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, 2008 Free Software
   4    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 #ifndef GCC_REGS_H
  23 #define GCC_REGS_H
  24
  25 #include "machmode.h"
  26 #include "hard-reg-set.h"
  27
  28 #define REG_BYTES(R) mode_size[(int) GET_MODE (R)]
  29
  30 /* When you only have the mode of a pseudo register before it has a hard
  31    register chosen for it, this reports the size of each hard register
  32    a pseudo in such a mode would get allocated to.  A target may
  33    override this.  */
  34
  35 #ifndef REGMODE_NATURAL_SIZE
  36 #define REGMODE_NATURAL_SIZE(MODE)      UNITS_PER_WORD
  37 #endif
  38
  39 /* Maximum register number used in this function, plus one.  */
  40
  41 extern int max_regno;
  42
  43 /* REG_N_REFS and REG_N_SETS are initialized by a call to
  44    regstat_init_n_sets_and_refs from the current values of
  45    DF_REG_DEF_COUNT and DF_REG_USE_COUNT.  REG_N_REFS and REG_N_SETS
  46    should only be used if a pass need to change these values in some
  47    magical way or or the pass needs to have accurate values for these
  48    and is not using incremental df scanning.
  49
  50    At the end of a pass that uses REG_N_REFS and REG_N_SETS, a call
  51    should be made to regstat_free_n_sets_and_refs.
  52
  53    Local alloc seems to play pretty loose with these values.
  54    REG_N_REFS is set to 0 if the register is used in an asm.
  55    Furthermore, local_alloc calls regclass to hack both REG_N_REFS and
  56    REG_N_SETS for three address insns.  Other passes seem to have
  57    other special values.  */
  58
  59
  60
  61 /* Structure to hold values for REG_N_SETS (i) and REG_N_REFS (i). */
  62
  63 struct regstat_n_sets_and_refs_t
  64 {
  65   int sets;                     /* # of times (REG n) is set */
  66   int refs;                     /* # of times (REG n) is used or set */
  67 };
  68
  69 extern struct regstat_n_sets_and_refs_t *regstat_n_sets_and_refs;
  70
  71 /* Indexed by n, gives number of times (REG n) is used or set.  */
  72 static inline int
  73 REG_N_REFS(int regno)
  74 {
  75   return regstat_n_sets_and_refs[regno].refs;
  76 }
  77
  78 /* Indexed by n, gives number of times (REG n) is used or set.  */
  79 #define SET_REG_N_REFS(N,V) (regstat_n_sets_and_refs[N].refs = V)
  80 #define INC_REG_N_REFS(N,V) (regstat_n_sets_and_refs[N].refs += V)
  81
  82 /* Indexed by n, gives number of times (REG n) is set.  */
  83 static inline int
  84 REG_N_SETS (int regno)
  85 {
  86   return regstat_n_sets_and_refs[regno].sets;
  87 }
  88
  89 /* Indexed by n, gives number of times (REG n) is set.  */
  90 #define SET_REG_N_SETS(N,V) (regstat_n_sets_and_refs[N].sets = V)
  91 #define INC_REG_N_SETS(N,V) (regstat_n_sets_and_refs[N].sets += V)
  92
  93
  94 /* Functions defined in reg-stat.c.  */
  95 extern void regstat_init_n_sets_and_refs (void);
  96 extern void regstat_free_n_sets_and_refs (void);
  97 extern void regstat_compute_ri (void);
  98 extern void regstat_free_ri (void);
  99 extern bitmap regstat_get_setjmp_crosses (void);
 100 extern void regstat_compute_calls_crossed (void);
 101 extern void regstat_free_calls_crossed (void);
 102
 103
 104 /* Register information indexed by register number.  This structure is
 105    initialized by calling regstat_compute_ri and is destroyed by
 106    calling regstat_free_ri.  */
 107 struct reg_info_t
 108 {
 109   int freq;                     /* # estimated frequency (REG n) is used or set */
 110   int deaths;                   /* # of times (REG n) dies */
 111   int live_length;              /* # of instructions (REG n) is live */
 112   int calls_crossed;            /* # of calls (REG n) is live across */
 113   int freq_calls_crossed;       /* # estimated frequency (REG n) crosses call */
 114   int throw_calls_crossed;      /* # of calls that may throw (REG n) is live across */
 115   int basic_block;              /* # of basic blocks (REG n) is used in */
 116 };
 117
 118 extern struct reg_info_t *reg_info_p;
 119
 120 /* The number allocated elements of reg_info_p.  */
 121 extern size_t reg_info_p_size;
 122
 123 /* Estimate frequency of references to register N.  */
 124
 125 #define REG_FREQ(N) (reg_info_p[N].freq)
 126
 127 /* The weights for each insn varies from 0 to REG_FREQ_BASE.
 128    This constant does not need to be high, as in infrequently executed
 129    regions we want to count instructions equivalently to optimize for
 130    size instead of speed.  */
 131 #define REG_FREQ_MAX 1000
 132
 133 /* Compute register frequency from the BB frequency.  When optimizing for size,
 134    or profile driven feedback is available and the function is never executed,
 135    frequency is always equivalent.  Otherwise rescale the basic block
 136    frequency.  */
 137 #define REG_FREQ_FROM_BB(bb) (optimize_size                                   \
 138                               || (flag_branch_probabilities                   \
 139                                   && !ENTRY_BLOCK_PTR->count)                 \
 140                               ? REG_FREQ_MAX                                  \
 141                               : ((bb)->frequency * REG_FREQ_MAX / BB_FREQ_MAX)\
 142                               ? ((bb)->frequency * REG_FREQ_MAX / BB_FREQ_MAX)\
 143                               : 1)
 144
 145 /* Indexed by N, gives number of insns in which register N dies.
 146    Note that if register N is live around loops, it can die
 147    in transitions between basic blocks, and that is not counted here.
 148    So this is only a reliable indicator of how many regions of life there are
 149    for registers that are contained in one basic block.  */
 150
 151 #define REG_N_DEATHS(N) (reg_info_p[N].deaths)
 152
 153 /* Get the number of consecutive words required to hold pseudo-reg N.  */
 154
 155 #define PSEUDO_REGNO_SIZE(N) \
 156   ((GET_MODE_SIZE (PSEUDO_REGNO_MODE (N)) + UNITS_PER_WORD - 1)         \
 157    / UNITS_PER_WORD)
 158
 159 /* Get the number of bytes required to hold pseudo-reg N.  */
 160
 161 #define PSEUDO_REGNO_BYTES(N) \
 162   GET_MODE_SIZE (PSEUDO_REGNO_MODE (N))
 163
 164 /* Get the machine mode of pseudo-reg N.  */
 165
 166 #define PSEUDO_REGNO_MODE(N) GET_MODE (regno_reg_rtx[N])
 167
 168 /* Indexed by N, gives number of CALL_INSNS across which (REG n) is live.  */
 169
 170 #define REG_N_CALLS_CROSSED(N)  (reg_info_p[N].calls_crossed)
 171 #define REG_FREQ_CALLS_CROSSED(N)  (reg_info_p[N].freq_calls_crossed)
 172
 173 /* Indexed by N, gives number of CALL_INSNS that may throw, across which
 174    (REG n) is live.  */
 175
 176 #define REG_N_THROWING_CALLS_CROSSED(N) (reg_info_p[N].throw_calls_crossed)
 177
 178 /* Total number of instructions at which (REG n) is live.  The larger
 179    this is, the less priority (REG n) gets for allocation in a hard
 180    register (in global-alloc).  This is set in df-problems.c whenever
 181    register info is requested and remains valid for the rest of the
 182    compilation of the function; it is used to control register
 183    allocation.
 184
 185    local-alloc.c may alter this number to change the priority.
 186
 187    Negative values are special.
 188    -1 is used to mark a pseudo reg which has a constant or memory equivalent
 189    and is used infrequently enough that it should not get a hard register.
 190    -2 is used to mark a pseudo reg for a parameter, when a frame pointer
 191    is not required.  global.c makes an allocno for this but does
 192    not try to assign a hard register to it.  */
 193
 194 #define REG_LIVE_LENGTH(N)  (reg_info_p[N].live_length)
 195
 196 /* Indexed by n, gives number of basic block that  (REG n) is used in.
 197    If the value is REG_BLOCK_GLOBAL (-1),
 198    it means (REG n) is used in more than one basic block.
 199    REG_BLOCK_UNKNOWN (0) means it hasn't been seen yet so we don't know.
 200    This information remains valid for the rest of the compilation
 201    of the current function; it is used to control register allocation.  */
 202
 203 #define REG_BLOCK_UNKNOWN 0
 204 #define REG_BLOCK_GLOBAL -1
 205
 206 #define REG_BASIC_BLOCK(N) (reg_info_p[N].basic_block)
 207
 208 /* Vector of substitutions of register numbers,
 209    used to map pseudo regs into hardware regs.
 210
 211    This can't be folded into reg_n_info without changing all of the
 212    machine dependent directories, since the reload functions
 213    in the machine dependent files access it.  */
 214
 215 extern short *reg_renumber;
 216
 217 /* Vector indexed by machine mode saying whether there are regs of that mode.  */
 218
 219 extern bool have_regs_of_mode [MAX_MACHINE_MODE];
 220
 221 /* For each hard register, the widest mode object that it can contain.
 222    This will be a MODE_INT mode if the register can hold integers.  Otherwise
 223    it will be a MODE_FLOAT or a MODE_CC mode, whichever is valid for the
 224    register.  */
 225
 226 extern enum machine_mode reg_raw_mode[FIRST_PSEUDO_REGISTER];
 227
 228 /* Flag set by local-alloc or global-alloc if they decide to allocate
 229    something in a call-clobbered register.  */
 230
 231 extern int caller_save_needed;
 232
 233 /* Predicate to decide whether to give a hard reg to a pseudo which
 234    is referenced REFS times and would need to be saved and restored
 235    around a call CALLS times.  */
 236
 237 #ifndef CALLER_SAVE_PROFITABLE
 238 #define CALLER_SAVE_PROFITABLE(REFS, CALLS)  (4 * (CALLS) < (REFS))
 239 #endif
 240
 241 /* On most machines a register class is likely to be spilled if it
 242    only has one register.  */
 243 #ifndef CLASS_LIKELY_SPILLED_P
 244 #define CLASS_LIKELY_SPILLED_P(CLASS) (reg_class_size[(int) (CLASS)] == 1)
 245 #endif
 246
 247 /* Select a register mode required for caller save of hard regno REGNO.  */
 248 #ifndef HARD_REGNO_CALLER_SAVE_MODE
 249 #define HARD_REGNO_CALLER_SAVE_MODE(REGNO, NREGS, MODE) \
 250   choose_hard_reg_mode (REGNO, NREGS, false)
 251 #endif
 252
 253 /* Registers that get partially clobbered by a call in a given mode.
 254    These must not be call used registers.  */
 255 #ifndef HARD_REGNO_CALL_PART_CLOBBERED
 256 #define HARD_REGNO_CALL_PART_CLOBBERED(REGNO, MODE) 0
 257 #endif
 258
 259 /* 1 if the corresponding class does contain register of given
 260    mode.  */
 261 extern char contains_reg_of_mode [N_REG_CLASSES] [MAX_MACHINE_MODE];
 262
 263 typedef unsigned short move_table[N_REG_CLASSES];
 264
 265 /* Maximum cost of moving from a register in one class to a register
 266    in another class.  */
 267 extern move_table *move_cost[MAX_MACHINE_MODE];
 268
 269 /* Specify number of hard registers given machine mode occupy.  */
 270 extern unsigned char hard_regno_nregs[FIRST_PSEUDO_REGISTER][MAX_MACHINE_MODE];
 271
 272 /* Similar, but here we don't have to move if the first index is a
 273    subset of the second so in that case the cost is zero.  */
 274 extern move_table *may_move_in_cost[MAX_MACHINE_MODE];
 275
 276 /* Similar, but here we don't have to move if the first index is a
 277    superset of the second so in that case the cost is zero.  */
 278 extern move_table *may_move_out_cost[MAX_MACHINE_MODE];
 279
 280 /* Return an exclusive upper bound on the registers occupied by hard
 281    register (reg:MODE REGNO).  */
 282
 283 static inline unsigned int
 284 end_hard_regno (enum machine_mode mode, unsigned int regno)
 285 {
 286   return regno + hard_regno_nregs[regno][(int) mode];
 287 }
 288
 289 /* Likewise for hard register X.  */
 290
 291 #define END_HARD_REGNO(X) end_hard_regno (GET_MODE (X), REGNO (X))
 292
 293 /* Likewise for hard or pseudo register X.  */
 294
 295 #define END_REGNO(X) (HARD_REGISTER_P (X) ? END_HARD_REGNO (X) : REGNO (X) + 1)
 296
 297 /* Add to REGS all the registers required to store a value of mode MODE
 298    in register REGNO.  */
 299
 300 static inline void
 301 add_to_hard_reg_set (HARD_REG_SET *regs, enum machine_mode mode,
 302                      unsigned int regno)
 303 {
 304   unsigned int end_regno;
 305
 306   end_regno = end_hard_regno (mode, regno);
 307   do
 308     SET_HARD_REG_BIT (*regs, regno);
 309   while (++regno < end_regno);
 310 }
 311
 312 /* Likewise, but remove the registers.  */
 313
 314 static inline void
 315 remove_from_hard_reg_set (HARD_REG_SET *regs, enum machine_mode mode,
 316                           unsigned int regno)
 317 {
 318   unsigned int end_regno;
 319
 320   end_regno = end_hard_regno (mode, regno);
 321   do
 322     CLEAR_HARD_REG_BIT (*regs, regno);
 323   while (++regno < end_regno);
 324 }
 325
 326 /* Return true if REGS contains the whole of (reg:MODE REGNO).  */
 327
 328 static inline bool
 329 in_hard_reg_set_p (const HARD_REG_SET regs, enum machine_mode mode,
 330                    unsigned int regno)
 331 {
 332   unsigned int end_regno;
 333
 334   if (!TEST_HARD_REG_BIT (regs, regno))
 335     return false;
 336
 337   end_regno = end_hard_regno (mode, regno);
 338   while (++regno < end_regno)
 339     if (!TEST_HARD_REG_BIT (regs, regno))
 340       return false;
 341
 342   return true;
 343 }
 344
 345 /* Return true if (reg:MODE REGNO) includes an element of REGS.  */
 346
 347 static inline bool
 348 overlaps_hard_reg_set_p (const HARD_REG_SET regs, enum machine_mode mode,
 349                          unsigned int regno)
 350 {
 351   unsigned int end_regno;
 352
 353   if (TEST_HARD_REG_BIT (regs, regno))
 354     return true;
 355
 356   end_regno = end_hard_regno (mode, regno);
 357   while (++regno < end_regno)
 358     if (TEST_HARD_REG_BIT (regs, regno))
 359       return true;
 360
 361   return false;
 362 }
 363
 364 #endif /* GCC_REGS_H */