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
21static int my_id;
22
23static 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
35static 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
46static 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
59static 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
103static 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
111static 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
123static 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
133static 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
144void 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