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 throw_calls_crossed;      /* # of calls that may throw (REG n) is live across */
 119   int basic_block;              /* # of basic blocks (REG n) is used in */
 120 };
 121
 122 extern struct reg_info_t *reg_info_p;
 123
 124 /* The number allocated elements of reg_info_p.  */
 125 extern size_t reg_info_p_size;
 126
 127 /* Estimate frequency of references to register N.  */
 128
 129 #define REG_FREQ(N) (reg_info_p[N].freq)
 130
 131 /* The weights for each insn varries from 0 to REG_FREQ_BASE.
 132    This constant does not need to be high, as in infrequently executed
 133    regions we want to count instructions equivalently to optimize for
 134    size instead of speed.  */
 135 #define REG_FREQ_MAX 1000
 136
 137 /* Compute register frequency from the BB frequency.  When optimizing for size,
 138    or profile driven feedback is available and the function is never executed,
 139    frequency is always equivalent.  Otherwise rescale the basic block
 140    frequency.  */
 141 #define REG_FREQ_FROM_BB(bb) (optimize_size                                   \
 142                               || (flag_branch_probabilities                   \
 143                                   && !ENTRY_BLOCK_PTR->count)                 \
 144                               ? REG_FREQ_MAX                                  \
 145                               : ((bb)->frequency * REG_FREQ_MAX / BB_FREQ_MAX)\
 146                               ? ((bb)->frequency * REG_FREQ_MAX / BB_FREQ_MAX)\
 147                               : 1)
 148
 149 /* Indexed by N, gives number of insns in which register N dies.
 150    Note that if register N is live around loops, it can die
 151    in transitions between basic blocks, and that is not counted here.
 152    So this is only a reliable indicator of how many regions of life there are
 153    for registers that are contained in one basic block.  */
 154
 155 #define REG_N_DEATHS(N) (reg_info_p[N].deaths)
 156
 157 /* Get the number of consecutive words required to hold pseudo-reg N.  */
 158
 159 #define PSEUDO_REGNO_SIZE(N) \
 160   ((GET_MODE_SIZE (PSEUDO_REGNO_MODE (N)) + UNITS_PER_WORD - 1)         \
 161    / UNITS_PER_WORD)
 162
 163 /* Get the number of bytes required to hold pseudo-reg N.  */
 164
 165 #define PSEUDO_REGNO_BYTES(N) \
 166   GET_MODE_SIZE (PSEUDO_REGNO_MODE (N))
 167
 168 /* Get the machine mode of pseudo-reg N.  */
 169
 170 #define PSEUDO_REGNO_MODE(N) GET_MODE (regno_reg_rtx[N])
 171
 172 /* Indexed by N, gives number of CALL_INSNS across which (REG n) is live.  */
 173
 174 #define REG_N_CALLS_CROSSED(N)  (reg_info_p[N].calls_crossed)
 175
 176 /* Indexed by N, gives number of CALL_INSNS that may throw, across which
 177    (REG n) is live.  */
 178
 179 #define REG_N_THROWING_CALLS_CROSSED(N) (reg_info_p[N].throw_calls_crossed)
 180
 181 /* Total number of instructions at which (REG n) is live.  The larger
 182    this is, the less priority (REG n) gets for allocation in a hard
 183    register (in global-alloc).  This is set in df-problems.c whenever
 184    register info is requested and remains valid for the rest of the
 185    compilation of the function; it is used to control register
 186    allocation.
 187
 188    local-alloc.c may alter this number to change the priority.
 189
 190    Negative values are special.
 191    -1 is used to mark a pseudo reg which has a constant or memory equivalent
 192    and is used infrequently enough that it should not get a hard register.
 193    -2 is used to mark a pseudo reg for a parameter, when a frame pointer
 194    is not required.  global.c makes an allocno for this but does
 195    not try to assign a hard register to it.  */
 196
 197 #define REG_LIVE_LENGTH(N)  (reg_info_p[N].live_length)
 198
 199 /* Indexed by n, gives number of basic block that  (REG n) is used in.
 200    If the value is REG_BLOCK_GLOBAL (-1),
 201    it means (REG n) is used in more than one basic block.
 202    REG_BLOCK_UNKNOWN (0) means it hasn't been seen yet so we don't know.
 203    This information remains valid for the rest of the compilation
 204    of the current function; it is used to control register allocation.  */
 205
 206 #define REG_BLOCK_UNKNOWN 0
 207 #define REG_BLOCK_GLOBAL -1
 208
 209 #define REG_BASIC_BLOCK(N) (reg_info_p[N].basic_block)
 210
 211 /* Vector of substitutions of register numbers,
 212    used to map pseudo regs into hardware regs.
 213
 214    This can't be folded into reg_n_info without changing all of the
 215    machine dependent directories, since the reload functions
 216    in the machine dependent files access it.  */
 217
 218 extern short *reg_renumber;
 219
 220 /* Vector indexed by machine mode saying whether there are regs of that mode.  */
 221
 222 extern bool have_regs_of_mode [MAX_MACHINE_MODE];
 223
 224 /* For each hard register, the widest mode object that it can contain.
 225    This will be a MODE_INT mode if the register can hold integers.  Otherwise
 226    it will be a MODE_FLOAT or a MODE_CC mode, whichever is valid for the
 227    register.  */
 228
 229 extern enum machine_mode reg_raw_mode[FIRST_PSEUDO_REGISTER];
 230
 231 /* Flag set by local-alloc or global-alloc if they decide to allocate
 232    something in a call-clobbered register.  */
 233
 234 extern int caller_save_needed;
 235
 236 /* Predicate to decide whether to give a hard reg to a pseudo which
 237    is referenced REFS times and would need to be saved and restored
 238    around a call CALLS times.  */
 239
 240 #ifndef CALLER_SAVE_PROFITABLE
 241 #define CALLER_SAVE_PROFITABLE(REFS, CALLS)  (4 * (CALLS) < (REFS))
 242 #endif
 243
 244 /* On most machines a register class is likely to be spilled if it
 245    only has one register.  */
 246 #ifndef CLASS_LIKELY_SPILLED_P
 247 #define CLASS_LIKELY_SPILLED_P(CLASS) (reg_class_size[(int) (CLASS)] == 1)
 248 #endif
 249
 250 /* Select a register mode required for caller save of hard regno REGNO.  */
 251 #ifndef HARD_REGNO_CALLER_SAVE_MODE
 252 #define HARD_REGNO_CALLER_SAVE_MODE(REGNO, NREGS, MODE) \
 253   choose_hard_reg_mode (REGNO, NREGS, false)
 254 #endif
 255
 256 /* Registers that get partially clobbered by a call in a given mode.
 257    These must not be call used registers.  */
 258 #ifndef HARD_REGNO_CALL_PART_CLOBBERED
 259 #define HARD_REGNO_CALL_PART_CLOBBERED(REGNO, MODE) 0
 260 #endif
 261
 262 /* Specify number of hard registers given machine mode occupy.  */
 263 extern unsigned char hard_regno_nregs[FIRST_PSEUDO_REGISTER][MAX_MACHINE_MODE];
 264
 265 /* Return an exclusive upper bound on the registers occupied by hard
 266    register (reg:MODE REGNO).  */
 267
 268 static inline unsigned int
 269 end_hard_regno (enum machine_mode mode, unsigned int regno)
 270 {
 271   return regno + hard_regno_nregs[regno][(int) mode];
 272 }
 273
 274 /* Likewise for hard register X.  */
 275
 276 #define END_HARD_REGNO(X) end_hard_regno (GET_MODE (X), REGNO (X))
 277
 278 /* Likewise for hard or pseudo register X.  */
 279
 280 #define END_REGNO(X) (HARD_REGISTER_P (X) ? END_HARD_REGNO (X) : REGNO (X) + 1)
 281
 282 /* Add to REGS all the registers required to store a value of mode MODE
 283    in register REGNO.  */
 284
 285 static inline void
 286 add_to_hard_reg_set (HARD_REG_SET *regs, enum machine_mode mode,
 287                      unsigned int regno)
 288 {
 289   unsigned int end_regno;
 290
 291   end_regno = end_hard_regno (mode, regno);
 292   do
 293     SET_HARD_REG_BIT (*regs, regno);
 294   while (++regno < end_regno);
 295 }
 296
 297 /* Likewise, but remove the registers.  */
 298
 299 static inline void
 300 remove_from_hard_reg_set (HARD_REG_SET *regs, enum machine_mode mode,
 301                           unsigned int regno)
 302 {
 303   unsigned int end_regno;
 304
 305   end_regno = end_hard_regno (mode, regno);
 306   do
 307     CLEAR_HARD_REG_BIT (*regs, regno);
 308   while (++regno < end_regno);
 309 }
 310
 311 /* Return true if REGS contains the whole of (reg:MODE REGNO).  */
 312
 313 static inline bool
 314 in_hard_reg_set_p (const HARD_REG_SET regs, enum machine_mode mode,
 315                    unsigned int regno)
 316 {
 317   unsigned int end_regno;
 318
 319   if (!TEST_HARD_REG_BIT (regs, regno))
 320     return false;
 321
 322   end_regno = end_hard_regno (mode, regno);
 323   while (++regno < end_regno)
 324     if (!TEST_HARD_REG_BIT (regs, regno))
 325       return false;
 326
 327   return true;
 328 }
 329
 330 /* Return true if (reg:MODE REGNO) includes an element of REGS.  */
 331
 332 static inline bool
 333 overlaps_hard_reg_set_p (const HARD_REG_SET regs, enum machine_mode mode,
 334                          unsigned int regno)
 335 {
 336   unsigned int end_regno;
 337
 338   if (TEST_HARD_REG_BIT (regs, regno))
 339     return true;
 340
 341   end_regno = end_hard_regno (mode, regno);
 342   while (++regno < end_regno)
 343     if (TEST_HARD_REG_BIT (regs, regno))
 344       return true;
 345
 346   return false;
 347 }
 348
 349 #endif /* GCC_REGS_H */