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
  20 static int my_id;
  21
  22 static int is_bitshift(struct expression *expr)
  23 {
  24         expr = strip_expr(expr);
  25
  26         if (expr->type != EXPR_BINOP)
  27                 return 0;
  28         if (expr->op == SPECIAL_LEFTSHIFT || expr->op == SPECIAL_RIGHTSHIFT)
  29                 return 1;
  30         return 0;
  31 }
  32
  33 static void match_logic(struct expression *expr)
  34 {
  35         sval_t sval;
  36
  37         if (expr->type != EXPR_LOGICAL)
  38                 return;
  39
  40         if (get_macro_name(expr->pos))
  41                 return;
  42
  43         if (!get_value(expr->right, &sval)) {
  44                 if (!get_value(expr->left, &sval))
  45                         return;
  46         }
  47
  48         if (sval.value == 0 || sval.value == 1)
  49                 return;
  50
  51         sm_msg("warn: should this be a bitwise op?");
  52 }
  53
  54 static void match_assign(struct expression *expr)
  55 {
  56         struct expression *right;
  57
  58         right = strip_expr(expr->right);
  59         if (right->type != EXPR_LOGICAL)
  60                 return;
  61         if (is_bitshift(right->left) || is_bitshift(right->right))
  62                 sm_msg("warn: should this be a bitwise op?");
  63 }
  64
  65 void check_logical_instead_of_bitwise(int id)
  66 {
  67         my_id = id;
  68
  69         add_hook(&match_logic, LOGIC_HOOK);
  70         add_hook(&match_assign, ASSIGNMENT_HOOK);
  71 }