InstCombine: ((A & ~B) ^ (~A & B)) to A ^ B

[oota-llvm.git] / lib / Transforms / InstCombine / InstCombineShifts.cpp

diff --git a/lib/Transforms/InstCombine/InstCombineShifts.cpp b/lib/Transforms/InstCombine/InstCombineShifts.cpp
index 2495747da5fe6321fce069fed8915009ccaea352..3d0cc05f30c6fb407325da6910b6122adf415fd5 100644 (file)
--- a/lib/Transforms/InstCombine/InstCombineShifts.cpp
+++ b/lib/Transforms/InstCombine/InstCombineShifts.cpp
@@ -488,7 +488,7 @@ Instruction *InstCombiner::FoldShiftByConstant(Value *Op0, Constant *Op1,
       }
 
 
-      // If the operand is an bitwise operator with a constant RHS, and the
+      // If the operand is a bitwise operator with a constant RHS, and the
       // shift is the only use, we can pull it out of the shift.
       if (ConstantInt *Op0C = dyn_cast<ConstantInt>(Op0BO->getOperand(1))) {
         bool isValid = true;     // Valid only for And, Or, Xor
@@ -815,10 +815,5 @@ Instruction *InstCombiner::visitAShr(BinaryOperator &I) {
                         APInt::getSignBit(I.getType()->getScalarSizeInBits())))
     return BinaryOperator::CreateLShr(Op0, Op1);
 
-  // Arithmetic shifting an all-sign-bit value is a no-op.
-  unsigned NumSignBits = ComputeNumSignBits(Op0);
-  if (NumSignBits == Op0->getType()->getScalarSizeInBits())
-    return ReplaceInstUsesWith(I, Op0);
-
   return nullptr;
 }