diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp --- a/llvm/lib/Analysis/ValueTracking.cpp +++ b/llvm/lib/Analysis/ValueTracking.cpp @@ -2872,11 +2872,24 @@ // If X and Y are non-zero then so is X * Y as long as the multiplication // does not overflow. const OverflowingBinaryOperator *BO = cast(V); - if ((Q.IIQ.hasNoSignedWrap(BO) || Q.IIQ.hasNoUnsignedWrap(BO)) && - isKnownNonZero(I->getOperand(0), DemandedElts, Depth, Q) && - isKnownNonZero(I->getOperand(1), DemandedElts, Depth, Q)) - return true; - break; + if (Q.IIQ.hasNoSignedWrap(BO) || Q.IIQ.hasNoUnsignedWrap(BO)) + return isKnownNonZero(I->getOperand(0), DemandedElts, Depth, Q) && + isKnownNonZero(I->getOperand(1), DemandedElts, Depth, Q); + + // If either X or Y is odd, then if the other is non-zero the result can't + // be zero. + KnownBits XKnown = + computeKnownBits(I->getOperand(0), DemandedElts, Depth, Q); + if (XKnown.One[0]) + return isKnownNonZero(I->getOperand(1), DemandedElts, Depth, Q); + + KnownBits YKnown = + computeKnownBits(I->getOperand(1), DemandedElts, Depth, Q); + if (YKnown.One[0]) + return XKnown.isNonZero() || + isKnownNonZero(I->getOperand(0), DemandedElts, Depth, Q); + + return KnownBits::mul(XKnown, YKnown).isNonZero(); } case Instruction::Select: // (C ? X : Y) != 0 if X != 0 and Y != 0. diff --git a/llvm/test/Analysis/ValueTracking/known-non-zero.ll b/llvm/test/Analysis/ValueTracking/known-non-zero.ll --- a/llvm/test/Analysis/ValueTracking/known-non-zero.ll +++ b/llvm/test/Analysis/ValueTracking/known-non-zero.ll @@ -767,13 +767,9 @@ define i1 @mul_nonzero_odd(i8 %xx, i8 %y, i8 %ind) { ; CHECK-LABEL: @mul_nonzero_odd( -; CHECK-NEXT: [[XO:%.*]] = or i8 [[XX:%.*]], 1 ; CHECK-NEXT: [[Y_NZ:%.*]] = icmp ne i8 [[Y:%.*]], 0 ; CHECK-NEXT: call void @llvm.assume(i1 [[Y_NZ]]) -; CHECK-NEXT: [[X:%.*]] = mul i8 [[XO]], [[Y]] -; CHECK-NEXT: [[Z:%.*]] = or i8 [[X]], [[IND:%.*]] -; CHECK-NEXT: [[R:%.*]] = icmp eq i8 [[Z]], 0 -; CHECK-NEXT: ret i1 [[R]] +; CHECK-NEXT: ret i1 false ; %xo = or i8 %xx, 1 %y_nz = icmp ne i8 %y, 0