[PATCH] D122915: [AArch64] Fold lsr+bfi in tryBitfieldInsertOpFromOr

[chenglin.bi via Phabricator via llvm-commits]

bcl5980 added a comment.

In D122915#3431002 <https://reviews.llvm.org/D122915#3431002>, @efriedma wrote:

> Yes, this is my "solution 1".  "Solution 2" would be defining AArch64ISD::BFM, and moving all the code from tryBitfieldInsertOpFromOr into a DAGCombine.  The advantage of that is that we can perform general DAGCombine optimizations afterwards, not just this specific one.  The disadvantage is that you have to be careful not to block other optimizations. (And it's more work to modify the current code.)

Thanks for the detail explaination.


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