check_logical_instead_of_bitwise.c

   1 /*
   2  * Copyright (C) 2012 Oracle.
   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
  23 static int is_bitshift(struct expression *expr)
  24 {
  25         expr = strip_expr(expr);
  26
  27         if (expr->type != EXPR_BINOP)
  28                 return 0;
  29         if (expr->op == SPECIAL_LEFTSHIFT)
  30                 return 1;
  31         return 0;
  32 }
  33
  34 static void match_logic(struct expression *expr)
  35 {
  36         sval_t sval;
  37
  38         if (expr->type != EXPR_LOGICAL)
  39                 return;
  40
  41         if (get_macro_name(expr->pos))
  42                 return;
  43
  44         if (!get_value(expr->right, &sval)) {
  45                 if (!get_value(expr->left, &sval))
  46                         return;
  47         }
  48
  49         if (sval.value == 0 || sval.value == 1)
  50                 return;
  51
  52         sm_warning("should this be a bitwise op?");
  53 }
  54
  55 static void match_assign(struct expression *expr)
  56 {
  57         struct expression *right;
  58
  59         right = strip_expr(expr->right);
  60         if (right->type != EXPR_LOGICAL)
  61                 return;
  62         if (is_bitshift(right->left) || is_bitshift(right->right))
  63                 sm_warning("should this be a bitwise op?");
  64 }
  65
  66 void check_logical_instead_of_bitwise(int id)
  67 {
  68         my_id = id;
  69
  70         add_hook(&match_logic, LOGIC_HOOK);
  71         add_hook(&match_assign, ASSIGNMENT_HOOK);
  72 }