regs.h revision 117395
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 5This file is part of GCC. 6 7GCC is free software; you can redistribute it and/or modify it under 8the terms of the GNU General Public License as published by the Free 9Software Foundation; either version 2, or (at your option) any later 10version. 11 12GCC is distributed in the hope that it will be useful, but WITHOUT ANY 13WARRANTY; without even the implied warranty of MERCHANTABILITY or 14FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 15for more details. 16 17You should have received a copy of the GNU General Public License 18along with GCC; see the file COPYING. If not, write to the Free 19Software Foundation, 59 Temple Place - Suite 330, Boston, MA 2002111-1307, USA. */ 21 22 23#include "varray.h" 24#include "hard-reg-set.h" 25#include "basic-block.h" 26 27#define REG_BYTES(R) mode_size[(int) GET_MODE (R)] 28 29/* When you only have the mode of a pseudo register before it has a hard 30 register chosen for it, this reports the size of each hard register 31 a pseudo in such a mode would get allocated to. A target may 32 override this. */ 33 34#ifndef REGMODE_NATURAL_SIZE 35#define REGMODE_NATURAL_SIZE(MODE) UNITS_PER_WORD 36#endif 37 38#ifndef SMALL_REGISTER_CLASSES 39#define SMALL_REGISTER_CLASSES 0 40#endif 41 42/* Maximum register number used in this function, plus one. */ 43 44extern int max_regno; 45 46/* Register information indexed by register number */ 47typedef struct reg_info_def 48{ /* fields set by reg_scan */ 49 int first_uid; /* UID of first insn to use (REG n) */ 50 int last_uid; /* UID of last insn to use (REG n) */ 51 int last_note_uid; /* UID of last note to use (REG n) */ 52 53 /* fields set by reg_scan & flow_analysis */ 54 int sets; /* # of times (REG n) is set */ 55 56 /* fields set by flow_analysis */ 57 int refs; /* # of times (REG n) is used or set */ 58 int freq; /* # estimated frequency (REG n) is used or set */ 59 int deaths; /* # of times (REG n) dies */ 60 int live_length; /* # of instructions (REG n) is live */ 61 int calls_crossed; /* # of calls (REG n) is live across */ 62 int basic_block; /* # of basic blocks (REG n) is used in */ 63 char changes_mode; /* whether (SUBREG (REG n)) exists and 64 is illegal. */ 65} reg_info; 66 67extern varray_type reg_n_info; 68 69extern bitmap_head subregs_of_mode; 70 71/* Indexed by n, gives number of times (REG n) is used or set. */ 72 73#define REG_N_REFS(N) (VARRAY_REG (reg_n_info, N)->refs) 74 75/* Estimate frequency of references to register N. */ 76 77#define REG_FREQ(N) (VARRAY_REG (reg_n_info, N)->freq) 78 79/* The weights for each insn varries from 0 to REG_FREQ_BASE. 80 This constant does not need to be high, as in infrequently executed 81 regions we want to count instructions equivalently to optimize for 82 size instead of speed. */ 83#define REG_FREQ_MAX 1000 84 85/* Compute register frequency from the BB frequency. When optimizing for size, 86 or profile driven feedback is available and the function is never executed, 87 frequency is always equivalent. Otherwise rescale the basic block 88 frequency. */ 89#define REG_FREQ_FROM_BB(bb) (optimize_size \ 90 || (flag_branch_probabilities \ 91 && !ENTRY_BLOCK_PTR->count) \ 92 ? REG_FREQ_MAX \ 93 : ((bb)->frequency * REG_FREQ_MAX / BB_FREQ_MAX)\ 94 ? ((bb)->frequency * REG_FREQ_MAX / BB_FREQ_MAX)\ 95 : 1) 96 97/* Indexed by n, gives number of times (REG n) is set. 98 ??? both regscan and flow allocate space for this. We should settle 99 on just copy. */ 100 101#define REG_N_SETS(N) (VARRAY_REG (reg_n_info, N)->sets) 102 103/* Indexed by N, gives number of insns in which register N dies. 104 Note that if register N is live around loops, it can die 105 in transitions between basic blocks, and that is not counted here. 106 So this is only a reliable indicator of how many regions of life there are 107 for registers that are contained in one basic block. */ 108 109#define REG_N_DEATHS(N) (VARRAY_REG (reg_n_info, N)->deaths) 110 111/* Get the number of consecutive words required to hold pseudo-reg N. */ 112 113#define PSEUDO_REGNO_SIZE(N) \ 114 ((GET_MODE_SIZE (PSEUDO_REGNO_MODE (N)) + UNITS_PER_WORD - 1) \ 115 / UNITS_PER_WORD) 116 117/* Get the number of bytes required to hold pseudo-reg N. */ 118 119#define PSEUDO_REGNO_BYTES(N) \ 120 GET_MODE_SIZE (PSEUDO_REGNO_MODE (N)) 121 122/* Get the machine mode of pseudo-reg N. */ 123 124#define PSEUDO_REGNO_MODE(N) GET_MODE (regno_reg_rtx[N]) 125 126/* Indexed by N, gives number of CALL_INSNS across which (REG n) is live. */ 127 128#define REG_N_CALLS_CROSSED(N) (VARRAY_REG (reg_n_info, N)->calls_crossed) 129 130/* Total number of instructions at which (REG n) is live. 131 The larger this is, the less priority (REG n) gets for 132 allocation in a hard register (in global-alloc). 133 This is set in flow.c and remains valid for the rest of the compilation 134 of the function; it is used to control register allocation. 135 136 local-alloc.c may alter this number to change the priority. 137 138 Negative values are special. 139 -1 is used to mark a pseudo reg which has a constant or memory equivalent 140 and is used infrequently enough that it should not get a hard register. 141 -2 is used to mark a pseudo reg for a parameter, when a frame pointer 142 is not required. global.c makes an allocno for this but does 143 not try to assign a hard register to it. */ 144 145#define REG_LIVE_LENGTH(N) (VARRAY_REG (reg_n_info, N)->live_length) 146 147/* Vector of substitutions of register numbers, 148 used to map pseudo regs into hardware regs. 149 150 This can't be folded into reg_n_info without changing all of the 151 machine dependent directories, since the reload functions 152 in the machine dependent files access it. */ 153 154extern short *reg_renumber; 155 156/* Vector indexed by hardware reg 157 saying whether that reg is ever used. */ 158 159extern char regs_ever_live[FIRST_PSEUDO_REGISTER]; 160 161/* Vector indexed by hardware reg giving its name. */ 162 163extern const char * reg_names[FIRST_PSEUDO_REGISTER]; 164 165/* For each hard register, the widest mode object that it can contain. 166 This will be a MODE_INT mode if the register can hold integers. Otherwise 167 it will be a MODE_FLOAT or a MODE_CC mode, whichever is valid for the 168 register. */ 169 170extern enum machine_mode reg_raw_mode[FIRST_PSEUDO_REGISTER]; 171 172/* Vector indexed by regno; gives uid of first insn using that reg. 173 This is computed by reg_scan for use by cse and loop. 174 It is sometimes adjusted for subsequent changes during loop, 175 but not adjusted by cse even if cse invalidates it. */ 176 177#define REGNO_FIRST_UID(N) (VARRAY_REG (reg_n_info, N)->first_uid) 178 179/* Vector indexed by regno; gives uid of last insn using that reg. 180 This is computed by reg_scan for use by cse and loop. 181 It is sometimes adjusted for subsequent changes during loop, 182 but not adjusted by cse even if cse invalidates it. 183 This is harmless since cse won't scan through a loop end. */ 184 185#define REGNO_LAST_UID(N) (VARRAY_REG (reg_n_info, N)->last_uid) 186 187/* Similar, but includes insns that mention the reg in their notes. */ 188 189#define REGNO_LAST_NOTE_UID(N) (VARRAY_REG (reg_n_info, N)->last_note_uid) 190 191/* List made of EXPR_LIST rtx's which gives pairs of pseudo registers 192 that have to go in the same hard reg. */ 193extern rtx regs_may_share; 194 195/* Flag set by local-alloc or global-alloc if they decide to allocate 196 something in a call-clobbered register. */ 197 198extern int caller_save_needed; 199 200/* Predicate to decide whether to give a hard reg to a pseudo which 201 is referenced REFS times and would need to be saved and restored 202 around a call CALLS times. */ 203 204#ifndef CALLER_SAVE_PROFITABLE 205#define CALLER_SAVE_PROFITABLE(REFS, CALLS) (4 * (CALLS) < (REFS)) 206#endif 207 208/* On most machines a register class is likely to be spilled if it 209 only has one register. */ 210#ifndef CLASS_LIKELY_SPILLED_P 211#define CLASS_LIKELY_SPILLED_P(CLASS) (reg_class_size[(int) (CLASS)] == 1) 212#endif 213 214/* Select a register mode required for caller save of hard regno REGNO. */ 215#ifndef HARD_REGNO_CALLER_SAVE_MODE 216#define HARD_REGNO_CALLER_SAVE_MODE(REGNO, NREGS, MODE) \ 217 choose_hard_reg_mode (REGNO, NREGS) 218#endif 219 220/* Registers that get partially clobbered by a call in a given mode. 221 These must not be call used registers. */ 222#ifndef HARD_REGNO_CALL_PART_CLOBBERED 223#define HARD_REGNO_CALL_PART_CLOBBERED(REGNO, MODE) 0 224#endif 225 226/* Allocate reg_n_info tables */ 227extern void allocate_reg_info PARAMS ((size_t, int, int)); 228