From 7ef167ae1f41c692688fd357e2aa2fa13ad93426 Mon Sep 17 00:00:00 2001 From: Karthik Bhat Date: Wed, 13 Aug 2014 05:13:14 +0000 Subject: [PATCH] InstCombine: Combine (xor (or %a, %b) (xor %a, %b)) to (add %a, %b) Correctness proof of the transform using CVC3- $ cat t.cvc A, B : BITVECTOR(32); QUERY BVXOR(A | B, BVXOR(A,B) ) = A & B; $ cvc3 t.cvc Valid. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215524 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/InstCombine/InstCombineAndOrXor.cpp | 12 ++++++++++++ test/Transforms/InstCombine/or-xor.ll | 11 +++++++++++ 2 files changed, 23 insertions(+) diff --git a/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp index 971995694e9..b83d3c64150 100644 --- a/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp +++ b/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp @@ -2508,6 +2508,18 @@ Instruction *InstCombiner::visitXor(BinaryOperator &I) { if ((A == C && B == D) || (A == D && B == C)) return BinaryOperator::CreateXor(A, B); } + // (A ^ B)^(A | B) -> A & B + if (match(Op0I, m_Xor(m_Value(A), m_Value(B))) && + match(Op1I, m_Or(m_Value(C), m_Value(D)))) { + if ((A == C && B == D) || (A == D && B == C)) + return BinaryOperator::CreateAnd(A, B); + } + // (A | B)^(A ^ B) -> A & B + if (match(Op0I, m_Or(m_Value(A), m_Value(B))) && + match(Op1I, m_Xor(m_Value(C), m_Value(D)))) { + if ((A == C && B == D) || (A == D && B == C)) + return BinaryOperator::CreateAnd(A, B); + } // (A & B) ^ (A ^ B) -> (A | B) if (match(Op0I, m_And(m_Value(A), m_Value(B))) && match(Op1I, m_Xor(m_Specific(A), m_Specific(B)))) diff --git a/test/Transforms/InstCombine/or-xor.ll b/test/Transforms/InstCombine/or-xor.ll index 5c15c456f8d..6984c44d9a3 100644 --- a/test/Transforms/InstCombine/or-xor.ll +++ b/test/Transforms/InstCombine/or-xor.ll @@ -136,3 +136,14 @@ define i32 @test13(i32 %x, i32 %y) { ; CHECK-NEXT: %and = and i32 %x, %y ; CHECK-NEXT: ret i32 %and } + +; ((x | y) ^ (x ^ y)) -> (x & y) +define i32 @test15(i32 %x, i32 %y) { + %1 = xor i32 %y, %x + %2 = or i32 %y, %x + %3 = xor i32 %2, %1 + ret i32 %3 +; CHECK-LABEL: @test15( +; CHECK-NEXT: %1 = and i32 %y, %x +; CHECK-NEXT: ret i32 %1 +} -- 2.11.0