This patch implements transform for pattern "(A & B) | ((~A) ^ B) -> (~A ^ B)".

Patch Credit to Ankit Jain !

Differential Revision: http://reviews.llvm.org/D4655

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214476 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
index 51564088e6795cba929979c3adc537a2f890900a..60e81ebfd0cbbca2093562fe00eacd42630b62f8 100644 (file)
--- a/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ b/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -2167,6 +2167,16 @@ Instruction *InstCombiner::visitOr(BinaryOperator &I) {
         return BinaryOperator::CreateOr(Not, Op0);
       }
 
         return BinaryOperator::CreateOr(Not, Op0);
       }
 

+  // (A & B) | ((~A) ^ B) -> (~A ^ B)
+  if (match(Op0, m_And(m_Value(A), m_Value(B))) &&
+      match(Op1, m_Xor(m_Not(m_Specific(A)), m_Specific(B))))
+    return BinaryOperator::CreateXor(Builder->CreateNot(A), B);
+
+  // ((~A) ^ B) | (A & B) -> (~A ^ B)
+  if (match(Op0, m_Xor(m_Not(m_Value(A)), m_Value(B))) &&
+      match(Op1, m_And(m_Specific(A), m_Specific(B))))
+    return BinaryOperator::CreateXor(Builder->CreateNot(A), B);
+

   if (SwappedForXor)
     std::swap(Op0, Op1);
 
   if (SwappedForXor)
     std::swap(Op0, Op1);
 

diff --git a/test/Transforms/InstCombine/or.ll b/test/Transforms/InstCombine/or.ll
index 1a493df6153fb23cd3a91ab59e8d69860d6bea70..8e2e6ad96772aa064a77f6a4817a3a1534688857 100644 (file)
--- a/test/Transforms/InstCombine/or.ll
+++ b/test/Transforms/InstCombine/or.ll
@@ -427,3 +427,25 @@ define i32 @test40(i32 %a, i32 %b) {
  %or = or i32 %and, %xor
  ret i32 %or
 }
  %or = or i32 %and, %xor
  ret i32 %or
 }

+
+define i32 @test41(i32 %a, i32 %b) {
+; CHECK-LABEL: test41(
+; CHECK-NEXT: %1 = xor i32 %a, -1
+; CHECK-NEXT: %or = xor i32 %1, %b
+ %and = and i32 %a, %b
+ %nega = xor i32 %a, -1
+ %xor = xor i32 %nega, %b
+ %or = or i32 %and, %xor
+ ret i32 %or
+}
+
+define i32 @test42(i32 %a, i32 %b) {
+; CHECK-LABEL: test42(
+; CHECK-NEXT: %1 = xor i32 %a, -1
+; CHECK-NEXT: %or = xor i32 %1, %b
+ %nega = xor i32 %a, -1
+ %xor = xor i32 %nega, %b
+ %and = and i32 %a, %b
+ %or = or i32 %xor, %and
+ ret i32 %or
+}