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 #include "smatch_extra.h"
  20
  21 static int my_id;
  22
  23 static void match_shift_mask(struct expression *expr)
  24 {
  25         struct expression *right, *shifter;
  26         struct range_list *rl;
  27         char *str;
  28
  29         expr = strip_expr(expr);
  30         if (expr->type != EXPR_BINOP || expr->op != '&')
  31                 return;
  32
  33         if (get_type(expr->left) != &ullong_ctype)
  34                 return;
  35
  36         if (type_bits(get_type(expr->right)) == 64)
  37                 return;
  38
  39         right = strip_expr(expr->right);
  40         if (right->type != EXPR_BINOP || right->op != SPECIAL_LEFTSHIFT)
  41                 return;
  42
  43         shifter = strip_expr(right->right);
  44         get_real_absolute_rl(shifter, &rl);
  45         if (rl_max(rl).uvalue < 32)
  46                 return;
  47
  48         str = expr_to_str(expr->right);
  49         sm_warning("should '%s' be a 64 bit type?", str);
  50         free_string(str);
  51 }
  52
  53 static void match_shift_assignment(struct expression *expr)
  54 {
  55         struct symbol *left_type, *right_type;
  56         struct expression *right;
  57         sval_t sval;
  58         sval_t bits, shifter;
  59         char *name;
  60
  61         right = strip_expr(expr->right);
  62         if (right->type != EXPR_BINOP || right->op != SPECIAL_LEFTSHIFT)
  63                 return;
  64
  65         left_type = get_type(expr->left);
  66         if (left_type != &llong_ctype && left_type != &ullong_ctype)
  67                 return;
  68
  69         right_type = get_type(expr->right);
  70
  71         if (type_bits(right_type) == 64)
  72                 return;
  73
  74         if (get_value(right, &sval))
  75                 return;
  76
  77         get_absolute_max(right->left, &bits);
  78         get_absolute_max(right->right, &shifter);
  79
  80         bits = sval_cast(&ullong_ctype, bits);
  81         if (sval_cmp_val(shifter, 32) < 0) {
  82                 sval = sval_binop(bits, SPECIAL_LEFTSHIFT, shifter);
  83                 if (sval_cmp_val(sval, UINT_MAX) < 0)
  84                         return;
  85         }
  86
  87         name = expr_to_str_sym(right, NULL);
  88         sm_warning("should '%s' be a 64 bit type?", name);
  89         free_string(name);
  90 }
  91
  92 void check_64bit_shift(int id)
  93 {
  94         my_id = id;
  95
  96         if (!option_spammy)
  97                 return;
  98
  99         add_hook(&match_shift_assignment, ASSIGNMENT_HOOK);
 100         add_hook(&match_shift_mask, BINOP_HOOK);
 101 }