This is a follow-up suggested in D119060. Instead of checking each of the bottom 2 bits individually, we can check them together and handle the possibility that we demand both together.
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| Differential D119139
[InstCombine] generalize 2 LSB of demanded bits for X*X ClosedPublic Authored by spatel on Feb 7 2022, 7:06 AM.
Details Summary This is a follow-up suggested in D119060. Instead of checking each of the bottom 2 bits individually, we can check them together and handle the possibility that we demand both together.
Diff Detail Event TimelineThis revision is now accepted and ready to land.Feb 7 2022, 7:26 AM Comment Actions
Sure - I'll push this one and then update DAG tests/logic to correspond. This revision was landed with ongoing or failed builds.Feb 7 2022, 8:35 AM Closed by commit rG897d92faeff6: [InstCombine] generalize 2 LSB of demanded bits for X*X (authored by spatel). · Explain Why This revision was automatically updated to reflect the committed changes.
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Diff 406436 llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
llvm/test/Transforms/InstCombine/mul-masked-bits.ll
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