[Bug target/82941] New: Missing vzeroupper with -mavx512f -O2

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82941

            Bug ID: 82941
           Summary: Missing vzeroupper with -mavx512f -O2
           Product: gcc
           Version: 8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hjl.tools at gmail dot com
                CC: pavel.v.chupin at gmail dot com, ubizjak at gmail dot com
  Target Milestone: ---
            Target: x86

[hjl@gnu-6 vzeroupper-skx-1]$ cat bar.c
#include <immintrin.h>

extern __m512d y, z;

void
foo ()
{
  z = y;
}
[hjl@gnu-6 vzeroupper-skx-1]$ make bar.s
/export/build/gnu/gcc/build-x86_64-linux/gcc/xgcc
-B/export/build/gnu/gcc/build-x86_64-linux/gcc/ -O2 -march=skylake-avx512 -S
bar.c
[hjl@gnu-6 vzeroupper-skx-1]$ cat bar.s
        .file   "bar.c"
        .text
        .p2align 4,,15
        .globl  foo
        .type   foo, @function
foo:
.LFB4897:
        .cfi_startproc
        vmovapd y(%rip), %zmm0
        vmovapd %zmm0, z(%rip)
        ret
        .cfi_endproc
.LFE4897:
        .size   foo, .-foo
        .ident  "GCC: (GNU) 8.0.0 20171110 (experimental)"
        .section        .note.GNU-stack,"",@progbits
[hjl@gnu-6 vzeroupper-skx-1]$