From e8be18e8a32141fa54b37b27889e334ca1653488 Mon Sep 17 00:00:00 2001
From: David Majnemer <david.majnemer@gmail.com>
Date: Mon, 11 Aug 2014 22:32:02 +0000
Subject: [PATCH] InstCombine: Combine (add (and %a, %b) (or %a, %b)) to (add
 %a, %b)

What follows bellow is a correctness proof of the transform using CVC3.

$ < t.cvc
A, B : BITVECTOR(32);

QUERY BVPLUS(32, A & B, A | B) = BVPLUS(32, A, B);

$ cvc3 < t.cvc
Valid.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215400 91177308-0d34-0410-b5e6-96231b3b80d8
---
 .../InstCombine/InstCombineAddSub.cpp         | 24 ++++++++++-
 test/Transforms/InstCombine/add2.ll           | 40 +++++++++++++++++++
 2 files changed, 63 insertions(+), 1 deletion(-)

diff --git a/lib/Transforms/InstCombine/InstCombineAddSub.cpp b/lib/Transforms/InstCombine/InstCombineAddSub.cpp
index ed0e1c90888..b18c10dd57b 100644
--- a/lib/Transforms/InstCombine/InstCombineAddSub.cpp
+++ b/lib/Transforms/InstCombine/InstCombineAddSub.cpp
@@ -1240,7 +1240,7 @@ Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
     }
   }
 
-  // Check for (x & y) + (x ^ y)
+  // (add (xor A, B) (and A, B)) --> (or A, B)
   {
     Value *A = nullptr, *B = nullptr;
     if (match(RHS, m_Xor(m_Value(A), m_Value(B))) &&
@@ -1254,6 +1254,28 @@ Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
       return BinaryOperator::CreateOr(A, B);
   }
 
+  // (add (or A, B) (and A, B)) --> (add A, B)
+  {
+    Value *A = nullptr, *B = nullptr;
+    if (match(RHS, m_Or(m_Value(A), m_Value(B))) &&
+        (match(LHS, m_And(m_Specific(A), m_Specific(B))) ||
+         match(LHS, m_And(m_Specific(B), m_Specific(A))))) {
+      auto *New = BinaryOperator::CreateAdd(A, B);
+      New->setHasNoSignedWrap(I.hasNoSignedWrap());
+      New->setHasNoUnsignedWrap(I.hasNoUnsignedWrap());
+      return New;
+    }
+
+    if (match(LHS, m_Or(m_Value(A), m_Value(B))) &&
+        (match(RHS, m_And(m_Specific(A), m_Specific(B))) ||
+         match(RHS, m_And(m_Specific(B), m_Specific(A))))) {
+      auto *New = BinaryOperator::CreateAdd(A, B);
+      New->setHasNoSignedWrap(I.hasNoSignedWrap());
+      New->setHasNoUnsignedWrap(I.hasNoUnsignedWrap());
+      return New;
+    }
+  }
+
   // TODO(jingyue): Consider WillNotOverflowSignedAdd and
   // WillNotOverflowUnsignedAdd to reduce the number of invocations of
   // computeKnownBits.
diff --git a/test/Transforms/InstCombine/add2.ll b/test/Transforms/InstCombine/add2.ll
index d7eac4b0fd2..2a63082e111 100644
--- a/test/Transforms/InstCombine/add2.ll
+++ b/test/Transforms/InstCombine/add2.ll
@@ -313,3 +313,43 @@ define i16 @add_cttz_2(i16 %a) {
   ret i16 %b
 }
 !1 = metadata !{i16 0, i16 32}
+
+define i32 @add_or_and(i32 %x, i32 %y) {
+  %or = or i32 %x, %y
+  %and = and i32 %x, %y
+  %add = add i32 %or, %and
+  ret i32 %add
+; CHECK-LABEL: @add_or_and(
+; CHECK-NEXT: add i32 %x, %y
+; CHECK-NEXT: ret i32
+}
+
+define i32 @add_nsw_or_and(i32 %x, i32 %y) {
+  %or = or i32 %x, %y
+  %and = and i32 %x, %y
+  %add = add nsw i32 %or, %and
+  ret i32 %add
+; CHECK-LABEL: @add_nsw_or_and(
+; CHECK-NEXT: add nsw i32 %x, %y
+; CHECK-NEXT: ret i32
+}
+
+define i32 @add_nuw_or_and(i32 %x, i32 %y) {
+  %or = or i32 %x, %y
+  %and = and i32 %x, %y
+  %add = add nuw i32 %or, %and
+  ret i32 %add
+; CHECK-LABEL: @add_nuw_or_and(
+; CHECK-NEXT: add nuw i32 %x, %y
+; CHECK-NEXT: ret i32
+}
+
+define i32 @add_nuw_nsw_or_and(i32 %x, i32 %y) {
+  %or = or i32 %x, %y
+  %and = and i32 %x, %y
+  %add = add nsw nuw i32 %or, %and
+  ret i32 %add
+; CHECK-LABEL: @add_nuw_nsw_or_and(
+; CHECK-NEXT: add nuw nsw i32 %x, %y
+; CHECK-NEXT: ret i32
+}
-- 
2.34.1