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[InstCombine] Don't transform code if DoTransform is false
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Authored by Carrot on Jun 18 2021, 12:53 PM.

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Summary

In patch https://reviews.llvm.org/D72396, it doesn't check DoTransform before transforming the code, and generates wrong result for the attached test case.

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Event Timeline

Carrot created this revision.Jun 18 2021, 12:53 PM
Carrot requested review of this revision.Jun 18 2021, 12:53 PM
Herald added a project: Restricted Project. · View Herald TranscriptJun 18 2021, 12:53 PM
lebedev.ri accepted this revision.Jun 18 2021, 1:04 PM

LG
I think that function is misdesigned, but i can't suggest an easy good alternative.

llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
959

Please add a comment to the function explaining this weird DoTransform behaviour.

This revision is now accepted and ready to land.Jun 18 2021, 1:04 PM
Carrot updated this revision to Diff 353092.Jun 18 2021, 1:56 PM
Carrot marked an inline comment as done.

Thanks for the quick review!
Will commit this version.

This revision was landed with ongoing or failed builds.Jun 18 2021, 6:03 PM
This revision was automatically updated to reflect the committed changes.