[Bug target/82897] New: Unnecessary zero-extension when loading mask register from memory

[ubizjak at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82897

            Bug ID: 82897
           Summary: Unnecessary zero-extension when loading mask register
                    from memory
           Product: gcc
           Version: 8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: ubizjak at gmail dot com
  Target Milestone: ---

Following testcase:

--cut here--
__mmask16 m;

__m512i
foo (__m512i x, __m512i y, int a)
{
  return _mm512_mask_srai_epi32 (y, m, x, a);
}
--cut here--

compiles with -O2 -mavx512f to:

        movl    %edi, %edi
        vmovdqa64       %zmm1, %zmm2
-->     movzwl  m(%rip), %eax
        vmovq   %rdi, %xmm3
-->     kmovw   %eax, %k1
        vpsrad  %xmm3, %zmm0, %zmm2{%k1}
        vmovdqa64       %zmm2, %zmm0
        ret

Note unnecessary zero-extension when mask reg is loaded from memory.