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
 176 extern struct target_reload default_target_reload;
 177 #if SWITCHABLE_TARGET
 178 extern struct target_reload *this_target_reload;
 179 #else
 180 #define this_target_reload (&default_target_reload)
 181 #endif
 182
 183 #define indirect_symref_ok \
 184   (this_target_reload->x_indirect_symref_ok)
 185 #define double_reg_address_ok \
 186   (this_target_reload->x_double_reg_address_ok)
 187
 188 extern GTY (()) VEC(rtx,gc) *reg_equiv_memory_loc_vec;
 189 extern rtx *reg_equiv_constant;
 190 extern rtx *reg_equiv_invariant;
 191 extern rtx *reg_equiv_memory_loc;
 192 extern rtx *reg_equiv_address;
 193 extern rtx *reg_equiv_mem;
 194 extern rtx *reg_equiv_alt_mem_list;
 195
 196 /* Element N is the list of insns that initialized reg N from its equivalent
 197    constant or memory slot.  */
 198 extern GTY((length("reg_equiv_init_size"))) rtx *reg_equiv_init;
 199
 200 /* The size of the previous array, for GC purposes.  */
 201 extern GTY(()) int reg_equiv_init_size;
 202
 203 /* All the "earlyclobber" operands of the current insn
 204    are recorded here.  */
 205 extern int n_earlyclobbers;
 206 extern rtx reload_earlyclobbers[MAX_RECOG_OPERANDS];
 207
 208 /* Save the number of operands.  */
 209 extern int reload_n_operands;
 210
 211 /* First uid used by insns created by reload in this function.
 212    Used in find_equiv_reg.  */
 213 extern int reload_first_uid;
 214
 215 extern int num_not_at_initial_offset;
 216
 217 #if defined SET_HARD_REG_BIT && defined CLEAR_REG_SET
 218 /* This structure describes instructions which are relevant for reload.
 219    Apart from all regular insns, this also includes CODE_LABELs, since they
 220    must be examined for register elimination.  */
 221 struct insn_chain
 222 {
 223   /* Links to the neighbor instructions.  */
 224   struct insn_chain *next, *prev;
 225
 226   /* Link through a chains set up by calculate_needs_all_insns, containing
 227      all insns that need reloading.  */
 228   struct insn_chain *next_need_reload;
 229
 230   /* The rtx of the insn.  */
 231   rtx insn;
 232
 233   /* The basic block this insn is in.  */
 234   int block;
 235
 236   /* Nonzero if find_reloads said the insn requires reloading.  */
 237   unsigned int need_reload:1;
 238   /* Nonzero if find_reloads needs to be run during reload_as_needed to
 239      perform modifications on any operands.  */
 240   unsigned int need_operand_change:1;
 241   /* Nonzero if eliminate_regs_in_insn said it requires eliminations.  */
 242   unsigned int need_elim:1;
 243   /* Nonzero if this insn was inserted by perform_caller_saves.  */
 244   unsigned int is_caller_save_insn:1;
 245
 246   /* Register life information: record all live hard registers, and
 247      all live pseudos that have a hard register.  This set also
 248      contains pseudos spilled by IRA.  */
 249   bitmap_head live_throughout;
 250   bitmap_head dead_or_set;
 251
 252   /* Copies of the global variables computed by find_reloads.  */
 253   struct reload *rld;
 254   int n_reloads;
 255
 256   /* Indicates which registers have already been used for spills.  */
 257   HARD_REG_SET used_spill_regs;
 258 };
 259
 260 /* A chain of insn_chain structures to describe all non-note insns in
 261    a function.  */
 262 extern struct insn_chain *reload_insn_chain;
 263
 264 /* Allocate a new insn_chain structure.  */
 265 extern struct insn_chain *new_insn_chain (void);
 266 #endif
 267
 268 #if defined SET_HARD_REG_BIT
 269 extern void compute_use_by_pseudos (HARD_REG_SET *, bitmap);
 270 #endif
 271
 272 /* Functions from reload.c:  */
 273
 274 extern enum reg_class secondary_reload_class (bool, enum reg_class,
 275                                               enum machine_mode, rtx);
 276
 277 #ifdef GCC_INSN_CODES_H
 278 extern enum reg_class scratch_reload_class (enum insn_code);
 279 #endif
 280
 281 /* Return a memory location that will be used to copy X in mode MODE.
 282    If we haven't already made a location for this mode in this insn,
 283    call find_reloads_address on the location being returned.  */
 284 extern rtx get_secondary_mem (rtx, enum machine_mode, int, enum reload_type);
 285
 286 /* Clear any secondary memory locations we've made.  */
 287 extern void clear_secondary_mem (void);
 288
 289 /* Transfer all replacements that used to be in reload FROM to be in
 290    reload TO.  */
 291 extern void transfer_replacements (int, int);
 292
 293 /* IN_RTX is the value loaded by a reload that we now decided to inherit,
 294    or a subpart of it.  If we have any replacements registered for IN_RTX,
 295    cancel the reloads that were supposed to load them.
 296    Return nonzero if we canceled any reloads.  */
 297 extern int remove_address_replacements (rtx in_rtx);
 298
 299 /* Like rtx_equal_p except that it allows a REG and a SUBREG to match
 300    if they are the same hard reg, and has special hacks for
 301    autoincrement and autodecrement.  */
 302 extern int operands_match_p (rtx, rtx);
 303
 304 /* Return 1 if altering OP will not modify the value of CLOBBER.  */
 305 extern int safe_from_earlyclobber (rtx, rtx);
 306
 307 /* Search the body of INSN for values that need reloading and record them
 308    with push_reload.  REPLACE nonzero means record also where the values occur
 309    so that subst_reloads can be used.  */
 310 extern int find_reloads (rtx, int, int, int, short *);
 311
 312 /* Compute the sum of X and Y, making canonicalizations assumed in an
 313    address, namely: sum constant integers, surround the sum of two
 314    constants with a CONST, put the constant as the second operand, and
 315    group the constant on the outermost sum.  */
 316 extern rtx form_sum (enum machine_mode, rtx, rtx);
 317
 318 /* Substitute into the current INSN the registers into which we have reloaded
 319    the things that need reloading.  */
 320 extern void subst_reloads (rtx);
 321
 322 /* Make a copy of any replacements being done into X and move those copies
 323    to locations in Y, a copy of X.  We only look at the highest level of
 324    the RTL.  */
 325 extern void copy_replacements (rtx, rtx);
 326
 327 /* Change any replacements being done to *X to be done to *Y */
 328 extern void move_replacements (rtx *x, rtx *y);
 329
 330 /* If LOC was scheduled to be replaced by something, return the replacement.
 331    Otherwise, return *LOC.  */
 332 extern rtx find_replacement (rtx *);
 333
 334 /* Nonzero if modifying X will affect IN.  */
 335 extern int reg_overlap_mentioned_for_reload_p (rtx, rtx);
 336
 337 /* Check the insns before INSN to see if there is a suitable register
 338    containing the same value as GOAL.  */
 339 extern rtx find_equiv_reg (rtx, rtx, enum reg_class, int, short *,
 340                            int, enum machine_mode);
 341
 342 /* Return 1 if register REGNO is the subject of a clobber in insn INSN.  */
 343 extern int regno_clobbered_p (unsigned int, rtx, enum machine_mode, int);
 344
 345 /* Return 1 if X is an operand of an insn that is being earlyclobbered.  */
 346 extern int earlyclobber_operand_p (rtx);
 347
 348 /* Record one reload that needs to be performed.  */
 349 extern int push_reload (rtx, rtx, rtx *, rtx *, enum reg_class,
 350                         enum machine_mode, enum machine_mode,
 351                         int, int, int, enum reload_type);
 352
 353 /* Functions in postreload.c:  */
 354 extern void reload_cse_regs (rtx);
 355
 356 /* Functions in reload1.c:  */
 357
 358 /* Initialize the reload pass once per compilation.  */
 359 extern void init_reload (void);
 360
 361 /* The reload pass itself.  */
 362 extern int reload (rtx, int);
 363
 364 /* Mark the slots in regs_ever_live for the hard regs
 365    used by pseudo-reg number REGNO.  */
 366 extern void mark_home_live (int);
 367
 368 /* Scan X and replace any eliminable registers (such as fp) with a
 369    replacement (such as sp), plus an offset.  */
 370 extern rtx eliminate_regs (rtx, enum machine_mode, rtx);
 371 extern bool elimination_target_reg_p (rtx);
 372
 373 /* Called from the register allocator to estimate costs of eliminating
 374    invariant registers.  */
 375 extern void calculate_elim_costs_all_insns (void);
 376
 377 /* Deallocate the reload register used by reload number R.  */
 378 extern void deallocate_reload_reg (int r);
 379
 380 /* True if caller-save has been reinitialized.  */
 381 extern bool caller_save_initialized_p;
 382
 383 /* Functions in caller-save.c:  */
 384
 385 /* Initialize for caller-save.  */
 386 extern void init_caller_save (void);
 387
 388 /* Initialize save areas by showing that we haven't allocated any yet.  */
 389 extern void init_save_areas (void);
 390
 391 /* Allocate save areas for any hard registers that might need saving.  */
 392 extern void setup_save_areas (void);
 393
 394 /* Find the places where hard regs are live across calls and save them.  */
 395 extern void save_call_clobbered_regs (void);
 396
 397 /* Replace (subreg (reg)) with the appropriate (reg) for any operands.  */
 398 extern void cleanup_subreg_operands (rtx);
 399
 400 /* Debugging support.  */
 401 extern void debug_reload_to_stream (FILE *);
 402 extern void debug_reload (void);
 403
 404 /* Compute the actual register we should reload to, in case we're
 405    reloading to/from a register that is wider than a word.  */
 406 extern rtx reload_adjust_reg_for_mode (rtx, enum machine_mode);