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[X86][SSE] lowerV2I64Shuffle - use undef elements in PSHUFD mask widening

Authored by RKSimon on Sun, Jul 26, 8:03 AM.

Description

[X86][SSE] lowerV2I64Shuffle - use undef elements in PSHUFD mask widening

If we lower a v2i64 shuffle to PSHUFD, we currently clamp undef elements to 0, (elements 0,1 of the v4i32) which can result in the shuffle referencing more elements of the source vector than expected, affecting later shuffle combines and KnownBits/SimplifyDemanded calls.

By ensuring we widen the undef mask element we allow getV4X86ShuffleImm8 to use inline elements as the default, which are more likely to fold.

Details

Committed
RKSimonSun, Jul 26, 8:04 AM
Parents
rGd135744c34dc: [MLIR][Affine] Add test for non-hyperrectangular loop tiling
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