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, reg_class_t, reg_class_t);
  34 extern int memory_move_cost (enum machine_mode, enum reg_class, bool);
  35 extern int memory_move_secondary_cost (enum 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   enum machine_mode inmode;
  88   /* The mode this operand should have when reloaded, on output.  */
  89   enum machine_mode outmode;
  90
  91   /* The mode of the reload register.  */
  92   enum 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   bool 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   enum 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 extern GTY (()) VEC(rtx,gc) *reg_equiv_memory_loc_vec;
 208 extern rtx *reg_equiv_constant;
 209 extern rtx *reg_equiv_invariant;
 210 extern rtx *reg_equiv_memory_loc;
 211 extern rtx *reg_equiv_address;
 212 extern rtx *reg_equiv_mem;
 213 extern rtx *reg_equiv_alt_mem_list;
 214
 215 /* Element N is the list of insns that initialized reg N from its equivalent
 216    constant or memory slot.  */
 217 extern GTY((length("reg_equiv_init_size"))) rtx *reg_equiv_init;
 218
 219 /* The size of the previous array, for GC purposes.  */
 220 extern GTY(()) int reg_equiv_init_size;
 221
 222 /* All the "earlyclobber" operands of the current insn
 223    are recorded here.  */
 224 extern int n_earlyclobbers;
 225 extern rtx reload_earlyclobbers[MAX_RECOG_OPERANDS];
 226
 227 /* Save the number of operands.  */
 228 extern int reload_n_operands;
 229
 230 /* First uid used by insns created by reload in this function.
 231    Used in find_equiv_reg.  */
 232 extern int reload_first_uid;
 233
 234 extern int num_not_at_initial_offset;
 235
 236 #if defined SET_HARD_REG_BIT && defined CLEAR_REG_SET
 237 /* This structure describes instructions which are relevant for reload.
 238    Apart from all regular insns, this also includes CODE_LABELs, since they
 239    must be examined for register elimination.  */
 240 struct insn_chain
 241 {
 242   /* Links to the neighbor instructions.  */
 243   struct insn_chain *next, *prev;
 244
 245   /* Link through a chains set up by calculate_needs_all_insns, containing
 246      all insns that need reloading.  */
 247   struct insn_chain *next_need_reload;
 248
 249   /* The rtx of the insn.  */
 250   rtx insn;
 251
 252   /* The basic block this insn is in.  */
 253   int block;
 254
 255   /* Nonzero if find_reloads said the insn requires reloading.  */
 256   unsigned int need_reload:1;
 257   /* Nonzero if find_reloads needs to be run during reload_as_needed to
 258      perform modifications on any operands.  */
 259   unsigned int need_operand_change:1;
 260   /* Nonzero if eliminate_regs_in_insn said it requires eliminations.  */
 261   unsigned int need_elim:1;
 262   /* Nonzero if this insn was inserted by perform_caller_saves.  */
 263   unsigned int is_caller_save_insn:1;
 264
 265   /* Register life information: record all live hard registers, and
 266      all live pseudos that have a hard register.  This set also
 267      contains pseudos spilled by IRA.  */
 268   bitmap_head live_throughout;
 269   bitmap_head dead_or_set;
 270
 271   /* Copies of the global variables computed by find_reloads.  */
 272   struct reload *rld;
 273   int n_reloads;
 274
 275   /* Indicates which registers have already been used for spills.  */
 276   HARD_REG_SET used_spill_regs;
 277 };
 278
 279 /* A chain of insn_chain structures to describe all non-note insns in
 280    a function.  */
 281 extern struct insn_chain *reload_insn_chain;
 282
 283 /* Allocate a new insn_chain structure.  */
 284 extern struct insn_chain *new_insn_chain (void);
 285 #endif
 286
 287 #if defined SET_HARD_REG_BIT
 288 extern void compute_use_by_pseudos (HARD_REG_SET *, bitmap);
 289 #endif
 290
 291 /* Functions from reload.c:  */
 292
 293 extern reg_class_t secondary_reload_class (bool, reg_class_t,
 294                                            enum machine_mode, rtx);
 295
 296 #ifdef GCC_INSN_CODES_H
 297 extern enum reg_class scratch_reload_class (enum insn_code);
 298 #endif
 299
 300 /* Return a memory location that will be used to copy X in mode MODE.
 301    If we haven't already made a location for this mode in this insn,
 302    call find_reloads_address on the location being returned.  */
 303 extern rtx get_secondary_mem (rtx, enum machine_mode, int, enum reload_type);
 304
 305 /* Clear any secondary memory locations we've made.  */
 306 extern void clear_secondary_mem (void);
 307
 308 /* Transfer all replacements that used to be in reload FROM to be in
 309    reload TO.  */
 310 extern void transfer_replacements (int, int);
 311
 312 /* IN_RTX is the value loaded by a reload that we now decided to inherit,
 313    or a subpart of it.  If we have any replacements registered for IN_RTX,
 314    cancel the reloads that were supposed to load them.
 315    Return nonzero if we canceled any reloads.  */
 316 extern int remove_address_replacements (rtx in_rtx);
 317
 318 /* Like rtx_equal_p except that it allows a REG and a SUBREG to match
 319    if they are the same hard reg, and has special hacks for
 320    autoincrement and autodecrement.  */
 321 extern int operands_match_p (rtx, rtx);
 322
 323 /* Return 1 if altering OP will not modify the value of CLOBBER.  */
 324 extern int safe_from_earlyclobber (rtx, rtx);
 325
 326 /* Search the body of INSN for values that need reloading and record them
 327    with push_reload.  REPLACE nonzero means record also where the values occur
 328    so that subst_reloads can be used.  */
 329 extern int find_reloads (rtx, int, int, int, short *);
 330
 331 /* Compute the sum of X and Y, making canonicalizations assumed in an
 332    address, namely: sum constant integers, surround the sum of two
 333    constants with a CONST, put the constant as the second operand, and
 334    group the constant on the outermost sum.  */
 335 extern rtx form_sum (enum machine_mode, rtx, rtx);
 336
 337 /* Substitute into the current INSN the registers into which we have reloaded
 338    the things that need reloading.  */
 339 extern void subst_reloads (rtx);
 340
 341 /* Make a copy of any replacements being done into X and move those copies
 342    to locations in Y, a copy of X.  We only look at the highest level of
 343    the RTL.  */
 344 extern void copy_replacements (rtx, rtx);
 345
 346 /* Change any replacements being done to *X to be done to *Y */
 347 extern void move_replacements (rtx *x, rtx *y);
 348
 349 /* If LOC was scheduled to be replaced by something, return the replacement.
 350    Otherwise, return *LOC.  */
 351 extern rtx find_replacement (rtx *);
 352
 353 /* Nonzero if modifying X will affect IN.  */
 354 extern int reg_overlap_mentioned_for_reload_p (rtx, rtx);
 355
 356 /* Check the insns before INSN to see if there is a suitable register
 357    containing the same value as GOAL.  */
 358 extern rtx find_equiv_reg (rtx, rtx, enum reg_class, int, short *,
 359                            int, enum machine_mode);
 360
 361 /* Return 1 if register REGNO is the subject of a clobber in insn INSN.  */
 362 extern int regno_clobbered_p (unsigned int, rtx, enum machine_mode, int);
 363
 364 /* Return 1 if X is an operand of an insn that is being earlyclobbered.  */
 365 extern int earlyclobber_operand_p (rtx);
 366
 367 /* Record one reload that needs to be performed.  */
 368 extern int push_reload (rtx, rtx, rtx *, rtx *, enum reg_class,
 369                         enum machine_mode, enum machine_mode,
 370                         int, int, int, enum reload_type);
 371
 372 /* Functions in postreload.c:  */
 373 extern void reload_cse_regs (rtx);
 374
 375 /* Functions in reload1.c:  */
 376
 377 /* Initialize the reload pass once per compilation.  */
 378 extern void init_reload (void);
 379
 380 /* The reload pass itself.  */
 381 extern int reload (rtx, int);
 382
 383 /* Mark the slots in regs_ever_live for the hard regs
 384    used by pseudo-reg number REGNO.  */
 385 extern void mark_home_live (int);
 386
 387 /* Scan X and replace any eliminable registers (such as fp) with a
 388    replacement (such as sp), plus an offset.  */
 389 extern rtx eliminate_regs (rtx, enum machine_mode, rtx);
 390 extern bool elimination_target_reg_p (rtx);
 391
 392 /* Called from the register allocator to estimate costs of eliminating
 393    invariant registers.  */
 394 extern void calculate_elim_costs_all_insns (void);
 395
 396 /* Deallocate the reload register used by reload number R.  */
 397 extern void deallocate_reload_reg (int r);
 398
 399 /* Functions in caller-save.c:  */
 400
 401 /* Initialize for caller-save.  */
 402 extern void init_caller_save (void);
 403
 404 /* Initialize save areas by showing that we haven't allocated any yet.  */
 405 extern void init_save_areas (void);
 406
 407 /* Allocate save areas for any hard registers that might need saving.  */
 408 extern void setup_save_areas (void);
 409
 410 /* Find the places where hard regs are live across calls and save them.  */
 411 extern void save_call_clobbered_regs (void);
 412
 413 /* Replace (subreg (reg)) with the appropriate (reg) for any operands.  */
 414 extern void cleanup_subreg_operands (rtx);
 415
 416 /* Debugging support.  */
 417 extern void debug_reload_to_stream (FILE *);
 418 extern void debug_reload (void);
 419
 420 /* Compute the actual register we should reload to, in case we're
 421    reloading to/from a register that is wider than a word.  */
 422 extern rtx reload_adjust_reg_for_mode (rtx, enum machine_mode);