[PATCH] D155307: [InstCombine] Allow KnownBits to be propagated

[Noah Goldstein via Phabricator via llvm-commits]

goldstein.w.n added inline comments.


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Comment at: llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp:924
+          LHSKnown = computeKnownBits(I->getOperand(0), Depth + 1, I);
           if (DemandedMaskLHS.isSubsetOf(LHSKnown.Zero | LHSKnown.One)) {
+            Constant *NewLHS = Constant::getIntegerValue(VTy, LHSKnown.One);
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Maybe cleaner is `if (DemandedMaskLHS.isSubsetOf(LHSKnown.Zero | LHSKnown.One) && !match(I->getOperand(0), m_SpecificInt(LHSKnown.Zero | LHSKnown.One))`

Then you can just keep the original code in the if statement.


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Comment at: llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp:929
+              return I;
+            }
+          } else {
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Do we need to cleanup the constants if we don't actually insert them?


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D155307/new/

https://reviews.llvm.org/D155307