clang/test/Sema/warn-bitwise-compare.c

   1 // RUN: %clang_cc1 -fsyntax-only -verify -Wtautological-bitwise-compare %s
   2 // RUN: %clang_cc1 -fsyntax-only -verify -Wall -Wno-unused %s
   3
   4 #define mydefine 2
   5 #define mydefine2 -2
   6
   7 enum {
   8   ZERO,
   9   ONE,
  10 };
  11
  12 void f(int x) {
  13   if ((8 & x) == 3) {}  // expected-warning {{bitwise comparison always evaluates to false}}
  14   if ((x & 8) == 4) {}  // expected-warning {{bitwise comparison always evaluates to false}}
  15   if ((-8 & x) == 3) {}  // expected-warning {{bitwise comparison always evaluates to false}}
  16   if ((x & -8) == 4) {}  // expected-warning {{bitwise comparison always evaluates to false}}
  17
  18   if ((x & 8) != 4) {}  // expected-warning {{bitwise comparison always evaluates to true}}
  19   if ((2 & x) != 4) {}  // expected-warning {{bitwise comparison always evaluates to true}}
  20   if ((x & -8) != 4) {}  // expected-warning {{bitwise comparison always evaluates to true}}
  21   if ((-2 & x) != 3) {}  // expected-warning {{bitwise comparison always evaluates to true}}
  22
  23   if ((x | 4) == 3) {}  // expected-warning {{bitwise comparison always evaluates to false}}
  24   if ((x | 3) != 4) {}  // expected-warning {{bitwise comparison always evaluates to true}}
  25   if ((5 | x) != 3) {}  // expected-warning {{bitwise comparison always evaluates to true}}
  26
  27   if ((x | -4) == 3) {}  // expected-warning {{bitwise comparison always evaluates to false}}
  28   if ((x | -3) != 4) {}  // expected-warning {{bitwise comparison always evaluates to true}}
  29   if ((-5 | x) != 3) {}  // expected-warning {{bitwise comparison always evaluates to true}}
  30
  31   if ((x & 0x15) == 0x13) {} // expected-warning {{bitwise comparison always evaluates to false}}
  32   if ((x & 0xFFEB) == 0x13) {} // expected-warning {{bitwise comparison always evaluates to false}}
  33
  34   if ((0x23 | x) == 0x155){} // expected-warning {{bitwise comparison always evaluates to false}}
  35   if ((0xFFDD | x) == 0x155){} // expected-warning {{bitwise comparison always evaluates to false}}
  36
  37   if (!!((8 & x) == 3)) {}  // expected-warning {{bitwise comparison always evaluates to false}}
  38   if (!!((-8 & x) == 3)) {}  // expected-warning {{bitwise comparison always evaluates to false}}
  39
  40   int y = ((8 & x) == 3) ? 1 : 2;  // expected-warning {{bitwise comparison always evaluates to false}}
  41   y = ((-8 & x) == 3) ? 1 : 2;  // expected-warning {{bitwise comparison always evaluates to false}}
  42   y = ((3 | x) != 5) ? 1 : 2;  // expected-warning {{bitwise comparison always evaluates to true}}
  43   y = ((-3 | x) != 5) ? 1 : 2;  // expected-warning {{bitwise comparison always evaluates to true}}
  44
  45   if ((x & 0) != !0) {} // expected-warning {{bitwise comparison always evaluates to true}}
  46   if ((x & 0) == !0) {} // expected-warning {{bitwise comparison always evaluates to false}}
  47   if ((x & 2) == !0) {} // expected-warning {{bitwise comparison always evaluates to false}}
  48
  49   if ((x | 4) == +3) {}  // expected-warning {{bitwise comparison always evaluates to false}}
  50   if ((x | 3) != +4) {}  // expected-warning {{bitwise comparison always evaluates to true}}
  51
  52   if ((x & 8) != ~4) {}  // expected-warning {{bitwise comparison always evaluates to true}}
  53   if ((x & 0) == ~4) {}  // expected-warning {{bitwise comparison always evaluates to false}}
  54
  55   if ((x & 8) == 8) {}
  56   if ((x & 8) != 8) {}
  57   if ((x | 4) == 4) {}
  58   if ((x | 4) != 4) {}
  59
  60   if ((x | 4) == +4) {}
  61   if ((x | 4) != +4) {}
  62
  63   if ((x & 1) == !12) {}
  64   if ((x | 0) == !0) {}
  65
  66   if ((x | 1) == ~4) {}
  67   if ((x | 1) != ~0) {}
  68
  69   if ((-2 & x) != 4) {}
  70   if ((x & -8) == -8) {}
  71   if ((x & -8) != -8) {}
  72   if ((x | -4) == -4) {}
  73   if ((x | -4) != -4) {}
  74
  75   if ((x & 9) == 8) {}
  76   if ((x & 9) != 8) {}
  77   if ((x | 4) == 5) {}
  78   if ((x | 4) != 5) {}
  79
  80   if ((x & -9) == -10) {}
  81   if ((x & -9) != -10) {}
  82   if ((x | -4) == -3) {}
  83   if ((x | -4) != -3) {}
  84
  85   if ((x^0) == 0) {}
  86
  87   if ((x & mydefine) == 8) {}
  88   if ((x | mydefine) == 4) {}
  89
  90   if ((x & mydefine2) == 8) {}
  91   if ((x | mydefine2) == 4) {}
  92
  93   if ((x & 1) == 1L) {}
  94
  95   if (0 != (x | !0LL)) {} // expected-warning {{bitwise comparison always evaluates to true}}
  96 }
  97
  98 void g(int x) {
  99   if (x | 5) {}  // expected-warning {{bitwise or with non-zero value always evaluates to true}}
 100   if (5 | x) {}  // expected-warning {{bitwise or with non-zero value always evaluates to true}}
 101   if (!((x | 5))) {}  // expected-warning {{bitwise or with non-zero value always evaluates to true}}
 102
 103   if (x | -1) {}  // expected-warning {{bitwise or with non-zero value always evaluates to true}}
 104   if (x | ONE) {}  // expected-warning {{bitwise or with non-zero value always evaluates to true}}
 105
 106   if (x | ZERO) {}
 107 }