[Bug target/82015] New: PowerPC should check if 2nd argument to __builtin_unpackv1ti and similar functions is 0 or 1

["meissner at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82015

            Bug ID: 82015
           Summary: PowerPC should check if 2nd argument to
                    __builtin_unpackv1ti and similar functions is 0 or 1
           Product: gcc
           Version: 8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: meissner at gcc dot gnu.org
  Target Milestone: ---

If you have the code:

vector __int128_t a[10] = { 1,2,3,4,5,6,7,8,9,0 };

vector __int128_t foo()
{
  unsigned long long x = __builtin_unpack_vector_int128(a[0], 11);
  unsigned long long y = x*2;
  vector __int128_t z = __builtin_pack_vector_int128(x,y);
  return z;
}

The compiler sees that the 2nd argument is not 0 nor 1, and puts it into a
register.  Instead the compiler should complain if any of the 128-bit unpack
functions pass something other than 0 or 1 in the 2nd argument.