gcc/regs.h

   1 /* Define per-register tables for data flow info and register allocation.
   2    Copyright (C) 1987, 1993, 1994 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, 675 Mass Ave, Cambridge, MA 02139, USA.  */
  19
  20
  21
  22 #define REG_BYTES(R) mode_size[(int) GET_MODE (R)]
  23
  24 /* Get the number of consecutive hard regs required to hold the REG rtx R.
  25    When something may be an explicit hard reg, REG_SIZE is the only
  26    valid way to get this value.  You cannot get it from the regno.  */
  27
  28 #define REG_SIZE(R) \
  29   ((mode_size[(int) GET_MODE (R)] + UNITS_PER_WORD - 1) / UNITS_PER_WORD)
  30
  31 /* Maximum register number used in this function, plus one.  */
  32
  33 extern int max_regno;
  34
  35 /* Maximum number of SCRATCH rtx's in each block of this function.  */
  36
  37 extern int max_scratch;
  38
  39 /* Indexed by n, gives number of times (REG n) is used or set.
  40    References within loops may be counted more times.  */
  41
  42 extern int *reg_n_refs;
  43
  44 /* Indexed by n, gives number of times (REG n) is set.  */
  45
  46 extern short *reg_n_sets;
  47
  48 /* Indexed by N, gives number of insns in which register N dies.
  49    Note that if register N is live around loops, it can die
  50    in transitions between basic blocks, and that is not counted here.
  51    So this is only a reliable indicator of how many regions of life there are
  52    for registers that are contained in one basic block.  */
  53
  54 extern short *reg_n_deaths;
  55
  56 /* Indexed by N; says whether a psuedo register N was ever used
  57    within a SUBREG that changes the size of the reg.  Some machines prohibit
  58    such objects to be in certain (usually floating-point) registers.  */
  59
  60 extern char *reg_changes_size;
  61
  62 /* Get the number of consecutive words required to hold pseudo-reg N.  */
  63
  64 #define PSEUDO_REGNO_SIZE(N) \
  65   ((GET_MODE_SIZE (PSEUDO_REGNO_MODE (N)) + UNITS_PER_WORD - 1)         \
  66    / UNITS_PER_WORD)
  67
  68 /* Get the number of bytes required to hold pseudo-reg N.  */
  69
  70 #define PSEUDO_REGNO_BYTES(N) \
  71   GET_MODE_SIZE (PSEUDO_REGNO_MODE (N))
  72
  73 /* Get the machine mode of pseudo-reg N.  */
  74
  75 #define PSEUDO_REGNO_MODE(N) GET_MODE (regno_reg_rtx[N])
  76
  77 /* Indexed by N, gives number of CALL_INSNS across which (REG n) is live.  */
  78
  79 extern int *reg_n_calls_crossed;
  80
  81 /* Total number of instructions at which (REG n) is live.
  82    The larger this is, the less priority (REG n) gets for
  83    allocation in a hard register (in global-alloc).
  84    This is set in flow.c and remains valid for the rest of the compilation
  85    of the function; it is used to control register allocation.
  86
  87    local-alloc.c may alter this number to change the priority.
  88
  89    Negative values are special.
  90    -1 is used to mark a pseudo reg which has a constant or memory equivalent
  91    and is used infrequently enough that it should not get a hard register.
  92    -2 is used to mark a pseudo reg for a parameter, when a frame pointer
  93    is not required.  global.c makes an allocno for this but does
  94    not try to assign a hard register to it.  */
  95
  96 extern int *reg_live_length;
  97
  98 /* Vector of substitutions of register numbers,
  99    used to map pseudo regs into hardware regs.  */
 100
 101 extern short *reg_renumber;
 102
 103 /* Vector indexed by hardware reg
 104    saying whether that reg is ever used.  */
 105
 106 extern char regs_ever_live[FIRST_PSEUDO_REGISTER];
 107
 108 /* Vector indexed by hardware reg giving its name.  */
 109
 110 extern char *reg_names[FIRST_PSEUDO_REGISTER];
 111
 112 /* For each hard register, the widest mode object that it can contain.
 113    This will be a MODE_INT mode if the register can hold integers.  Otherwise
 114    it will be a MODE_FLOAT or a MODE_CC mode, whichever is valid for the
 115    register.  */
 116
 117 extern enum machine_mode reg_raw_mode[FIRST_PSEUDO_REGISTER];
 118
 119 /* Vector indexed by regno; gives uid of first insn using that reg.
 120    This is computed by reg_scan for use by cse and loop.
 121    It is sometimes adjusted for subsequent changes during loop,
 122    but not adjusted by cse even if cse invalidates it.  */
 123
 124 extern int *regno_first_uid;
 125
 126 /* Vector indexed by regno; gives uid of last insn using that reg.
 127    This is computed by reg_scan for use by cse and loop.
 128    It is sometimes adjusted for subsequent changes during loop,
 129    but not adjusted by cse even if cse invalidates it.
 130    This is harmless since cse won't scan through a loop end.  */
 131
 132 extern int *regno_last_uid;
 133
 134 /* Similar, but includes insns that mention the reg in their notes.  */
 135
 136 extern int *regno_last_note_uid;
 137
 138 /* Vector indexed by regno; contains 1 for a register is considered a pointer.
 139    Reloading, etc. will use a pointer register rather than a non-pointer
 140    as the base register in an address, when there is a choice of two regs.  */
 141
 142 extern char *regno_pointer_flag;
 143 #define REGNO_POINTER_FLAG(REGNO) regno_pointer_flag[REGNO]
 144
 145 /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
 146    that have to go in the same hard reg.  */
 147 extern rtx regs_may_share;
 148
 149 /* Vector mapping pseudo regno into the REG rtx for that register.
 150    This is computed by reg_scan.  */
 151
 152 extern rtx *regno_reg_rtx;
 153
 154 /* Flag set by local-alloc or global-alloc if they decide to allocate
 155    something in a call-clobbered register.  */
 156
 157 extern int caller_save_needed;
 158
 159 /* Predicate to decide whether to give a hard reg to a pseudo which
 160    is referenced REFS times and would need to be saved and restored
 161    around a call CALLS times.  */
 162
 163 #ifndef CALLER_SAVE_PROFITABLE
 164 #define CALLER_SAVE_PROFITABLE(REFS, CALLS)  (4 * (CALLS) < (REFS))
 165 #endif
 166
 167 /* Allocated in local_alloc.  */
 168
 169 /* A list of SCRATCH rtl allocated by local-alloc.  */
 170 extern rtx *scratch_list;
 171 /* The basic block in which each SCRATCH is used.  */
 172 extern int *scratch_block;
 173 /* The length of the arrays pointed to by scratch_block and scratch_list.  */
 174 extern int scratch_list_length;