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 GNU CC.
   6
   7 GNU CC is free software; you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 2, or (at your option)
  10 any later version.
  11
  12 GNU CC is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GNU CC; see the file COPYING.  If not, write to
  19 the Free Software Foundation, 59 Temple Place - Suite 330,
  20 Boston, MA 02111-1307, USA.  */
  21
  22
  23 #include "varray.h"
  24
  25 #define REG_BYTES(R) mode_size[(int) GET_MODE (R)]
  26
  27 /* Get the number of consecutive hard regs required to hold the REG or
  28    SUBREG rtx R.
  29    When something may be an explicit hard reg, REG_SIZE is the only
  30    valid way to get this value.  You cannot get it from the regno.
  31
  32    A target may override this definition, the case where you would do
  33    this is where there are registers which are smaller than WORD_SIZE
  34    such as the SFmode registers on sparc64.  */
  35
  36 #ifndef REG_SIZE
  37 #define REG_SIZE(R) \
  38   ((mode_size[(int) GET_MODE (R)] + UNITS_PER_WORD - 1) / UNITS_PER_WORD)
  39 #endif
  40
  41 /* When you only have the mode of a pseudo register before it has a hard
  42    register chosen for it, this reports the size of each hard register
  43    a pseudo in such a mode would get allocated to.  Like REG_SIZE, a
  44    target may override this.  */
  45
  46 #ifndef REGMODE_NATURAL_SIZE
  47 #define REGMODE_NATURAL_SIZE(MODE)      UNITS_PER_WORD
  48 #endif
  49
  50 #ifndef SMALL_REGISTER_CLASSES
  51 #define SMALL_REGISTER_CLASSES 0
  52 #endif
  53
  54 /* Maximum register number used in this function, plus one.  */
  55
  56 extern int max_regno;
  57
  58 /* Register information indexed by register number */
  59 typedef struct reg_info_def
  60 {                               /* fields set by reg_scan */
  61   int first_uid;                /* UID of first insn to use (REG n) */
  62   int last_uid;                 /* UID of last insn to use (REG n) */
  63   int last_note_uid;            /* UID of last note to use (REG n) */
  64
  65                                 /* fields set by reg_scan & flow_analysis */
  66   int sets;                     /* # of times (REG n) is set */
  67
  68                                 /* fields set by flow_analysis */
  69   int refs;                     /* # of times (REG n) is used or set */
  70   int deaths;                   /* # of times (REG n) dies */
  71   int live_length;              /* # of instructions (REG n) is live */
  72   int calls_crossed;            /* # of calls (REG n) is live across */
  73   int basic_block;              /* # of basic blocks (REG n) is used in */
  74   char changes_mode;            /* whether (SUBREG (REG n)) exists and
  75                                    is illegal.  */
  76 } reg_info;
  77
  78 extern varray_type reg_n_info;
  79
  80 /* Indexed by n, gives number of times (REG n) is used or set.
  81    References within loops may be counted more times.  */
  82
  83 #define REG_N_REFS(N) (VARRAY_REG (reg_n_info, N)->refs)
  84
  85 /* Indexed by n, gives number of times (REG n) is set.
  86    ??? both regscan and flow allocate space for this.  We should settle
  87    on just copy.  */
  88
  89 #define REG_N_SETS(N) (VARRAY_REG (reg_n_info, N)->sets)
  90
  91 /* Indexed by N, gives number of insns in which register N dies.
  92    Note that if register N is live around loops, it can die
  93    in transitions between basic blocks, and that is not counted here.
  94    So this is only a reliable indicator of how many regions of life there are
  95    for registers that are contained in one basic block.  */
  96
  97 #define REG_N_DEATHS(N) (VARRAY_REG (reg_n_info, N)->deaths)
  98
  99 /* Indexed by N; says whether a pseudo register N was ever used
 100    within a SUBREG that changes the mode of the reg in some way
 101    that is illegal for a given class (usually floating-point)
 102    of registers.  */
 103
 104 #define REG_CHANGES_MODE(N) (VARRAY_REG (reg_n_info, N)->changes_mode)
 105
 106 /* Get the number of consecutive words required to hold pseudo-reg N.  */
 107
 108 #define PSEUDO_REGNO_SIZE(N) \
 109   ((GET_MODE_SIZE (PSEUDO_REGNO_MODE (N)) + UNITS_PER_WORD - 1)         \
 110    / UNITS_PER_WORD)
 111
 112 /* Get the number of bytes required to hold pseudo-reg N.  */
 113
 114 #define PSEUDO_REGNO_BYTES(N) \
 115   GET_MODE_SIZE (PSEUDO_REGNO_MODE (N))
 116
 117 /* Get the machine mode of pseudo-reg N.  */
 118
 119 #define PSEUDO_REGNO_MODE(N) GET_MODE (regno_reg_rtx[N])
 120
 121 /* Indexed by N, gives number of CALL_INSNS across which (REG n) is live.  */
 122
 123 #define REG_N_CALLS_CROSSED(N) (VARRAY_REG (reg_n_info, N)->calls_crossed)
 124
 125 /* Total number of instructions at which (REG n) is live.
 126    The larger this is, the less priority (REG n) gets for
 127    allocation in a hard register (in global-alloc).
 128    This is set in flow.c and remains valid for the rest of the compilation
 129    of the function; it is used to control register allocation.
 130
 131    local-alloc.c may alter this number to change the priority.
 132
 133    Negative values are special.
 134    -1 is used to mark a pseudo reg which has a constant or memory equivalent
 135    and is used infrequently enough that it should not get a hard register.
 136    -2 is used to mark a pseudo reg for a parameter, when a frame pointer
 137    is not required.  global.c makes an allocno for this but does
 138    not try to assign a hard register to it.  */
 139
 140 #define REG_LIVE_LENGTH(N) (VARRAY_REG (reg_n_info, N)->live_length)
 141
 142 /* Vector of substitutions of register numbers,
 143    used to map pseudo regs into hardware regs.
 144
 145    This can't be folded into reg_n_info without changing all of the
 146    machine dependent directories, since the reload functions
 147    in the machine dependent files access it.  */
 148
 149 extern short *reg_renumber;
 150
 151 /* Vector indexed by hardware reg
 152    saying whether that reg is ever used.  */
 153
 154 extern char regs_ever_live[FIRST_PSEUDO_REGISTER];
 155
 156 /* Vector indexed by hardware reg giving its name.  */
 157
 158 extern const char * reg_names[FIRST_PSEUDO_REGISTER];
 159
 160 /* For each hard register, the widest mode object that it can contain.
 161    This will be a MODE_INT mode if the register can hold integers.  Otherwise
 162    it will be a MODE_FLOAT or a MODE_CC mode, whichever is valid for the
 163    register.  */
 164
 165 extern enum machine_mode reg_raw_mode[FIRST_PSEUDO_REGISTER];
 166
 167 /* Vector indexed by regno; gives uid of first insn using that reg.
 168    This is computed by reg_scan for use by cse and loop.
 169    It is sometimes adjusted for subsequent changes during loop,
 170    but not adjusted by cse even if cse invalidates it.  */
 171
 172 #define REGNO_FIRST_UID(N) (VARRAY_REG (reg_n_info, N)->first_uid)
 173
 174 /* Vector indexed by regno; gives uid of last insn using that reg.
 175    This is computed by reg_scan for use by cse and loop.
 176    It is sometimes adjusted for subsequent changes during loop,
 177    but not adjusted by cse even if cse invalidates it.
 178    This is harmless since cse won't scan through a loop end.  */
 179
 180 #define REGNO_LAST_UID(N) (VARRAY_REG (reg_n_info, N)->last_uid)
 181
 182 /* Similar, but includes insns that mention the reg in their notes.  */
 183
 184 #define REGNO_LAST_NOTE_UID(N) (VARRAY_REG (reg_n_info, N)->last_note_uid)
 185
 186 /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
 187    that have to go in the same hard reg.  */
 188 extern rtx regs_may_share;
 189
 190 /* Flag set by local-alloc or global-alloc if they decide to allocate
 191    something in a call-clobbered register.  */
 192
 193 extern int caller_save_needed;
 194
 195 /* Predicate to decide whether to give a hard reg to a pseudo which
 196    is referenced REFS times and would need to be saved and restored
 197    around a call CALLS times.  */
 198
 199 #ifndef CALLER_SAVE_PROFITABLE
 200 #define CALLER_SAVE_PROFITABLE(REFS, CALLS)  (4 * (CALLS) < (REFS))
 201 #endif
 202
 203 /* On most machines a register class is likely to be spilled if it
 204    only has one register.  */
 205 #ifndef CLASS_LIKELY_SPILLED_P
 206 #define CLASS_LIKELY_SPILLED_P(CLASS) (reg_class_size[(int) (CLASS)] == 1)
 207 #endif
 208
 209 /* Select a register mode required for caller save of hard regno REGNO.  */
 210 #ifndef HARD_REGNO_CALLER_SAVE_MODE
 211 #define HARD_REGNO_CALLER_SAVE_MODE(REGNO, NREGS, MODE) \
 212   choose_hard_reg_mode (REGNO, NREGS)
 213 #endif
 214
 215 /* Registers that get partially clobbered by a call in a given mode.
 216    These must not be call used registers.  */
 217 #ifndef HARD_REGNO_CALL_PART_CLOBBERED
 218 #define HARD_REGNO_CALL_PART_CLOBBERED(REGNO, MODE) 0
 219 #endif
 220
 221 /* Allocate reg_n_info tables */
 222 extern void allocate_reg_info PARAMS ((size_t, int, int));