[llvm-bugs] [Bug 40758] New: [X86][SSE] Adjust shouldFoldShiftPairToMask for btver2 targets for uniform constant shifts

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=40758

            Bug ID: 40758
           Summary: [X86][SSE] Adjust shouldFoldShiftPairToMask for btver2
                    targets for uniform constant shifts
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Windows NT
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Backend: X86
          Assignee: unassignedbugs at nondot.org
          Reporter: llvm-dev at redking.me.uk
                CC: andrea.dibiagio at gmail.com, craig.topper at gmail.com,
                    llvm-bugs at lists.llvm.org, llvm-dev at redking.me.uk,
                    spatel+llvm at rotateright.com

As discussed on https://reviews.llvm.org/D58225, for the btver2 (Jaguar) target
(and maybe some others), it would be better to use 2 uniform constant shifts
than a shift and a mask loaded from constant pool (even if the mask is lifted
out of a hot loop I don't think it gives any benefit).

This probably means yet another Feature bit.....

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