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