check_64bit_shift.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 void match_shift_assignment(struct expression *expr)
  23 {
  24         struct symbol *left_type, *right_type;
  25         struct expression *right;
  26         sval_t sval;
  27         sval_t bits, shifter;
  28         char *name;
  29
  30         right = strip_expr(expr->right);
  31         if (right->type != EXPR_BINOP || right->op != SPECIAL_LEFTSHIFT)
  32                 return;
  33
  34         left_type = get_type(expr->left);
  35         if (left_type != &llong_ctype && left_type != &ullong_ctype)
  36                 return;
  37
  38         right_type = get_type(expr->right);
  39
  40         if (type_bits(right_type) == 64)
  41                 return;
  42
  43         if (get_value(right, &sval))
  44                 return;
  45
  46         get_absolute_max(right->left, &bits);
  47         get_absolute_max(right->right, &shifter);
  48
  49         bits = sval_cast(&ullong_ctype, bits);
  50         if (sval_cmp_val(shifter, 32) < 0) {
  51                 sval = sval_binop(bits, SPECIAL_LEFTSHIFT, shifter);
  52                 if (sval_cmp_val(sval, UINT_MAX) < 0)
  53                         return;
  54         }
  55
  56         name = expr_to_str_sym(right, NULL);
  57         sm_msg("warn: should '%s' be a 64 bit type?", name);
  58         free_string(name);
  59 }
  60
  61 void check_64bit_shift(int id)
  62 {
  63         my_id = id;
  64
  65         add_hook(&match_shift_assignment, ASSIGNMENT_HOOK);
  66 }