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1 /* -Wnonnull-compare warning support.
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2 Copyright (C) 2016-2018 Free Software Foundation, Inc.
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3 Contributed by Jakub Jelinek <jakub@redhat.com>
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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
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8 it under the terms of the GNU General Public License as published by
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9 the Free Software Foundation; either version 3, or (at your option)
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10 any later version.
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11
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12 GCC is distributed in the hope that it will be useful,
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13 but WITHOUT ANY WARRANTY; without even the implied warranty of
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14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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15 GNU General Public License 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 "backend.h"
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25 #include "tree.h"
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26 #include "gimple.h"
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27 #include "tree-pass.h"
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28 #include "ssa.h"
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29 #include "diagnostic-core.h"
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30 #include "tree-dfa.h"
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31
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32 /* Warn about comparison of nonnull_arg_p argument initial values
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33 with NULL. */
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34
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35 static void
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36 do_warn_nonnull_compare (function *fun, tree arg)
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37 {
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38 if (!POINTER_TYPE_P (TREE_TYPE (arg))
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39 && TREE_CODE (TREE_TYPE (arg)) != OFFSET_TYPE)
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40 return;
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41
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42 if (!nonnull_arg_p (arg))
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43 return;
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44
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45 tree d = ssa_default_def (fun, arg);
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46 if (d == NULL_TREE)
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47 return;
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48
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49 use_operand_p use_p;
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50 imm_use_iterator iter;
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51
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52 FOR_EACH_IMM_USE_FAST (use_p, iter, d)
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53 {
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54 gimple *stmt = USE_STMT (use_p);
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55 tree op = NULL_TREE;
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56 location_t loc = gimple_location (stmt);
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57 if (gimple_code (stmt) == GIMPLE_COND)
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58 switch (gimple_cond_code (stmt))
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59 {
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60 case EQ_EXPR:
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61 case NE_EXPR:
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62 if (gimple_cond_lhs (stmt) == d)
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63 op = gimple_cond_rhs (stmt);
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64 break;
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65 default:
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66 break;
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67 }
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68 else if (is_gimple_assign (stmt))
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69 switch (gimple_assign_rhs_code (stmt))
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70 {
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71 case EQ_EXPR:
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72 case NE_EXPR:
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73 if (gimple_assign_rhs1 (stmt) == d)
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74 op = gimple_assign_rhs2 (stmt);
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75 break;
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76 case COND_EXPR:
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77 switch (TREE_CODE (gimple_assign_rhs1 (stmt)))
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78 {
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79 case EQ_EXPR:
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80 case NE_EXPR:
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81 op = gimple_assign_rhs1 (stmt);
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82 if (TREE_OPERAND (op, 0) != d)
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83 {
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84 op = NULL_TREE;
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85 break;
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86 }
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87 loc = EXPR_LOC_OR_LOC (op, loc);
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88 op = TREE_OPERAND (op, 1);
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89 break;
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90 default:
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91 break;
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92 }
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93 break;
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94 default:
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95 break;
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96 }
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97 if (op
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98 && (POINTER_TYPE_P (TREE_TYPE (arg))
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99 ? integer_zerop (op) : integer_minus_onep (op))
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100 && !gimple_no_warning_p (stmt))
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101 warning_at (loc, OPT_Wnonnull_compare,
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102 "nonnull argument %qD compared to NULL", arg);
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103 }
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104 }
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105
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106 namespace {
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107
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108 const pass_data pass_data_warn_nonnull_compare =
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109 {
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110 GIMPLE_PASS, /* type */
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111 "*nonnullcmp", /* name */
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112 OPTGROUP_NONE, /* optinfo_flags */
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113 TV_NONE, /* tv_id */
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114 PROP_ssa, /* properties_required */
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115 0, /* properties_provided */
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116 0, /* properties_destroyed */
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117 0, /* todo_flags_start */
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118 0, /* todo_flags_finish */
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119 };
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120
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121 class pass_warn_nonnull_compare : public gimple_opt_pass
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122 {
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123 public:
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124 pass_warn_nonnull_compare (gcc::context *ctxt)
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125 : gimple_opt_pass (pass_data_warn_nonnull_compare, ctxt)
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126 {}
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127
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128 /* opt_pass methods: */
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129 virtual bool gate (function *) { return warn_nonnull_compare; }
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130
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131 virtual unsigned int execute (function *);
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132
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133 }; // class pass_warn_nonnull_compare
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134
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135 unsigned int
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136 pass_warn_nonnull_compare::execute (function *fun)
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137 {
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138 if (fun->static_chain_decl)
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139 do_warn_nonnull_compare (fun, fun->static_chain_decl);
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140
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141 for (tree arg = DECL_ARGUMENTS (cfun->decl); arg; arg = DECL_CHAIN (arg))
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142 do_warn_nonnull_compare (fun, arg);
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143 return 0;
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144 }
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145
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146 } // anon namespace
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147
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148 gimple_opt_pass *
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149 make_pass_warn_nonnull_compare (gcc::context *ctxt)
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150 {
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151 return new pass_warn_nonnull_compare (ctxt);
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152 }
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