[Bug tree-optimization/126720] [15/16/17 Regression] wrong code with -O3 since r15-2275

[jakub at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126720

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[15/16/17 Regression] wrong |[15/16/17 Regression] wrong
                   |code with -O3               |code with -O3 since
                   |                            |r15-2275
                 CC|                            |jakub at gcc dot gnu.org,
                   |                            |law at gcc dot gnu.org
           Keywords|needs-bisection             |

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Started with r15-2275-g679086172b84be18c55fdbb9cda7e97806e7c083
Slightly cleaned up testcase:
typedef short V __attribute__((vector_size (sizeof (int))));
typedef unsigned short W __attribute__((vector_size (sizeof (int))));
unsigned a;
unsigned char b;
_Bool c;

int
main ()
{
#if __SIZEOF_SHORT__ == 2 && __SIZEOF_INT__ == 4
  unsigned short d;
  W e;
  unsigned short f = 0;
l1:
  d = ~f;
  e = (W) 0;
  f = d;
  d = e[b];
  e = (((union { unsigned src; W dst; }) (unsigned) f).dst);
  e = (V) e < 0;
  f = 29834 >> d;
  e = __builtin_shufflevector (e, e, 3, 1);
  e = ~e;
l2:
  e = ~e;
  e = ~e;
  e[1] = ~f;
l3:
  switch (~(((union { W src; unsigned dst }) e).dst))
    {
    case 1955201024:
      goto l5;
    case 4033962:
      goto l4;
    default:
      __builtin_trap ();
    }
l4:
  if (c)
    goto l2;
  goto l1;
l5:
  e = e >= 0;
  if (d == 3)
    return 0;
  a = a > 0U;
  if (b)
    goto l3;
#endif
}