https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84786
Bug ID: 84786 Summary: [miscompilation] vunpcklpd accessing xmm16-22 targeting KNL Product: gcc Version: 7.2.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: target Assignee: unassigned at gcc dot gnu.org Reporter: kretz at kde dot org Target Milestone: --- I see generated code, such as: 424821:· vpxord %zmm17,%zmm17,%zmm17 424827:· vpxord %zmm18,%zmm18,%zmm18 [...] 424855:· vunpcklpd %xmm17,%xmm0,%xmm1 [...] 424891:· vunpcklpd %xmm18,%xmm1,%xmm1 when compiling with `-O2 -march=knl`. Apparently the `_mm_unpacklo_pd` intrinsic is incorrectly translated to an encoding that allows the upper 16 SIMD registers for the first register. Reducing a test case will take some time.