gcc/reload.h

   1 /* Communication between reload.c, reload1.c and the rest of compiler.
   2    Copyright (C) 1987, 1991, 1992, 1993, 1994, 1995, 1997, 1998, 1999,
   3    2000, 2001, 2003, 2004, 2007, 2008 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 3, 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 COPYING3.  If not see
  19 <http://www.gnu.org/licenses/>.  */
  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 MEMORY_MOVE_COST isn't defined, give it a default here.  */
  33 #ifndef MEMORY_MOVE_COST
  34 #define MEMORY_MOVE_COST(MODE,CLASS,IN) \
  35   (4 + memory_move_secondary_cost ((MODE), (CLASS), (IN)))
  36 #endif
  37 extern int memory_move_secondary_cost (enum machine_mode, enum reg_class, int);
  38
  39 /* Maximum number of reloads we can need.  */
  40 #define MAX_RELOADS (2 * MAX_RECOG_OPERANDS * (MAX_REGS_PER_ADDRESS + 1))
  41
  42 /* Encode the usage of a reload.  The following codes are supported:
  43
  44    RELOAD_FOR_INPUT             reload of an input operand
  45    RELOAD_FOR_OUTPUT            likewise, for output
  46    RELOAD_FOR_INSN              a reload that must not conflict with anything
  47                                 used in the insn, but may conflict with
  48                                 something used before or after the insn
  49    RELOAD_FOR_INPUT_ADDRESS     reload for parts of the address of an object
  50                                 that is an input reload
  51    RELOAD_FOR_INPADDR_ADDRESS   reload needed for RELOAD_FOR_INPUT_ADDRESS
  52    RELOAD_FOR_OUTPUT_ADDRESS    like RELOAD_FOR INPUT_ADDRESS, for output
  53    RELOAD_FOR_OUTADDR_ADDRESS   reload needed for RELOAD_FOR_OUTPUT_ADDRESS
  54    RELOAD_FOR_OPERAND_ADDRESS   reload for the address of a non-reloaded
  55                                 operand; these don't conflict with
  56                                 any other addresses.
  57    RELOAD_FOR_OPADDR_ADDR       reload needed for RELOAD_FOR_OPERAND_ADDRESS
  58                                 reloads; usually secondary reloads
  59    RELOAD_OTHER                 none of the above, usually multiple uses
  60    RELOAD_FOR_OTHER_ADDRESS     reload for part of the address of an input
  61                                 that is marked RELOAD_OTHER.
  62
  63    This used to be "enum reload_when_needed" but some debuggers have trouble
  64    with an enum tag and variable of the same name.  */
  65
  66 enum reload_type
  67 {
  68   RELOAD_FOR_INPUT, RELOAD_FOR_OUTPUT, RELOAD_FOR_INSN,
  69   RELOAD_FOR_INPUT_ADDRESS, RELOAD_FOR_INPADDR_ADDRESS,
  70   RELOAD_FOR_OUTPUT_ADDRESS, RELOAD_FOR_OUTADDR_ADDRESS,
  71   RELOAD_FOR_OPERAND_ADDRESS, RELOAD_FOR_OPADDR_ADDR,
  72   RELOAD_OTHER, RELOAD_FOR_OTHER_ADDRESS
  73 };
  74
  75 #ifdef GCC_INSN_CODES_H
  76 /* Each reload is recorded with a structure like this.  */
  77 struct reload
  78 {
  79   /* The value to reload from */
  80   rtx in;
  81   /* Where to store reload-reg afterward if nec (often the same as
  82      reload_in)  */
  83   rtx out;
  84
  85   /* The class of registers to reload into.  */
  86   enum reg_class rclass;
  87
  88   /* The mode this operand should have when reloaded, on input.  */
  89   enum machine_mode inmode;
  90   /* The mode this operand should have when reloaded, on output.  */
  91   enum machine_mode outmode;
  92
  93   /* The mode of the reload register.  */
  94   enum machine_mode mode;
  95
  96   /* the largest number of registers this reload will require.  */
  97   unsigned int nregs;
  98
  99   /* Positive amount to increment or decrement by if
 100      reload_in is a PRE_DEC, PRE_INC, POST_DEC, POST_INC.
 101      Ignored otherwise (don't assume it is zero).  */
 102   int inc;
 103   /* A reg for which reload_in is the equivalent.
 104      If reload_in is a symbol_ref which came from
 105      reg_equiv_constant, then this is the pseudo
 106      which has that symbol_ref as equivalent.  */
 107   rtx in_reg;
 108   rtx out_reg;
 109
 110   /* Used in find_reload_regs to record the allocated register.  */
 111   int regno;
 112   /* This is the register to reload into.  If it is zero when `find_reloads'
 113      returns, you must find a suitable register in the class specified by
 114      reload_reg_class, and store here an rtx for that register with mode from
 115      reload_inmode or reload_outmode.  */
 116   rtx reg_rtx;
 117   /* The operand number being reloaded.  This is used to group related reloads
 118      and need not always be equal to the actual operand number in the insn,
 119      though it current will be; for in-out operands, it is one of the two
 120      operand numbers.  */
 121   int opnum;
 122
 123   /* Gives the reload number of a secondary input reload, when needed;
 124      otherwise -1.  */
 125   int secondary_in_reload;
 126   /* Gives the reload number of a secondary output reload, when needed;
 127      otherwise -1.  */
 128   int secondary_out_reload;
 129   /* If a secondary input reload is required, gives the INSN_CODE that uses the
 130      secondary reload as a scratch register, or CODE_FOR_nothing if the
 131      secondary reload register is to be an intermediate register.  */
 132   enum insn_code secondary_in_icode;
 133   /* Likewise, for a secondary output reload.  */
 134   enum insn_code secondary_out_icode;
 135
 136   /* Classifies reload as needed either for addressing an input reload,
 137      addressing an output, for addressing a non-reloaded mem ref, or for
 138      unspecified purposes (i.e., more than one of the above).  */
 139   enum reload_type when_needed;
 140
 141   /* Nonzero for an optional reload.  Optional reloads are ignored unless the
 142      value is already sitting in a register.  */
 143   unsigned int optional:1;
 144   /* nonzero if this reload shouldn't be combined with another reload.  */
 145   unsigned int nocombine:1;
 146   /* Nonzero if this is a secondary register for one or more reloads.  */
 147   unsigned int secondary_p:1;
 148   /* Nonzero if this reload must use a register not already allocated to a
 149      group.  */
 150   unsigned int nongroup:1;
 151 };
 152
 153 extern struct reload rld[MAX_RELOADS];
 154 extern int n_reloads;
 155 #endif
 156
 157 extern GTY (()) VEC(rtx,gc) *reg_equiv_memory_loc_vec;
 158 extern rtx *reg_equiv_constant;
 159 extern rtx *reg_equiv_invariant;
 160 extern rtx *reg_equiv_memory_loc;
 161 extern rtx *reg_equiv_address;
 162 extern rtx *reg_equiv_mem;
 163 extern rtx *reg_equiv_alt_mem_list;
 164
 165 /* Element N is the list of insns that initialized reg N from its equivalent
 166    constant or memory slot.  */
 167 extern GTY((length("reg_equiv_init_size"))) rtx *reg_equiv_init;
 168
 169 /* The size of the previous array, for GC purposes.  */
 170 extern GTY(()) int reg_equiv_init_size;
 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 #if defined SET_HARD_REG_BIT && defined CLEAR_REG_SET
 196 /* This structure describes instructions which are relevant for reload.
 197    Apart from all regular insns, this also includes CODE_LABELs, since they
 198    must be examined for register elimination.  */
 199 struct insn_chain
 200 {
 201   /* Links to the neighbor instructions.  */
 202   struct insn_chain *next, *prev;
 203
 204   /* Link through a chains set up by calculate_needs_all_insns, containing
 205      all insns that need reloading.  */
 206   struct insn_chain *next_need_reload;
 207
 208   /* The basic block this insn is in.  */
 209   int block;
 210   /* The rtx of the insn.  */
 211   rtx insn;
 212   /* Register life information: record all live hard registers, and
 213      all live pseudos that have a hard register.  This set also
 214      contains pseudos spilled by IRA.  */
 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 extern bool elimination_target_reg_p (rtx);
 346
 347 /* Deallocate the reload register used by reload number R.  */
 348 extern void deallocate_reload_reg (int r);
 349
 350 /* Functions in caller-save.c:  */
 351
 352 /* Initialize for caller-save.  */
 353 extern void init_caller_save (void);
 354
 355 /* Initialize save areas by showing that we haven't allocated any yet.  */
 356 extern void init_save_areas (void);
 357
 358 /* Allocate save areas for any hard registers that might need saving.  */
 359 extern void setup_save_areas (void);
 360
 361 /* Find the places where hard regs are live across calls and save them.  */
 362 extern void save_call_clobbered_regs (void);
 363
 364 /* Replace (subreg (reg)) with the appropriate (reg) for any operands.  */
 365 extern void cleanup_subreg_operands (rtx);
 366
 367 /* Debugging support.  */
 368 extern void debug_reload_to_stream (FILE *);
 369 extern void debug_reload (void);
 370
 371 /* Compute the actual register we should reload to, in case we're
 372    reloading to/from a register that is wider than a word.  */
 373 extern rtx reload_adjust_reg_for_mode (rtx, enum machine_mode);