[llvm-bugs] [Bug 34875] New: [X86] X86movss/X86movsd should select BLENDPS/BLENDPD instruction during isel unless optimizing for size

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=34875

            Bug ID: 34875
           Summary: [X86] X86movss/X86movsd should select BLENDPS/BLENDPD
                    instruction during isel unless optimizing for size
           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

Currently X86movss/X86movsd selects the MOVSS/MOVSD instructions which
frequently get commuted to BLENDPS/BLENDPD and then commuted again to
BLENDPS/BLENDPD with immediate of 1. This ultimately prevents MOVSS/MOVSD from
appearing in code when BLENDPS/BLENDPD is available, but is a little goofy.

Ideally, we should just select BLENDPS/BLENDPD directly during isel.

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