Reenable the transform "(X*Y)/Y->X" when the multiplication is known not to
overflow (nsw flag), which was disabled because it breaks 254.gap. I have
informed the GAP authors of the mistake in their code, and arranged for the
testsuite to use -fwrapv when compiling this benchmark.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124746 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/InstructionSimplify.cpp b/lib/Analysis/InstructionSimplify.cpp
index 6ca4ddd..4b9b648 100644
--- a/lib/Analysis/InstructionSimplify.cpp
+++ b/lib/Analysis/InstructionSimplify.cpp
@@ -798,11 +798,11 @@
Value *X = 0, *Y = 0;
if (match(Op0, m_Mul(m_Value(X), m_Value(Y))) && (X == Op1 || Y == Op1)) {
if (Y != Op1) std::swap(X, Y); // Ensure expression is (X * Y) / Y, Y = Op1
-// BinaryOperator *Mul = cast<BinaryOperator>(Op0);
-// // If the Mul knows it does not overflow, then we are good to go.
-// if ((isSigned && Mul->hasNoSignedWrap()) ||
-// (!isSigned && Mul->hasNoUnsignedWrap()))
-// return X;
+ BinaryOperator *Mul = cast<BinaryOperator>(Op0);
+ // If the Mul knows it does not overflow, then we are good to go.
+ if ((isSigned && Mul->hasNoSignedWrap()) ||
+ (!isSigned && Mul->hasNoUnsignedWrap()))
+ return X;
// If X has the form X = A / Y then X * Y cannot overflow.
if (BinaryOperator *Div = dyn_cast<BinaryOperator>(X))
if (Div->getOpcode() == Opcode && Div->getOperand(1) == Y)