gcc/reload.h

   1 /* Communication between reload.c, reload1.c and the rest of compiler.
   2    Copyright (C) 1987-2015 Free Software Foundation, Inc.
   3
   4 This file is part of GCC.
   5
   6 GCC is free software; you can redistribute it and/or modify it under
   7 the terms of the GNU General Public License as published by the Free
   8 Software Foundation; either version 3, or (at your option) any later
   9 version.
  10
  11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14 for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GCC; see the file COPYING3.  If not see
  18 <http://www.gnu.org/licenses/>.  */
  19
  20 #ifndef GCC_RELOAD_H
  21 #define GCC_RELOAD_H
  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 (machine_mode, reg_class_t, reg_class_t);
  34 extern int memory_move_cost (machine_mode, reg_class_t, bool);
  35 extern int memory_move_secondary_cost (machine_mode, reg_class_t, bool);
  36
  37 /* Maximum number of reloads we can need.  */
  38 #define MAX_RELOADS (2 * MAX_RECOG_OPERANDS * (MAX_REGS_PER_ADDRESS + 1))
  39
  40 /* Encode the usage of a reload.  The following codes are supported:
  41
  42    RELOAD_FOR_INPUT             reload of an input operand
  43    RELOAD_FOR_OUTPUT            likewise, for output
  44    RELOAD_FOR_INSN              a reload that must not conflict with anything
  45                                 used in the insn, but may conflict with
  46                                 something used before or after the insn
  47    RELOAD_FOR_INPUT_ADDRESS     reload for parts of the address of an object
  48                                 that is an input reload
  49    RELOAD_FOR_INPADDR_ADDRESS   reload needed for RELOAD_FOR_INPUT_ADDRESS
  50    RELOAD_FOR_OUTPUT_ADDRESS    like RELOAD_FOR INPUT_ADDRESS, for output
  51    RELOAD_FOR_OUTADDR_ADDRESS   reload needed for RELOAD_FOR_OUTPUT_ADDRESS
  52    RELOAD_FOR_OPERAND_ADDRESS   reload for the address of a non-reloaded
  53                                 operand; these don't conflict with
  54                                 any other addresses.
  55    RELOAD_FOR_OPADDR_ADDR       reload needed for RELOAD_FOR_OPERAND_ADDRESS
  56                                 reloads; usually secondary reloads
  57    RELOAD_OTHER                 none of the above, usually multiple uses
  58    RELOAD_FOR_OTHER_ADDRESS     reload for part of the address of an input
  59                                 that is marked RELOAD_OTHER.
  60
  61    This used to be "enum reload_when_needed" but some debuggers have trouble
  62    with an enum tag and variable of the same name.  */
  63
  64 enum reload_type
  65 {
  66   RELOAD_FOR_INPUT, RELOAD_FOR_OUTPUT, RELOAD_FOR_INSN,
  67   RELOAD_FOR_INPUT_ADDRESS, RELOAD_FOR_INPADDR_ADDRESS,
  68   RELOAD_FOR_OUTPUT_ADDRESS, RELOAD_FOR_OUTADDR_ADDRESS,
  69   RELOAD_FOR_OPERAND_ADDRESS, RELOAD_FOR_OPADDR_ADDR,
  70   RELOAD_OTHER, RELOAD_FOR_OTHER_ADDRESS
  71 };
  72
  73 #ifdef GCC_INSN_CODES_H
  74 /* Each reload is recorded with a structure like this.  */
  75 struct reload
  76 {
  77   /* The value to reload from */
  78   rtx in;
  79   /* Where to store reload-reg afterward if nec (often the same as
  80      reload_in)  */
  81   rtx out;
  82
  83   /* The class of registers to reload into.  */
  84   enum reg_class rclass;
  85
  86   /* The mode this operand should have when reloaded, on input.  */
  87   machine_mode inmode;
  88   /* The mode this operand should have when reloaded, on output.  */
  89   machine_mode outmode;
  90
  91   /* The mode of the reload register.  */
  92   machine_mode mode;
  93
  94   /* the largest number of registers this reload will require.  */
  95   unsigned int nregs;
  96
  97   /* Positive amount to increment or decrement by if
  98      reload_in is a PRE_DEC, PRE_INC, POST_DEC, POST_INC.
  99      Ignored otherwise (don't assume it is zero).  */
 100   int inc;
 101   /* A reg for which reload_in is the equivalent.
 102      If reload_in is a symbol_ref which came from
 103      reg_equiv_constant, then this is the pseudo
 104      which has that symbol_ref as equivalent.  */
 105   rtx in_reg;
 106   rtx out_reg;
 107
 108   /* Used in find_reload_regs to record the allocated register.  */
 109   int regno;
 110   /* This is the register to reload into.  If it is zero when `find_reloads'
 111      returns, you must find a suitable register in the class specified by
 112      reload_reg_class, and store here an rtx for that register with mode from
 113      reload_inmode or reload_outmode.  */
 114   rtx reg_rtx;
 115   /* The operand number being reloaded.  This is used to group related reloads
 116      and need not always be equal to the actual operand number in the insn,
 117      though it current will be; for in-out operands, it is one of the two
 118      operand numbers.  */
 119   int opnum;
 120
 121   /* Gives the reload number of a secondary input reload, when needed;
 122      otherwise -1.  */
 123   int secondary_in_reload;
 124   /* Gives the reload number of a secondary output reload, when needed;
 125      otherwise -1.  */
 126   int secondary_out_reload;
 127   /* If a secondary input reload is required, gives the INSN_CODE that uses the
 128      secondary reload as a scratch register, or CODE_FOR_nothing if the
 129      secondary reload register is to be an intermediate register.  */
 130   enum insn_code secondary_in_icode;
 131   /* Likewise, for a secondary output reload.  */
 132   enum insn_code secondary_out_icode;
 133
 134   /* Classifies reload as needed either for addressing an input reload,
 135      addressing an output, for addressing a non-reloaded mem ref, or for
 136      unspecified purposes (i.e., more than one of the above).  */
 137   enum reload_type when_needed;
 138
 139   /* Nonzero for an optional reload.  Optional reloads are ignored unless the
 140      value is already sitting in a register.  */
 141   unsigned int optional:1;
 142   /* nonzero if this reload shouldn't be combined with another reload.  */
 143   unsigned int nocombine:1;
 144   /* Nonzero if this is a secondary register for one or more reloads.  */
 145   unsigned int secondary_p:1;
 146   /* Nonzero if this reload must use a register not already allocated to a
 147      group.  */
 148   unsigned int nongroup:1;
 149 };
 150
 151 extern struct reload rld[MAX_RELOADS];
 152 extern int n_reloads;
 153 #endif
 154
 155 /* Target-dependent globals.  */
 156 struct target_reload {
 157   /* Nonzero if indirect addressing is supported when the innermost MEM is
 158      of the form (MEM (SYMBOL_REF sym)).  It is assumed that the level to
 159      which these are valid is the same as spill_indirect_levels, above.  */
 160   bool x_indirect_symref_ok;
 161
 162   /* Nonzero if an address (plus (reg frame_pointer) (reg ...)) is valid.  */
 163   bool x_double_reg_address_ok;
 164
 165   /* Nonzero if indirect addressing is supported on the machine; this means
 166      that spilling (REG n) does not require reloading it into a register in
 167      order to do (MEM (REG n)) or (MEM (PLUS (REG n) (CONST_INT c))).  The
 168      value indicates the level of indirect addressing supported, e.g., two
 169      means that (MEM (MEM (REG n))) is also valid if (REG n) does not get
 170      a hard register.  */
 171   unsigned char x_spill_indirect_levels;
 172
 173   /* True if caller-save has been reinitialized.  */
 174   bool x_caller_save_initialized_p;
 175
 176   /* Modes for each hard register that we can save.  The smallest mode is wide
 177      enough to save the entire contents of the register.  When saving the
 178      register because it is live we first try to save in multi-register modes.
 179      If that is not possible the save is done one register at a time.  */
 180   machine_mode (x_regno_save_mode
 181                      [FIRST_PSEUDO_REGISTER]
 182                      [MAX_MOVE_MAX / MIN_UNITS_PER_WORD + 1]);
 183
 184   /* We will only make a register eligible for caller-save if it can be
 185      saved in its widest mode with a simple SET insn as long as the memory
 186      address is valid.  We record the INSN_CODE is those insns here since
 187      when we emit them, the addresses might not be valid, so they might not
 188      be recognized.  */
 189   int x_cached_reg_save_code[FIRST_PSEUDO_REGISTER][MAX_MACHINE_MODE];
 190   int x_cached_reg_restore_code[FIRST_PSEUDO_REGISTER][MAX_MACHINE_MODE];
 191 };
 192
 193 extern struct target_reload default_target_reload;
 194 #if SWITCHABLE_TARGET
 195 extern struct target_reload *this_target_reload;
 196 #else
 197 #define this_target_reload (&default_target_reload)
 198 #endif
 199
 200 #define indirect_symref_ok \
 201   (this_target_reload->x_indirect_symref_ok)
 202 #define double_reg_address_ok \
 203   (this_target_reload->x_double_reg_address_ok)
 204 #define caller_save_initialized_p \
 205   (this_target_reload->x_caller_save_initialized_p)
 206
 207 /* Register equivalences.  Indexed by register number.  */
 208 struct reg_equivs_t
 209 {
 210   /* The constant value to which pseudo reg N is equivalent,
 211      or zero if pseudo reg N is not equivalent to a constant.
 212      find_reloads looks at this in order to replace pseudo reg N
 213      with the constant it stands for.  */
 214   rtx constant;
 215
 216   /* An invariant value to which pseudo reg N is equivalent.
 217      eliminate_regs_in_insn uses this to replace pseudos in particular
 218      contexts.  */
 219   rtx invariant;
 220
 221   /* A memory location to which pseudo reg N is equivalent,
 222      prior to any register elimination (such as frame pointer to stack
 223      pointer).  Depending on whether or not it is a valid address, this value
 224      is transferred to either equiv_address or equiv_mem.  */
 225   rtx memory_loc;
 226
 227   /* The address of stack slot to which pseudo reg N is equivalent.
 228      This is used when the address is not valid as a memory address
 229      (because its displacement is too big for the machine.)  */
 230   rtx address;
 231
 232   /* The memory slot to which pseudo reg N is equivalent,
 233      or zero if pseudo reg N is not equivalent to a memory slot.  */
 234   rtx mem;
 235
 236   /* An EXPR_LIST of REG_EQUIVs containing MEMs with
 237      alternate representations of the location of pseudo reg N.  */
 238   rtx_expr_list *alt_mem_list;
 239
 240   /* The list of insns that initialized reg N from its equivalent
 241      constant or memory slot.  */
 242   rtx_insn_list *init;
 243 };
 244
 245 #define reg_equiv_constant(ELT) \
 246   (*reg_equivs)[(ELT)].constant
 247 #define reg_equiv_invariant(ELT) \
 248   (*reg_equivs)[(ELT)].invariant
 249 #define reg_equiv_memory_loc(ELT) \
 250   (*reg_equivs)[(ELT)].memory_loc
 251 #define reg_equiv_address(ELT) \
 252   (*reg_equivs)[(ELT)].address
 253 #define reg_equiv_mem(ELT) \
 254   (*reg_equivs)[(ELT)].mem
 255 #define reg_equiv_alt_mem_list(ELT) \
 256   (*reg_equivs)[(ELT)].alt_mem_list
 257 #define reg_equiv_init(ELT) \
 258   (*reg_equivs)[(ELT)].init
 259
 260 extern vec<reg_equivs_t, va_gc> *reg_equivs;
 261
 262 /* All the "earlyclobber" operands of the current insn
 263    are recorded here.  */
 264 extern int n_earlyclobbers;
 265 extern rtx reload_earlyclobbers[MAX_RECOG_OPERANDS];
 266
 267 /* Save the number of operands.  */
 268 extern int reload_n_operands;
 269
 270 /* First uid used by insns created by reload in this function.
 271    Used in find_equiv_reg.  */
 272 extern int reload_first_uid;
 273
 274 extern int num_not_at_initial_offset;
 275
 276 #if defined SET_HARD_REG_BIT && defined CLEAR_REG_SET
 277 /* This structure describes instructions which are relevant for reload.
 278    Apart from all regular insns, this also includes CODE_LABELs, since they
 279    must be examined for register elimination.  */
 280 struct insn_chain
 281 {
 282   /* Links to the neighbor instructions.  */
 283   struct insn_chain *next, *prev;
 284
 285   /* Link through a chains set up by calculate_needs_all_insns, containing
 286      all insns that need reloading.  */
 287   struct insn_chain *next_need_reload;
 288
 289   /* The rtx of the insn.  */
 290   rtx_insn *insn;
 291
 292   /* The basic block this insn is in.  */
 293   int block;
 294
 295   /* Nonzero if find_reloads said the insn requires reloading.  */
 296   unsigned int need_reload:1;
 297   /* Nonzero if find_reloads needs to be run during reload_as_needed to
 298      perform modifications on any operands.  */
 299   unsigned int need_operand_change:1;
 300   /* Nonzero if eliminate_regs_in_insn said it requires eliminations.  */
 301   unsigned int need_elim:1;
 302   /* Nonzero if this insn was inserted by perform_caller_saves.  */
 303   unsigned int is_caller_save_insn:1;
 304
 305   /* Register life information: record all live hard registers, and
 306      all live pseudos that have a hard register.  This set also
 307      contains pseudos spilled by IRA.  */
 308   bitmap_head live_throughout;
 309   bitmap_head dead_or_set;
 310
 311   /* Copies of the global variables computed by find_reloads.  */
 312   struct reload *rld;
 313   int n_reloads;
 314
 315   /* Indicates which registers have already been used for spills.  */
 316   HARD_REG_SET used_spill_regs;
 317 };
 318
 319 /* A chain of insn_chain structures to describe all non-note insns in
 320    a function.  */
 321 extern struct insn_chain *reload_insn_chain;
 322
 323 /* Allocate a new insn_chain structure.  */
 324 extern struct insn_chain *new_insn_chain (void);
 325 #endif
 326
 327 #if defined SET_HARD_REG_BIT
 328 extern void compute_use_by_pseudos (HARD_REG_SET *, bitmap);
 329 #endif
 330
 331 /* Functions from reload.c:  */
 332
 333 extern reg_class_t secondary_reload_class (bool, reg_class_t,
 334                                            machine_mode, rtx);
 335
 336 #ifdef GCC_INSN_CODES_H
 337 extern enum reg_class scratch_reload_class (enum insn_code);
 338 #endif
 339
 340 /* Return a memory location that will be used to copy X in mode MODE.
 341    If we haven't already made a location for this mode in this insn,
 342    call find_reloads_address on the location being returned.  */
 343 extern rtx get_secondary_mem (rtx, machine_mode, int, enum reload_type);
 344
 345 /* Clear any secondary memory locations we've made.  */
 346 extern void clear_secondary_mem (void);
 347
 348 /* Transfer all replacements that used to be in reload FROM to be in
 349    reload TO.  */
 350 extern void transfer_replacements (int, int);
 351
 352 /* IN_RTX is the value loaded by a reload that we now decided to inherit,
 353    or a subpart of it.  If we have any replacements registered for IN_RTX,
 354    cancel the reloads that were supposed to load them.
 355    Return nonzero if we canceled any reloads.  */
 356 extern int remove_address_replacements (rtx in_rtx);
 357
 358 /* Like rtx_equal_p except that it allows a REG and a SUBREG to match
 359    if they are the same hard reg, and has special hacks for
 360    autoincrement and autodecrement.  */
 361 extern int operands_match_p (rtx, rtx);
 362
 363 /* Return 1 if altering OP will not modify the value of CLOBBER.  */
 364 extern int safe_from_earlyclobber (rtx, rtx);
 365
 366 /* Search the body of INSN for values that need reloading and record them
 367    with push_reload.  REPLACE nonzero means record also where the values occur
 368    so that subst_reloads can be used.  */
 369 extern int find_reloads (rtx_insn *, int, int, int, short *);
 370
 371 /* Compute the sum of X and Y, making canonicalizations assumed in an
 372    address, namely: sum constant integers, surround the sum of two
 373    constants with a CONST, put the constant as the second operand, and
 374    group the constant on the outermost sum.  */
 375 extern rtx form_sum (machine_mode, rtx, rtx);
 376
 377 /* Substitute into the current INSN the registers into which we have reloaded
 378    the things that need reloading.  */
 379 extern void subst_reloads (rtx_insn *);
 380
 381 /* Make a copy of any replacements being done into X and move those copies
 382    to locations in Y, a copy of X.  We only look at the highest level of
 383    the RTL.  */
 384 extern void copy_replacements (rtx, rtx);
 385
 386 /* Change any replacements being done to *X to be done to *Y */
 387 extern void move_replacements (rtx *x, rtx *y);
 388
 389 /* If LOC was scheduled to be replaced by something, return the replacement.
 390    Otherwise, return *LOC.  */
 391 extern rtx find_replacement (rtx *);
 392
 393 /* Nonzero if modifying X will affect IN.  */
 394 extern int reg_overlap_mentioned_for_reload_p (rtx, rtx);
 395
 396 /* Check the insns before INSN to see if there is a suitable register
 397    containing the same value as GOAL.  */
 398 extern rtx find_equiv_reg (rtx, rtx_insn *, enum reg_class, int, short *,
 399                            int, machine_mode);
 400
 401 /* Return 1 if register REGNO is the subject of a clobber in insn INSN.  */
 402 extern int regno_clobbered_p (unsigned int, rtx_insn *, machine_mode, int);
 403
 404 /* Return 1 if X is an operand of an insn that is being earlyclobbered.  */
 405 extern int earlyclobber_operand_p (rtx);
 406
 407 /* Record one reload that needs to be performed.  */
 408 extern int push_reload (rtx, rtx, rtx *, rtx *, enum reg_class,
 409                         machine_mode, machine_mode,
 410                         int, int, int, enum reload_type);
 411
 412 /* Functions in reload1.c:  */
 413
 414 /* Initialize the reload pass once per compilation.  */
 415 extern void init_reload (void);
 416
 417 /* The reload pass itself.  */
 418 extern bool reload (rtx_insn *, int);
 419
 420 /* Mark the slots in regs_ever_live for the hard regs
 421    used by pseudo-reg number REGNO.  */
 422 extern void mark_home_live (int);
 423
 424 /* Scan X and replace any eliminable registers (such as fp) with a
 425    replacement (such as sp), plus an offset.  */
 426 extern rtx eliminate_regs (rtx, machine_mode, rtx);
 427 extern bool elimination_target_reg_p (rtx);
 428
 429 /* Called from the register allocator to estimate costs of eliminating
 430    invariant registers.  */
 431 extern void calculate_elim_costs_all_insns (void);
 432
 433 /* Deallocate the reload register used by reload number R.  */
 434 extern void deallocate_reload_reg (int r);
 435
 436 /* Functions in caller-save.c:  */
 437
 438 /* Initialize for caller-save.  */
 439 extern void init_caller_save (void);
 440
 441 /* Initialize save areas by showing that we haven't allocated any yet.  */
 442 extern void init_save_areas (void);
 443
 444 /* Allocate save areas for any hard registers that might need saving.  */
 445 extern void setup_save_areas (void);
 446
 447 /* Find the places where hard regs are live across calls and save them.  */
 448 extern void save_call_clobbered_regs (void);
 449
 450 /* Replace (subreg (reg)) with the appropriate (reg) for any operands.  */
 451 extern void cleanup_subreg_operands (rtx_insn *);
 452
 453 /* Debugging support.  */
 454 extern void debug_reload_to_stream (FILE *);
 455 extern void debug_reload (void);
 456
 457 /* Compute the actual register we should reload to, in case we're
 458    reloading to/from a register that is wider than a word.  */
 459 extern rtx reload_adjust_reg_for_mode (rtx, machine_mode);
 460
 461 /* Allocate or grow the reg_equiv tables, initializing new entries to 0.  */
 462 extern void grow_reg_equivs (void);
 463
 464 #endif /* GCC_RELOAD_H */