The current gcc trunk mis-compiles the following code on x86_64-linux at -O3 in 32-bit mode. This is a regression from 4.8.x. 

$ gcc-trunk -v   
gcc version 4.9.0 20130710 (experimental) [trunk revision 200864] (GCC) 
$
$ gcc-trunk -m32 -O3 small.c
$ a.out
0
$ gcc-trunk -m32 -O2 small.c
$ a.out
1
$ gcc-4.8 -m32 -O3 small.c
$ a.out
1
$ 


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int printf (const char *, ...);

int a, b = 1, c, *d = &c, f, *g, h, j;
static int e;

int
main ()
{
  int i;
  for (i = 0; i < 2; i++)
    {
      long long k = b;
      int l;
      for (f = 0; f < 8; f++)
	{
	  int *m = &e;
	  j = *d;
	  h = a * j - 1;
	  *m = (h == 0) < k;
	  g = &l;
	}
    }
  printf ("%d\n", e);
  return 0;
}