From 78061f4db4fa979b3dcd345674c5c6b42616ad51 Mon Sep 17 00:00:00 2001
From: Suyog Sarda <suyog.sarda@samsung.com>
Date: Fri, 1 Aug 2014 04:59:26 +0000
Subject: [PATCH] This patch implements transform for pattern "(A | B) & ((~A)
 ^ B) -> (A & B)".

Differential Revision: http://reviews.llvm.org/D4628



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214478 91177308-0d34-0410-b5e6-96231b3b80d8
---
 .../InstCombine/InstCombineAndOrXor.cpp       | 10 ++++++++
 test/Transforms/InstCombine/or-xor.ll         | 24 +++++++++++++++++++
 2 files changed, 34 insertions(+)

diff --git a/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
index add2f29b341..3fd5b7bbd8c 100644
--- a/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ b/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -1295,6 +1295,16 @@ Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
       if (match(Op1, m_Xor(m_Specific(B), m_Specific(A))))
         if (Op0->hasOneUse() || cast<BinaryOperator>(Op0)->hasOneUse())
           return BinaryOperator::CreateAnd(Op1, Builder->CreateNot(C));
+
+    // (A | B) & ((~A) ^ B) -> (A & B)
+    if (match(Op0, m_Or(m_Value(A), m_Value(B))) &&
+        match(Op1, m_Xor(m_Not(m_Specific(A)), m_Specific(B))))
+      return BinaryOperator::CreateAnd(A, B);
+
+    // ((~A) ^ B) & (A | B) -> (A & B)
+    if (match(Op0, m_Xor(m_Not(m_Value(A)), m_Value(B))) &&
+        match(Op1, m_Or(m_Specific(A), m_Specific(B))))
+      return BinaryOperator::CreateAnd(A, B);
   }
 
   if (ICmpInst *RHS = dyn_cast<ICmpInst>(Op1))
diff --git a/test/Transforms/InstCombine/or-xor.ll b/test/Transforms/InstCombine/or-xor.ll
index 3f247e27522..5c15c456f8d 100644
--- a/test/Transforms/InstCombine/or-xor.ll
+++ b/test/Transforms/InstCombine/or-xor.ll
@@ -112,3 +112,27 @@ define i32 @test11(i32 %A, i32 %B) {
 ; CHECK-LABEL: @test11(
 ; CHECK-NEXT: ret i32 -1
 }
+
+; (x | y) & ((~x) ^ y) -> (x & y)
+define i32 @test12(i32 %x, i32 %y) {
+ %or = or i32 %x, %y
+ %neg = xor i32 %x, -1
+ %xor = xor i32 %neg, %y
+ %and = and i32 %or, %xor
+ ret i32 %and
+; CHECK-LABEL: @test12(
+; CHECK-NEXT: %and = and i32 %x, %y
+; CHECK-NEXT: ret i32 %and
+}
+
+; ((~x) ^ y) & (x | y) -> (x & y)
+define i32 @test13(i32 %x, i32 %y) {
+ %neg = xor i32 %x, -1
+ %xor = xor i32 %neg, %y
+ %or = or i32 %x, %y
+ %and = and i32 %xor, %or
+ ret i32 %and
+; CHECK-LABEL: @test13(
+; CHECK-NEXT: %and = and i32 %x, %y
+; CHECK-NEXT: ret i32 %and
+}