1 /* -Wnonnull-compare warning support.
2 Copyright (C) 2016-2021 Free Software Foundation, Inc.
3 Contributed by Jakub Jelinek <jakub@redhat.com>
4
5 This file is part of GCC.
6
7 GCC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3, or (at your option)
10 any later version.
11
12 GCC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
16
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING3. If not see
19 <http://www.gnu.org/licenses/>. */
20
21 #include "config.h"
22 #include "system.h"
23 #include "coretypes.h"
24 #include "backend.h"
25 #include "tree.h"
26 #include "gimple.h"
27 #include "tree-pass.h"
28 #include "ssa.h"
29 #include "diagnostic-core.h"
30 #include "tree-dfa.h"
31
32 /* Warn about comparison of nonnull_arg_p argument initial values
33 with NULL. */
34
35 static void
do_warn_nonnull_compare(function * fun,tree arg)36 do_warn_nonnull_compare (function *fun, tree arg)
37 {
38 if (!POINTER_TYPE_P (TREE_TYPE (arg))
39 && TREE_CODE (TREE_TYPE (arg)) != OFFSET_TYPE)
40 return;
41
42 if (!nonnull_arg_p (arg))
43 return;
44
45 tree d = ssa_default_def (fun, arg);
46 if (d == NULL_TREE)
47 return;
48
49 use_operand_p use_p;
50 imm_use_iterator iter;
51
52 FOR_EACH_IMM_USE_FAST (use_p, iter, d)
53 {
54 gimple *stmt = USE_STMT (use_p);
55 tree op = NULL_TREE;
56 location_t loc = gimple_location (stmt);
57 if (gimple_code (stmt) == GIMPLE_COND)
58 switch (gimple_cond_code (stmt))
59 {
60 case EQ_EXPR:
61 case NE_EXPR:
62 if (gimple_cond_lhs (stmt) == d)
63 op = gimple_cond_rhs (stmt);
64 break;
65 default:
66 break;
67 }
68 else if (is_gimple_assign (stmt))
69 switch (gimple_assign_rhs_code (stmt))
70 {
71 case EQ_EXPR:
72 case NE_EXPR:
73 if (gimple_assign_rhs1 (stmt) == d)
74 op = gimple_assign_rhs2 (stmt);
75 break;
76 case COND_EXPR:
77 switch (TREE_CODE (gimple_assign_rhs1 (stmt)))
78 {
79 case EQ_EXPR:
80 case NE_EXPR:
81 op = gimple_assign_rhs1 (stmt);
82 if (TREE_OPERAND (op, 0) != d)
83 {
84 op = NULL_TREE;
85 break;
86 }
87 loc = EXPR_LOC_OR_LOC (op, loc);
88 op = TREE_OPERAND (op, 1);
89 break;
90 default:
91 break;
92 }
93 break;
94 default:
95 break;
96 }
97 if (op
98 && (POINTER_TYPE_P (TREE_TYPE (arg))
99 ? integer_zerop (op) : integer_minus_onep (op))
100 && !gimple_no_warning_p (stmt))
101 warning_at (loc, OPT_Wnonnull_compare,
102 "%<nonnull%> argument %qD compared to NULL", arg);
103 }
104 }
105
106 namespace {
107
108 const pass_data pass_data_warn_nonnull_compare =
109 {
110 GIMPLE_PASS, /* type */
111 "*nonnullcmp", /* name */
112 OPTGROUP_NONE, /* optinfo_flags */
113 TV_NONE, /* tv_id */
114 PROP_ssa, /* properties_required */
115 0, /* properties_provided */
116 0, /* properties_destroyed */
117 0, /* todo_flags_start */
118 0, /* todo_flags_finish */
119 };
120
121 class pass_warn_nonnull_compare : public gimple_opt_pass
122 {
123 public:
pass_warn_nonnull_compare(gcc::context * ctxt)124 pass_warn_nonnull_compare (gcc::context *ctxt)
125 : gimple_opt_pass (pass_data_warn_nonnull_compare, ctxt)
126 {}
127
128 /* opt_pass methods: */
gate(function *)129 virtual bool gate (function *) { return warn_nonnull_compare; }
130
131 virtual unsigned int execute (function *);
132
133 }; // class pass_warn_nonnull_compare
134
135 unsigned int
execute(function * fun)136 pass_warn_nonnull_compare::execute (function *fun)
137 {
138 if (fun->static_chain_decl)
139 do_warn_nonnull_compare (fun, fun->static_chain_decl);
140
141 for (tree arg = DECL_ARGUMENTS (cfun->decl); arg; arg = DECL_CHAIN (arg))
142 do_warn_nonnull_compare (fun, arg);
143 return 0;
144 }
145
146 } // anon namespace
147
148 gimple_opt_pass *
make_pass_warn_nonnull_compare(gcc::context * ctxt)149 make_pass_warn_nonnull_compare (gcc::context *ctxt)
150 {
151 return new pass_warn_nonnull_compare (ctxt);
152 }
153