[PATCH] D88569: [DAGCombiner] Call SimplifyDemandedBits to simplify EXTRACT_VECTOR_ELT

[Jay Foad via Phabricator via llvm-commits]

foad planned changes to this revision.
foad added a comment.

This clearly needs work. The original motivation was to be able to remove SIFoldOperands::tryFoldCndMask which is a MIR optimisation that removes a v_cndmask (select) instruction if the values being selected are the same. We sometimes generate these when a 64-bit select is lowered to a pair of 32-bit selects, and the high or low halves of the 64-bit values were the same. I was hoping to fold this away during selection so we wouldn't have to do it later in SIFoldOperands.


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  https://reviews.llvm.org/D88569/new/

https://reviews.llvm.org/D88569