gcc/regs.h

   1 /* Define per-register tables for data flow info and register allocation.
   2    Copyright (C) 1987, 1993, 1994, 1995, 1997, 1998 Free Software Foundation, Inc.
   3
   4 This file is part of GNU CC.
   5
   6 GNU CC is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU CC is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 GNU General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU CC; see the file COPYING.  If not, write to
  18 the Free Software Foundation, 59 Temple Place - Suite 330,
  19 Boston, MA 02111-1307, USA.  */
  20
  21
  22 #include "varray.h"
  23
  24 #define REG_BYTES(R) mode_size[(int) GET_MODE (R)]
  25
  26 /* Get the number of consecutive hard regs required to hold the REG rtx R.
  27    When something may be an explicit hard reg, REG_SIZE is the only
  28    valid way to get this value.  You cannot get it from the regno.  */
  29
  30 #define REG_SIZE(R) \
  31   ((mode_size[(int) GET_MODE (R)] + UNITS_PER_WORD - 1) / UNITS_PER_WORD)
  32
  33 #ifndef SMALL_REGISTER_CLASSES
  34 #define SMALL_REGISTER_CLASSES 0
  35 #endif
  36
  37 /* Maximum register number used in this function, plus one.  */
  38
  39 extern int max_regno;
  40
  41 /* Register information indexed by register number */
  42 typedef struct reg_info_def {
  43                                 /* fields set by reg_scan */
  44   int first_uid;                /* UID of first insn to use (REG n) */
  45   int last_uid;                 /* UID of last insn to use (REG n) */
  46   int last_note_uid;            /* UID of last note to use (REG n) */
  47
  48                                 /* fields set by both reg_scan and flow_analysis */
  49   int sets;                     /* # of times (REG n) is set */
  50
  51                                 /* fields set by flow_analysis */
  52   int refs;                     /* # of times (REG n) is used or set */
  53   int deaths;                   /* # of times (REG n) dies */
  54   int live_length;              /* # of instructions (REG n) is live */
  55   int calls_crossed;            /* # of calls (REG n) is live across */
  56   int basic_block;              /* # of basic blocks (REG n) is used in */
  57   char changes_size;            /* whether (SUBREG (REG n)) changes size */
  58 } reg_info;
  59
  60 extern varray_type reg_n_info;
  61
  62 extern unsigned int reg_n_max;
  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 size of the reg.  Some machines prohibit
  85    such objects to be in certain (usually floating-point) registers.  */
  86
  87 #define REG_CHANGES_SIZE(N) (VARRAY_REG (reg_n_info, N)->changes_size)
  88
  89 /* Get the number of consecutive words required to hold pseudo-reg N.  */
  90
  91 #define PSEUDO_REGNO_SIZE(N) \
  92   ((GET_MODE_SIZE (PSEUDO_REGNO_MODE (N)) + UNITS_PER_WORD - 1)         \
  93    / UNITS_PER_WORD)
  94
  95 /* Get the number of bytes required to hold pseudo-reg N.  */
  96
  97 #define PSEUDO_REGNO_BYTES(N) \
  98   GET_MODE_SIZE (PSEUDO_REGNO_MODE (N))
  99
 100 /* Get the machine mode of pseudo-reg N.  */
 101
 102 #define PSEUDO_REGNO_MODE(N) GET_MODE (regno_reg_rtx[N])
 103
 104 /* Indexed by N, gives number of CALL_INSNS across which (REG n) is live.  */
 105
 106 #define REG_N_CALLS_CROSSED(N) (VARRAY_REG (reg_n_info, N)->calls_crossed)
 107
 108 /* Total number of instructions at which (REG n) is live.
 109    The larger this is, the less priority (REG n) gets for
 110    allocation in a hard register (in global-alloc).
 111    This is set in flow.c and remains valid for the rest of the compilation
 112    of the function; it is used to control register allocation.
 113
 114    local-alloc.c may alter this number to change the priority.
 115
 116    Negative values are special.
 117    -1 is used to mark a pseudo reg which has a constant or memory equivalent
 118    and is used infrequently enough that it should not get a hard register.
 119    -2 is used to mark a pseudo reg for a parameter, when a frame pointer
 120    is not required.  global.c makes an allocno for this but does
 121    not try to assign a hard register to it.  */
 122
 123 #define REG_LIVE_LENGTH(N) (VARRAY_REG (reg_n_info, N)->live_length)
 124
 125 /* Vector of substitutions of register numbers,
 126    used to map pseudo regs into hardware regs.
 127
 128    This can't be folded into reg_n_info without changing all of the
 129    machine dependent directories, since the reload functions
 130    in the machine dependent files access it.  */
 131
 132 extern short *reg_renumber;
 133
 134 /* Vector indexed by hardware reg
 135    saying whether that reg is ever used.  */
 136
 137 extern char regs_ever_live[FIRST_PSEUDO_REGISTER];
 138
 139 /* Vector indexed by hardware reg giving its name.  */
 140
 141 extern char *reg_names[FIRST_PSEUDO_REGISTER];
 142
 143 /* For each hard register, the widest mode object that it can contain.
 144    This will be a MODE_INT mode if the register can hold integers.  Otherwise
 145    it will be a MODE_FLOAT or a MODE_CC mode, whichever is valid for the
 146    register.  */
 147
 148 extern enum machine_mode reg_raw_mode[FIRST_PSEUDO_REGISTER];
 149
 150 /* Vector indexed by regno; gives uid of first insn using that reg.
 151    This is computed by reg_scan for use by cse and loop.
 152    It is sometimes adjusted for subsequent changes during loop,
 153    but not adjusted by cse even if cse invalidates it.  */
 154
 155 #define REGNO_FIRST_UID(N) (VARRAY_REG (reg_n_info, N)->first_uid)
 156
 157 /* Vector indexed by regno; gives uid of last insn using that reg.
 158    This is computed by reg_scan for use by cse and loop.
 159    It is sometimes adjusted for subsequent changes during loop,
 160    but not adjusted by cse even if cse invalidates it.
 161    This is harmless since cse won't scan through a loop end.  */
 162
 163 #define REGNO_LAST_UID(N) (VARRAY_REG (reg_n_info, N)->last_uid)
 164
 165 /* Similar, but includes insns that mention the reg in their notes.  */
 166
 167 #define REGNO_LAST_NOTE_UID(N) (VARRAY_REG (reg_n_info, N)->last_note_uid)
 168
 169 /* This is reset to LAST_VIRTUAL_REGISTER + 1 at the start of each function.
 170    After rtl generation, it is 1 plus the largest register number used.  */
 171
 172 extern int reg_rtx_no;
 173
 174 /* Vector indexed by regno; contains 1 for a register is considered a pointer.
 175    Reloading, etc. will use a pointer register rather than a non-pointer
 176    as the base register in an address, when there is a choice of two regs.  */
 177
 178 extern char *regno_pointer_flag;
 179 #define REGNO_POINTER_FLAG(REGNO) regno_pointer_flag[REGNO]
 180 extern int regno_pointer_flag_length;
 181
 182 /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
 183    that have to go in the same hard reg.  */
 184 extern rtx regs_may_share;
 185
 186 /* Vector mapping pseudo regno into the REG rtx for that register.
 187    This is computed by reg_scan.  */
 188
 189 extern rtx *regno_reg_rtx;
 190
 191 /* Flag set by local-alloc or global-alloc if they decide to allocate
 192    something in a call-clobbered register.  */
 193
 194 extern int caller_save_needed;
 195
 196 /* Predicate to decide whether to give a hard reg to a pseudo which
 197    is referenced REFS times and would need to be saved and restored
 198    around a call CALLS times.  */
 199
 200 #ifndef CALLER_SAVE_PROFITABLE
 201 #define CALLER_SAVE_PROFITABLE(REFS, CALLS)  (4 * (CALLS) < (REFS))
 202 #endif
 203
 204 /* On most machines a register class is likely to be spilled if it
 205    only has one register.  */
 206 #ifndef CLASS_LIKELY_SPILLED_P
 207 #define CLASS_LIKELY_SPILLED_P(CLASS) (reg_class_size[(int) (CLASS)] == 1)
 208 #endif
 209
 210 /* Select a register mode required for caller save of hard regno REGNO.  */
 211 #ifndef HARD_REGNO_CALLER_SAVE_MODE
 212 #define HARD_REGNO_CALLER_SAVE_MODE(REGNO, NREGS) \
 213   choose_hard_reg_mode (REGNO, NREGS)
 214 #endif
 215
 216 /* Registers that get partially clobbered by a call in a given mode.
 217    These must not be call used registers.  */
 218 #ifndef HARD_REGNO_CALL_PART_CLOBBERED
 219 #define HARD_REGNO_CALL_PART_CLOBBERED(REGNO, MODE) 0
 220 #endif
 221
 222 /* Allocate reg_n_info tables */
 223 extern void allocate_reg_info PROTO((size_t, int, int));