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