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