0
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1 /* Functions dealing with attribute handling, used by most front ends.
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2 Copyright (C) 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001,
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3 2002, 2003, 2004, 2005, 2007, 2008 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 #include "config.h"
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22 #include "system.h"
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23 #include "coretypes.h"
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24 #include "tm.h"
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25 #include "tree.h"
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26 #include "flags.h"
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27 #include "toplev.h"
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28 #include "output.h"
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29 #include "rtl.h"
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30 #include "ggc.h"
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31 #include "tm_p.h"
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32 #include "cpplib.h"
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33 #include "target.h"
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34 #include "langhooks.h"
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35 #include "hashtab.h"
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36 #include "c-common.h"
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37
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38 static void init_attributes (void);
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39
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40 /* Table of the tables of attributes (common, language, format, machine)
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41 searched. */
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42 static const struct attribute_spec *attribute_tables[4];
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43
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44 /* Hashtable mapping names (represented as substrings) to attribute specs. */
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45 static htab_t attribute_hash;
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46
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47 /* Substring representation. */
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48
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49 struct substring
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50 {
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51 const char *str;
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52 int length;
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53 };
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54
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55 static bool attributes_initialized = false;
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56
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57 /* Default empty table of attributes. */
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58
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59 static const struct attribute_spec empty_attribute_table[] =
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60 {
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61 { NULL, 0, 0, false, false, false, NULL }
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62 };
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63
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64 /* Return base name of the attribute. Ie '__attr__' is turned into 'attr'.
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65 To avoid need for copying, we simply return length of the string. */
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66
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67 static void
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68 extract_attribute_substring (struct substring *str)
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69 {
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70 if (str->length > 4 && str->str[0] == '_' && str->str[1] == '_'
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71 && str->str[str->length - 1] == '_' && str->str[str->length - 2] == '_')
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72 {
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73 str->length -= 4;
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74 str->str += 2;
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75 }
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76 }
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77
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78 /* Simple hash function to avoid need to scan whole string. */
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79
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80 static inline hashval_t
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81 substring_hash (const char *str, int l)
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82 {
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83 return str[0] + str[l - 1] * 256 + l * 65536;
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84 }
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85
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86 /* Used for attribute_hash. */
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87
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88 static hashval_t
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89 hash_attr (const void *p)
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90 {
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91 const struct attribute_spec *const spec = (const struct attribute_spec *) p;
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92 const int l = strlen (spec->name);
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93
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94 return substring_hash (spec->name, l);
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95 }
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96
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97 /* Used for attribute_hash. */
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98
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99 static int
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100 eq_attr (const void *p, const void *q)
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101 {
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102 const struct attribute_spec *const spec = (const struct attribute_spec *) p;
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103 const struct substring *const str = (const struct substring *) q;
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104
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105 return (!strncmp (spec->name, str->str, str->length) && !spec->name[str->length]);
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106 }
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107
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108 /* Initialize attribute tables, and make some sanity checks
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109 if --enable-checking. */
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110
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111 static void
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112 init_attributes (void)
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113 {
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114 size_t i;
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115 int k;
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116
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117 attribute_tables[0] = lang_hooks.common_attribute_table;
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118 attribute_tables[1] = lang_hooks.attribute_table;
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119 attribute_tables[2] = lang_hooks.format_attribute_table;
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120 attribute_tables[3] = targetm.attribute_table;
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121
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122 /* Translate NULL pointers to pointers to the empty table. */
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123 for (i = 0; i < ARRAY_SIZE (attribute_tables); i++)
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124 if (attribute_tables[i] == NULL)
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125 attribute_tables[i] = empty_attribute_table;
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126
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127 #ifdef ENABLE_CHECKING
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128 /* Make some sanity checks on the attribute tables. */
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129 for (i = 0; i < ARRAY_SIZE (attribute_tables); i++)
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130 {
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131 int j;
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132
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133 for (j = 0; attribute_tables[i][j].name != NULL; j++)
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134 {
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135 /* The name must not begin and end with __. */
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136 const char *name = attribute_tables[i][j].name;
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137 int len = strlen (name);
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138
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139 gcc_assert (!(name[0] == '_' && name[1] == '_'
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140 && name[len - 1] == '_' && name[len - 2] == '_'));
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141
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142 /* The minimum and maximum lengths must be consistent. */
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143 gcc_assert (attribute_tables[i][j].min_length >= 0);
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144
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145 gcc_assert (attribute_tables[i][j].max_length == -1
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146 || (attribute_tables[i][j].max_length
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147 >= attribute_tables[i][j].min_length));
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148
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149 /* An attribute cannot require both a DECL and a TYPE. */
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150 gcc_assert (!attribute_tables[i][j].decl_required
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151 || !attribute_tables[i][j].type_required);
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152
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153 /* If an attribute requires a function type, in particular
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154 it requires a type. */
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155 gcc_assert (!attribute_tables[i][j].function_type_required
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156 || attribute_tables[i][j].type_required);
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157 }
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158 }
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159
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160 /* Check that each name occurs just once in each table. */
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161 for (i = 0; i < ARRAY_SIZE (attribute_tables); i++)
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162 {
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163 int j, k;
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164 for (j = 0; attribute_tables[i][j].name != NULL; j++)
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165 for (k = j + 1; attribute_tables[i][k].name != NULL; k++)
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166 gcc_assert (strcmp (attribute_tables[i][j].name,
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167 attribute_tables[i][k].name));
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168 }
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169 /* Check that no name occurs in more than one table. */
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170 for (i = 0; i < ARRAY_SIZE (attribute_tables); i++)
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171 {
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172 size_t j, k, l;
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173
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174 for (j = i + 1; j < ARRAY_SIZE (attribute_tables); j++)
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175 for (k = 0; attribute_tables[i][k].name != NULL; k++)
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176 for (l = 0; attribute_tables[j][l].name != NULL; l++)
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177 gcc_assert (strcmp (attribute_tables[i][k].name,
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178 attribute_tables[j][l].name));
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179 }
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180 #endif
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181
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182 attribute_hash = htab_create (200, hash_attr, eq_attr, NULL);
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183 for (i = 0; i < ARRAY_SIZE (attribute_tables); i++)
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184 for (k = 0; attribute_tables[i][k].name != NULL; k++)
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185 {
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186 struct substring str;
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187 const void **slot;
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188
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189 str.str = attribute_tables[i][k].name;
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190 str.length = strlen (attribute_tables[i][k].name);
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191 slot = (const void **)htab_find_slot_with_hash (attribute_hash, &str,
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192 substring_hash (str.str, str.length),
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193 INSERT);
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194 gcc_assert (!*slot);
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195 *slot = &attribute_tables[i][k];
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196 }
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197 attributes_initialized = true;
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198 }
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199
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200 /* Return the spec for the attribute named NAME. */
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201
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202 const struct attribute_spec *
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203 lookup_attribute_spec (tree name)
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204 {
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205 struct substring attr;
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206
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207 attr.str = IDENTIFIER_POINTER (name);
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208 attr.length = IDENTIFIER_LENGTH (name);
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209 extract_attribute_substring (&attr);
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210 return (const struct attribute_spec *)
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211 htab_find_with_hash (attribute_hash, &attr,
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212 substring_hash (attr.str, attr.length));
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213 }
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214
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215 /* Process the attributes listed in ATTRIBUTES and install them in *NODE,
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216 which is either a DECL (including a TYPE_DECL) or a TYPE. If a DECL,
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217 it should be modified in place; if a TYPE, a copy should be created
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218 unless ATTR_FLAG_TYPE_IN_PLACE is set in FLAGS. FLAGS gives further
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219 information, in the form of a bitwise OR of flags in enum attribute_flags
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220 from tree.h. Depending on these flags, some attributes may be
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221 returned to be applied at a later stage (for example, to apply
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222 a decl attribute to the declaration rather than to its type). */
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223
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224 tree
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225 decl_attributes (tree *node, tree attributes, int flags)
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226 {
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227 tree a;
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228 tree returned_attrs = NULL_TREE;
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229
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230 if (TREE_TYPE (*node) == error_mark_node)
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231 return NULL_TREE;
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232
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233 if (!attributes_initialized)
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234 init_attributes ();
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235
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236 /* If this is a function and the user used #pragma GCC optimize, add the
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237 options to the attribute((optimize(...))) list. */
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238 if (TREE_CODE (*node) == FUNCTION_DECL && current_optimize_pragma)
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239 {
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240 tree cur_attr = lookup_attribute ("optimize", attributes);
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241 tree opts = copy_list (current_optimize_pragma);
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242
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243 if (! cur_attr)
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244 attributes
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245 = tree_cons (get_identifier ("optimize"), opts, attributes);
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246 else
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247 TREE_VALUE (cur_attr) = chainon (opts, TREE_VALUE (cur_attr));
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248 }
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249
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250 if (TREE_CODE (*node) == FUNCTION_DECL
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251 && optimization_current_node != optimization_default_node
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252 && !DECL_FUNCTION_SPECIFIC_OPTIMIZATION (*node))
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253 DECL_FUNCTION_SPECIFIC_OPTIMIZATION (*node) = optimization_current_node;
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254
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255 /* If this is a function and the user used #pragma GCC target, add the
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256 options to the attribute((target(...))) list. */
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257 if (TREE_CODE (*node) == FUNCTION_DECL
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258 && current_target_pragma
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259 && targetm.target_option.valid_attribute_p (*node, NULL_TREE,
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260 current_target_pragma, 0))
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261 {
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262 tree cur_attr = lookup_attribute ("target", attributes);
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263 tree opts = copy_list (current_target_pragma);
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264
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265 if (! cur_attr)
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266 attributes = tree_cons (get_identifier ("target"), opts, attributes);
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267 else
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268 TREE_VALUE (cur_attr) = chainon (opts, TREE_VALUE (cur_attr));
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269 }
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270
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271 targetm.insert_attributes (*node, &attributes);
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272
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273 for (a = attributes; a; a = TREE_CHAIN (a))
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274 {
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275 tree name = TREE_PURPOSE (a);
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276 tree args = TREE_VALUE (a);
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277 tree *anode = node;
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278 const struct attribute_spec *spec = lookup_attribute_spec (name);
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279 bool no_add_attrs = 0;
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280 tree fn_ptr_tmp = NULL_TREE;
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281
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282 if (spec == NULL)
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283 {
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284 warning (OPT_Wattributes, "%qs attribute directive ignored",
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285 IDENTIFIER_POINTER (name));
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286 continue;
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287 }
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288 else if (list_length (args) < spec->min_length
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289 || (spec->max_length >= 0
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290 && list_length (args) > spec->max_length))
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291 {
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292 error ("wrong number of arguments specified for %qs attribute",
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293 IDENTIFIER_POINTER (name));
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294 continue;
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295 }
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296 gcc_assert (is_attribute_p (spec->name, name));
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297
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298 if (spec->decl_required && !DECL_P (*anode))
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299 {
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300 if (flags & ((int) ATTR_FLAG_DECL_NEXT
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301 | (int) ATTR_FLAG_FUNCTION_NEXT
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302 | (int) ATTR_FLAG_ARRAY_NEXT))
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303 {
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304 /* Pass on this attribute to be tried again. */
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305 returned_attrs = tree_cons (name, args, returned_attrs);
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306 continue;
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307 }
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308 else
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309 {
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310 warning (OPT_Wattributes, "%qs attribute does not apply to types",
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311 IDENTIFIER_POINTER (name));
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312 continue;
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313 }
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314 }
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315
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316 /* If we require a type, but were passed a decl, set up to make a
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317 new type and update the one in the decl. ATTR_FLAG_TYPE_IN_PLACE
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318 would have applied if we'd been passed a type, but we cannot modify
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319 the decl's type in place here. */
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320 if (spec->type_required && DECL_P (*anode))
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321 {
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322 anode = &TREE_TYPE (*anode);
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323 /* Allow ATTR_FLAG_TYPE_IN_PLACE for the type's naming decl. */
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324 if (!(TREE_CODE (*anode) == TYPE_DECL
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325 && *anode == TYPE_NAME (TYPE_MAIN_VARIANT
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326 (TREE_TYPE (*anode)))))
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327 flags &= ~(int) ATTR_FLAG_TYPE_IN_PLACE;
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328 }
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329
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330 if (spec->function_type_required && TREE_CODE (*anode) != FUNCTION_TYPE
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331 && TREE_CODE (*anode) != METHOD_TYPE)
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332 {
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333 if (TREE_CODE (*anode) == POINTER_TYPE
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334 && (TREE_CODE (TREE_TYPE (*anode)) == FUNCTION_TYPE
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335 || TREE_CODE (TREE_TYPE (*anode)) == METHOD_TYPE))
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336 {
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337 /* OK, this is a bit convoluted. We can't just make a copy
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338 of the pointer type and modify its TREE_TYPE, because if
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339 we change the attributes of the target type the pointer
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340 type needs to have a different TYPE_MAIN_VARIANT. So we
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341 pull out the target type now, frob it as appropriate, and
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342 rebuild the pointer type later.
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343
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344 This would all be simpler if attributes were part of the
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345 declarator, grumble grumble. */
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346 fn_ptr_tmp = TREE_TYPE (*anode);
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347 anode = &fn_ptr_tmp;
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348 flags &= ~(int) ATTR_FLAG_TYPE_IN_PLACE;
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349 }
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350 else if (flags & (int) ATTR_FLAG_FUNCTION_NEXT)
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351 {
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352 /* Pass on this attribute to be tried again. */
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353 returned_attrs = tree_cons (name, args, returned_attrs);
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354 continue;
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355 }
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356
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357 if (TREE_CODE (*anode) != FUNCTION_TYPE
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358 && TREE_CODE (*anode) != METHOD_TYPE)
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359 {
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360 warning (OPT_Wattributes,
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361 "%qs attribute only applies to function types",
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362 IDENTIFIER_POINTER (name));
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363 continue;
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364 }
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365 }
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366
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367 if (TYPE_P (*anode)
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368 && (flags & (int) ATTR_FLAG_TYPE_IN_PLACE)
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369 && TYPE_SIZE (*anode) != NULL_TREE)
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370 {
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371 warning (OPT_Wattributes, "type attributes ignored after type is already defined");
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372 continue;
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373 }
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374
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375 if (spec->handler != NULL)
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376 returned_attrs = chainon ((*spec->handler) (anode, name, args,
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377 flags, &no_add_attrs),
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378 returned_attrs);
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379
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380 /* Layout the decl in case anything changed. */
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381 if (spec->type_required && DECL_P (*node)
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382 && (TREE_CODE (*node) == VAR_DECL
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383 || TREE_CODE (*node) == PARM_DECL
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384 || TREE_CODE (*node) == RESULT_DECL))
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385 relayout_decl (*node);
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386
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387 if (!no_add_attrs)
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388 {
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389 tree old_attrs;
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390 tree a;
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391
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392 if (DECL_P (*anode))
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393 old_attrs = DECL_ATTRIBUTES (*anode);
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394 else
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395 old_attrs = TYPE_ATTRIBUTES (*anode);
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396
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397 for (a = lookup_attribute (spec->name, old_attrs);
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398 a != NULL_TREE;
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399 a = lookup_attribute (spec->name, TREE_CHAIN (a)))
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400 {
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401 if (simple_cst_equal (TREE_VALUE (a), args) == 1)
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402 break;
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403 }
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404
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405 if (a == NULL_TREE)
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406 {
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407 /* This attribute isn't already in the list. */
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408 if (DECL_P (*anode))
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409 DECL_ATTRIBUTES (*anode) = tree_cons (name, args, old_attrs);
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410 else if (flags & (int) ATTR_FLAG_TYPE_IN_PLACE)
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411 {
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412 TYPE_ATTRIBUTES (*anode) = tree_cons (name, args, old_attrs);
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413 /* If this is the main variant, also push the attributes
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414 out to the other variants. */
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415 if (*anode == TYPE_MAIN_VARIANT (*anode))
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416 {
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417 tree variant;
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418 for (variant = *anode; variant;
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419 variant = TYPE_NEXT_VARIANT (variant))
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420 {
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421 if (TYPE_ATTRIBUTES (variant) == old_attrs)
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422 TYPE_ATTRIBUTES (variant)
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423 = TYPE_ATTRIBUTES (*anode);
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424 else if (!lookup_attribute
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425 (spec->name, TYPE_ATTRIBUTES (variant)))
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426 TYPE_ATTRIBUTES (variant) = tree_cons
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427 (name, args, TYPE_ATTRIBUTES (variant));
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428 }
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429 }
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430 }
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431 else
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432 *anode = build_type_attribute_variant (*anode,
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433 tree_cons (name, args,
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434 old_attrs));
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435 }
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436 }
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437
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438 if (fn_ptr_tmp)
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439 {
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440 /* Rebuild the function pointer type and put it in the
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441 appropriate place. */
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442 fn_ptr_tmp = build_pointer_type (fn_ptr_tmp);
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443 if (DECL_P (*node))
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444 TREE_TYPE (*node) = fn_ptr_tmp;
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445 else
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446 {
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447 gcc_assert (TREE_CODE (*node) == POINTER_TYPE);
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448 *node = fn_ptr_tmp;
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449 }
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450 }
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451 }
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452
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453 return returned_attrs;
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454 }
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