Index: llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp =================================================================== --- llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp +++ llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp @@ -892,6 +892,15 @@ if (!match(Op1, m_APInt(C))) return nullptr; + // (X | C2) + C --> (X | C2) ^ C2 + // (C2 | X) + C --> (C2 | X) ^ C2 + // iff (C2 == -C) + const APInt *C2; + if (match(Op0, m_Or(m_Value(), m_APInt(C2))) && + *C2 == -*C) + return BinaryOperator::CreateXor(Op0, + ConstantInt::get(Add.getType(), *C2)); + if (C->isSignMask()) { // If wrapping is not allowed, then the addition must set the sign bit: // X + (signmask) --> X | signmask @@ -906,7 +915,6 @@ // Is this add the last step in a convoluted sext? // add(zext(xor i16 X, -32768), -32768) --> sext X Type *Ty = Add.getType(); - const APInt *C2; if (match(Op0, m_ZExt(m_Xor(m_Value(X), m_APInt(C2)))) && C2->isMinSignedValue() && C2->sext(Ty->getScalarSizeInBits()) == *C) return CastInst::Create(Instruction::SExt, X, Ty); Index: llvm/test/Transforms/InstCombine/add.ll =================================================================== --- llvm/test/Transforms/InstCombine/add.ll +++ llvm/test/Transforms/InstCombine/add.ll @@ -982,9 +982,8 @@ ; (X | C1) + C2 --> (X | C1) ^ C1 iff (C1 == -C2) define i32 @test44(i32 %A) { ; CHECK-LABEL: @test44( -; CHECK-NEXT: [[B:%.*]] = or i32 [[A:%.*]], 123 -; CHECK-NEXT: [[C:%.*]] = add nsw i32 [[B]], -123 -; CHECK-NEXT: ret i32 [[C]] +; CHECK-NEXT: [[TMP1:%.*]] = and i32 [[A:%.*]], -124 +; CHECK-NEXT: ret i32 [[TMP1]] ; %B = or i32 %A, 123 %C = add i32 %B, -123 @@ -994,8 +993,8 @@ define i32 @test44_extra_use(i32 %A) { ; CHECK-LABEL: @test44_extra_use( ; CHECK-NEXT: [[B:%.*]] = or i32 [[A:%.*]], 123 -; CHECK-NEXT: [[C:%.*]] = add nsw i32 [[B]], -123 -; CHECK-NEXT: [[D:%.*]] = mul i32 [[B]], [[C]] +; CHECK-NEXT: [[TMP1:%.*]] = and i32 [[A]], -124 +; CHECK-NEXT: [[D:%.*]] = mul i32 [[B]], [[TMP1]] ; CHECK-NEXT: ret i32 [[D]] ; %B = or i32 %A, 123 @@ -1017,9 +1016,8 @@ define <2 x i32> @test44_vec(<2 x i32> %A) { ; CHECK-LABEL: @test44_vec( -; CHECK-NEXT: [[B:%.*]] = or <2 x i32> [[A:%.*]], -; CHECK-NEXT: [[C:%.*]] = add nsw <2 x i32> [[B]], -; CHECK-NEXT: ret <2 x i32> [[C]] +; CHECK-NEXT: [[TMP1:%.*]] = and <2 x i32> [[A:%.*]], +; CHECK-NEXT: ret <2 x i32> [[TMP1]] ; %B = or <2 x i32> %A, %C = add <2 x i32> %B, Index: llvm/test/Transforms/InstCombine/sub.ll =================================================================== --- llvm/test/Transforms/InstCombine/sub.ll +++ llvm/test/Transforms/InstCombine/sub.ll @@ -1270,9 +1270,8 @@ ; Check (X | Y) - Y --> X & ~Y when Y is a constant define i32 @test70(i32 %A) { ; CHECK-LABEL: @test70( -; CHECK-NEXT: [[B:%.*]] = or i32 [[A:%.*]], 123 -; CHECK-NEXT: [[C:%.*]] = add nsw i32 [[B]], -123 -; CHECK-NEXT: ret i32 [[C]] +; CHECK-NEXT: [[TMP1:%.*]] = and i32 [[A:%.*]], -124 +; CHECK-NEXT: ret i32 [[TMP1]] ; %B = or i32 %A, 123 %C = sub i32 %B, 123