regs.h revision 146895
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 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 69/* Indexed by n, gives number of times (REG n) is used or set. */ 70 71#define REG_N_REFS(N) (VARRAY_REG (reg_n_info, N)->refs) 72 73/* Estimate frequency of references to register N. */ 74 75#define REG_FREQ(N) (VARRAY_REG (reg_n_info, N)->freq) 76 77/* The weights for each insn varries from 0 to REG_FREQ_BASE. 78 This constant does not need to be high, as in infrequently executed 79 regions we want to count instructions equivalently to optimize for 80 size instead of speed. */ 81#define REG_FREQ_MAX 1000 82 83/* Compute register frequency from the BB frequency. When optimizing for size, 84 or profile driven feedback is available and the function is never executed, 85 frequency is always equivalent. Otherwise rescale the basic block 86 frequency. */ 87#define REG_FREQ_FROM_BB(bb) (optimize_size \ 88 || (flag_branch_probabilities \ 89 && !ENTRY_BLOCK_PTR->count) \ 90 ? REG_FREQ_MAX \ 91 : ((bb)->frequency * REG_FREQ_MAX / BB_FREQ_MAX)\ 92 ? ((bb)->frequency * REG_FREQ_MAX / BB_FREQ_MAX)\ 93 : 1) 94 95/* Indexed by n, gives number of times (REG n) is set. 96 ??? both regscan and flow allocate space for this. We should settle 97 on just copy. */ 98 99#define REG_N_SETS(N) (VARRAY_REG (reg_n_info, N)->sets) 100 101/* Indexed by N, gives number of insns in which register N dies. 102 Note that if register N is live around loops, it can die 103 in transitions between basic blocks, and that is not counted here. 104 So this is only a reliable indicator of how many regions of life there are 105 for registers that are contained in one basic block. */ 106 107#define REG_N_DEATHS(N) (VARRAY_REG (reg_n_info, N)->deaths) 108 109/* Get the number of consecutive words required to hold pseudo-reg N. */ 110 111#define PSEUDO_REGNO_SIZE(N) \ 112 ((GET_MODE_SIZE (PSEUDO_REGNO_MODE (N)) + UNITS_PER_WORD - 1) \ 113 / UNITS_PER_WORD) 114 115/* Get the number of bytes required to hold pseudo-reg N. */ 116 117#define PSEUDO_REGNO_BYTES(N) \ 118 GET_MODE_SIZE (PSEUDO_REGNO_MODE (N)) 119 120/* Get the machine mode of pseudo-reg N. */ 121 122#define PSEUDO_REGNO_MODE(N) GET_MODE (regno_reg_rtx[N]) 123 124/* Indexed by N, gives number of CALL_INSNS across which (REG n) is live. */ 125 126#define REG_N_CALLS_CROSSED(N) (VARRAY_REG (reg_n_info, N)->calls_crossed) 127 128/* Total number of instructions at which (REG n) is live. 129 The larger this is, the less priority (REG n) gets for 130 allocation in a hard register (in global-alloc). 131 This is set in flow.c and remains valid for the rest of the compilation 132 of the function; it is used to control register allocation. 133 134 local-alloc.c may alter this number to change the priority. 135 136 Negative values are special. 137 -1 is used to mark a pseudo reg which has a constant or memory equivalent 138 and is used infrequently enough that it should not get a hard register. 139 -2 is used to mark a pseudo reg for a parameter, when a frame pointer 140 is not required. global.c makes an allocno for this but does 141 not try to assign a hard register to it. */ 142 143#define REG_LIVE_LENGTH(N) (VARRAY_REG (reg_n_info, N)->live_length) 144 145/* Vector of substitutions of register numbers, 146 used to map pseudo regs into hardware regs. 147 148 This can't be folded into reg_n_info without changing all of the 149 machine dependent directories, since the reload functions 150 in the machine dependent files access it. */ 151 152extern short *reg_renumber; 153 154/* Vector indexed by hardware reg saying whether that reg is ever used. */ 155 156extern char regs_ever_live[FIRST_PSEUDO_REGISTER]; 157 158/* Like regs_ever_live, but saying whether reg is set by asm statements. */ 159 160extern char regs_asm_clobbered[FIRST_PSEUDO_REGISTER]; 161 162/* For each hard register, the widest mode object that it can contain. 163 This will be a MODE_INT mode if the register can hold integers. Otherwise 164 it will be a MODE_FLOAT or a MODE_CC mode, whichever is valid for the 165 register. */ 166 167extern enum machine_mode reg_raw_mode[FIRST_PSEUDO_REGISTER]; 168 169/* Vector indexed by regno; gives uid of first insn using that reg. 170 This is computed by reg_scan for use by cse and loop. 171 It is sometimes adjusted for subsequent changes during loop, 172 but not adjusted by cse even if cse invalidates it. */ 173 174#define REGNO_FIRST_UID(N) (VARRAY_REG (reg_n_info, N)->first_uid) 175 176/* Vector indexed by regno; gives uid of last insn using that reg. 177 This is computed by reg_scan for use by cse and loop. 178 It is sometimes adjusted for subsequent changes during loop, 179 but not adjusted by cse even if cse invalidates it. 180 This is harmless since cse won't scan through a loop end. */ 181 182#define REGNO_LAST_UID(N) (VARRAY_REG (reg_n_info, N)->last_uid) 183 184/* Similar, but includes insns that mention the reg in their notes. */ 185 186#define REGNO_LAST_NOTE_UID(N) (VARRAY_REG (reg_n_info, N)->last_note_uid) 187 188/* List made of EXPR_LIST rtx's which gives pairs of pseudo registers 189 that have to go in the same hard reg. */ 190extern rtx regs_may_share; 191 192/* Flag set by local-alloc or global-alloc if they decide to allocate 193 something in a call-clobbered register. */ 194 195extern int caller_save_needed; 196 197/* Predicate to decide whether to give a hard reg to a pseudo which 198 is referenced REFS times and would need to be saved and restored 199 around a call CALLS times. */ 200 201#ifndef CALLER_SAVE_PROFITABLE 202#define CALLER_SAVE_PROFITABLE(REFS, CALLS) (4 * (CALLS) < (REFS)) 203#endif 204 205/* On most machines a register class is likely to be spilled if it 206 only has one register. */ 207#ifndef CLASS_LIKELY_SPILLED_P 208#define CLASS_LIKELY_SPILLED_P(CLASS) (reg_class_size[(int) (CLASS)] == 1) 209#endif 210 211/* Select a register mode required for caller save of hard regno REGNO. */ 212#ifndef HARD_REGNO_CALLER_SAVE_MODE 213#define HARD_REGNO_CALLER_SAVE_MODE(REGNO, NREGS, MODE) \ 214 choose_hard_reg_mode (REGNO, NREGS, false) 215#endif 216 217/* Registers that get partially clobbered by a call in a given mode. 218 These must not be call used registers. */ 219#ifndef HARD_REGNO_CALL_PART_CLOBBERED 220#define HARD_REGNO_CALL_PART_CLOBBERED(REGNO, MODE) 0 221#endif 222 223/* Allocate reg_n_info tables */ 224extern void allocate_reg_info (size_t, int, int); 225