[Bug target/68627] New: [i386, AVX-512] Illegal insn generated while compiling spec2k6/437.leslie3d for KNL

[kyukhin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68627

            Bug ID: 68627
           Summary: [i386, AVX-512] Illegal insn generated while compiling
                    spec2k6/437.leslie3d for KNL
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: kyukhin at gcc dot gnu.org
  Target Milestone: ---

Created attachment 36876
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=36876&action=edit
Reproducer

Attached reduced testcase.

When -march=knl switch is passed, AVX-512 insn illegally generated.

$ gfortran -Ofast -mavx512f test.f -S
$ grep vbroadcastsd test.s | grep ymm
        vbroadcastsd    %xmm11, %ymm7

We need to force %zmm source for this broadcast and limit alternative to
at least AVX-512F