gcc/reload.h

   1 /* Communication between reload.c, reload1.c and the rest of compiler.
   2    Copyright (C) 1987-2021 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   poly_int64_pod 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 indirect addressing is supported on the machine; this means
 163      that spilling (REG n) does not require reloading it into a register in
 164      order to do (MEM (REG n)) or (MEM (PLUS (REG n) (CONST_INT c))).  The
 165      value indicates the level of indirect addressing supported, e.g., two
 166      means that (MEM (MEM (REG n))) is also valid if (REG n) does not get
 167      a hard register.  */
 168   unsigned char x_spill_indirect_levels;
 169
 170   /* True if caller-save has been reinitialized.  */
 171   bool x_caller_save_initialized_p;
 172
 173   /* Modes for each hard register that we can save.  The smallest mode is wide
 174      enough to save the entire contents of the register.  When saving the
 175      register because it is live we first try to save in multi-register modes.
 176      If that is not possible the save is done one register at a time.  */
 177   machine_mode (x_regno_save_mode
 178                      [FIRST_PSEUDO_REGISTER]
 179                      [MAX_MOVE_MAX / MIN_UNITS_PER_WORD + 1]);
 180
 181   /* Nonzero if an address (plus (reg frame_pointer) (reg ...)) is valid
 182      in the given mode.  */
 183   bool x_double_reg_address_ok[MAX_MACHINE_MODE];
 184
 185   /* We will only make a register eligible for caller-save if it can be
 186      saved in its widest mode with a simple SET insn as long as the memory
 187      address is valid.  We record the INSN_CODE is those insns here since
 188      when we emit them, the addresses might not be valid, so they might not
 189      be recognized.  */
 190   int x_cached_reg_save_code[FIRST_PSEUDO_REGISTER][MAX_MACHINE_MODE];
 191   int x_cached_reg_restore_code[FIRST_PSEUDO_REGISTER][MAX_MACHINE_MODE];
 192 };
 193
 194 extern struct target_reload default_target_reload;
 195 #if SWITCHABLE_TARGET
 196 extern struct target_reload *this_target_reload;
 197 #else
 198 #define this_target_reload (&default_target_reload)
 199 #endif
 200
 201 #define indirect_symref_ok \
 202   (this_target_reload->x_indirect_symref_ok)
 203 #define double_reg_address_ok \
 204   (this_target_reload->x_double_reg_address_ok)
 205 #define caller_save_initialized_p \
 206   (this_target_reload->x_caller_save_initialized_p)
 207
 208 /* Register equivalences.  Indexed by register number.  */
 209 struct reg_equivs_t
 210 {
 211   /* The constant value to which pseudo reg N is equivalent,
 212      or zero if pseudo reg N is not equivalent to a constant.
 213      find_reloads looks at this in order to replace pseudo reg N
 214      with the constant it stands for.  */
 215   rtx constant;
 216
 217   /* An invariant value to which pseudo reg N is equivalent.
 218      eliminate_regs_in_insn uses this to replace pseudos in particular
 219      contexts.  */
 220   rtx invariant;
 221
 222   /* A memory location to which pseudo reg N is equivalent,
 223      prior to any register elimination (such as frame pointer to stack
 224      pointer).  Depending on whether or not it is a valid address, this value
 225      is transferred to either equiv_address or equiv_mem.  */
 226   rtx memory_loc;
 227
 228   /* The address of stack slot to which pseudo reg N is equivalent.
 229      This is used when the address is not valid as a memory address
 230      (because its displacement is too big for the machine.)  */
 231   rtx address;
 232
 233   /* The memory slot to which pseudo reg N is equivalent,
 234      or zero if pseudo reg N is not equivalent to a memory slot.  */
 235   rtx mem;
 236
 237   /* An EXPR_LIST of REG_EQUIVs containing MEMs with
 238      alternate representations of the location of pseudo reg N.  */
 239   rtx_expr_list *alt_mem_list;
 240
 241   /* The list of insns that initialized reg N from its equivalent
 242      constant or memory slot.  */
 243   rtx_insn_list *init;
 244 };
 245
 246 #define reg_equiv_constant(ELT) \
 247   (*reg_equivs)[(ELT)].constant
 248 #define reg_equiv_invariant(ELT) \
 249   (*reg_equivs)[(ELT)].invariant
 250 #define reg_equiv_memory_loc(ELT) \
 251   (*reg_equivs)[(ELT)].memory_loc
 252 #define reg_equiv_address(ELT) \
 253   (*reg_equivs)[(ELT)].address
 254 #define reg_equiv_mem(ELT) \
 255   (*reg_equivs)[(ELT)].mem
 256 #define reg_equiv_alt_mem_list(ELT) \
 257   (*reg_equivs)[(ELT)].alt_mem_list
 258 #define reg_equiv_init(ELT) \
 259   (*reg_equivs)[(ELT)].init
 260
 261 extern vec<reg_equivs_t, va_gc> *reg_equivs;
 262
 263 /* All the "earlyclobber" operands of the current insn
 264    are recorded here.  */
 265 extern int n_earlyclobbers;
 266 extern rtx reload_earlyclobbers[MAX_RECOG_OPERANDS];
 267
 268 /* Save the number of operands.  */
 269 extern int reload_n_operands;
 270
 271 /* First uid used by insns created by reload in this function.
 272    Used in find_equiv_reg.  */
 273 extern int reload_first_uid;
 274
 275 extern int num_not_at_initial_offset;
 276
 277 #if defined HARD_CONST && defined CLEAR_REG_SET
 278 /* This structure describes instructions which are relevant for reload.
 279    Apart from all regular insns, this also includes CODE_LABELs, since they
 280    must be examined for register elimination.  */
 281 class insn_chain
 282 {
 283 public:
 284   /* Links to the neighbor instructions.  */
 285   class insn_chain *next, *prev;
 286
 287   /* Link through a chains set up by calculate_needs_all_insns, containing
 288      all insns that need reloading.  */
 289   class insn_chain *next_need_reload;
 290
 291   /* The rtx of the insn.  */
 292   rtx_insn *insn;
 293
 294   /* The basic block this insn is in.  */
 295   int block;
 296
 297   /* Nonzero if find_reloads said the insn requires reloading.  */
 298   unsigned int need_reload:1;
 299   /* Nonzero if find_reloads needs to be run during reload_as_needed to
 300      perform modifications on any operands.  */
 301   unsigned int need_operand_change:1;
 302   /* Nonzero if eliminate_regs_in_insn said it requires eliminations.  */
 303   unsigned int need_elim:1;
 304   /* Nonzero if this insn was inserted by perform_caller_saves.  */
 305   unsigned int is_caller_save_insn:1;
 306
 307   /* Register life information: record all live hard registers, and
 308      all live pseudos that have a hard register.  This set also
 309      contains pseudos spilled by IRA.  */
 310   bitmap_head live_throughout;
 311   bitmap_head dead_or_set;
 312
 313   /* Copies of the global variables computed by find_reloads.  */
 314   struct reload *rld;
 315   int n_reloads;
 316
 317   /* Indicates which registers have already been used for spills.  */
 318   HARD_REG_SET used_spill_regs;
 319 };
 320
 321 /* A chain of insn_chain structures to describe all non-note insns in
 322    a function.  */
 323 extern class insn_chain *reload_insn_chain;
 324
 325 /* Allocate a new insn_chain structure.  */
 326 extern class insn_chain *new_insn_chain (void);
 327 #endif
 328
 329 #if defined HARD_CONST
 330 extern void compute_use_by_pseudos (HARD_REG_SET *, bitmap);
 331 #endif
 332
 333 /* Functions from reload.c:  */
 334
 335 extern reg_class_t secondary_reload_class (bool, reg_class_t,
 336                                            machine_mode, rtx);
 337
 338 #ifdef GCC_INSN_CODES_H
 339 extern enum reg_class scratch_reload_class (enum insn_code);
 340 #endif
 341
 342 /* Return a memory location that will be used to copy X in mode MODE.
 343    If we haven't already made a location for this mode in this insn,
 344    call find_reloads_address on the location being returned.  */
 345 extern rtx get_secondary_mem (rtx, machine_mode, int, enum reload_type);
 346
 347 /* Clear any secondary memory locations we've made.  */
 348 extern void clear_secondary_mem (void);
 349
 350 /* Transfer all replacements that used to be in reload FROM to be in
 351    reload TO.  */
 352 extern void transfer_replacements (int, int);
 353
 354 /* IN_RTX is the value loaded by a reload that we now decided to inherit,
 355    or a subpart of it.  If we have any replacements registered for IN_RTX,
 356    cancel the reloads that were supposed to load them.
 357    Return nonzero if we canceled any reloads.  */
 358 extern int remove_address_replacements (rtx in_rtx);
 359
 360 /* Like rtx_equal_p except that it allows a REG and a SUBREG to match
 361    if they are the same hard reg, and has special hacks for
 362    autoincrement and autodecrement.  */
 363 extern int operands_match_p (rtx, rtx);
 364
 365 /* Return 1 if altering OP will not modify the value of CLOBBER.  */
 366 extern int safe_from_earlyclobber (rtx, rtx);
 367
 368 /* Search the body of INSN for values that need reloading and record them
 369    with push_reload.  REPLACE nonzero means record also where the values occur
 370    so that subst_reloads can be used.  */
 371 extern int find_reloads (rtx_insn *, int, int, int, short *);
 372
 373 /* Compute the sum of X and Y, making canonicalizations assumed in an
 374    address, namely: sum constant integers, surround the sum of two
 375    constants with a CONST, put the constant as the second operand, and
 376    group the constant on the outermost sum.  */
 377 extern rtx form_sum (machine_mode, rtx, rtx);
 378
 379 /* Substitute into the current INSN the registers into which we have reloaded
 380    the things that need reloading.  */
 381 extern void subst_reloads (rtx_insn *);
 382
 383 /* Make a copy of any replacements being done into X and move those copies
 384    to locations in Y, a copy of X.  We only look at the highest level of
 385    the RTL.  */
 386 extern void copy_replacements (rtx, rtx);
 387
 388 /* Change any replacements being done to *X to be done to *Y */
 389 extern void move_replacements (rtx *x, rtx *y);
 390
 391 /* If LOC was scheduled to be replaced by something, return the replacement.
 392    Otherwise, return *LOC.  */
 393 extern rtx find_replacement (rtx *);
 394
 395 /* Nonzero if modifying X will affect IN.  */
 396 extern int reg_overlap_mentioned_for_reload_p (rtx, rtx);
 397
 398 /* Check the insns before INSN to see if there is a suitable register
 399    containing the same value as GOAL.  */
 400 extern rtx find_equiv_reg (rtx, rtx_insn *, enum reg_class, int, short *,
 401                            int, machine_mode);
 402
 403 /* Return 1 if register REGNO is the subject of a clobber in insn INSN.  */
 404 extern int regno_clobbered_p (unsigned int, rtx_insn *, machine_mode, int);
 405
 406 /* Return 1 if X is an operand of an insn that is being earlyclobbered.  */
 407 extern int earlyclobber_operand_p (rtx);
 408
 409 /* Record one reload that needs to be performed.  */
 410 extern int push_reload (rtx, rtx, rtx *, rtx *, enum reg_class,
 411                         machine_mode, machine_mode,
 412                         int, int, int, enum reload_type);
 413
 414 /* Functions in reload1.c:  */
 415
 416 /* Initialize the reload pass once per compilation.  */
 417 extern void init_reload (void);
 418
 419 /* The reload pass itself.  */
 420 extern bool reload (rtx_insn *, int);
 421
 422 /* Mark the slots in regs_ever_live for the hard regs
 423    used by pseudo-reg number REGNO.  */
 424 extern void mark_home_live (int);
 425
 426 /* Scan X and replace any eliminable registers (such as fp) with a
 427    replacement (such as sp), plus an offset.  */
 428 extern rtx eliminate_regs (rtx, machine_mode, rtx);
 429 extern bool elimination_target_reg_p (rtx);
 430
 431 /* Called from the register allocator to estimate costs of eliminating
 432    invariant registers.  */
 433 extern void calculate_elim_costs_all_insns (void);
 434
 435 /* Deallocate the reload register used by reload number R.  */
 436 extern void deallocate_reload_reg (int r);
 437
 438 /* Functions in caller-save.c:  */
 439
 440 /* Initialize for caller-save.  */
 441 extern void init_caller_save (void);
 442
 443 /* Initialize save areas by showing that we haven't allocated any yet.  */
 444 extern void init_save_areas (void);
 445
 446 /* Allocate save areas for any hard registers that might need saving.  */
 447 extern void setup_save_areas (void);
 448
 449 /* Find the places where hard regs are live across calls and save them.  */
 450 extern void save_call_clobbered_regs (void);
 451
 452 /* Replace (subreg (reg)) with the appropriate (reg) for any operands.  */
 453 extern void cleanup_subreg_operands (rtx_insn *);
 454
 455 /* Debugging support.  */
 456 extern void debug_reload_to_stream (FILE *);
 457 extern void debug_reload (void);
 458
 459 /* Compute the actual register we should reload to, in case we're
 460    reloading to/from a register that is wider than a word.  */
 461 extern rtx reload_adjust_reg_for_mode (rtx, machine_mode);
 462
 463 /* Allocate or grow the reg_equiv tables, initializing new entries to 0.  */
 464 extern void grow_reg_equivs (void);
 465
 466 #endif /* GCC_RELOAD_H */