[llvm-bugs] [Bug 34876] New: [X86] Should we prefer AVX VBLENDPS/VBLENDPS over VMOVSS/VMOVSD even with AVX512?

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=34876

            Bug ID: 34876
           Summary: [X86] Should we prefer AVX VBLENDPS/VBLENDPS over
                    VMOVSS/VMOVSD even with AVX512?
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Backend: X86
          Assignee: unassignedbugs at nondot.org
          Reporter: craig.topper at gmail.com
                CC: llvm-bugs at lists.llvm.org

There are no EVEX versions of VBLENDPS/VBLENDPD so when AVX512 is enabled we
prefer EVEX VMOVSS/VMOVSD. This enables us to use the XMM16-XMM31 registers,
but the BLEND instructions have better throughput and that may outweight the
increased register freedom.

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