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