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 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 2, 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 COPYING.  If not, write to the Free
  19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
  20 02111-1307, USA.  */
  21
  22
  23 #include "varray.h"
  24 #include "hard-reg-set.h"
  25 #include "basic-block.h"
  26
  27 #define REG_BYTES(R) mode_size[(int) GET_MODE (R)]
  28
  29 /* When you only have the mode of a pseudo register before it has a hard
  30    register chosen for it, this reports the size of each hard register
  31    a pseudo in such a mode would get allocated to.  A target may
  32    override this.  */
  33
  34 #ifndef REGMODE_NATURAL_SIZE
  35 #define REGMODE_NATURAL_SIZE(MODE)      UNITS_PER_WORD
  36 #endif
  37
  38 #ifndef SMALL_REGISTER_CLASSES
  39 #define SMALL_REGISTER_CLASSES 0
  40 #endif
  41
  42 /* Maximum register number used in this function, plus one.  */
  43
  44 extern int max_regno;
  45
  46 /* Register information indexed by register number */
  47 typedef struct reg_info_def
  48 {                               /* fields set by reg_scan */
  49   int first_uid;                /* UID of first insn to use (REG n) */
  50   int last_uid;                 /* UID of last insn to use (REG n) */
  51   int last_note_uid;            /* UID of last note to use (REG n) */
  52
  53                                 /* fields set by reg_scan & flow_analysis */
  54   int sets;                     /* # of times (REG n) is set */
  55
  56                                 /* fields set by flow_analysis */
  57   int refs;                     /* # of times (REG n) is used or set */
  58   int freq;                     /* # estimated frequency (REG n) is used or set */
  59   int deaths;                   /* # of times (REG n) dies */
  60   int live_length;              /* # of instructions (REG n) is live */
  61   int calls_crossed;            /* # of calls (REG n) is live across */
  62   int basic_block;              /* # of basic blocks (REG n) is used in */
  63   char changes_mode;            /* whether (SUBREG (REG n)) exists and
  64                                    is illegal.  */
  65 } reg_info;
  66
  67 extern varray_type reg_n_info;
  68
  69 extern bitmap_head subregs_of_mode;
  70
  71 /* Indexed by n, gives number of times (REG n) is used or set.  */
  72
  73 #define REG_N_REFS(N) (VARRAY_REG (reg_n_info, N)->refs)
  74
  75 /* Estimate frequency of references to register N.  */
  76
  77 #define REG_FREQ(N) (VARRAY_REG (reg_n_info, N)->freq)
  78
  79 /* The weights for each insn varries from 0 to REG_FREQ_BASE.
  80    This constant does not need to be high, as in infrequently executed
  81    regions we want to count instructions equivalently to optimize for
  82    size instead of speed.  */
  83 #define REG_FREQ_MAX 1000
  84
  85 /* Compute register frequency from the BB frequency.  When optimizing for size,
  86    or profile driven feedback is available and the function is never executed,
  87    frequency is always equivalent.  Otherwise rescale the basic block
  88    frequency.  */
  89 #define REG_FREQ_FROM_BB(bb) (optimize_size                                   \
  90                               || (flag_branch_probabilities                   \
  91                                   && !ENTRY_BLOCK_PTR->count)                 \
  92                               ? REG_FREQ_MAX                                  \
  93                               : ((bb)->frequency * REG_FREQ_MAX / BB_FREQ_MAX)\
  94                               ? ((bb)->frequency * REG_FREQ_MAX / BB_FREQ_MAX)\
  95                               : 1)
  96
  97 /* Indexed by n, gives number of times (REG n) is set.
  98    ??? both regscan and flow allocate space for this.  We should settle
  99    on just copy.  */
 100
 101 #define REG_N_SETS(N) (VARRAY_REG (reg_n_info, N)->sets)
 102
 103 /* Indexed by N, gives number of insns in which register N dies.
 104    Note that if register N is live around loops, it can die
 105    in transitions between basic blocks, and that is not counted here.
 106    So this is only a reliable indicator of how many regions of life there are
 107    for registers that are contained in one basic block.  */
 108
 109 #define REG_N_DEATHS(N) (VARRAY_REG (reg_n_info, N)->deaths)
 110
 111 /* Get the number of consecutive words required to hold pseudo-reg N.  */
 112
 113 #define PSEUDO_REGNO_SIZE(N) \
 114   ((GET_MODE_SIZE (PSEUDO_REGNO_MODE (N)) + UNITS_PER_WORD - 1)         \
 115    / UNITS_PER_WORD)
 116
 117 /* Get the number of bytes required to hold pseudo-reg N.  */
 118
 119 #define PSEUDO_REGNO_BYTES(N) \
 120   GET_MODE_SIZE (PSEUDO_REGNO_MODE (N))
 121
 122 /* Get the machine mode of pseudo-reg N.  */
 123
 124 #define PSEUDO_REGNO_MODE(N) GET_MODE (regno_reg_rtx[N])
 125
 126 /* Indexed by N, gives number of CALL_INSNS across which (REG n) is live.  */
 127
 128 #define REG_N_CALLS_CROSSED(N) (VARRAY_REG (reg_n_info, N)->calls_crossed)
 129
 130 /* Total number of instructions at which (REG n) is live.
 131    The larger this is, the less priority (REG n) gets for
 132    allocation in a hard register (in global-alloc).
 133    This is set in flow.c and remains valid for the rest of the compilation
 134    of the function; it is used to control register allocation.
 135
 136    local-alloc.c may alter this number to change the priority.
 137
 138    Negative values are special.
 139    -1 is used to mark a pseudo reg which has a constant or memory equivalent
 140    and is used infrequently enough that it should not get a hard register.
 141    -2 is used to mark a pseudo reg for a parameter, when a frame pointer
 142    is not required.  global.c makes an allocno for this but does
 143    not try to assign a hard register to it.  */
 144
 145 #define REG_LIVE_LENGTH(N) (VARRAY_REG (reg_n_info, N)->live_length)
 146
 147 /* Vector of substitutions of register numbers,
 148    used to map pseudo regs into hardware regs.
 149
 150    This can't be folded into reg_n_info without changing all of the
 151    machine dependent directories, since the reload functions
 152    in the machine dependent files access it.  */
 153
 154 extern short *reg_renumber;
 155
 156 /* Vector indexed by hardware reg
 157    saying whether that reg is ever used.  */
 158
 159 extern char regs_ever_live[FIRST_PSEUDO_REGISTER];
 160
 161 /* Vector indexed by hardware reg giving its name.  */
 162
 163 extern const char * reg_names[FIRST_PSEUDO_REGISTER];
 164
 165 /* For each hard register, the widest mode object that it can contain.
 166    This will be a MODE_INT mode if the register can hold integers.  Otherwise
 167    it will be a MODE_FLOAT or a MODE_CC mode, whichever is valid for the
 168    register.  */
 169
 170 extern enum machine_mode reg_raw_mode[FIRST_PSEUDO_REGISTER];
 171
 172 /* Vector indexed by regno; gives uid of first insn using that reg.
 173    This is computed by reg_scan for use by cse and loop.
 174    It is sometimes adjusted for subsequent changes during loop,
 175    but not adjusted by cse even if cse invalidates it.  */
 176
 177 #define REGNO_FIRST_UID(N) (VARRAY_REG (reg_n_info, N)->first_uid)
 178
 179 /* Vector indexed by regno; gives uid of last insn using that reg.
 180    This is computed by reg_scan for use by cse and loop.
 181    It is sometimes adjusted for subsequent changes during loop,
 182    but not adjusted by cse even if cse invalidates it.
 183    This is harmless since cse won't scan through a loop end.  */
 184
 185 #define REGNO_LAST_UID(N) (VARRAY_REG (reg_n_info, N)->last_uid)
 186
 187 /* Similar, but includes insns that mention the reg in their notes.  */
 188
 189 #define REGNO_LAST_NOTE_UID(N) (VARRAY_REG (reg_n_info, N)->last_note_uid)
 190
 191 /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
 192    that have to go in the same hard reg.  */
 193 extern rtx regs_may_share;
 194
 195 /* Flag set by local-alloc or global-alloc if they decide to allocate
 196    something in a call-clobbered register.  */
 197
 198 extern int caller_save_needed;
 199
 200 /* Predicate to decide whether to give a hard reg to a pseudo which
 201    is referenced REFS times and would need to be saved and restored
 202    around a call CALLS times.  */
 203
 204 #ifndef CALLER_SAVE_PROFITABLE
 205 #define CALLER_SAVE_PROFITABLE(REFS, CALLS)  (4 * (CALLS) < (REFS))
 206 #endif
 207
 208 /* On most machines a register class is likely to be spilled if it
 209    only has one register.  */
 210 #ifndef CLASS_LIKELY_SPILLED_P
 211 #define CLASS_LIKELY_SPILLED_P(CLASS) (reg_class_size[(int) (CLASS)] == 1)
 212 #endif
 213
 214 /* Select a register mode required for caller save of hard regno REGNO.  */
 215 #ifndef HARD_REGNO_CALLER_SAVE_MODE
 216 #define HARD_REGNO_CALLER_SAVE_MODE(REGNO, NREGS, MODE) \
 217   choose_hard_reg_mode (REGNO, NREGS)
 218 #endif
 219
 220 /* Registers that get partially clobbered by a call in a given mode.
 221    These must not be call used registers.  */
 222 #ifndef HARD_REGNO_CALL_PART_CLOBBERED
 223 #define HARD_REGNO_CALL_PART_CLOBBERED(REGNO, MODE) 0
 224 #endif
 225
 226 /* Allocate reg_n_info tables */
 227 extern void allocate_reg_info PARAMS ((size_t, int, int));