO((int, char *));
 246
 247 /* Return 1 if altering OP will not modify the value of CLOBBER. */
 248 extern int safe_from_earlyclobber PROTO((rtx, rtx));
 249
 250 /* Search the body of INSN for values that need reloading and record them
 251    with push_reload.  REPLACE nonzero means record also where the values occur
 252    so that subst_reloads can be used.  */
 253 extern void find_reloads PROTO((rtx, int, int, int, short *));
 254
 255 /* Compute the sum of X and Y, making canonicalizations assumed in an
 256    address, namely: sum constant integers, surround the sum of two
 257    constants with a CONST, put the constant as the second operand, and
 258    group the constant on the outermost sum.  */
 259 extern rtx form_sum PROTO((rtx, rtx));
 260
 261 /* Substitute into the current INSN the registers into which we have reloaded
 262    the things that need reloading.  */
 263 extern void subst_reloads PROTO((void));
 264
 265 /* Make a copy of any replacements being done into X and move those copies
 266    to locations in Y, a copy of X.  We only look at the highest level of
 267    the RTL.  */
 268 extern void copy_replacements PROTO((rtx, rtx));
 269
 270 /* Change any replacements being done to *X to be done to *Y */
 271 extern void move_replacements PROTO((rtx *x, rtx *y));
 272
 273 /* If LOC was scheduled to be replaced by something, return the replacement.
 274    Otherwise, return *LOC.  */
 275 extern rtx find_replacement PROTO((rtx *));
 276
 277 /* Return nonzero if register in range [REGNO, ENDREGNO)
 278    appears either explicitly or implicitly in X
 279    other than being stored into.  */
 280 extern int refers_to_regno_for_reload_p PROTO((int, int, rtx, rtx *));
 281
 282 /* Nonzero if modifying X will affect IN.  */
 283 extern int reg_overlap_mentioned_for_reload_p PROTO((rtx, rtx));
 284
 285 /* Return nonzero if anything in X contains a MEM.  Look also for pseudo
 286    registers.  */
 287 extern int refers_to_mem_for_reload_p PROTO((rtx));
 288
 289 /* Check the insns before INSN to see if there is a suitable register
 290    containing the same value as GOAL.  */
 291 extern rtx find_equiv_reg PROTO((rtx, rtx, enum reg_class, int, short *,
 292                                  int, enum machine_mode));
 293
 294 /* Return 1 if register REGNO is the subject of a clobber in insn INSN.  */
 295 extern int regno_clobbered_p PROTO((int, rtx));
 296
 297 /* Functions in reload1.c:  */
 298
 299 extern int reloads_conflict             PROTO ((int, int));
 300
 301 int count_occurrences            PROTO((rtx, rtx));
 302
 303 /* Initialize the reload pass once per compilation.  */
 304 extern void init_reload PROTO((void));
 305
 306 /* The reload pass itself.  */
 307 extern int reload PROTO((rtx, int, FILE *));
 308
 309 /* Mark the slots in regs_ever_live for the hard regs
 310    used by pseudo-reg number REGNO.  */
 311 extern void mark_home_live PROTO((int));
 312
 313 /* Scan X and replace any eliminable registers (such as fp) with a
 314    replacement (such as sp), plus an offset.  */
 315 extern rtx eliminate_regs PROTO((rtx, enum machine_mode, rtx));
 316
 317 /* Emit code to perform a reload from IN (which may be a reload register) to
 318    OUT (which may also be a reload register).  IN or OUT is from operand
 319    OPNUM with reload type TYPE.  */
 320 extern rtx gen_reload PROTO((rtx, rtx, int, enum reload_type));
 321
 322 /* Functions in caller-save.c:  */
 323
 324 /* Initialize for caller-save.  */
 325 extern void init_caller_save PROTO((void));
 326
 327 /* Initialize save areas by showing that we haven't allocated any yet.  */
 328 extern void init_save_areas PROTO((void));
 329
 330 /* Allocate save areas for any hard registers that might need saving.  */
 331 extern void setup_save_areas PROTO((void));
 332
 333 /* Find the places where hard regs are live across calls and save them.  */
 334 extern void save_call_clobbered_regs PROTO((void));