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[X86][SSE] Move VZEXT_MOVL removal into SimplifyDemandedVectorEltsForTargetNode

Authored by RKSimon on May 4 2020, 9:21 AM.



This patch replaces the VZEXT_MOVL removal from combineShuffle with a more general version based in SimplifyDemandedVectorEltsForTargetNode.

By making use a call to computeKnownBits we can always remove the VZEXT_MOVL if the upper elements of the source operand are known to be zero.

This requires us to add the conversion ops to computeKnownBitsForTargetNode as well.

I was hoping to do this even more generally by handling it in the target shuffle combines below but this is yet another occasion where I need to finish D66004 first.

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RKSimon created this revision.May 4 2020, 9:21 AM
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craig.topper added inline comments.May 4 2020, 12:20 PM

Should this be in computeKnownBitsForTargetNode instead since we're not doing the simplification?

RKSimon marked an inline comment as done.May 4 2020, 1:50 PM
RKSimon added inline comments.

Sure, I'll check what it looks like using computeKnownBits instead.

RKSimon updated this revision to Diff 262079.May 5 2020, 5:41 AM

Use computeKnownBits instead

This revision is now accepted and ready to land.May 5 2020, 10:49 AM
RKSimon edited the summary of this revision. (Show Details)May 5 2020, 11:33 AM
This revision was automatically updated to reflect the committed changes.