1*1f5207b7SJohn Levon /*
2*1f5207b7SJohn Levon * Copyright (C) 2012 Oracle.
3*1f5207b7SJohn Levon *
4*1f5207b7SJohn Levon * This program is free software; you can redistribute it and/or
5*1f5207b7SJohn Levon * modify it under the terms of the GNU General Public License
6*1f5207b7SJohn Levon * as published by the Free Software Foundation; either version 2
7*1f5207b7SJohn Levon * of the License, or (at your option) any later version.
8*1f5207b7SJohn Levon *
9*1f5207b7SJohn Levon * This program is distributed in the hope that it will be useful,
10*1f5207b7SJohn Levon * but WITHOUT ANY WARRANTY; without even the implied warranty of
11*1f5207b7SJohn Levon * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12*1f5207b7SJohn Levon * GNU General Public License for more details.
13*1f5207b7SJohn Levon *
14*1f5207b7SJohn Levon * You should have received a copy of the GNU General Public License
15*1f5207b7SJohn Levon * along with this program; if not, see http://www.gnu.org/copyleft/gpl.txt
16*1f5207b7SJohn Levon */
17*1f5207b7SJohn Levon
18*1f5207b7SJohn Levon #include "smatch.h"
19*1f5207b7SJohn Levon
20*1f5207b7SJohn Levon static int my_id;
21*1f5207b7SJohn Levon
22*1f5207b7SJohn Levon #if 0
23*1f5207b7SJohn Levon static unsigned long long find_possible_bits(struct expression *expr)
24*1f5207b7SJohn Levon {
25*1f5207b7SJohn Levon sval_t sval;
26*1f5207b7SJohn Levon unsigned long long ret;
27*1f5207b7SJohn Levon int set;
28*1f5207b7SJohn Levon int i;
29*1f5207b7SJohn Levon
30*1f5207b7SJohn Levon expr = strip_expr(expr);
31*1f5207b7SJohn Levon
32*1f5207b7SJohn Levon if (get_implied_value(expr, &sval))
33*1f5207b7SJohn Levon return sval.uvalue;
34*1f5207b7SJohn Levon
35*1f5207b7SJohn Levon if (expr->type == EXPR_BINOP && (expr->op == '&' || expr->op == '|')) {
36*1f5207b7SJohn Levon unsigned long long left, right;
37*1f5207b7SJohn Levon
38*1f5207b7SJohn Levon left = find_possible_bits(expr->left);
39*1f5207b7SJohn Levon if (!left)
40*1f5207b7SJohn Levon return 0;
41*1f5207b7SJohn Levon right = find_possible_bits(expr->right);
42*1f5207b7SJohn Levon if (!right)
43*1f5207b7SJohn Levon return 0;
44*1f5207b7SJohn Levon
45*1f5207b7SJohn Levon if (expr->op == '&')
46*1f5207b7SJohn Levon return left & right;
47*1f5207b7SJohn Levon return left | right;
48*1f5207b7SJohn Levon }
49*1f5207b7SJohn Levon
50*1f5207b7SJohn Levon get_absolute_max(expr, &sval);
51*1f5207b7SJohn Levon ret = sval.value;
52*1f5207b7SJohn Levon
53*1f5207b7SJohn Levon set = false;
54*1f5207b7SJohn Levon for (i = 63; i >= 0; i--) {
55*1f5207b7SJohn Levon if (ret & 1 << i)
56*1f5207b7SJohn Levon set = true;
57*1f5207b7SJohn Levon if (set)
58*1f5207b7SJohn Levon ret |= 1 << i;
59*1f5207b7SJohn Levon }
60*1f5207b7SJohn Levon return ret;
61*1f5207b7SJohn Levon }
62*1f5207b7SJohn Levon #endif
63*1f5207b7SJohn Levon
get_possible_bits(struct expression * expr)64*1f5207b7SJohn Levon static unsigned long long get_possible_bits(struct expression *expr)
65*1f5207b7SJohn Levon {
66*1f5207b7SJohn Levon sval_t sval;
67*1f5207b7SJohn Levon
68*1f5207b7SJohn Levon expr = strip_expr(expr);
69*1f5207b7SJohn Levon if (expr->type != EXPR_BINOP)
70*1f5207b7SJohn Levon return 0;
71*1f5207b7SJohn Levon if (expr->op != '&')
72*1f5207b7SJohn Levon return 0;
73*1f5207b7SJohn Levon if (!get_implied_value(expr->right, &sval))
74*1f5207b7SJohn Levon return 0;
75*1f5207b7SJohn Levon
76*1f5207b7SJohn Levon return sval.uvalue;
77*1f5207b7SJohn Levon }
78*1f5207b7SJohn Levon
match_condition(struct expression * expr)79*1f5207b7SJohn Levon static void match_condition(struct expression *expr)
80*1f5207b7SJohn Levon {
81*1f5207b7SJohn Levon struct symbol *type;
82*1f5207b7SJohn Levon sval_t sval;
83*1f5207b7SJohn Levon unsigned long long left_mask, right_mask;
84*1f5207b7SJohn Levon char *str;
85*1f5207b7SJohn Levon
86*1f5207b7SJohn Levon type = get_type(expr);
87*1f5207b7SJohn Levon if (!type)
88*1f5207b7SJohn Levon type = &int_ctype;
89*1f5207b7SJohn Levon
90*1f5207b7SJohn Levon if (expr->type != EXPR_COMPARE)
91*1f5207b7SJohn Levon return;
92*1f5207b7SJohn Levon if (expr->op != SPECIAL_EQUAL && expr->op != SPECIAL_NOTEQUAL)
93*1f5207b7SJohn Levon return;
94*1f5207b7SJohn Levon
95*1f5207b7SJohn Levon if (!get_value(expr->right, &sval))
96*1f5207b7SJohn Levon return;
97*1f5207b7SJohn Levon right_mask = sval.uvalue;
98*1f5207b7SJohn Levon
99*1f5207b7SJohn Levon left_mask = get_possible_bits(expr->left);
100*1f5207b7SJohn Levon if (!left_mask)
101*1f5207b7SJohn Levon return;
102*1f5207b7SJohn Levon
103*1f5207b7SJohn Levon if (type_bits(type) < 64) {
104*1f5207b7SJohn Levon left_mask &= (1ULL << type_bits(type)) - 1;
105*1f5207b7SJohn Levon right_mask &= (1ULL << type_bits(type)) - 1;
106*1f5207b7SJohn Levon }
107*1f5207b7SJohn Levon
108*1f5207b7SJohn Levon if ((left_mask & right_mask) == right_mask)
109*1f5207b7SJohn Levon return;
110*1f5207b7SJohn Levon
111*1f5207b7SJohn Levon str = expr_to_str(expr);
112*1f5207b7SJohn Levon sm_warning("masked condition '%s' is always %s.", str,
113*1f5207b7SJohn Levon expr->op == SPECIAL_EQUAL ? "false" : "true");
114*1f5207b7SJohn Levon free_string(str);
115*1f5207b7SJohn Levon }
116*1f5207b7SJohn Levon
check_impossible_mask(int id)117*1f5207b7SJohn Levon void check_impossible_mask(int id)
118*1f5207b7SJohn Levon {
119*1f5207b7SJohn Levon my_id = id;
120*1f5207b7SJohn Levon
121*1f5207b7SJohn Levon add_hook(&match_condition, CONDITION_HOOK);
122*1f5207b7SJohn Levon }
123