Index: llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp =================================================================== --- llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp +++ llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp @@ -2524,6 +2524,11 @@ match(Op1, m_Not(m_Specific(A)))) return BinaryOperator::CreateOr(A, Builder->CreateNot(B)); + // (A & ~B) ^ (~A) -> ~(A & B) + if (match(Op0, m_And(m_Value(A), m_Not(m_Value(B)))) && + match(Op1, m_Not(m_Specific(A)))) + return BinaryOperator::CreateNot(Builder->CreateAnd(A, B)); + // (icmp1 A, B) ^ (icmp2 A, B) --> (icmp3 A, B) if (ICmpInst *RHS = dyn_cast(I.getOperand(1))) if (ICmpInst *LHS = dyn_cast(I.getOperand(0))) Index: llvm/trunk/test/Transforms/InstCombine/xor2.ll =================================================================== --- llvm/trunk/test/Transforms/InstCombine/xor2.ll +++ llvm/trunk/test/Transforms/InstCombine/xor2.ll @@ -145,3 +145,25 @@ ; CHECK-LABEL: @test12( ; CHECK-NEXT: ret i32 0 } + +define i32 @test13(i32 %a, i32 %b) { + %negb = xor i32 %b, -1 + %and = and i32 %a, %negb + %nega = xor i32 %a, -1 + %xor = xor i32 %and, %nega + ret i32 %xor +; CHECK-LABEL: @test13( +; CHECK-NEXT: %1 = and i32 %a, %b +; CHECK-NEXT: %xor = xor i32 %1, -1 +} + +define i32 @test14(i32 %a, i32 %b) { + %nega = xor i32 %a, -1 + %negb = xor i32 %b, -1 + %and = and i32 %a, %negb + %xor = xor i32 %nega, %and + ret i32 %xor +; CHECK-LABEL: @test14( +; CHECK-NEXT: %1 = and i32 %a, %b +; CHECK-NEXT: %xor = xor i32 %1, -1 +}