[Bug middle-end/28436] New: accessing an element via a "pointer" on a vector does not cause vec_extract to be used

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

Just like PR 28367:
#define vector __attribute__((vector_size(16)))
float f(vector float t)
{
  return *(float*)&t;
}

We get a full vector store which we can get around with a stvewx which just
stores that one element and we can get that via a vec_extract pattern.

On x86_64 has the same issue, maybe even worse as there is no need to go
through memory there.
X86_64 produces:
f:
.LFB2:
        movaps  %xmm0, -24(%rsp)
        movss   -24(%rsp), %xmm0
        ret
When really it should produce just a ret.


-- 
           Summary: accessing an element via a "pointer"  on a vector does
                    not cause vec_extract to be used
           Product: gcc
           Version: 4.2.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: normal
          Priority: P3
         Component: middle-end
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: pinskia at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28436