111
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1 /* Code coverage instrumentation for fuzzing.
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2 Copyright (C) 2015-2020 Free Software Foundation, Inc.
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3 Contributed by Dmitry Vyukov <dvyukov@google.com> and
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4 Wish Wu <wishwu007@gmail.com>
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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 #include "config.h"
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23 #include "system.h"
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24 #include "coretypes.h"
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25 #include "backend.h"
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26 #include "tree.h"
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27 #include "gimple.h"
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28 #include "basic-block.h"
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29 #include "options.h"
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30 #include "flags.h"
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31 #include "memmodel.h"
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32 #include "tm_p.h"
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33 #include "stmt.h"
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34 #include "gimple-iterator.h"
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35 #include "gimple-builder.h"
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36 #include "tree-cfg.h"
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37 #include "tree-pass.h"
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38 #include "tree-iterator.h"
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39 #include "fold-const.h"
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40 #include "stringpool.h"
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41 #include "attribs.h"
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42 #include "output.h"
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43 #include "cgraph.h"
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44 #include "asan.h"
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45
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46 namespace {
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47
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48 /* Instrument one comparison operation, which compares lhs and rhs.
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49 Call the instrumentation function with the comparison operand.
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50 For integral comparisons if exactly one of the comparison operands is
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51 constant, call __sanitizer_cov_trace_const_cmp* instead of
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52 __sanitizer_cov_trace_cmp*. */
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53
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54 static void
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55 instrument_comparison (gimple_stmt_iterator *gsi, tree lhs, tree rhs)
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56 {
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57 tree type = TREE_TYPE (lhs);
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58 enum built_in_function fncode = END_BUILTINS;
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59 tree to_type = NULL_TREE;
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60 bool c = false;
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61
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62 if (INTEGRAL_TYPE_P (type))
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63 {
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64 c = (is_gimple_min_invariant (lhs)
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65 ^ is_gimple_min_invariant (rhs));
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66 switch (int_size_in_bytes (type))
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67 {
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68 case 1:
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69 fncode = c ? BUILT_IN_SANITIZER_COV_TRACE_CONST_CMP1
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70 : BUILT_IN_SANITIZER_COV_TRACE_CMP1;
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71 to_type = unsigned_char_type_node;
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72 break;
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73 case 2:
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74 fncode = c ? BUILT_IN_SANITIZER_COV_TRACE_CONST_CMP2
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75 : BUILT_IN_SANITIZER_COV_TRACE_CMP2;
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76 to_type = uint16_type_node;
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77 break;
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78 case 4:
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79 fncode = c ? BUILT_IN_SANITIZER_COV_TRACE_CONST_CMP4
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80 : BUILT_IN_SANITIZER_COV_TRACE_CMP4;
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81 to_type = uint32_type_node;
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82 break;
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83 default:
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84 fncode = c ? BUILT_IN_SANITIZER_COV_TRACE_CONST_CMP8
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85 : BUILT_IN_SANITIZER_COV_TRACE_CMP8;
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86 to_type = uint64_type_node;
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87 break;
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88 }
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89 }
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90 else if (SCALAR_FLOAT_TYPE_P (type))
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91 {
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92 if (TYPE_MODE (type) == TYPE_MODE (float_type_node))
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93 {
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94 fncode = BUILT_IN_SANITIZER_COV_TRACE_CMPF;
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95 to_type = float_type_node;
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96 }
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97 else if (TYPE_MODE (type) == TYPE_MODE (double_type_node))
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98 {
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99 fncode = BUILT_IN_SANITIZER_COV_TRACE_CMPD;
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100 to_type = double_type_node;
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101 }
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102 }
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103
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104 if (to_type != NULL_TREE)
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105 {
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106 gimple_seq seq = NULL;
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107
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108 if (!useless_type_conversion_p (to_type, type))
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109 {
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110 if (TREE_CODE (lhs) == INTEGER_CST)
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111 lhs = fold_convert (to_type, lhs);
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112 else
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113 {
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114 gimple_seq_add_stmt (&seq, build_type_cast (to_type, lhs));
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115 lhs = gimple_assign_lhs (gimple_seq_last_stmt (seq));
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116 }
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117
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118 if (TREE_CODE (rhs) == INTEGER_CST)
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119 rhs = fold_convert (to_type, rhs);
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120 else
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121 {
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122 gimple_seq_add_stmt (&seq, build_type_cast (to_type, rhs));
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123 rhs = gimple_assign_lhs (gimple_seq_last_stmt (seq));
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124 }
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125 }
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126
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127 if (c && !is_gimple_min_invariant (lhs))
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128 std::swap (lhs, rhs);
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129
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130 tree fndecl = builtin_decl_implicit (fncode);
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131 gimple *gcall = gimple_build_call (fndecl, 2, lhs, rhs);
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132 gimple_seq_add_stmt (&seq, gcall);
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133
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134 gimple_seq_set_location (seq, gimple_location (gsi_stmt (*gsi)));
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135 gsi_insert_seq_before (gsi, seq, GSI_SAME_STMT);
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136 }
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137 }
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138
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139 /* Instrument switch statement. Call __sanitizer_cov_trace_switch with
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140 the value of the index and array that contains number of case values,
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141 the bitsize of the index and the case values converted to uint64_t. */
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142
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143 static void
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144 instrument_switch (gimple_stmt_iterator *gsi, gimple *stmt, function *fun)
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145 {
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146 gswitch *switch_stmt = as_a<gswitch *> (stmt);
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147 tree index = gimple_switch_index (switch_stmt);
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148 HOST_WIDE_INT size_in_bytes = int_size_in_bytes (TREE_TYPE (index));
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149 if (size_in_bytes == -1 || size_in_bytes > 8)
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150 return;
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151
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152 location_t loc = gimple_location (stmt);
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153 unsigned i, n = gimple_switch_num_labels (switch_stmt), num = 0;
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154 for (i = 1; i < n; ++i)
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155 {
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156 tree label = gimple_switch_label (switch_stmt, i);
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157
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158 tree low_case = CASE_LOW (label);
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159 if (low_case != NULL_TREE)
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160 num++;
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161
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162 tree high_case = CASE_HIGH (label);
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163 if (high_case != NULL_TREE)
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164 num++;
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165 }
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166
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167 tree case_array_type
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168 = build_array_type (build_type_variant (uint64_type_node, 1, 0),
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169 build_index_type (size_int (num + 2 - 1)));
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170
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171 char name[64];
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172 static size_t case_array_count = 0;
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173 ASM_GENERATE_INTERNAL_LABEL (name, "LCASEARRAY", case_array_count++);
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174 tree case_array_var = build_decl (loc, VAR_DECL, get_identifier (name),
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175 case_array_type);
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176 TREE_STATIC (case_array_var) = 1;
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177 TREE_PUBLIC (case_array_var) = 0;
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178 TREE_CONSTANT (case_array_var) = 1;
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179 TREE_READONLY (case_array_var) = 1;
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180 DECL_EXTERNAL (case_array_var) = 0;
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181 DECL_ARTIFICIAL (case_array_var) = 1;
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182 DECL_IGNORED_P (case_array_var) = 1;
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183
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184 vec <constructor_elt, va_gc> *v = NULL;
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185 vec_alloc (v, num + 2);
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186 CONSTRUCTOR_APPEND_ELT (v, NULL_TREE,
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187 build_int_cst (uint64_type_node, num));
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188 CONSTRUCTOR_APPEND_ELT (v, NULL_TREE,
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189 build_int_cst (uint64_type_node,
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190 size_in_bytes * BITS_PER_UNIT));
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191 for (i = 1; i < n; ++i)
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192 {
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193 tree label = gimple_switch_label (switch_stmt, i);
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194
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195 tree low_case = CASE_LOW (label);
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196 if (low_case != NULL_TREE)
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197 CONSTRUCTOR_APPEND_ELT (v, NULL_TREE,
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198 fold_convert (uint64_type_node, low_case));
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199
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200 tree high_case = CASE_HIGH (label);
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201 if (high_case != NULL_TREE)
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202 CONSTRUCTOR_APPEND_ELT (v, NULL_TREE,
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203 fold_convert (uint64_type_node, high_case));
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204 }
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205 tree ctor = build_constructor (case_array_type, v);
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206 TREE_STATIC (ctor) = 1;
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207 TREE_PUBLIC (ctor) = 0;
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208 TREE_CONSTANT (ctor) = 1;
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209 TREE_READONLY (ctor) = 1;
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210 DECL_INITIAL (case_array_var) = ctor;
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211 varpool_node::finalize_decl (case_array_var);
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212 add_local_decl (fun, case_array_var);
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213
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214 gimple_seq seq = NULL;
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215
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216 if (!useless_type_conversion_p (uint64_type_node, TREE_TYPE (index)))
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217 {
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218 if (TREE_CODE (index) == INTEGER_CST)
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219 index = fold_convert (uint64_type_node, index);
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220 else
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221 {
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222 gimple_seq_add_stmt (&seq, build_type_cast (uint64_type_node, index));
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223 index = gimple_assign_lhs (gimple_seq_last_stmt (seq));
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224 }
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225 }
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226
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227 tree fndecl = builtin_decl_implicit (BUILT_IN_SANITIZER_COV_TRACE_SWITCH);
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228 gimple *gcall = gimple_build_call (fndecl, 2, index,
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229 build_fold_addr_expr (case_array_var));
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230 gimple_seq_add_stmt (&seq, gcall);
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231
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232 gimple_seq_set_location (seq, loc);
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233 gsi_insert_seq_before (gsi, seq, GSI_SAME_STMT);
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234 }
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235
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236 unsigned
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237 sancov_pass (function *fun)
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238 {
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239 initialize_sanitizer_builtins ();
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240
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241 /* Insert callback into beginning of every BB. */
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242 if (flag_sanitize_coverage & SANITIZE_COV_TRACE_PC)
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243 {
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244 basic_block bb;
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245 tree fndecl = builtin_decl_implicit (BUILT_IN_SANITIZER_COV_TRACE_PC);
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246 FOR_EACH_BB_FN (bb, fun)
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247 {
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248 gimple_stmt_iterator gsi = gsi_start_nondebug_after_labels_bb (bb);
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249 if (gsi_end_p (gsi))
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250 continue;
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251 gimple *stmt = gsi_stmt (gsi);
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252 gimple *gcall = gimple_build_call (fndecl, 0);
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253 gimple_set_location (gcall, gimple_location (stmt));
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254 gsi_insert_before (&gsi, gcall, GSI_SAME_STMT);
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255 }
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256 }
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257
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258 /* Insert callback into every comparison related operation. */
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259 if (flag_sanitize_coverage & SANITIZE_COV_TRACE_CMP)
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260 {
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261 basic_block bb;
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262 FOR_EACH_BB_FN (bb, fun)
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263 {
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264 gimple_stmt_iterator gsi;
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265 for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
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266 {
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267 gimple *stmt = gsi_stmt (gsi);
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268 enum tree_code rhs_code;
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269 switch (gimple_code (stmt))
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270 {
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271 case GIMPLE_ASSIGN:
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272 rhs_code = gimple_assign_rhs_code (stmt);
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273 if (TREE_CODE_CLASS (rhs_code) == tcc_comparison)
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274 instrument_comparison (&gsi,
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275 gimple_assign_rhs1 (stmt),
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276 gimple_assign_rhs2 (stmt));
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277 else if (rhs_code == COND_EXPR
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278 && COMPARISON_CLASS_P (gimple_assign_rhs1 (stmt)))
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279 {
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280 tree cond = gimple_assign_rhs1 (stmt);
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281 instrument_comparison (&gsi, TREE_OPERAND (cond, 0),
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282 TREE_OPERAND (cond, 1));
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283 }
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284 break;
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285 case GIMPLE_COND:
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286 instrument_comparison (&gsi,
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287 gimple_cond_lhs (stmt),
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288 gimple_cond_rhs (stmt));
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289 break;
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290
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291 case GIMPLE_SWITCH:
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292 instrument_switch (&gsi, stmt, fun);
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293 break;
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294
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295 default:
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296 break;
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297 }
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298 }
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299 }
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300 }
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301 return 0;
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302 }
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303
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304 template <bool O0> class pass_sancov : public gimple_opt_pass
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305 {
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306 public:
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307 pass_sancov (gcc::context *ctxt) : gimple_opt_pass (data, ctxt) {}
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308
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309 static const pass_data data;
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310 opt_pass *
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311 clone ()
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312 {
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313 return new pass_sancov<O0> (m_ctxt);
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314 }
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315 virtual bool
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316 gate (function *)
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317 {
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318 return flag_sanitize_coverage && (!O0 || !optimize);
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319 }
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320 virtual unsigned int
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321 execute (function *fun)
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322 {
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323 return sancov_pass (fun);
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324 }
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325 }; // class pass_sancov
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326
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327 template <bool O0>
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328 const pass_data pass_sancov<O0>::data = {
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329 GIMPLE_PASS, /* type */
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330 O0 ? "sancov_O0" : "sancov", /* name */
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331 OPTGROUP_NONE, /* optinfo_flags */
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332 TV_NONE, /* tv_id */
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333 (PROP_cfg), /* properties_required */
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334 0, /* properties_provided */
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335 0, /* properties_destroyed */
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336 0, /* todo_flags_start */
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337 TODO_update_ssa, /* todo_flags_finish */
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338 };
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339
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340 } // anon namespace
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341
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342 gimple_opt_pass *
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343 make_pass_sancov (gcc::context *ctxt)
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344 {
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345 return new pass_sancov<false> (ctxt);
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346 }
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347
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348 gimple_opt_pass *
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349 make_pass_sancov_O0 (gcc::context *ctxt)
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350 {
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351 return new pass_sancov<true> (ctxt);
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352 }
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