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1 /* Define per-register tables for data flow info and register allocation.
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2 Copyright (C) 1987, 1993, 1994, 1995, 1996, 1997, 1998,
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3 1999, 2000, 2003, 2004, 2005, 2006, 2007, 2008 Free Software
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4 Foundation, Inc.
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5
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6 This file is part of GCC.
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7
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8 GCC is free software; you can redistribute it and/or modify it under
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9 the terms of the GNU General Public License as published by the Free
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10 Software Foundation; either version 3, or (at your option) any later
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11 version.
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12
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13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
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15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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16 for more details.
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17
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18 You should have received a copy of the GNU General Public License
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19 along with GCC; see the file COPYING3. If not see
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20 <http://www.gnu.org/licenses/>. */
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21
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22 #ifndef GCC_REGS_H
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23 #define GCC_REGS_H
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24
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25 #include "varray.h"
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26 #include "obstack.h"
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27 #include "hard-reg-set.h"
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28 #include "basic-block.h"
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29
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30 #define REG_BYTES(R) mode_size[(int) GET_MODE (R)]
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31
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32 /* When you only have the mode of a pseudo register before it has a hard
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33 register chosen for it, this reports the size of each hard register
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34 a pseudo in such a mode would get allocated to. A target may
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35 override this. */
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36
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37 #ifndef REGMODE_NATURAL_SIZE
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38 #define REGMODE_NATURAL_SIZE(MODE) UNITS_PER_WORD
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39 #endif
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40
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41 #ifndef SMALL_REGISTER_CLASSES
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42 #define SMALL_REGISTER_CLASSES 0
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43 #endif
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44
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45 /* Maximum register number used in this function, plus one. */
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46
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47 extern int max_regno;
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48
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49 /* REG_N_REFS and REG_N_SETS are initialized by a call to
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50 regstat_init_n_sets_and_refs from the current values of
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51 DF_REG_DEF_COUNT and DF_REG_USE_COUNT. REG_N_REFS and REG_N_SETS
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52 should only be used if a pass need to change these values in some
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53 magical way or or the pass needs to have accurate values for these
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54 and is not using incremental df scanning.
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55
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56 At the end of a pass that uses REG_N_REFS and REG_N_SETS, a call
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57 should be made to regstat_free_n_sets_and_refs.
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58
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59 Local alloc seems to play pretty loose with these values.
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60 REG_N_REFS is set to 0 if the register is used in an asm.
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61 Furthermore, local_alloc calls regclass to hack both REG_N_REFS and
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62 REG_N_SETS for three address insns. Other passes seem to have
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63 other special values. */
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64
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65
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66
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67 /* Structure to hold values for REG_N_SETS (i) and REG_N_REFS (i). */
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68
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69 struct regstat_n_sets_and_refs_t
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70 {
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71 int sets; /* # of times (REG n) is set */
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72 int refs; /* # of times (REG n) is used or set */
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73 };
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74
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75 extern struct regstat_n_sets_and_refs_t *regstat_n_sets_and_refs;
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76
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77 /* Indexed by n, gives number of times (REG n) is used or set. */
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78 static inline int
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79 REG_N_REFS(int regno)
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80 {
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81 return regstat_n_sets_and_refs[regno].refs;
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82 }
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83
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84 /* Indexed by n, gives number of times (REG n) is used or set. */
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85 #define SET_REG_N_REFS(N,V) (regstat_n_sets_and_refs[N].refs = V)
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86 #define INC_REG_N_REFS(N,V) (regstat_n_sets_and_refs[N].refs += V)
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87
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88 /* Indexed by n, gives number of times (REG n) is set. */
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89 static inline int
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90 REG_N_SETS (int regno)
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91 {
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92 return regstat_n_sets_and_refs[regno].sets;
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93 }
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94
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95 /* Indexed by n, gives number of times (REG n) is set. */
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96 #define SET_REG_N_SETS(N,V) (regstat_n_sets_and_refs[N].sets = V)
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97 #define INC_REG_N_SETS(N,V) (regstat_n_sets_and_refs[N].sets += V)
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98
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99
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100 /* Functions defined in reg-stat.c. */
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101 extern void regstat_init_n_sets_and_refs (void);
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102 extern void regstat_free_n_sets_and_refs (void);
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103 extern void regstat_compute_ri (void);
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104 extern void regstat_free_ri (void);
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105 extern bitmap regstat_get_setjmp_crosses (void);
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106 extern void regstat_compute_calls_crossed (void);
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107 extern void regstat_free_calls_crossed (void);
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108
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109
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110 /* Register information indexed by register number. This structure is
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111 initialized by calling regstat_compute_ri and is destroyed by
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112 calling regstat_free_ri. */
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113 struct reg_info_t
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114 {
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115 int freq; /* # estimated frequency (REG n) is used or set */
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116 int deaths; /* # of times (REG n) dies */
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117 int live_length; /* # of instructions (REG n) is live */
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118 int calls_crossed; /* # of calls (REG n) is live across */
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119 int freq_calls_crossed; /* # estimated frequency (REG n) crosses call */
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120 int throw_calls_crossed; /* # of calls that may throw (REG n) is live across */
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121 int basic_block; /* # of basic blocks (REG n) is used in */
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122 };
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123
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124 extern struct reg_info_t *reg_info_p;
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125
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126 /* The number allocated elements of reg_info_p. */
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127 extern size_t reg_info_p_size;
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128
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129 /* Estimate frequency of references to register N. */
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130
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131 #define REG_FREQ(N) (reg_info_p[N].freq)
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132
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133 /* The weights for each insn varies from 0 to REG_FREQ_BASE.
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134 This constant does not need to be high, as in infrequently executed
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135 regions we want to count instructions equivalently to optimize for
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136 size instead of speed. */
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137 #define REG_FREQ_MAX 1000
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138
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139 /* Compute register frequency from the BB frequency. When optimizing for size,
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140 or profile driven feedback is available and the function is never executed,
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141 frequency is always equivalent. Otherwise rescale the basic block
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142 frequency. */
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143 #define REG_FREQ_FROM_BB(bb) (optimize_size \
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144 || (flag_branch_probabilities \
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145 && !ENTRY_BLOCK_PTR->count) \
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146 ? REG_FREQ_MAX \
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147 : ((bb)->frequency * REG_FREQ_MAX / BB_FREQ_MAX)\
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148 ? ((bb)->frequency * REG_FREQ_MAX / BB_FREQ_MAX)\
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149 : 1)
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150
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151 /* Indexed by N, gives number of insns in which register N dies.
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152 Note that if register N is live around loops, it can die
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153 in transitions between basic blocks, and that is not counted here.
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154 So this is only a reliable indicator of how many regions of life there are
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155 for registers that are contained in one basic block. */
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156
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157 #define REG_N_DEATHS(N) (reg_info_p[N].deaths)
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158
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159 /* Get the number of consecutive words required to hold pseudo-reg N. */
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160
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161 #define PSEUDO_REGNO_SIZE(N) \
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162 ((GET_MODE_SIZE (PSEUDO_REGNO_MODE (N)) + UNITS_PER_WORD - 1) \
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163 / UNITS_PER_WORD)
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164
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165 /* Get the number of bytes required to hold pseudo-reg N. */
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166
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167 #define PSEUDO_REGNO_BYTES(N) \
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168 GET_MODE_SIZE (PSEUDO_REGNO_MODE (N))
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169
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170 /* Get the machine mode of pseudo-reg N. */
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171
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172 #define PSEUDO_REGNO_MODE(N) GET_MODE (regno_reg_rtx[N])
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173
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174 /* Indexed by N, gives number of CALL_INSNS across which (REG n) is live. */
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175
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176 #define REG_N_CALLS_CROSSED(N) (reg_info_p[N].calls_crossed)
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177 #define REG_FREQ_CALLS_CROSSED(N) (reg_info_p[N].freq_calls_crossed)
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178
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179 /* Indexed by N, gives number of CALL_INSNS that may throw, across which
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180 (REG n) is live. */
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181
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182 #define REG_N_THROWING_CALLS_CROSSED(N) (reg_info_p[N].throw_calls_crossed)
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183
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184 /* Total number of instructions at which (REG n) is live. The larger
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185 this is, the less priority (REG n) gets for allocation in a hard
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186 register (in global-alloc). This is set in df-problems.c whenever
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187 register info is requested and remains valid for the rest of the
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188 compilation of the function; it is used to control register
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189 allocation.
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190
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191 local-alloc.c may alter this number to change the priority.
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192
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193 Negative values are special.
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194 -1 is used to mark a pseudo reg which has a constant or memory equivalent
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195 and is used infrequently enough that it should not get a hard register.
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196 -2 is used to mark a pseudo reg for a parameter, when a frame pointer
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197 is not required. global.c makes an allocno for this but does
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198 not try to assign a hard register to it. */
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199
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200 #define REG_LIVE_LENGTH(N) (reg_info_p[N].live_length)
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201
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202 /* Indexed by n, gives number of basic block that (REG n) is used in.
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203 If the value is REG_BLOCK_GLOBAL (-1),
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204 it means (REG n) is used in more than one basic block.
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205 REG_BLOCK_UNKNOWN (0) means it hasn't been seen yet so we don't know.
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206 This information remains valid for the rest of the compilation
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207 of the current function; it is used to control register allocation. */
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208
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209 #define REG_BLOCK_UNKNOWN 0
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210 #define REG_BLOCK_GLOBAL -1
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211
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212 #define REG_BASIC_BLOCK(N) (reg_info_p[N].basic_block)
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213
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214 /* Vector of substitutions of register numbers,
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215 used to map pseudo regs into hardware regs.
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216
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217 This can't be folded into reg_n_info without changing all of the
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218 machine dependent directories, since the reload functions
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219 in the machine dependent files access it. */
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220
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221 extern short *reg_renumber;
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222
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223 /* Vector indexed by machine mode saying whether there are regs of that mode. */
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224
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225 extern bool have_regs_of_mode [MAX_MACHINE_MODE];
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226
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227 /* For each hard register, the widest mode object that it can contain.
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228 This will be a MODE_INT mode if the register can hold integers. Otherwise
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229 it will be a MODE_FLOAT or a MODE_CC mode, whichever is valid for the
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230 register. */
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231
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232 extern enum machine_mode reg_raw_mode[FIRST_PSEUDO_REGISTER];
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233
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234 /* Flag set by local-alloc or global-alloc if they decide to allocate
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235 something in a call-clobbered register. */
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236
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237 extern int caller_save_needed;
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238
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239 /* Predicate to decide whether to give a hard reg to a pseudo which
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240 is referenced REFS times and would need to be saved and restored
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241 around a call CALLS times. */
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242
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243 #ifndef CALLER_SAVE_PROFITABLE
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244 #define CALLER_SAVE_PROFITABLE(REFS, CALLS) (4 * (CALLS) < (REFS))
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245 #endif
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246
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247 /* On most machines a register class is likely to be spilled if it
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248 only has one register. */
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249 #ifndef CLASS_LIKELY_SPILLED_P
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250 #define CLASS_LIKELY_SPILLED_P(CLASS) (reg_class_size[(int) (CLASS)] == 1)
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251 #endif
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252
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253 /* Select a register mode required for caller save of hard regno REGNO. */
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254 #ifndef HARD_REGNO_CALLER_SAVE_MODE
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255 #define HARD_REGNO_CALLER_SAVE_MODE(REGNO, NREGS, MODE) \
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256 choose_hard_reg_mode (REGNO, NREGS, false)
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257 #endif
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258
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259 /* Registers that get partially clobbered by a call in a given mode.
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260 These must not be call used registers. */
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261 #ifndef HARD_REGNO_CALL_PART_CLOBBERED
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262 #define HARD_REGNO_CALL_PART_CLOBBERED(REGNO, MODE) 0
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263 #endif
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264
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265 /* 1 if the corresponding class does contain register of given
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266 mode. */
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267 extern char contains_reg_of_mode [N_REG_CLASSES] [MAX_MACHINE_MODE];
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268
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269 typedef unsigned short move_table[N_REG_CLASSES];
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270
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271 /* Maximum cost of moving from a register in one class to a register
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272 in another class. */
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273 extern move_table *move_cost[MAX_MACHINE_MODE];
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274
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275 /* Specify number of hard registers given machine mode occupy. */
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276 extern unsigned char hard_regno_nregs[FIRST_PSEUDO_REGISTER][MAX_MACHINE_MODE];
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277
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278 /* Similar, but here we don't have to move if the first index is a
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279 subset of the second so in that case the cost is zero. */
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280 extern move_table *may_move_in_cost[MAX_MACHINE_MODE];
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281
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282 /* Similar, but here we don't have to move if the first index is a
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283 superset of the second so in that case the cost is zero. */
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284 extern move_table *may_move_out_cost[MAX_MACHINE_MODE];
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285
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286 /* Return an exclusive upper bound on the registers occupied by hard
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287 register (reg:MODE REGNO). */
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288
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289 static inline unsigned int
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290 end_hard_regno (enum machine_mode mode, unsigned int regno)
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291 {
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292 return regno + hard_regno_nregs[regno][(int) mode];
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293 }
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294
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295 /* Likewise for hard register X. */
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296
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297 #define END_HARD_REGNO(X) end_hard_regno (GET_MODE (X), REGNO (X))
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298
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299 /* Likewise for hard or pseudo register X. */
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300
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301 #define END_REGNO(X) (HARD_REGISTER_P (X) ? END_HARD_REGNO (X) : REGNO (X) + 1)
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302
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303 /* Add to REGS all the registers required to store a value of mode MODE
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304 in register REGNO. */
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305
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306 static inline void
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307 add_to_hard_reg_set (HARD_REG_SET *regs, enum machine_mode mode,
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308 unsigned int regno)
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309 {
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310 unsigned int end_regno;
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311
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312 end_regno = end_hard_regno (mode, regno);
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313 do
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314 SET_HARD_REG_BIT (*regs, regno);
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315 while (++regno < end_regno);
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316 }
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317
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318 /* Likewise, but remove the registers. */
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319
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320 static inline void
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321 remove_from_hard_reg_set (HARD_REG_SET *regs, enum machine_mode mode,
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322 unsigned int regno)
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323 {
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324 unsigned int end_regno;
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325
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326 end_regno = end_hard_regno (mode, regno);
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327 do
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328 CLEAR_HARD_REG_BIT (*regs, regno);
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329 while (++regno < end_regno);
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330 }
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331
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332 /* Return true if REGS contains the whole of (reg:MODE REGNO). */
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333
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334 static inline bool
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335 in_hard_reg_set_p (const HARD_REG_SET regs, enum machine_mode mode,
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336 unsigned int regno)
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337 {
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338 unsigned int end_regno;
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339
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340 if (!TEST_HARD_REG_BIT (regs, regno))
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341 return false;
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342
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343 end_regno = end_hard_regno (mode, regno);
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344 while (++regno < end_regno)
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345 if (!TEST_HARD_REG_BIT (regs, regno))
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346 return false;
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347
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348 return true;
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349 }
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350
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351 /* Return true if (reg:MODE REGNO) includes an element of REGS. */
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352
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353 static inline bool
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354 overlaps_hard_reg_set_p (const HARD_REG_SET regs, enum machine_mode mode,
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355 unsigned int regno)
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356 {
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357 unsigned int end_regno;
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358
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359 if (TEST_HARD_REG_BIT (regs, regno))
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360 return true;
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361
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362 end_regno = end_hard_regno (mode, regno);
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363 while (++regno < end_regno)
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364 if (TEST_HARD_REG_BIT (regs, regno))
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365 return true;
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366
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367 return false;
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368 }
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369
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370 #endif /* GCC_REGS_H */
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