Revert r298711 "[InstCombine] Provide a way to calculate KnownZero/One for Add/Sub in SimplifyDemandedUseBits without recursing into ComputeKnownBits"

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llvm-svn: 298745

1 files changed, 4 insertions, 5 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
index d10fa06f0c2..41d4a4820bf 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
@@ -538,7 +538,7 @@ Value *InstCombiner::SimplifyDemandedUseBits(Value *V, APInt DemandedMask,
                                LHSKnownZero, LHSKnownOne, Depth + 1) ||
           ShrinkDemandedConstant(I, 1, DemandedFromOps) ||
           SimplifyDemandedBits(I->getOperandUse(1), DemandedFromOps,
-                               RHSKnownZero, RHSKnownOne, Depth + 1)) {
+                               LHSKnownZero, LHSKnownOne, Depth + 1)) {
         // Disable the nsw and nuw flags here: We can no longer guarantee that
         // we won't wrap after simplification. Removing the nsw/nuw flags is
         // legal here because the top bit is not demanded.
@@ -549,10 +549,9 @@ Value *InstCombiner::SimplifyDemandedUseBits(Value *V, APInt DemandedMask,
       }
     }
 
-    // Otherwise compute the known bits using the RHS/LHS known bits.
-    bool NSW = cast<OverflowingBinaryOperator>(I)->hasNoSignedWrap();
-    computeKnownBitsForAddSub(V, NSW, KnownZero, KnownOne, LHSKnownZero,
-                              LHSKnownOne, RHSKnownZero, RHSKnownOne);
+    // Otherwise just hand the add/sub off to computeKnownBits to fill in
+    // the known zeros and ones.
+    computeKnownBits(V, KnownZero, KnownOne, Depth, CxtI);
     break;
   }
   case Instruction::Shl: