1 /*
2 * Copyright (C) 2010 Dan Carpenter.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version 2
7 * of the License, or (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, see http://www.gnu.org/copyleft/gpl.txt
16 */
17
18 #include "smatch.h"
19 #include "smatch_extra.h"
20
21 static int my_id;
22
is_bool(struct expression * expr)23 static int is_bool(struct expression *expr)
24 {
25 struct symbol *type;
26
27 type = get_type(expr);
28 if (!type)
29 return 0;
30 if (type_bits(type) == 1 && type->ctype.modifiers & MOD_UNSIGNED)
31 return 1;
32 return 0;
33 }
34
is_bool_from_context(struct expression * expr)35 static int is_bool_from_context(struct expression *expr)
36 {
37 sval_t sval;
38
39 if (!get_implied_max(expr, &sval) || sval.uvalue > 1)
40 return 0;
41 if (!get_implied_min(expr, &sval) || sval.value < 0)
42 return 0;
43 return 1;
44 }
45
is_bool_op(struct expression * expr)46 static int is_bool_op(struct expression *expr)
47 {
48 expr = strip_expr(expr);
49
50 if (expr->type == EXPR_PREOP && expr->op == '!')
51 return 1;
52 if (expr->type == EXPR_COMPARE)
53 return 1;
54 if (expr->type == EXPR_LOGICAL)
55 return 1;
56 return is_bool(expr);
57 }
58
match_condition(struct expression * expr)59 static void match_condition(struct expression *expr)
60 {
61 int print = 0;
62
63 if (expr->type == EXPR_COMPARE) {
64 if (expr->left->type == EXPR_COMPARE || expr->right->type == EXPR_COMPARE)
65 print = 1;
66 if (expr->left->type == EXPR_PREOP && expr->left->op == '!') {
67 if (expr->left->unop->type == EXPR_PREOP && expr->left->unop->op == '!')
68 return;
69 if (expr->right->op == '!')
70 return;
71 if (is_bool(expr->right))
72 return;
73 if (is_bool(expr->left->unop))
74 return;
75 if (is_bool_from_context(expr->left->unop))
76 return;
77 print = 1;
78 }
79 }
80
81 if (expr->type == EXPR_BINOP) {
82 if (expr->left->type == EXPR_COMPARE || expr->right->type == EXPR_COMPARE)
83 print = 1;
84 }
85
86 if (print) {
87 sm_warning("add some parenthesis here?");
88 return;
89 }
90
91 if (expr->type == EXPR_BINOP && expr->op == '&') {
92 int i = 0;
93
94 if (is_bool_op(expr->left))
95 i++;
96 if (is_bool_op(expr->right))
97 i++;
98 if (i == 1)
99 sm_warning("maybe use && instead of &");
100 }
101 }
102
match_binop(struct expression * expr)103 static void match_binop(struct expression *expr)
104 {
105 if (expr->op != '&')
106 return;
107 if (expr->left->op == '!')
108 sm_warning("add some parenthesis here?");
109 }
110
match_mask(struct expression * expr)111 static void match_mask(struct expression *expr)
112 {
113 if (expr->op != '&')
114 return;
115 if (expr->right->type != EXPR_BINOP)
116 return;
117 if (expr->right->op != SPECIAL_RIGHTSHIFT)
118 return;
119
120 sm_warning("shift has higher precedence than mask");
121 }
122
match_mask_compare(struct expression * expr)123 static void match_mask_compare(struct expression *expr)
124 {
125 if (expr->op != '&')
126 return;
127 if (expr->right->type != EXPR_COMPARE)
128 return;
129
130 sm_warning("compare has higher precedence than mask");
131 }
132
match_subtract_shift(struct expression * expr)133 static void match_subtract_shift(struct expression *expr)
134 {
135 if (expr->op != SPECIAL_LEFTSHIFT)
136 return;
137 if (expr->right->type != EXPR_BINOP)
138 return;
139 if (expr->right->op != '-')
140 return;
141 sm_warning("subtract is higher precedence than shift");
142 }
143
check_precedence(int id)144 void check_precedence(int id)
145 {
146 my_id = id;
147
148 add_hook(&match_condition, CONDITION_HOOK);
149 add_hook(&match_binop, BINOP_HOOK);
150 add_hook(&match_mask, BINOP_HOOK);
151 add_hook(&match_mask_compare, BINOP_HOOK);
152 add_hook(&match_subtract_shift, BINOP_HOOK);
153 }
154