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, 2010
   4    Free Software Foundation, Inc.
   5
   6 This file is part of GCC.
   7
   8 GCC is free software; you can redistribute it and/or modify it under
   9 the terms of the GNU General Public License as published by the Free
  10 Software Foundation; either version 3, or (at your option) any later
  11 version.
  12
  13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  16 for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with GCC; see the file COPYING3.  If not see
  20 <http://www.gnu.org/licenses/>.  */
  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 extern int register_move_cost (enum machine_mode, enum reg_class,
  34                                enum reg_class);
  35 extern int memory_move_cost (enum machine_mode, enum reg_class, bool);
  36 extern int memory_move_secondary_cost (enum machine_mode, enum reg_class,
  37                                        bool);
  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 /* Target-dependent globals.  */
 158 struct target_reload {
 159   /* Nonzero if indirect addressing is supported when the innermost MEM is
 160      of the form (MEM (SYMBOL_REF sym)).  It is assumed that the level to
 161      which these are valid is the same as spill_indirect_levels, above.  */
 162   bool x_indirect_symref_ok;
 163
 164   /* Nonzero if an address (plus (reg frame_pointer) (reg ...)) is valid.  */
 165   bool x_double_reg_address_ok;
 166
 167   /* Nonzero if indirect addressing is supported on the machine; this means
 168      that spilling (REG n) does not require reloading it into a register in
 169      order to do (MEM (REG n)) or (MEM (PLUS (REG n) (CONST_INT c))).  The
 170      value indicates the level of indirect addressing supported, e.g., two
 171      means that (MEM (MEM (REG n))) is also valid if (REG n) does not get
 172      a hard register.  */
 173   bool x_spill_indirect_levels;
 174
 175   /* True if caller-save has been reinitialized.  */
 176   bool x_caller_save_initialized_p;
 177
 178   /* Modes for each hard register that we can save.  The smallest mode is wide
 179      enough to save the entire contents of the register.  When saving the
 180      register because it is live we first try to save in multi-register modes.
 181      If that is not possible the save is done one register at a time.  */
 182   enum machine_mode (x_regno_save_mode
 183                      [FIRST_PSEUDO_REGISTER]
 184                      [MAX_MOVE_MAX / MIN_UNITS_PER_WORD + 1]);
 185
 186   /* We will only make a register eligible for caller-save if it can be
 187      saved in its widest mode with a simple SET insn as long as the memory
 188      address is valid.  We record the INSN_CODE is those insns here since
 189      when we emit them, the addresses might not be valid, so they might not
 190      be recognized.  */
 191   int x_cached_reg_save_code[FIRST_PSEUDO_REGISTER][MAX_MACHINE_MODE];
 192   int x_cached_reg_restore_code[FIRST_PSEUDO_REGISTER][MAX_MACHINE_MODE];
 193 };
 194
 195 extern struct target_reload default_target_reload;
 196 #if SWITCHABLE_TARGET
 197 extern struct target_reload *this_target_reload;
 198 #else
 199 #define this_target_reload (&default_target_reload)
 200 #endif
 201
 202 #define indirect_symref_ok \
 203   (this_target_reload->x_indirect_symref_ok)
 204 #define double_reg_address_ok \
 205   (this_target_reload->x_double_reg_address_ok)
 206 #define caller_save_initialized_p \
 207   (this_target_reload->x_caller_save_initialized_p)
 208
 209 extern GTY (()) VEC(rtx,gc) *reg_equiv_memory_loc_vec;
 210 extern rtx *reg_equiv_constant;
 211 extern rtx *reg_equiv_invariant;
 212 extern rtx *reg_equiv_memory_loc;
 213 extern rtx *reg_equiv_address;
 214 extern rtx *reg_equiv_mem;
 215 extern rtx *reg_equiv_alt_mem_list;
 216
 217 /* Element N is the list of insns that initialized reg N from its equivalent
 218    constant or memory slot.  */
 219 extern GTY((length("reg_equiv_init_size"))) rtx *reg_equiv_init;
 220
 221 /* The size of the previous array, for GC purposes.  */
 222 extern GTY(()) int reg_equiv_init_size;
 223
 224 /* All the "earlyclobber" operands of the current insn
 225    are recorded here.  */
 226 extern int n_earlyclobbers;
 227 extern rtx reload_earlyclobbers[MAX_RECOG_OPERANDS];
 228
 229 /* Save the number of operands.  */
 230 extern int reload_n_operands;
 231
 232 /* First uid used by insns created by reload in this function.
 233    Used in find_equiv_reg.  */
 234 extern int reload_first_uid;
 235
 236 extern int num_not_at_initial_offset;
 237
 238 #if defined SET_HARD_REG_BIT && defined CLEAR_REG_SET
 239 /* This structure describes instructions which are relevant for reload.
 240    Apart from all regular insns, this also includes CODE_LABELs, since they
 241    must be examined for register elimination.  */
 242 struct insn_chain
 243 {
 244   /* Links to the neighbor instructions.  */
 245   struct insn_chain *next, *prev;
 246
 247   /* Link through a chains set up by calculate_needs_all_insns, containing
 248      all insns that need reloading.  */
 249   struct insn_chain *next_need_reload;
 250
 251   /* The rtx of the insn.  */
 252   rtx insn;
 253
 254   /* The basic block this insn is in.  */
 255   int block;
 256
 257   /* Nonzero if find_reloads said the insn requires reloading.  */
 258   unsigned int need_reload:1;
 259   /* Nonzero if find_reloads needs to be run during reload_as_needed to
 260      perform modifications on any operands.  */
 261   unsigned int need_operand_change:1;
 262   /* Nonzero if eliminate_regs_in_insn said it requires eliminations.  */
 263   unsigned int need_elim:1;
 264   /* Nonzero if this insn was inserted by perform_caller_saves.  */
 265   unsigned int is_caller_save_insn:1;
 266
 267   /* Register life information: record all live hard registers, and
 268      all live pseudos that have a hard register.  This set also
 269      contains pseudos spilled by IRA.  */
 270   bitmap_head live_throughout;
 271   bitmap_head dead_or_set;
 272
 273   /* Copies of the global variables computed by find_reloads.  */
 274   struct reload *rld;
 275   int n_reloads;
 276
 277   /* Indicates which registers have already been used for spills.  */
 278   HARD_REG_SET used_spill_regs;
 279 };
 280
 281 /* A chain of insn_chain structures to describe all non-note insns in
 282    a function.  */
 283 extern struct insn_chain *reload_insn_chain;
 284
 285 /* Allocate a new insn_chain structure.  */
 286 extern struct insn_chain *new_insn_chain (void);
 287 #endif
 288
 289 #if defined SET_HARD_REG_BIT
 290 extern void compute_use_by_pseudos (HARD_REG_SET *, bitmap);
 291 #endif
 292
 293 /* Functions from reload.c:  */
 294
 295 extern enum reg_class secondary_reload_class (bool, enum reg_class,
 296                                               enum machine_mode, rtx);
 297
 298 #ifdef GCC_INSN_CODES_H
 299 extern enum reg_class scratch_reload_class (enum insn_code);
 300 #endif
 301
 302 /* Return a memory location that will be used to copy X in mode MODE.
 303    If we haven't already made a location for this mode in this insn,
 304    call find_reloads_address on the location being returned.  */
 305 extern rtx get_secondary_mem (rtx, enum machine_mode, int, enum reload_type);
 306
 307 /* Clear any secondary memory locations we've made.  */
 308 extern void clear_secondary_mem (void);
 309
 310 /* Transfer all replacements that used to be in reload FROM to be in
 311    reload TO.  */
 312 extern void transfer_replacements (int, int);
 313
 314 /* IN_RTX is the value loaded by a reload that we now decided to inherit,
 315    or a subpart of it.  If we have any replacements registered for IN_RTX,
 316    cancel the reloads that were supposed to load them.
 317    Return nonzero if we canceled any reloads.  */
 318 extern int remove_address_replacements (rtx in_rtx);
 319
 320 /* Like rtx_equal_p except that it allows a REG and a SUBREG to match
 321    if they are the same hard reg, and has special hacks for
 322    autoincrement and autodecrement.  */
 323 extern int operands_match_p (rtx, rtx);
 324
 325 /* Return 1 if altering OP will not modify the value of CLOBBER.  */
 326 extern int safe_from_earlyclobber (rtx, rtx);
 327
 328 /* Search the body of INSN for values that need reloading and record them
 329    with push_reload.  REPLACE nonzero means record also where the values occur
 330    so that subst_reloads can be used.  */
 331 extern int find_reloads (rtx, int, int, int, short *);
 332
 333 /* Compute the sum of X and Y, making canonicalizations assumed in an
 334    address, namely: sum constant integers, surround the sum of two
 335    constants with a CONST, put the constant as the second operand, and
 336    group the constant on the outermost sum.  */
 337 extern rtx form_sum (enum machine_mode, rtx, rtx);
 338
 339 /* Substitute into the current INSN the registers into which we have reloaded
 340    the things that need reloading.  */
 341 extern void subst_reloads (rtx);
 342
 343 /* Make a copy of any replacements being done into X and move those copies
 344    to locations in Y, a copy of X.  We only look at the highest level of
 345    the RTL.  */
 346 extern void copy_replacements (rtx, rtx);
 347
 348 /* Change any replacements being done to *X to be done to *Y */
 349 extern void move_replacements (rtx *x, rtx *y);
 350
 351 /* If LOC was scheduled to be replaced by something, return the replacement.
 352    Otherwise, return *LOC.  */
 353 extern rtx find_replacement (rtx *);
 354
 355 /* Nonzero if modifying X will affect IN.  */
 356 extern int reg_overlap_mentioned_for_reload_p (rtx, rtx);
 357
 358 /* Check the insns before INSN to see if there is a suitable register
 359    containing the same value as GOAL.  */
 360 extern rtx find_equiv_reg (rtx, rtx, enum reg_class, int, short *,
 361                            int, enum machine_mode);
 362
 363 /* Return 1 if register REGNO is the subject of a clobber in insn INSN.  */
 364 extern int regno_clobbered_p (unsigned int, rtx, enum machine_mode, int);
 365
 366 /* Return 1 if X is an operand of an insn that is being earlyclobbered.  */
 367 extern int earlyclobber_operand_p (rtx);
 368
 369 /* Record one reload that needs to be performed.  */
 370 extern int push_reload (rtx, rtx, rtx *, rtx *, enum reg_class,
 371                         enum machine_mode, enum machine_mode,
 372                         int, int, int, enum reload_type);
 373
 374 /* Functions in postreload.c:  */
 375 extern void reload_cse_regs (rtx);
 376
 377 /* Functions in reload1.c:  */
 378
 379 /* Initialize the reload pass once per compilation.  */
 380 extern void init_reload (void);
 381
 382 /* The reload pass itself.  */
 383 extern int reload (rtx, int);
 384
 385 /* Mark the slots in regs_ever_live for the hard regs
 386    used by pseudo-reg number REGNO.  */
 387 extern void mark_home_live (int);
 388
 389 /* Scan X and replace any eliminable registers (such as fp) with a
 390    replacement (such as sp), plus an offset.  */
 391 extern rtx eliminate_regs (rtx, enum machine_mode, rtx);
 392 extern bool elimination_target_reg_p (rtx);
 393
 394 /* Called from the register allocator to estimate costs of eliminating
 395    invariant registers.  */
 396 extern void calculate_elim_costs_all_insns (void);
 397
 398 /* Deallocate the reload register used by reload number R.  */
 399 extern void deallocate_reload_reg (int r);
 400
 401 /* Functions in caller-save.c:  */
 402
 403 /* Initialize for caller-save.  */
 404 extern void init_caller_save (void);
 405
 406 /* Initialize save areas by showing that we haven't allocated any yet.  */
 407 extern void init_save_areas (void);
 408
 409 /* Allocate save areas for any hard registers that might need saving.  */
 410 extern void setup_save_areas (void);
 411
 412 /* Find the places where hard regs are live across calls and save them.  */
 413 extern void save_call_clobbered_regs (void);
 414
 415 /* Replace (subreg (reg)) with the appropriate (reg) for any operands.  */
 416 extern void cleanup_subreg_operands (rtx);
 417
 418 /* Debugging support.  */
 419 extern void debug_reload_to_stream (FILE *);
 420 extern void debug_reload (void);
 421
 422 /* Compute the actual register we should reload to, in case we're
 423    reloading to/from a register that is wider than a word.  */
 424 extern rtx reload_adjust_reg_for_mode (rtx, enum machine_mode);