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