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 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
  23 #include "varray.h"
  24
  25 #define REG_BYTES(R) mode_size[(int) GET_MODE (R)]
  26
  27 /* Get the number of consecutive hard regs required to hold the REG or
  28    SUBREG rtx R.
  29    When something may be an explicit hard reg, REG_SIZE is the only
  30    valid way to get this value.  You cannot get it from the regno.
  31
  32    A target may override this definition, the case where you would do
  33    this is where there are registers which are smaller than WORD_SIZE
  34    such as the SFmode registers on sparc64.  */
  35
  36 #ifndef REG_SIZE
  37 #define REG_SIZE(R) \
  38   ((mode_size[(int) GET_MODE (R)] + UNITS_PER_WORD - 1) / UNITS_PER_WORD)
  39 #endif
  40
  41 /* When you only have the mode of a pseudo register before it has a hard
  42    register chosen for it, this reports the size of each hard register
  43    a pseudo in such a mode would get allocated to.  Like REG_SIZE, a
  44    target may override this.  */
  45
  46 #ifndef REGMODE_NATURAL_SIZE
  47 #define REGMODE_NATURAL_SIZE(MODE)      UNITS_PER_WORD
  48 #endif
  49
  50 #ifndef SMALL_REGISTER_CLASSES
  51 #define SMALL_REGISTER_CLASSES 0
  52 #endif
  53
  54 /* Maximum register number used in this function, plus one.  */
  55
  56 extern int max_regno;
  57
  58 /* Register information indexed by register number */
  59 typedef struct reg_info_def
  60 {                               /* fields set by reg_scan */
  61   int first_uid;                /* UID of first insn to use (REG n) */
  62   int last_uid;                 /* UID of last insn to use (REG n) */
  63   int last_note_uid;            /* UID of last note to use (REG n) */
  64
  65                                 /* fields set by reg_scan & flow_analysis */
  66   int sets;                     /* # of times (REG n) is set */
  67
  68                                 /* fields set by flow_analysis */
  69   int refs;                     /* # of times (REG n) is used or set */
  70   int freq;                     /* # estimated frequency (REG n) is used or set */
  71   int deaths;                   /* # of times (REG n) dies */
  72   int live_length;              /* # of instructions (REG n) is live */
  73   int calls_crossed;            /* # of calls (REG n) is live across */
  74   int basic_block;              /* # of basic blocks (REG n) is used in */
  75   char changes_mode;            /* whether (SUBREG (REG n)) exists and
  76                                    is illegal.  */
  77 } reg_info;
  78
  79 extern varray_type reg_n_info;
  80
  81 /* Indexed by n, gives number of times (REG n) is used or set.  */
  82
  83 #define REG_N_REFS(N) (VARRAY_REG (reg_n_info, N)->refs)
  84
  85 /* Estimate frequency of references to register N.  */
  86
  87 #define REG_FREQ(N) (VARRAY_REG (reg_n_info, N)->freq)
  88
  89 /* The weights for each insn varries from 0 to REG_FREQ_BASE.
  90    This constant does not need to be high, as in infrequently executed
  91    regions we want to count instructions equivalently to optimize for
  92    size instead of speed.  */
  93 #define REG_FREQ_MAX 1000
  94
  95 /* Compute register frequency from the BB frequency.  When optimizing for size,
  96    or profile driven feedback is available and the function is never executed,
  97    frequency is always equivalent.  Otherwise rescale the basic block
  98    frequency.  */
  99 #define REG_FREQ_FROM_BB(bb) (optimize_size                                   \
 100                               || (flag_branch_probabilities                   \
 101                                   && !ENTRY_BLOCK_PTR->count)                 \
 102                               ? REG_FREQ_MAX                                  \
 103                               : ((bb)->frequency * REG_FREQ_MAX / BB_FREQ_MAX)\
 104                               ? ((bb)->frequency * REG_FREQ_MAX / BB_FREQ_MAX)\
 105                               : 1)
 106
 107 /* Indexed by n, gives number of times (REG n) is set.
 108    ??? both regscan and flow allocate space for this.  We should settle
 109    on just copy.  */
 110
 111 #define REG_N_SETS(N) (VARRAY_REG (reg_n_info, N)->sets)
 112
 113 /* Indexed by N, gives number of insns in which register N dies.
 114    Note that if register N is live around loops, it can die
 115    in transitions between basic blocks, and that is not counted here.
 116    So this is only a reliable indicator of how many regions of life there are
 117    for registers that are contained in one basic block.  */
 118
 119 #define REG_N_DEATHS(N) (VARRAY_REG (reg_n_info, N)->deaths)
 120
 121 /* Indexed by N; says whether a pseudo register N was ever used
 122    within a SUBREG that changes the mode of the reg in some way
 123    that is illegal for a given class (usually floating-point)
 124    of registers.  */
 125
 126 #define REG_CHANGES_MODE(N) (VARRAY_REG (reg_n_info, N)->changes_mode)
 127
 128 /* Get the number of consecutive words required to hold pseudo-reg N.  */
 129
 130 #define PSEUDO_REGNO_SIZE(N) \
 131   ((GET_MODE_SIZE (PSEUDO_REGNO_MODE (N)) + UNITS_PER_WORD - 1)         \
 132    / UNITS_PER_WORD)
 133
 134 /* Get the number of bytes required to hold pseudo-reg N.  */
 135
 136 #define PSEUDO_REGNO_BYTES(N) \
 137   GET_MODE_SIZE (PSEUDO_REGNO_MODE (N))
 138
 139 /* Get the machine mode of pseudo-reg N.  */
 140
 141 #define PSEUDO_REGNO_MODE(N) GET_MODE (regno_reg_rtx[N])
 142
 143 /* Indexed by N, gives number of CALL_INSNS across which (REG n) is live.  */
 144
 145 #define REG_N_CALLS_CROSSED(N) (VARRAY_REG (reg_n_info, N)->calls_crossed)
 146
 147 /* Total number of instructions at which (REG n) is live.
 148    The larger this is, the less priority (REG n) gets for
 149    allocation in a hard register (in global-alloc).
 150    This is set in flow.c and remains valid for the rest of the compilation
 151    of the function; it is used to control register allocation.
 152
 153    local-alloc.c may alter this number to change the priority.
 154
 155    Negative values are special.
 156    -1 is used to mark a pseudo reg which has a constant or memory equivalent
 157    and is used infrequently enough that it should not get a hard register.
 158    -2 is used to mark a pseudo reg for a parameter, when a frame pointer
 159    is not required.  global.c makes an allocno for this but does
 160    not try to assign a hard register to it.  */
 161
 162 #define REG_LIVE_LENGTH(N) (VARRAY_REG (reg_n_info, N)->live_length)
 163
 164 /* Vector of substitutions of register numbers,
 165    used to map pseudo regs into hardware regs.
 166
 167    This can't be folded into reg_n_info without changing all of the
 168    machine dependent directories, since the reload functions
 169    in the machine dependent files access it.  */
 170
 171 extern short *reg_renumber;
 172
 173 /* Vector indexed by hardware reg
 174    saying whether that reg is ever used.  */
 175
 176 extern char regs_ever_live[FIRST_PSEUDO_REGISTER];
 177
 178 /* Vector indexed by hardware reg giving its name.  */
 179
 180 extern const char * reg_names[FIRST_PSEUDO_REGISTER];
 181
 182 /* For each hard register, the widest mode object that it can contain.
 183    This will be a MODE_INT mode if the register can hold integers.  Otherwise
 184    it will be a MODE_FLOAT or a MODE_CC mode, whichever is valid for the
 185    register.  */
 186
 187 extern enum machine_mode reg_raw_mode[FIRST_PSEUDO_REGISTER];
 188
 189 /* Vector indexed by regno; gives uid of first insn using that reg.
 190    This is computed by reg_scan for use by cse and loop.
 191    It is sometimes adjusted for subsequent changes during loop,
 192    but not adjusted by cse even if cse invalidates it.  */
 193
 194 #define REGNO_FIRST_UID(N) (VARRAY_REG (reg_n_info, N)->first_uid)
 195
 196 /* Vector indexed by regno; gives uid of last insn using that reg.
 197    This is computed by reg_scan for use by cse and loop.
 198    It is sometimes adjusted for subsequent changes during loop,
 199    but not adjusted by cse even if cse invalidates it.
 200    This is harmless since cse won't scan through a loop end.  */
 201
 202 #define REGNO_LAST_UID(N) (VARRAY_REG (reg_n_info, N)->last_uid)
 203
 204 /* Similar, but includes insns that mention the reg in their notes.  */
 205
 206 #define REGNO_LAST_NOTE_UID(N) (VARRAY_REG (reg_n_info, N)->last_note_uid)
 207
 208 /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
 209    that have to go in the same hard reg.  */
 210 extern rtx regs_may_share;
 211
 212 /* Flag set by local-alloc or global-alloc if they decide to allocate
 213    something in a call-clobbered register.  */
 214
 215 extern int caller_save_needed;
 216
 217 /* Predicate to decide whether to give a hard reg to a pseudo which
 218    is referenced REFS times and would need to be saved and restored
 219    around a call CALLS times.  */
 220
 221 #ifndef CALLER_SAVE_PROFITABLE
 222 #define CALLER_SAVE_PROFITABLE(REFS, CALLS)  (4 * (CALLS) < (REFS))
 223 #endif
 224
 225 /* On most machines a register class is likely to be spilled if it
 226    only has one register.  */
 227 #ifndef CLASS_LIKELY_SPILLED_P
 228 #define CLASS_LIKELY_SPILLED_P(CLASS) (reg_class_size[(int) (CLASS)] == 1)
 229 #endif
 230
 231 /* Select a register mode required for caller save of hard regno REGNO.  */
 232 #ifndef HARD_REGNO_CALLER_SAVE_MODE
 233 #define HARD_REGNO_CALLER_SAVE_MODE(REGNO, NREGS, MODE) \
 234   choose_hard_reg_mode (REGNO, NREGS)
 235 #endif
 236
 237 /* Registers that get partially clobbered by a call in a given mode.
 238    These must not be call used registers.  */
 239 #ifndef HARD_REGNO_CALL_PART_CLOBBERED
 240 #define HARD_REGNO_CALL_PART_CLOBBERED(REGNO, MODE) 0
 241 #endif
 242
 243 /* Allocate reg_n_info tables */
 244 extern void allocate_reg_info PARAMS ((size_t, int, int));