gcc/regs.h

   1 /* Define per-register tables for data flow info and register allocation.
   2    Copyright (C) 1987, 1993, 1994, 1995, 1996, 1997, 1998,
   3    1999, 2000, 2003, 2004, 2005, 2006, 2007 Free Software Foundation, Inc.
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 3, or (at your option) any later
  10 version.
  11
  12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING3.  If not see
  19 <http://www.gnu.org/licenses/>.  */
  20
  21 #ifndef GCC_REGS_H
  22 #define GCC_REGS_H
  23
  24 #include "varray.h"
  25 #include "obstack.h"
  26 #include "hard-reg-set.h"
  27 #include "basic-block.h"
  28
  29 #define REG_BYTES(R) mode_size[(int) GET_MODE (R)]
  30
  31 /* When you only have the mode of a pseudo register before it has a hard
  32    register chosen for it, this reports the size of each hard register
  33    a pseudo in such a mode would get allocated to.  A target may
  34    override this.  */
  35
  36 #ifndef REGMODE_NATURAL_SIZE
  37 #define REGMODE_NATURAL_SIZE(MODE)      UNITS_PER_WORD
  38 #endif
  39
  40 #ifndef SMALL_REGISTER_CLASSES
  41 #define SMALL_REGISTER_CLASSES 0
  42 #endif
  43
  44 /* Maximum register number used in this function, plus one.  */
  45
  46 extern int max_regno;
  47
  48 /* REG_N_REFS and REG_N_SETS are initialized by a call to
  49    regstat_init_n_sets_and_refs from the current values of
  50    DF_REG_DEF_COUNT and DF_REG_USE_COUNT.  REG_N_REFS and REG_N_SETS
  51    should only be used if a pass need to change these values in some
  52    magical way or or the pass needs to have accurate values for these
  53    and is not using incremental df scanning.
  54
  55    At the end of a pass that uses REG_N_REFS and REG_N_SETS, a call
  56    should be made to regstat_free_n_sets_and_refs.
  57
  58    Local alloc seems to play pretty loose with these values.
  59    REG_N_REFS is set to 0 if the register is used in an asm.
  60    Furthermore, local_alloc calls regclass to hack both REG_N_REFS and
  61    REG_N_SETS for three address insns.  Other passes seem to have
  62    other special values.  */
  63
  64
  65
  66 /* Structure to hold values for REG_N_SETS (i) and REG_N_REFS (i). */
  67
  68 struct regstat_n_sets_and_refs_t
  69 {
  70   int sets;                     /* # of times (REG n) is set */
  71   int refs;                     /* # of times (REG n) is used or set */
  72 };
  73
  74 extern struct regstat_n_sets_and_refs_t *regstat_n_sets_and_refs;
  75
  76 /* Indexed by n, gives number of times (REG n) is used or set.  */
  77 static inline int
  78 REG_N_REFS(int regno)
  79 {
  80   return regstat_n_sets_and_refs[regno].refs;
  81 }
  82
  83 /* Indexed by n, gives number of times (REG n) is used or set.  */
  84 #define SET_REG_N_REFS(N,V) (regstat_n_sets_and_refs[N].refs = V)
  85 #define INC_REG_N_REFS(N,V) (regstat_n_sets_and_refs[N].refs += V)
  86
  87 /* Indexed by n, gives number of times (REG n) is set.  */
  88 static inline int
  89 REG_N_SETS (int regno)
  90 {
  91   return regstat_n_sets_and_refs[regno].sets;
  92 }
  93
  94 /* Indexed by n, gives number of times (REG n) is set.  */
  95 #define SET_REG_N_SETS(N,V) (regstat_n_sets_and_refs[N].sets = V)
  96 #define INC_REG_N_SETS(N,V) (regstat_n_sets_and_refs[N].sets += V)
  97
  98
  99 /* Functions defined in reg-stat.c.  */
 100 extern void regstat_init_n_sets_and_refs (void);
 101 extern void regstat_free_n_sets_and_refs (void);
 102 extern void regstat_compute_ri (void);
 103 extern void regstat_free_ri (void);
 104 extern bitmap regstat_get_setjmp_crosses (void);
 105 extern void regstat_compute_calls_crossed (void);
 106 extern void regstat_free_calls_crossed (void);
 107
 108
 109 /* Register information indexed by register number.  This structure is
 110    initialized by calling regstat_compute_ri and is destroyed by
 111    calling regstat_free_ri.  */
 112 struct reg_info_t
 113 {
 114   int freq;                     /* # estimated frequency (REG n) is used or set */
 115   int deaths;                   /* # of times (REG n) dies */
 116   int live_length;              /* # of instructions (REG n) is live */
 117   int calls_crossed;            /* # of calls (REG n) is live across */
 118   int freq_calls_crossed;       /* # estimated frequency (REG n) crosses call */
 119   int throw_calls_crossed;      /* # of calls that may throw (REG n) is live across */
 120   int basic_block;              /* # of basic blocks (REG n) is used in */
 121 };
 122
 123 extern struct reg_info_t *reg_info_p;
 124
 125 /* The number allocated elements of reg_info_p.  */
 126 extern size_t reg_info_p_size;
 127
 128 /* Estimate frequency of references to register N.  */
 129
 130 #define REG_FREQ(N) (reg_info_p[N].freq)
 131
 132 /* The weights for each insn varries from 0 to REG_FREQ_BASE.
 133    This constant does not need to be high, as in infrequently executed
 134    regions we want to count instructions equivalently to optimize for
 135    size instead of speed.  */
 136 #define REG_FREQ_MAX 1000
 137
 138 /* Compute register frequency from the BB frequency.  When optimizing for size,
 139    or profile driven feedback is available and the function is never executed,
 140    frequency is always equivalent.  Otherwise rescale the basic block
 141    frequency.  */
 142 #define REG_FREQ_FROM_BB(bb) (optimize_size                                   \
 143                               || (flag_branch_probabilities                   \
 144                                   && !ENTRY_BLOCK_PTR->count)                 \
 145                               ? REG_FREQ_MAX                                  \
 146                               : ((bb)->frequency * REG_FREQ_MAX / BB_FREQ_MAX)\
 147                               ? ((bb)->frequency * REG_FREQ_MAX / BB_FREQ_MAX)\
 148                               : 1)
 149
 150 /* Indexed by N, gives number of insns in which register N dies.
 151    Note that if register N is live around loops, it can die
 152    in transitions between basic blocks, and that is not counted here.
 153    So this is only a reliable indicator of how many regions of life there are
 154    for registers that are contained in one basic block.  */
 155
 156 #define REG_N_DEATHS(N) (reg_info_p[N].deaths)
 157
 158 /* Get the number of consecutive words required to hold pseudo-reg N.  */
 159
 160 #define PSEUDO_REGNO_SIZE(N) \
 161   ((GET_MODE_SIZE (PSEUDO_REGNO_MODE (N)) + UNITS_PER_WORD - 1)         \
 162    / UNITS_PER_WORD)
 163
 164 /* Get the number of bytes required to hold pseudo-reg N.  */
 165
 166 #define PSEUDO_REGNO_BYTES(N) \
 167   GET_MODE_SIZE (PSEUDO_REGNO_MODE (N))
 168
 169 /* Get the machine mode of pseudo-reg N.  */
 170
 171 #define PSEUDO_REGNO_MODE(N) GET_MODE (regno_reg_rtx[N])
 172
 173 /* Indexed by N, gives number of CALL_INSNS across which (REG n) is live.  */
 174
 175 #define REG_N_CALLS_CROSSED(N)  (reg_info_p[N].calls_crossed)
 176 #define REG_FREQ_CALLS_CROSSED(N)  (reg_info_p[N].freq_calls_crossed)
 177
 178 /* Indexed by N, gives number of CALL_INSNS that may throw, across which
 179    (REG n) is live.  */
 180
 181 #define REG_N_THROWING_CALLS_CROSSED(N) (reg_info_p[N].throw_calls_crossed)
 182
 183 /* Total number of instructions at which (REG n) is live.  The larger
 184    this is, the less priority (REG n) gets for allocation in a hard
 185    register (in global-alloc).  This is set in df-problems.c whenever
 186    register info is requested and remains valid for the rest of the
 187    compilation of the function; it is used to control register
 188    allocation.
 189
 190    local-alloc.c may alter this number to change the priority.
 191
 192    Negative values are special.
 193    -1 is used to mark a pseudo reg which has a constant or memory equivalent
 194    and is used infrequently enough that it should not get a hard register.
 195    -2 is used to mark a pseudo reg for a parameter, when a frame pointer
 196    is not required.  global.c makes an allocno for this but does
 197    not try to assign a hard register to it.  */
 198
 199 #define REG_LIVE_LENGTH(N)  (reg_info_p[N].live_length)
 200
 201 /* Indexed by n, gives number of basic block that  (REG n) is used in.
 202    If the value is REG_BLOCK_GLOBAL (-1),
 203    it means (REG n) is used in more than one basic block.
 204    REG_BLOCK_UNKNOWN (0) means it hasn't been seen yet so we don't know.
 205    This information remains valid for the rest of the compilation
 206    of the current function; it is used to control register allocation.  */
 207
 208 #define REG_BLOCK_UNKNOWN 0
 209 #define REG_BLOCK_GLOBAL -1
 210
 211 #define REG_BASIC_BLOCK(N) (reg_info_p[N].basic_block)
 212
 213 /* Vector of substitutions of register numbers,
 214    used to map pseudo regs into hardware regs.
 215
 216    This can't be folded into reg_n_info without changing all of the
 217    machine dependent directories, since the reload functions
 218    in the machine dependent files access it.  */
 219
 220 extern short *reg_renumber;
 221
 222 /* Vector indexed by machine mode saying whether there are regs of that mode.  */
 223
 224 extern bool have_regs_of_mode [MAX_MACHINE_MODE];
 225
 226 /* For each hard register, the widest mode object that it can contain.
 227    This will be a MODE_INT mode if the register can hold integers.  Otherwise
 228    it will be a MODE_FLOAT or a MODE_CC mode, whichever is valid for the
 229    register.  */
 230
 231 extern enum machine_mode reg_raw_mode[FIRST_PSEUDO_REGISTER];
 232
 233 /* Flag set by local-alloc or global-alloc if they decide to allocate
 234    something in a call-clobbered register.  */
 235
 236 extern int caller_save_needed;
 237
 238 /* Predicate to decide whether to give a hard reg to a pseudo which
 239    is referenced REFS times and would need to be saved and restored
 240    around a call CALLS times.  */
 241
 242 #ifndef CALLER_SAVE_PROFITABLE
 243 #define CALLER_SAVE_PROFITABLE(REFS, CALLS)  (4 * (CALLS) < (REFS))
 244 #endif
 245
 246 /* On most machines a register class is likely to be spilled if it
 247    only has one register.  */
 248 #ifndef CLASS_LIKELY_SPILLED_P
 249 #define CLASS_LIKELY_SPILLED_P(CLASS) (reg_class_size[(int) (CLASS)] == 1)
 250 #endif
 251
 252 /* Select a register mode required for caller save of hard regno REGNO.  */
 253 #ifndef HARD_REGNO_CALLER_SAVE_MODE
 254 #define HARD_REGNO_CALLER_SAVE_MODE(REGNO, NREGS, MODE) \
 255   choose_hard_reg_mode (REGNO, NREGS, false)
 256 #endif
 257
 258 /* Registers that get partially clobbered by a call in a given mode.
 259    These must not be call used registers.  */
 260 #ifndef HARD_REGNO_CALL_PART_CLOBBERED
 261 #define HARD_REGNO_CALL_PART_CLOBBERED(REGNO, MODE) 0
 262 #endif
 263
 264 /* Specify number of hard registers given machine mode occupy.  */
 265 extern unsigned char hard_regno_nregs[FIRST_PSEUDO_REGISTER][MAX_MACHINE_MODE];
 266
 267 /* Return an exclusive upper bound on the registers occupied by hard
 268    register (reg:MODE REGNO).  */
 269
 270 static inline unsigned int
 271 end_hard_regno (enum machine_mode mode, unsigned int regno)
 272 {
 273   return regno + hard_regno_nregs[regno][(int) mode];
 274 }
 275
 276 /* Likewise for hard register X.  */
 277
 278 #define END_HARD_REGNO(X) end_hard_regno (GET_MODE (X), REGNO (X))
 279
 280 /* Likewise for hard or pseudo register X.  */
 281
 282 #define END_REGNO(X) (HARD_REGISTER_P (X) ? END_HARD_REGNO (X) : REGNO (X) + 1)
 283
 284 /* Add to REGS all the registers required to store a value of mode MODE
 285    in register REGNO.  */
 286
 287 static inline void
 288 add_to_hard_reg_set (HARD_REG_SET *regs, enum machine_mode mode,
 289                      unsigned int regno)
 290 {
 291   unsigned int end_regno;
 292
 293   end_regno = end_hard_regno (mode, regno);
 294   do
 295     SET_HARD_REG_BIT (*regs, regno);
 296   while (++regno < end_regno);
 297 }
 298
 299 /* Likewise, but remove the registers.  */
 300
 301 static inline void
 302 remove_from_hard_reg_set (HARD_REG_SET *regs, enum machine_mode mode,
 303                           unsigned int regno)
 304 {
 305   unsigned int end_regno;
 306
 307   end_regno = end_hard_regno (mode, regno);
 308   do
 309     CLEAR_HARD_REG_BIT (*regs, regno);
 310   while (++regno < end_regno);
 311 }
 312
 313 /* Return true if REGS contains the whole of (reg:MODE REGNO).  */
 314
 315 static inline bool
 316 in_hard_reg_set_p (const HARD_REG_SET regs, enum machine_mode mode,
 317                    unsigned int regno)
 318 {
 319   unsigned int end_regno;
 320
 321   if (!TEST_HARD_REG_BIT (regs, regno))
 322     return false;
 323
 324   end_regno = end_hard_regno (mode, regno);
 325   while (++regno < end_regno)
 326     if (!TEST_HARD_REG_BIT (regs, regno))
 327       return false;
 328
 329   return true;
 330 }
 331
 332 /* Return true if (reg:MODE REGNO) includes an element of REGS.  */
 333
 334 static inline bool
 335 overlaps_hard_reg_set_p (const HARD_REG_SET regs, enum machine_mode mode,
 336                          unsigned int regno)
 337 {
 338   unsigned int end_regno;
 339
 340   if (TEST_HARD_REG_BIT (regs, regno))
 341     return true;
 342
 343   end_regno = end_hard_regno (mode, regno);
 344   while (++regno < end_regno)
 345     if (TEST_HARD_REG_BIT (regs, regno))
 346       return true;
 347
 348   return false;
 349 }
 350
 351 #endif /* GCC_REGS_H */