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 freq;                     /* # estimated frequency (REG n) is used or set */
  71   int deaths;                   /* # of times (REG n) dies */
  72   int live_length;              /* # of instructions (REG n) is live */
  73   int calls_crossed;            /* # of calls (REG n) is live across */
  74   int basic_block;              /* # of basic blocks (REG n) is used in */
  75   char changes_mode;            /* whether (SUBREG (REG n)) exists and
  76                                    is illegal.  */
  77 } reg_info;
  78
  79 extern varray_type reg_n_info;
  80
  81 /* Indexed by n, gives number of times (REG n) is used or set.  */
  82
  83 #define REG_N_REFS(N) (VARRAY_REG (reg_n_info, N)->refs)
  84
  85 /* Estimate frequency of references to register N.  */
  86
  87 #define REG_FREQ(N) (VARRAY_REG (reg_n_info, N)->freq)
  88
  89 /* Indexed by n, gives number of times (REG n) is set.
  90    ??? both regscan and flow allocate space for this.  We should settle
  91    on just copy.  */
  92
  93 #define REG_N_SETS(N) (VARRAY_REG (reg_n_info, N)->sets)
  94
  95 /* Indexed by N, gives number of insns in which register N dies.
  96    Note that if register N is live around loops, it can die
  97    in transitions between basic blocks, and that is not counted here.
  98    So this is only a reliable indicator of how many regions of life there are
  99    for registers that are contained in one basic block.  */
 100
 101 #define REG_N_DEATHS(N) (VARRAY_REG (reg_n_info, N)->deaths)
 102
 103 /* Indexed by N; says whether a pseudo register N was ever used
 104    within a SUBREG that changes the mode of the reg in some way
 105    that is illegal for a given class (usually floating-point)
 106    of registers.  */
 107
 108 #define REG_CHANGES_MODE(N) (VARRAY_REG (reg_n_info, N)->changes_mode)
 109
 110 /* Get the number of consecutive words required to hold pseudo-reg N.  */
 111
 112 #define PSEUDO_REGNO_SIZE(N) \
 113   ((GET_MODE_SIZE (PSEUDO_REGNO_MODE (N)) + UNITS_PER_WORD - 1)         \
 114    / UNITS_PER_WORD)
 115
 116 /* Get the number of bytes required to hold pseudo-reg N.  */
 117
 118 #define PSEUDO_REGNO_BYTES(N) \
 119   GET_MODE_SIZE (PSEUDO_REGNO_MODE (N))
 120
 121 /* Get the machine mode of pseudo-reg N.  */
 122
 123 #define PSEUDO_REGNO_MODE(N) GET_MODE (regno_reg_rtx[N])
 124
 125 /* Indexed by N, gives number of CALL_INSNS across which (REG n) is live.  */
 126
 127 #define REG_N_CALLS_CROSSED(N) (VARRAY_REG (reg_n_info, N)->calls_crossed)
 128
 129 /* Total number of instructions at which (REG n) is live.
 130    The larger this is, the less priority (REG n) gets for
 131    allocation in a hard register (in global-alloc).
 132    This is set in flow.c and remains valid for the rest of the compilation
 133    of the function; it is used to control register allocation.
 134
 135    local-alloc.c may alter this number to change the priority.
 136
 137    Negative values are special.
 138    -1 is used to mark a pseudo reg which has a constant or memory equivalent
 139    and is used infrequently enough that it should not get a hard register.
 140    -2 is used to mark a pseudo reg for a parameter, when a frame pointer
 141    is not required.  global.c makes an allocno for this but does
 142    not try to assign a hard register to it.  */
 143
 144 #define REG_LIVE_LENGTH(N) (VARRAY_REG (reg_n_info, N)->live_length)
 145
 146 /* Vector of substitutions of register numbers,
 147    used to map pseudo regs into hardware regs.
 148
 149    This can't be folded into reg_n_info without changing all of the
 150    machine dependent directories, since the reload functions
 151    in the machine dependent files access it.  */
 152
 153 extern short *reg_renumber;
 154
 155 /* Vector indexed by hardware reg
 156    saying whether that reg is ever used.  */
 157
 158 extern char regs_ever_live[FIRST_PSEUDO_REGISTER];
 159
 160 /* Vector indexed by hardware reg giving its name.  */
 161
 162 extern const char * reg_names[FIRST_PSEUDO_REGISTER];
 163
 164 /* For each hard register, the widest mode object that it can contain.
 165    This will be a MODE_INT mode if the register can hold integers.  Otherwise
 166    it will be a MODE_FLOAT or a MODE_CC mode, whichever is valid for the
 167    register.  */
 168
 169 extern enum machine_mode reg_raw_mode[FIRST_PSEUDO_REGISTER];
 170
 171 /* Vector indexed by regno; gives uid of first insn using that reg.
 172    This is computed by reg_scan for use by cse and loop.
 173    It is sometimes adjusted for subsequent changes during loop,
 174    but not adjusted by cse even if cse invalidates it.  */
 175
 176 #define REGNO_FIRST_UID(N) (VARRAY_REG (reg_n_info, N)->first_uid)
 177
 178 /* Vector indexed by regno; gives uid of last insn using that reg.
 179    This is computed by reg_scan for use by cse and loop.
 180    It is sometimes adjusted for subsequent changes during loop,
 181    but not adjusted by cse even if cse invalidates it.
 182    This is harmless since cse won't scan through a loop end.  */
 183
 184 #define REGNO_LAST_UID(N) (VARRAY_REG (reg_n_info, N)->last_uid)
 185
 186 /* Similar, but includes insns that mention the reg in their notes.  */
 187
 188 #define REGNO_LAST_NOTE_UID(N) (VARRAY_REG (reg_n_info, N)->last_note_uid)
 189
 190 /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
 191    that have to go in the same hard reg.  */
 192 extern rtx regs_may_share;
 193
 194 /* Flag set by local-alloc or global-alloc if they decide to allocate
 195    something in a call-clobbered register.  */
 196
 197 extern int caller_save_needed;
 198
 199 /* Predicate to decide whether to give a hard reg to a pseudo which
 200    is referenced REFS times and would need to be saved and restored
 201    around a call CALLS times.  */
 202
 203 #ifndef CALLER_SAVE_PROFITABLE
 204 #define CALLER_SAVE_PROFITABLE(REFS, CALLS)  (4 * (CALLS) < (REFS))
 205 #endif
 206
 207 /* On most machines a register class is likely to be spilled if it
 208    only has one register.  */
 209 #ifndef CLASS_LIKELY_SPILLED_P
 210 #define CLASS_LIKELY_SPILLED_P(CLASS) (reg_class_size[(int) (CLASS)] == 1)
 211 #endif
 212
 213 /* Select a register mode required for caller save of hard regno REGNO.  */
 214 #ifndef HARD_REGNO_CALLER_SAVE_MODE
 215 #define HARD_REGNO_CALLER_SAVE_MODE(REGNO, NREGS, MODE) \
 216   choose_hard_reg_mode (REGNO, NREGS)
 217 #endif
 218
 219 /* Registers that get partially clobbered by a call in a given mode.
 220    These must not be call used registers.  */
 221 #ifndef HARD_REGNO_CALL_PART_CLOBBERED
 222 #define HARD_REGNO_CALL_PART_CLOBBERED(REGNO, MODE) 0
 223 #endif
 224
 225 /* Allocate reg_n_info tables */
 226 extern void allocate_reg_info PARAMS ((size_t, int, int));