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1 /* String pool for GCC.
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2 Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2007, 2008
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3 Free Software Foundation, Inc.
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4
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5 This file is part of GCC.
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6
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7 GCC is free software; you can redistribute it and/or modify it under
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8 the terms of the GNU General Public License as published by the Free
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9 Software Foundation; either version 3, or (at your option) any later
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10 version.
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11
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12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
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14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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15 for more details.
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16
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17 You should have received a copy of the GNU General Public License
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18 along with GCC; see the file COPYING3. If not see
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19 <http://www.gnu.org/licenses/>. */
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20
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21 /* String text, identifier text and identifier node allocator.
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22 Identifiers are uniquely stored in a hash table.
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23
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24 We use cpplib's hash table implementation. libiberty's
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25 hashtab.c is not used because it requires 100% average space
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26 overhead per string, which is unacceptable. Also, this algorithm
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27 is faster. */
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28
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29 #include "config.h"
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30 #include "system.h"
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31 #include "coretypes.h"
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32 #include "tm.h"
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33 #include "ggc.h"
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34 #include "tree.h"
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35 #include "symtab.h"
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36 #include "cpplib.h"
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37
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38 /* The "" allocated string. */
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39 const char empty_string[] = "";
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40
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41 /* Character strings, each containing a single decimal digit.
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42 Written this way to save space. */
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43 const char digit_vector[] = {
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44 '0', 0, '1', 0, '2', 0, '3', 0, '4', 0,
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45 '5', 0, '6', 0, '7', 0, '8', 0, '9', 0
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46 };
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47
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48 struct ht *ident_hash;
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49
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50 static hashnode alloc_node (hash_table *);
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51 static int mark_ident (struct cpp_reader *, hashnode, const void *);
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52
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53 static void *
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54 stringpool_ggc_alloc (size_t x)
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55 {
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56 return ggc_alloc (x);
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57 }
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58
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59 /* Initialize the string pool. */
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60 void
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61 init_stringpool (void)
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62 {
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63 /* Create with 16K (2^14) entries. */
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64 ident_hash = ht_create (14);
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65 ident_hash->alloc_node = alloc_node;
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66 ident_hash->alloc_subobject = stringpool_ggc_alloc;
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67 }
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68
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69 /* Allocate a hash node. */
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70 static hashnode
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71 alloc_node (hash_table *table ATTRIBUTE_UNUSED)
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72 {
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73 return GCC_IDENT_TO_HT_IDENT (make_node (IDENTIFIER_NODE));
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74 }
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75
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76 /* Allocate and return a string constant of length LENGTH, containing
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77 CONTENTS. If LENGTH is -1, CONTENTS is assumed to be a
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78 nul-terminated string, and the length is calculated using strlen. */
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79
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80 const char *
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81 ggc_alloc_string (const char *contents, int length)
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82 {
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83 char *result;
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84
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85 if (length == -1)
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86 length = strlen (contents);
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87
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88 if (length == 0)
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89 return empty_string;
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90 if (length == 1 && ISDIGIT (contents[0]))
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91 return digit_string (contents[0] - '0');
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92
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93 result = GGC_NEWVAR (char, length + 1);
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94 memcpy (result, contents, length);
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95 result[length] = '\0';
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96 return (const char *) result;
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97 }
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98
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99 /* Return an IDENTIFIER_NODE whose name is TEXT (a null-terminated string).
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100 If an identifier with that name has previously been referred to,
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101 the same node is returned this time. */
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102
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103 #undef get_identifier
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104
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105 tree
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106 get_identifier (const char *text)
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107 {
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108 hashnode ht_node = ht_lookup (ident_hash,
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109 (const unsigned char *) text,
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110 strlen (text), HT_ALLOC);
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111
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112 /* ht_node can't be NULL here. */
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113 return HT_IDENT_TO_GCC_IDENT (ht_node);
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114 }
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115
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116 /* Identical to get_identifier, except that the length is assumed
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117 known. */
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118
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119 tree
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120 get_identifier_with_length (const char *text, size_t length)
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121 {
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122 hashnode ht_node = ht_lookup (ident_hash,
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123 (const unsigned char *) text,
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124 length, HT_ALLOC);
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125
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126 /* ht_node can't be NULL here. */
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127 return HT_IDENT_TO_GCC_IDENT (ht_node);
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128 }
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129
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130 /* If an identifier with the name TEXT (a null-terminated string) has
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131 previously been referred to, return that node; otherwise return
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132 NULL_TREE. */
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133
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134 tree
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135 maybe_get_identifier (const char *text)
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136 {
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137 hashnode ht_node;
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138
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139 ht_node = ht_lookup (ident_hash, (const unsigned char *) text,
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140 strlen (text), HT_NO_INSERT);
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141 if (ht_node)
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142 return HT_IDENT_TO_GCC_IDENT (ht_node);
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143
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144 return NULL_TREE;
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145 }
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146
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147 /* Report some basic statistics about the string pool. */
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148
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149 void
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150 stringpool_statistics (void)
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151 {
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152 ht_dump_statistics (ident_hash);
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153 }
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154
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155 /* Mark an identifier for GC. */
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156
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157 static int
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158 mark_ident (struct cpp_reader *pfile ATTRIBUTE_UNUSED, hashnode h,
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159 const void *v ATTRIBUTE_UNUSED)
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160 {
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161 gt_ggc_m_9tree_node (HT_IDENT_TO_GCC_IDENT (h));
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162 return 1;
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163 }
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164
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165 /* Return true if an identifier should be removed from the table. */
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166
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167 static int
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168 maybe_delete_ident (struct cpp_reader *pfile ATTRIBUTE_UNUSED, hashnode h,
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169 const void *v ATTRIBUTE_UNUSED)
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170 {
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171 return !ggc_marked_p (HT_IDENT_TO_GCC_IDENT (h));
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172 }
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173
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174 /* Mark the trees hanging off the identifier node for GGC. These are
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175 handled specially (not using gengtype) because identifiers are only
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176 roots during one part of compilation. */
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177
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178 void
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179 ggc_mark_stringpool (void)
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180 {
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181 ht_forall (ident_hash, mark_ident, NULL);
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182 }
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183
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184 /* Purge the identifier hash of identifiers which are no longer
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185 referenced. */
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186
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187 void
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188 ggc_purge_stringpool (void)
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189 {
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190 ht_purge (ident_hash, maybe_delete_ident, NULL);
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191 }
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192
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193 /* Pointer-walking routine for strings (not very interesting, since
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194 strings don't contain pointers). */
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195
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196 void
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197 gt_pch_p_S (void *obj ATTRIBUTE_UNUSED, void *x ATTRIBUTE_UNUSED,
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198 gt_pointer_operator op ATTRIBUTE_UNUSED,
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199 void *cookie ATTRIBUTE_UNUSED)
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200 {
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201 }
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202
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203 /* PCH pointer-walking routine for strings. */
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204
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205 void
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206 gt_pch_n_S (const void *x)
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207 {
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208 gt_pch_note_object (CONST_CAST (void *, x), CONST_CAST (void *, x),
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209 >_pch_p_S, gt_types_enum_last);
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210 }
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211
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212 /* Handle saving and restoring the string pool for PCH. */
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213
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214 /* SPD is saved in the PCH file and holds the information needed
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215 to restore the string pool. */
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216
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217 struct string_pool_data GTY(())
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218 {
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219 struct ht_identifier * *
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220 GTY((length ("%h.nslots"),
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221 nested_ptr (union tree_node, "%h ? GCC_IDENT_TO_HT_IDENT (%h) : NULL",
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222 "%h ? HT_IDENT_TO_GCC_IDENT (%h) : NULL")))
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223 entries;
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224 unsigned int nslots;
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225 unsigned int nelements;
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226 };
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227
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228 static GTY(()) struct string_pool_data * spd;
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229
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230 /* Save the stringpool data in SPD. */
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231
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232 void
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233 gt_pch_save_stringpool (void)
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234 {
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235 spd = GGC_NEW (struct string_pool_data);
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236 spd->nslots = ident_hash->nslots;
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237 spd->nelements = ident_hash->nelements;
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238 spd->entries = GGC_NEWVEC (struct ht_identifier *, spd->nslots);
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239 memcpy (spd->entries, ident_hash->entries,
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240 spd->nslots * sizeof (spd->entries[0]));
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241 }
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242
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243 /* Return the stringpool to its state before gt_pch_save_stringpool
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244 was called. */
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245
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246 void
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247 gt_pch_fixup_stringpool (void)
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248 {
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249 }
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250
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251 /* A PCH file has been restored, which loaded SPD; fill the real hash table
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252 from SPD. */
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253
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254 void
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255 gt_pch_restore_stringpool (void)
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256 {
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257 ht_load (ident_hash, spd->entries, spd->nslots, spd->nelements, false);
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258 spd = NULL;
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259 }
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260
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261 #include "gt-stringpool.h"
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