Index: lib/Transforms/InstCombine/InstCombineAndOrXor.cpp =================================================================== --- lib/Transforms/InstCombine/InstCombineAndOrXor.cpp +++ lib/Transforms/InstCombine/InstCombineAndOrXor.cpp @@ -2528,6 +2528,31 @@ if (match(Op0I, m_Xor(m_Value(A), m_Value(B))) && match(Op1I, m_And(m_Specific(A), m_Specific(B)))) return BinaryOperator::CreateOr(A, B); + + // (~A ^ B) ^ (A & ~B) -> (A | ~B) + // (~A ^ B) ^ (~B & A) -> (A | ~B) + if (match(Op0I, m_Xor(m_Not(m_Value(A)), m_Value(B))) && + (match(Op1I, m_And(m_Specific(A), m_Not(m_Specific(B)))) || + match(Op1I, m_And(m_Not(m_Specific(B)), m_Specific(A))))) + return BinaryOperator::CreateOr(A, Builder->CreateNot(B)); + // (B ^ ~A) ^ (A & ~B) -> (A | ~B) + // (B ^ ~A) ^ (~B & A) -> (A | ~B) + if (match(Op0I, m_Xor(m_Value(B), m_Not(m_Value(A)))) && + (match(Op1I, m_And(m_Specific(A), m_Not(m_Specific(B)))) || + match(Op1I, m_And(m_Not(m_Specific(B)), m_Specific(A))))) + return BinaryOperator::CreateOr(A, Builder->CreateNot(B)); + // (A & ~B) ^ (B ^ ~A) -> (A | ~B) + // (A & ~B) ^ (~A ^ B) -> (A | ~B) + if (match(Op0I, m_And(m_Value(A), m_Not(m_Value(B)))) && + (match(Op1I, m_Xor(m_Specific(B), m_Not(m_Specific(A)))) || + match(Op1I, m_Xor(m_Not(m_Specific(A)), m_Specific(B))))) + return BinaryOperator::CreateOr(A, Builder->CreateNot(B)); + // (~B & A) ^ (B ^ ~A) -> (A | ~B) + // (~B & A) ^ (~A ^ B) -> (A | ~B) + if (match(Op0I, m_And(m_Not(m_Value(B)), m_Value(A))) && + (match(Op1I, m_Xor(m_Specific(B), m_Not(m_Specific(A)))) || + match(Op1I, m_Xor(m_Not(m_Specific(A)), m_Specific(B))))) + return BinaryOperator::CreateOr(A, Builder->CreateNot(B)); } // (A | B)^(~A) -> (A | ~B) Index: test/Transforms/InstCombine/or-xor.ll =================================================================== --- test/Transforms/InstCombine/or-xor.ll +++ test/Transforms/InstCombine/or-xor.ll @@ -147,3 +147,17 @@ ; CHECK-NEXT: %1 = and i32 %y, %x ; CHECK-NEXT: ret i32 %1 } + +; ((~x ^ y) ^ (x & ~y)) -> (x | ~y) +define i32 @test16(i32 %x, i32 %y) { + %1 = xor i32 %x, -1 + %2 = xor i32 %1, %y + %3 = xor i32 %y, -1 + %4 = and i32 %3, %x + %5 = xor i32 %2, %4 + ret i32 %5 +; CHECK-LABEL: @test16( +; CHECK-NEXT: %1 = xor i32 %y, -1 +; CHECK-NEXT: %2 = or i32 %x, %1 +; CHECK-NEXT: ret i32 %2 +}