[PATCH] D79987: [DAG] SimplifyDemandedVectorElts Bug fix for rG7cb5a51f386d

Mon May 25 00:29:37 PDT 2020

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In D79987#2041642 <https://reviews.llvm.org/D79987#2041642>, @RKSimon wrote:

> I'm still looking at fixing getFauxShuffleMask (PR45974) but that might take a while, so this sort of approach is probably necessary.
>
> Did you investigate replacing getTargetShuffleInputs with getTargetShuffleAndZeroables in the SimplifyDemandedBitsForTargetNode/SimplifyDemandedVectorEltsForTargetNode?

Hi, Simon. It seems I figure out why we do getFauxShuffleMask(...) for t1416: v8i32 = X86ISD::VBROADCAST t1414.
Is that because we are able to recursively simpify t1414(the real SRC of t1416) if we are simplifying the fauxshuffle created by getFauxShuffleMask(...)?

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