gcc/regs.h

   1 /* Define per-register tables for data flow info and register allocation.
   2    Copyright (C) 1987, 1993, 1994, 1995, 1996, 1997, 1998,
   3    1999, 2000, 2003, 2004 Free Software Foundation, Inc.
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 2, or (at your option) any later
  10 version.
  11
  12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING.  If not, write to the Free
  19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
  20 02111-1307, USA.  */
  21
  22 #ifndef GCC_REGS_H
  23 #define GCC_REGS_H
  24
  25 #include "varray.h"
  26 #include "hard-reg-set.h"
  27 #include "basic-block.h"
  28
  29 #define REG_BYTES(R) mode_size[(int) GET_MODE (R)]
  30
  31 /* When you only have the mode of a pseudo register before it has a hard
  32    register chosen for it, this reports the size of each hard register
  33    a pseudo in such a mode would get allocated to.  A target may
  34    override this.  */
  35
  36 #ifndef REGMODE_NATURAL_SIZE
  37 #define REGMODE_NATURAL_SIZE(MODE)      UNITS_PER_WORD
  38 #endif
  39
  40 #ifndef SMALL_REGISTER_CLASSES
  41 #define SMALL_REGISTER_CLASSES 0
  42 #endif
  43
  44 /* Maximum register number used in this function, plus one.  */
  45
  46 extern int max_regno;
  47
  48 /* Register information indexed by register number */
  49 typedef struct reg_info_def
  50 {                               /* fields set by reg_scan */
  51   int first_uid;                /* UID of first insn to use (REG n) */
  52   int last_uid;                 /* UID of last insn to use (REG n) */
  53   int last_note_uid;            /* UID of last note to use (REG n) */
  54
  55                                 /* fields set by reg_scan & flow_analysis */
  56   int sets;                     /* # of times (REG n) is set */
  57
  58                                 /* fields set by flow_analysis */
  59   int refs;                     /* # of times (REG n) is used or set */
  60   int freq;                     /* # estimated frequency (REG n) is used or set */
  61   int deaths;                   /* # of times (REG n) dies */
  62   int live_length;              /* # of instructions (REG n) is live */
  63   int calls_crossed;            /* # of calls (REG n) is live across */
  64   int basic_block;              /* # of basic blocks (REG n) is used in */
  65   char changes_mode;            /* whether (SUBREG (REG n)) exists and
  66                                    is illegal.  */
  67 } reg_info;
  68
  69 extern varray_type reg_n_info;
  70
  71 extern bitmap_head subregs_of_mode;
  72
  73 /* Indexed by n, gives number of times (REG n) is used or set.  */
  74
  75 #define REG_N_REFS(N) (VARRAY_REG (reg_n_info, N)->refs)
  76
  77 /* Estimate frequency of references to register N.  */
  78
  79 #define REG_FREQ(N) (VARRAY_REG (reg_n_info, N)->freq)
  80
  81 /* The weights for each insn varries from 0 to REG_FREQ_BASE.
  82    This constant does not need to be high, as in infrequently executed
  83    regions we want to count instructions equivalently to optimize for
  84    size instead of speed.  */
  85 #define REG_FREQ_MAX 1000
  86
  87 /* Compute register frequency from the BB frequency.  When optimizing for size,
  88    or profile driven feedback is available and the function is never executed,
  89    frequency is always equivalent.  Otherwise rescale the basic block
  90    frequency.  */
  91 #define REG_FREQ_FROM_BB(bb) (optimize_size                                   \
  92                               || (flag_branch_probabilities                   \
  93                                   && !ENTRY_BLOCK_PTR->count)                 \
  94                               ? REG_FREQ_MAX                                  \
  95                               : ((bb)->frequency * REG_FREQ_MAX / BB_FREQ_MAX)\
  96                               ? ((bb)->frequency * REG_FREQ_MAX / BB_FREQ_MAX)\
  97                               : 1)
  98
  99 /* Indexed by n, gives number of times (REG n) is set.
 100    ??? both regscan and flow allocate space for this.  We should settle
 101    on just copy.  */
 102
 103 #define REG_N_SETS(N) (VARRAY_REG (reg_n_info, N)->sets)
 104
 105 /* Indexed by N, gives number of insns in which register N dies.
 106    Note that if register N is live around loops, it can die
 107    in transitions between basic blocks, and that is not counted here.
 108    So this is only a reliable indicator of how many regions of life there are
 109    for registers that are contained in one basic block.  */
 110
 111 #define REG_N_DEATHS(N) (VARRAY_REG (reg_n_info, N)->deaths)
 112
 113 /* Get the number of consecutive words required to hold pseudo-reg N.  */
 114
 115 #define PSEUDO_REGNO_SIZE(N) \
 116   ((GET_MODE_SIZE (PSEUDO_REGNO_MODE (N)) + UNITS_PER_WORD - 1)         \
 117    / UNITS_PER_WORD)
 118
 119 /* Get the number of bytes required to hold pseudo-reg N.  */
 120
 121 #define PSEUDO_REGNO_BYTES(N) \
 122   GET_MODE_SIZE (PSEUDO_REGNO_MODE (N))
 123
 124 /* Get the machine mode of pseudo-reg N.  */
 125
 126 #define PSEUDO_REGNO_MODE(N) GET_MODE (regno_reg_rtx[N])
 127
 128 /* Indexed by N, gives number of CALL_INSNS across which (REG n) is live.  */
 129
 130 #define REG_N_CALLS_CROSSED(N) (VARRAY_REG (reg_n_info, N)->calls_crossed)
 131
 132 /* Total number of instructions at which (REG n) is live.
 133    The larger this is, the less priority (REG n) gets for
 134    allocation in a hard register (in global-alloc).
 135    This is set in flow.c and remains valid for the rest of the compilation
 136    of the function; it is used to control register allocation.
 137
 138    local-alloc.c may alter this number to change the priority.
 139
 140    Negative values are special.
 141    -1 is used to mark a pseudo reg which has a constant or memory equivalent
 142    and is used infrequently enough that it should not get a hard register.
 143    -2 is used to mark a pseudo reg for a parameter, when a frame pointer
 144    is not required.  global.c makes an allocno for this but does
 145    not try to assign a hard register to it.  */
 146
 147 #define REG_LIVE_LENGTH(N) (VARRAY_REG (reg_n_info, N)->live_length)
 148
 149 /* Vector of substitutions of register numbers,
 150    used to map pseudo regs into hardware regs.
 151
 152    This can't be folded into reg_n_info without changing all of the
 153    machine dependent directories, since the reload functions
 154    in the machine dependent files access it.  */
 155
 156 extern short *reg_renumber;
 157
 158 /* Vector indexed by hardware reg saying whether that reg is ever used.  */
 159
 160 extern char regs_ever_live[FIRST_PSEUDO_REGISTER];
 161
 162 /* Like regs_ever_live, but saying whether reg is set by asm statements.  */
 163
 164 extern char regs_asm_clobbered[FIRST_PSEUDO_REGISTER];
 165
 166 /* For each hard register, the widest mode object that it can contain.
 167    This will be a MODE_INT mode if the register can hold integers.  Otherwise
 168    it will be a MODE_FLOAT or a MODE_CC mode, whichever is valid for the
 169    register.  */
 170
 171 extern enum machine_mode reg_raw_mode[FIRST_PSEUDO_REGISTER];
 172
 173 /* Vector indexed by regno; gives uid of first insn using that reg.
 174    This is computed by reg_scan for use by cse and loop.
 175    It is sometimes adjusted for subsequent changes during loop,
 176    but not adjusted by cse even if cse invalidates it.  */
 177
 178 #define REGNO_FIRST_UID(N) (VARRAY_REG (reg_n_info, N)->first_uid)
 179
 180 /* Vector indexed by regno; gives uid of last insn using that reg.
 181    This is computed by reg_scan for use by cse and loop.
 182    It is sometimes adjusted for subsequent changes during loop,
 183    but not adjusted by cse even if cse invalidates it.
 184    This is harmless since cse won't scan through a loop end.  */
 185
 186 #define REGNO_LAST_UID(N) (VARRAY_REG (reg_n_info, N)->last_uid)
 187
 188 /* Similar, but includes insns that mention the reg in their notes.  */
 189
 190 #define REGNO_LAST_NOTE_UID(N) (VARRAY_REG (reg_n_info, N)->last_note_uid)
 191
 192 /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
 193    that have to go in the same hard reg.  */
 194 extern rtx regs_may_share;
 195
 196 /* Flag set by local-alloc or global-alloc if they decide to allocate
 197    something in a call-clobbered register.  */
 198
 199 extern int caller_save_needed;
 200
 201 /* Predicate to decide whether to give a hard reg to a pseudo which
 202    is referenced REFS times and would need to be saved and restored
 203    around a call CALLS times.  */
 204
 205 #ifndef CALLER_SAVE_PROFITABLE
 206 #define CALLER_SAVE_PROFITABLE(REFS, CALLS)  (4 * (CALLS) < (REFS))
 207 #endif
 208
 209 /* On most machines a register class is likely to be spilled if it
 210    only has one register.  */
 211 #ifndef CLASS_LIKELY_SPILLED_P
 212 #define CLASS_LIKELY_SPILLED_P(CLASS) (reg_class_size[(int) (CLASS)] == 1)
 213 #endif
 214
 215 /* Select a register mode required for caller save of hard regno REGNO.  */
 216 #ifndef HARD_REGNO_CALLER_SAVE_MODE
 217 #define HARD_REGNO_CALLER_SAVE_MODE(REGNO, NREGS, MODE) \
 218   choose_hard_reg_mode (REGNO, NREGS, false)
 219 #endif
 220
 221 /* Registers that get partially clobbered by a call in a given mode.
 222    These must not be call used registers.  */
 223 #ifndef HARD_REGNO_CALL_PART_CLOBBERED
 224 #define HARD_REGNO_CALL_PART_CLOBBERED(REGNO, MODE) 0
 225 #endif
 226
 227 /* Allocate reg_n_info tables */
 228 extern void allocate_reg_info (size_t, int, int);
 229
 230 /* Specify number of hard registers given machine mode occupy.  */
 231 extern unsigned char hard_regno_nregs[FIRST_PSEUDO_REGISTER][MAX_MACHINE_MODE];
 232
 233 #endif /* GCC_REGS_H */