We can safely avoid interfering with the subus combine if both inputs are freely truncatable. Either both extends, or an extend and a constant vector.
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[X86] Teach combineTruncatedArithmetic to handle some cases of ISD::SUB ClosedPublic Authored by craig.topper on Aug 16 2018, 5:39 PM.
Details Summary We can safely avoid interfering with the subus combine if both inputs are freely truncatable. Either both extends, or an extend and a constant vector.
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Event TimelineThis revision is now accepted and ready to land.Aug 17 2018, 5:55 AM Closed by commit rL340212: [X86] Teach combineTruncatedArithmetic to handle some cases of ISD::SUB (authored by ctopper). · Explain WhyAug 20 2018, 1:58 PM This revision was automatically updated to reflect the committed changes.
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Diff 161560 llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
llvm/trunk/test/CodeGen/X86/vector-trunc-math.ll
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