regs.h revision 50397
1/* Define per-register tables for data flow info and register allocation. 2 Copyright (C) 1987, 1993, 1994, 1995, 1997, 1998 Free Software Foundation, Inc. 3 4This file is part of GNU CC. 5 6GNU CC is free software; you can redistribute it and/or modify 7it under the terms of the GNU General Public License as published by 8the Free Software Foundation; either version 2, or (at your option) 9any later version. 10 11GNU CC is distributed in the hope that it will be useful, 12but WITHOUT ANY WARRANTY; without even the implied warranty of 13MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14GNU General Public License for more details. 15 16You should have received a copy of the GNU General Public License 17along with GNU CC; see the file COPYING. If not, write to 18the Free Software Foundation, 59 Temple Place - Suite 330, 19Boston, MA 02111-1307, USA. */ 20 21 22#include "varray.h" 23 24#define REG_BYTES(R) mode_size[(int) GET_MODE (R)] 25 26/* Get the number of consecutive hard regs required to hold the REG rtx R. 27 When something may be an explicit hard reg, REG_SIZE is the only 28 valid way to get this value. You cannot get it from the regno. */ 29 30#define REG_SIZE(R) \ 31 ((mode_size[(int) GET_MODE (R)] + UNITS_PER_WORD - 1) / UNITS_PER_WORD) 32 33#ifndef SMALL_REGISTER_CLASSES 34#define SMALL_REGISTER_CLASSES 0 35#endif 36 37/* Maximum register number used in this function, plus one. */ 38 39extern int max_regno; 40 41/* Maximum number of SCRATCH rtx's in each block of this function. */ 42 43extern int max_scratch; 44 45/* Register information indexed by register number */ 46typedef struct reg_info_def { 47 /* fields set by reg_scan */ 48 int first_uid; /* UID of first insn to use (REG n) */ 49 int last_uid; /* UID of last insn to use (REG n) */ 50 int last_note_uid; /* UID of last note to use (REG n) */ 51 52 /* fields set by both reg_scan and flow_analysis */ 53 int sets; /* # of times (REG n) is set */ 54 55 /* fields set by flow_analysis */ 56 int refs; /* # of times (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_size; /* whether (SUBREG (REG n)) changes size */ 62} reg_info; 63 64extern varray_type reg_n_info; 65 66extern unsigned int reg_n_max; 67 68/* Indexed by n, gives number of times (REG n) is used or set. 69 References within loops may be counted more times. */ 70 71#define REG_N_REFS(N) (VARRAY_REG (reg_n_info, N)->refs) 72 73/* Indexed by n, gives number of times (REG n) is set. 74 ??? both regscan and flow allocate space for this. We should settle 75 on just copy. */ 76 77#define REG_N_SETS(N) (VARRAY_REG (reg_n_info, N)->sets) 78 79/* Indexed by N, gives number of insns in which register N dies. 80 Note that if register N is live around loops, it can die 81 in transitions between basic blocks, and that is not counted here. 82 So this is only a reliable indicator of how many regions of life there are 83 for registers that are contained in one basic block. */ 84 85#define REG_N_DEATHS(N) (VARRAY_REG (reg_n_info, N)->deaths) 86 87/* Indexed by N; says whether a pseudo register N was ever used 88 within a SUBREG that changes the size of the reg. Some machines prohibit 89 such objects to be in certain (usually floating-point) registers. */ 90 91#define REG_CHANGES_SIZE(N) (VARRAY_REG (reg_n_info, N)->changes_size) 92 93/* Get the number of consecutive words required to hold pseudo-reg N. */ 94 95#define PSEUDO_REGNO_SIZE(N) \ 96 ((GET_MODE_SIZE (PSEUDO_REGNO_MODE (N)) + UNITS_PER_WORD - 1) \ 97 / UNITS_PER_WORD) 98 99/* Get the number of bytes required to hold pseudo-reg N. */ 100 101#define PSEUDO_REGNO_BYTES(N) \ 102 GET_MODE_SIZE (PSEUDO_REGNO_MODE (N)) 103 104/* Get the machine mode of pseudo-reg N. */ 105 106#define PSEUDO_REGNO_MODE(N) GET_MODE (regno_reg_rtx[N]) 107 108/* Indexed by N, gives number of CALL_INSNS across which (REG n) is live. */ 109 110#define REG_N_CALLS_CROSSED(N) (VARRAY_REG (reg_n_info, N)->calls_crossed) 111 112/* Total number of instructions at which (REG n) is live. 113 The larger this is, the less priority (REG n) gets for 114 allocation in a hard register (in global-alloc). 115 This is set in flow.c and remains valid for the rest of the compilation 116 of the function; it is used to control register allocation. 117 118 local-alloc.c may alter this number to change the priority. 119 120 Negative values are special. 121 -1 is used to mark a pseudo reg which has a constant or memory equivalent 122 and is used infrequently enough that it should not get a hard register. 123 -2 is used to mark a pseudo reg for a parameter, when a frame pointer 124 is not required. global.c makes an allocno for this but does 125 not try to assign a hard register to it. */ 126 127#define REG_LIVE_LENGTH(N) (VARRAY_REG (reg_n_info, N)->live_length) 128 129/* Vector of substitutions of register numbers, 130 used to map pseudo regs into hardware regs. 131 132 This can't be folded into reg_n_info without changing all of the 133 machine dependent directories, since the reload functions 134 in the machine dependent files access it. */ 135 136extern short *reg_renumber; 137 138/* Vector indexed by hardware reg 139 saying whether that reg is ever used. */ 140 141extern char regs_ever_live[FIRST_PSEUDO_REGISTER]; 142 143/* Vector indexed by hardware reg giving its name. */ 144 145extern char *reg_names[FIRST_PSEUDO_REGISTER]; 146 147/* For each hard register, the widest mode object that it can contain. 148 This will be a MODE_INT mode if the register can hold integers. Otherwise 149 it will be a MODE_FLOAT or a MODE_CC mode, whichever is valid for the 150 register. */ 151 152extern enum machine_mode reg_raw_mode[FIRST_PSEUDO_REGISTER]; 153 154/* Vector indexed by regno; gives uid of first insn using that reg. 155 This is computed by reg_scan for use by cse and loop. 156 It is sometimes adjusted for subsequent changes during loop, 157 but not adjusted by cse even if cse invalidates it. */ 158 159#define REGNO_FIRST_UID(N) (VARRAY_REG (reg_n_info, N)->first_uid) 160 161/* Vector indexed by regno; gives uid of last insn using that reg. 162 This is computed by reg_scan for use by cse and loop. 163 It is sometimes adjusted for subsequent changes during loop, 164 but not adjusted by cse even if cse invalidates it. 165 This is harmless since cse won't scan through a loop end. */ 166 167#define REGNO_LAST_UID(N) (VARRAY_REG (reg_n_info, N)->last_uid) 168 169/* Similar, but includes insns that mention the reg in their notes. */ 170 171#define REGNO_LAST_NOTE_UID(N) (VARRAY_REG (reg_n_info, N)->last_note_uid) 172 173/* This is reset to LAST_VIRTUAL_REGISTER + 1 at the start of each function. 174 After rtl generation, it is 1 plus the largest register number used. */ 175 176extern int reg_rtx_no; 177 178/* Vector indexed by regno; contains 1 for a register is considered a pointer. 179 Reloading, etc. will use a pointer register rather than a non-pointer 180 as the base register in an address, when there is a choice of two regs. */ 181 182extern char *regno_pointer_flag; 183#define REGNO_POINTER_FLAG(REGNO) regno_pointer_flag[REGNO] 184extern int regno_pointer_flag_length; 185 186/* List made of EXPR_LIST rtx's which gives pairs of pseudo registers 187 that have to go in the same hard reg. */ 188extern rtx regs_may_share; 189 190/* Vector mapping pseudo regno into the REG rtx for that register. 191 This is computed by reg_scan. */ 192 193extern rtx *regno_reg_rtx; 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/* Allocated in local_alloc. */ 215 216/* A list of SCRATCH rtl allocated by local-alloc. */ 217extern rtx *scratch_list; 218/* The basic block in which each SCRATCH is used. */ 219extern int *scratch_block; 220/* The length of the arrays pointed to by scratch_block and scratch_list. */ 221extern int scratch_list_length; 222 223/* Allocate reg_n_info tables */ 224extern void allocate_reg_info PROTO((size_t, int, int)); 225