gcc/regs.h

   1 /* Define per-register tables for data flow info and register allocation.
   2    Copyright (C) 1987, 1993 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 /* Get the number of consecutive words required to hold pseudo-reg N.  */
  57
  58 #define PSEUDO_REGNO_SIZE(N) \
  59   ((GET_MODE_SIZE (PSEUDO_REGNO_MODE (N)) + UNITS_PER_WORD - 1)         \
  60    / UNITS_PER_WORD)
  61
  62 /* Get the number of bytes required to hold pseudo-reg N.  */
  63
  64 #define PSEUDO_REGNO_BYTES(N) \
  65   GET_MODE_SIZE (PSEUDO_REGNO_MODE (N))
  66
  67 /* Get the machine mode of pseudo-reg N.  */
  68
  69 #define PSEUDO_REGNO_MODE(N) GET_MODE (regno_reg_rtx[N])
  70
  71 /* Indexed by N, gives number of CALL_INSNS across which (REG n) is live.  */
  72
  73 extern int *reg_n_calls_crossed;
  74
  75 /* Total number of instructions at which (REG n) is live.
  76    The larger this is, the less priority (REG n) gets for
  77    allocation in a hard register (in global-alloc).
  78    This is set in flow.c and remains valid for the rest of the compilation
  79    of the function; it is used to control register allocation.
  80
  81    local-alloc.c may alter this number to change the priority.
  82
  83    Negative values are special.
  84    -1 is used to mark a pseudo reg which has a constant or memory equivalent
  85    and is used infrequently enough that it should not get a hard register.
  86    -2 is used to mark a pseudo reg for a parameter, when a frame pointer
  87    is not required.  global.c makes an allocno for this but does
  88    not try to assign a hard register to it.  */
  89
  90 extern int *reg_live_length;
  91
  92 /* Vector of substitutions of register numbers,
  93    used to map pseudo regs into hardware regs.  */
  94
  95 extern short *reg_renumber;
  96
  97 /* Vector indexed by hardware reg
  98    saying whether that reg is ever used.  */
  99
 100 extern char regs_ever_live[FIRST_PSEUDO_REGISTER];
 101
 102 /* Vector indexed by hardware reg giving its name.  */
 103
 104 extern char *reg_names[FIRST_PSEUDO_REGISTER];
 105
 106 /* Vector indexed by regno; gives uid of first insn using that reg.
 107    This is computed by reg_scan for use by cse and loop.
 108    It is sometimes adjusted for subsequent changes during loop,
 109    but not adjusted by cse even if cse invalidates it.  */
 110
 111 extern int *regno_first_uid;
 112
 113 /* Vector indexed by regno; gives uid of last insn using that reg.
 114    This is computed by reg_scan for use by cse and loop.
 115    It is sometimes adjusted for subsequent changes during loop,
 116    but not adjusted by cse even if cse invalidates it.
 117    This is harmless since cse won't scan through a loop end.  */
 118
 119 extern int *regno_last_uid;
 120
 121 /* Similar, but includes insns that mention the reg in their notes.  */
 122
 123 extern int *regno_last_note_uid;
 124
 125 /* Vector indexed by regno; contains 1 for a register is considered a pointer.
 126    Reloading, etc. will use a pointer register rather than a non-pointer
 127    as the base register in an address, when there is a choice of two regs.  */
 128
 129 extern char *regno_pointer_flag;
 130 #define REGNO_POINTER_FLAG(REGNO) regno_pointer_flag[REGNO]
 131
 132 /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
 133    that have to go in the same hard reg.  */
 134 extern rtx regs_may_share;
 135
 136 /* Vector mapping pseudo regno into the REG rtx for that register.
 137    This is computed by reg_scan.  */
 138
 139 extern rtx *regno_reg_rtx;
 140
 141 /* Flag set by local-alloc or global-alloc if they decide to allocate
 142    something in a call-clobbered register.  */
 143
 144 extern int caller_save_needed;
 145
 146 /* Predicate to decide whether to give a hard reg to a pseudo which
 147    is referenced REFS times and would need to be saved and restored
 148    around a call CALLS times.  */
 149
 150 #ifndef CALLER_SAVE_PROFITABLE
 151 #define CALLER_SAVE_PROFITABLE(REFS, CALLS)  (4 * (CALLS) < (REFS))
 152 #endif
 153
 154 /* Allocated in local_alloc.  */
 155
 156 /* A list of SCRATCH rtl allocated by local-alloc.  */
 157 extern rtx *scratch_list;
 158 /* The basic block in which each SCRATCH is used.  */
 159 extern int *scratch_block;
 160 /* The length of the arrays pointed to by scratch_block and scratch_list.  */
 161 extern int scratch_list_length;