gcc/regs.h

   1 /* Define per-register tables for data flow info and register allocation.
   2    Copyright (C) 1987, 1993, 1994, 1995 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 /* Maximum register number used in this function, plus one.  */
  33
  34 extern int max_regno;
  35
  36 /* Maximum number of SCRATCH rtx's in each block of this function.  */
  37
  38 extern int max_scratch;
  39
  40 /* Indexed by n, gives number of times (REG n) is used or set.
  41    References within loops may be counted more times.  */
  42
  43 extern int *reg_n_refs;
  44
  45 /* Indexed by n, gives number of times (REG n) is set.  */
  46
  47 extern short *reg_n_sets;
  48
  49 /* Indexed by N, gives number of insns in which register N dies.
  50    Note that if register N is live around loops, it can die
  51    in transitions between basic blocks, and that is not counted here.
  52    So this is only a reliable indicator of how many regions of life there are
  53    for registers that are contained in one basic block.  */
  54
  55 extern short *reg_n_deaths;
  56
  57 /* Indexed by N; says whether a pseudo register N was ever used
  58    within a SUBREG that changes the size of the reg.  Some machines prohibit
  59    such objects to be in certain (usually floating-point) registers.  */
  60
  61 extern char *reg_changes_size;
  62
  63 /* Get the number of consecutive words required to hold pseudo-reg N.  */
  64
  65 #define PSEUDO_REGNO_SIZE(N) \
  66   ((GET_MODE_SIZE (PSEUDO_REGNO_MODE (N)) + UNITS_PER_WORD - 1)         \
  67    / UNITS_PER_WORD)
  68
  69 /* Get the number of bytes required to hold pseudo-reg N.  */
  70
  71 #define PSEUDO_REGNO_BYTES(N) \
  72   GET_MODE_SIZE (PSEUDO_REGNO_MODE (N))
  73
  74 /* Get the machine mode of pseudo-reg N.  */
  75
  76 #define PSEUDO_REGNO_MODE(N) GET_MODE (regno_reg_rtx[N])
  77
  78 /* Indexed by N, gives number of CALL_INSNS across which (REG n) is live.  */
  79
  80 extern int *reg_n_calls_crossed;
  81
  82 /* Total number of instructions at which (REG n) is live.
  83    The larger this is, the less priority (REG n) gets for
  84    allocation in a hard register (in global-alloc).
  85    This is set in flow.c and remains valid for the rest of the compilation
  86    of the function; it is used to control register allocation.
  87
  88    local-alloc.c may alter this number to change the priority.
  89
  90    Negative values are special.
  91    -1 is used to mark a pseudo reg which has a constant or memory equivalent
  92    and is used infrequently enough that it should not get a hard register.
  93    -2 is used to mark a pseudo reg for a parameter, when a frame pointer
  94    is not required.  global.c makes an allocno for this but does
  95    not try to assign a hard register to it.  */
  96
  97 extern int *reg_live_length;
  98
  99 /* Vector of substitutions of register numbers,
 100    used to map pseudo regs into hardware regs.  */
 101
 102 extern short *reg_renumber;
 103
 104 /* Vector indexed by hardware reg
 105    saying whether that reg is ever used.  */
 106
 107 extern char regs_ever_live[FIRST_PSEUDO_REGISTER];
 108
 109 /* Vector indexed by hardware reg giving its name.  */
 110
 111 extern char *reg_names[FIRST_PSEUDO_REGISTER];
 112
 113 /* For each hard register, the widest mode object that it can contain.
 114    This will be a MODE_INT mode if the register can hold integers.  Otherwise
 115    it will be a MODE_FLOAT or a MODE_CC mode, whichever is valid for the
 116    register.  */
 117
 118 extern enum machine_mode reg_raw_mode[FIRST_PSEUDO_REGISTER];
 119
 120 /* Vector indexed by regno; gives uid of first insn using that reg.
 121    This is computed by reg_scan for use by cse and loop.
 122    It is sometimes adjusted for subsequent changes during loop,
 123    but not adjusted by cse even if cse invalidates it.  */
 124
 125 extern int *regno_first_uid;
 126
 127 /* Vector indexed by regno; gives uid of last insn using that reg.
 128    This is computed by reg_scan for use by cse and loop.
 129    It is sometimes adjusted for subsequent changes during loop,
 130    but not adjusted by cse even if cse invalidates it.
 131    This is harmless since cse won't scan through a loop end.  */
 132
 133 extern int *regno_last_uid;
 134
 135 /* Similar, but includes insns that mention the reg in their notes.  */
 136
 137 extern int *regno_last_note_uid;
 138
 139 /* This is reset to LAST_VIRTUAL_REGISTER + 1 at the start of each function.
 140    After rtl generation, it is 1 plus the largest register number used.  */
 141
 142 extern int reg_rtx_no;
 143
 144 /* Vector indexed by regno; contains 1 for a register is considered a pointer.
 145    Reloading, etc. will use a pointer register rather than a non-pointer
 146    as the base register in an address, when there is a choice of two regs.  */
 147
 148 extern char *regno_pointer_flag;
 149 #define REGNO_POINTER_FLAG(REGNO) regno_pointer_flag[REGNO]
 150 extern int regno_pointer_flag_length;
 151
 152 /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
 153    that have to go in the same hard reg.  */
 154 extern rtx regs_may_share;
 155
 156 /* Vector mapping pseudo regno into the REG rtx for that register.
 157    This is computed by reg_scan.  */
 158
 159 extern rtx *regno_reg_rtx;
 160
 161 /* Flag set by local-alloc or global-alloc if they decide to allocate
 162    something in a call-clobbered register.  */
 163
 164 extern int caller_save_needed;
 165
 166 /* Predicate to decide whether to give a hard reg to a pseudo which
 167    is referenced REFS times and would need to be saved and restored
 168    around a call CALLS times.  */
 169
 170 #ifndef CALLER_SAVE_PROFITABLE
 171 #define CALLER_SAVE_PROFITABLE(REFS, CALLS)  (4 * (CALLS) < (REFS))
 172 #endif
 173
 174 /* On most machines a register class is likely to be spilled if it
 175    only has one register.  */
 176 #ifndef CLASS_LIKELY_SPILLED_P
 177 #define CLASS_LIKELY_SPILLED_P(CLASS) (reg_class_size[(int) (CLASS)] == 1)
 178 #endif
 179
 180 /* Allocated in local_alloc.  */
 181
 182 /* A list of SCRATCH rtl allocated by local-alloc.  */
 183 extern rtx *scratch_list;
 184 /* The basic block in which each SCRATCH is used.  */
 185 extern int *scratch_block;
 186 /* The length of the arrays pointed to by scratch_block and scratch_list.  */
 187 extern int scratch_list_length;