gcc/testsuite/gcc.dg/signbit-6.c

   1 /* { dg-do run } */
   2 /* { dg-options "-O1" } */
   3
   4 #include <stdint.h>
   5 #include <limits.h>
   6 #include <stdio.h>
   7
   8 #ifndef N
   9 #define N 65
  10 #endif
  11
  12 #ifndef TYPE
  13 #define TYPE int32_t
  14 #endif
  15
  16 #ifndef DEBUG
  17 #define DEBUG 1
  18 #endif
  19
  20 #define BASE ((TYPE) -1 < 0 ? -126 : 4)
  21
  22 __attribute__ ((noinline, noipa))
  23 void fun1(TYPE *x, int n)
  24 {
  25     for (int i = 0; i < n; i++)
  26       x[i] = (-x[i]) >> 31;
  27 }
  28
  29 __attribute__ ((noinline, noipa, optimize("O0")))
  30 void fun2(TYPE *x, int n)
  31 {
  32     for (int i = 0; i < n; i++)
  33       x[i] = (-x[i]) >> 31;
  34 }
  35
  36 int main ()
  37 {
  38   TYPE a[N];
  39   TYPE b[N];
  40
  41   /* This will invoke UB due to -INT32_MIN.  The test is supposed to pass
  42      because GCC is supposed to handle this UB case in a predictable way.  */
  43   a[0] = INT32_MIN;
  44   b[0] = INT32_MIN;
  45
  46   for (int i = 1; i < N; ++i)
  47     {
  48       a[i] = BASE + i * 13;
  49       b[i] = BASE + i * 13;
  50       if (DEBUG)
  51         printf ("%d: 0x%x\n", i, a[i]);
  52     }
  53
  54   fun1 (a, N);
  55   fun2 (b, N);
  56
  57   if (DEBUG)
  58     printf ("%d = 0x%x == 0x%x\n", 0, a[0], b[0]);
  59
  60   if (a[0] != 0x0 || b[0] != -1)
  61         __builtin_abort ();
  62
  63
  64   for (int i = 1; i < N; ++i)
  65     {
  66       if (DEBUG)
  67         printf ("%d = 0x%x == 0x%x\n", i, a[i], b[i]);
  68
  69       if (a[i] != b[i])
  70         __builtin_abort ();
  71     }
  72   return 0;
  73 }
  74