gcc/regs.h

   1 /* Define per-register tables for data flow info and register allocation.
   2    Copyright (C) 1987, 1993, 1994, 1995, 1997 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
  23 #define REG_BYTES(R) mode_size[(int) GET_MODE (R)]
  24
  25 /* Get the number of consecutive hard regs required to hold the REG rtx R.
  26    When something may be an explicit hard reg, REG_SIZE is the only
  27    valid way to get this value.  You cannot get it from the regno.  */
  28
  29 #define REG_SIZE(R) \
  30   ((mode_size[(int) GET_MODE (R)] + UNITS_PER_WORD - 1) / UNITS_PER_WORD)
  31
  32 #ifndef SMALL_REGISTER_CLASSES
  33 #define SMALL_REGISTER_CLASSES 0
  34 #endif
  35
  36 /* Maximum register number used in this function, plus one.  */
  37
  38 extern int max_regno;
  39
  40 /* Maximum number of SCRATCH rtx's in each block of this function.  */
  41
  42 extern int max_scratch;
  43
  44 /* Register information indexed by register number */
  45 typedef struct reg_info_def {
  46                                 /* fields set by reg_scan */
  47   int first_uid;                /* UID of first insn to use (REG n) */
  48   int last_uid;                 /* UID of last insn to use (REG n) */
  49   int last_note_uid;            /* UID of last note to use (REG n) */
  50
  51                                 /* fields set by both reg_scan and flow_analysis */
  52   int sets;                     /* # of times (REG n) is set */
  53
  54                                 /* fields set by flow_analysis */
  55   int refs;                     /* # of times (REG n) is used or set */
  56   int deaths;                   /* # of times (REG n) dies */
  57   int live_length;              /* # of instructions (REG n) is live */
  58   int calls_crossed;            /* # of calls (REG n) is live across */
  59   int basic_block;              /* # of basic blocks (REG n) is used in */
  60   char changes_size;            /* whether (SUBREG (REG n)) changes size */
  61 } reg_info;
  62
  63 extern reg_info *reg_n_info;
  64
  65 /* Indexed by n, gives number of times (REG n) is used or set.
  66    References within loops may be counted more times.  */
  67
  68 #define REG_N_REFS(N) (reg_n_info[(N)].refs)
  69
  70 /* Indexed by n, gives number of times (REG n) is set.
  71    ??? both regscan and flow allocate space for this.  We should settle
  72    on just copy.  */
  73
  74 #define REG_N_SETS(N) (reg_n_info[(N)].sets)
  75
  76 /* Indexed by N, gives number of insns in which register N dies.
  77    Note that if register N is live around loops, it can die
  78    in transitions between basic blocks, and that is not counted here.
  79    So this is only a reliable indicator of how many regions of life there are
  80    for registers that are contained in one basic block.  */
  81
  82 #define REG_N_DEATHS(N) (reg_n_info[(N)].deaths)
  83
  84 /* Indexed by N; says whether a pseudo register N was ever used
  85    within a SUBREG that changes the size of the reg.  Some machines prohibit
  86    such objects to be in certain (usually floating-point) registers.  */
  87
  88 #define REG_CHANGES_SIZE(N) (reg_n_info[(N)].changes_size)
  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) (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) (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 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) (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) (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) (reg_n_info[(N)].last_note_uid)
 169
 170 /* This is reset to LAST_VIRTUAL_REGISTER + 1 at the start of each function.
 171    After rtl generation, it is 1 plus the largest register number used.  */
 172
 173 extern int reg_rtx_no;
 174
 175 /* Vector indexed by regno; contains 1 for a register is considered a pointer.
 176    Reloading, etc. will use a pointer register rather than a non-pointer
 177    as the base register in an address, when there is a choice of two regs.  */
 178
 179 extern char *regno_pointer_flag;
 180 #define REGNO_POINTER_FLAG(REGNO) regno_pointer_flag[REGNO]
 181 extern int regno_pointer_flag_length;
 182
 183 /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
 184    that have to go in the same hard reg.  */
 185 extern rtx regs_may_share;
 186
 187 /* Vector mapping pseudo regno into the REG rtx for that register.
 188    This is computed by reg_scan.  */
 189
 190 extern rtx *regno_reg_rtx;
 191
 192 /* Flag set by local-alloc or global-alloc if they decide to allocate
 193    something in a call-clobbered register.  */
 194
 195 extern int caller_save_needed;
 196
 197 /* Predicate to decide whether to give a hard reg to a pseudo which
 198    is referenced REFS times and would need to be saved and restored
 199    around a call CALLS times.  */
 200
 201 #ifndef CALLER_SAVE_PROFITABLE
 202 #define CALLER_SAVE_PROFITABLE(REFS, CALLS)  (4 * (CALLS) < (REFS))
 203 #endif
 204
 205 /* On most machines a register class is likely to be spilled if it
 206    only has one register.  */
 207 #ifndef CLASS_LIKELY_SPILLED_P
 208 #define CLASS_LIKELY_SPILLED_P(CLASS) (reg_class_size[(int) (CLASS)] == 1)
 209 #endif
 210
 211 /* Allocated in local_alloc.  */
 212
 213 /* A list of SCRATCH rtl allocated by local-alloc.  */
 214 extern rtx *scratch_list;
 215 /* The basic block in which each SCRATCH is used.  */
 216 extern int *scratch_block;
 217 /* The length of the arrays pointed to by scratch_block and scratch_list.  */
 218 extern int scratch_list_length;
 219
 220 /* Allocate reg_n_info tables */
 221 extern void allocate_reg_info PROTO((int, int, int));