[PATCH] D135850: [AArch64] Enhance 'isBitfieldPositioningOp' to find pattern (shl(and(val,mask), N)

[Mingming Liu via Phabricator via llvm-commits]

mingmingl added a comment.

In D135850#3857910 <https://reviews.llvm.org/D135850#3857910>, @dmgreen wrote:

> This seems similar to a demand bits fold. Can it check that `AndMask` is a superset of `AllOnes >> Shift`?

Checking `AndMask` is a superset of `AllOnes  >> Shift` makes sense. Done by checking `isMask_64((AndImm << Shift) >> Shift)`.

- This patch previously introduced a bug (fixed in the latest reply) by checking `isShiftedMask_64((AndImm << Shift) >> Shift)`.

Also make refactor patch a parent of this one (bypassing D135844 <https://reviews.llvm.org/D135844>).


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  https://reviews.llvm.org/D135850/new/

https://reviews.llvm.org/D135850