[PATCH] D159372: [InstCombine] Fold ((A&B)^A)|((A&B)^B) to A^B

[Marc Auberer via Phabricator via llvm-commits]

marcauberer created this revision.
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((A & B) ^ A) | ((A & B) ^ B) -> A ^ B
((A & B) ^ B) | ((A & B) ^ A) -> A ^ B

Alive2: https://alive2.llvm.org/ce/z/i44xmq
Baseline tests: https://reviews.llvm.org/D159371


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D159372

Files:
  llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
  llvm/test/Transforms/InstCombine/or-xor-xor.ll


Index: llvm/test/Transforms/InstCombine/or-xor-xor.ll
===================================================================
--- llvm/test/Transforms/InstCombine/or-xor-xor.ll
+++ llvm/test/Transforms/InstCombine/or-xor-xor.ll
@@ -5,10 +5,7 @@
 
 define i1 @or_xor_xor_normal_variant1(i1 %a, i1 %b) {
 ; CHECK-LABEL: @or_xor_xor_normal_variant1(
-; CHECK-NEXT:    [[AND:%.*]] = and i1 [[A:%.*]], [[B:%.*]]
-; CHECK-NEXT:    [[XOR1:%.*]] = xor i1 [[AND]], [[A]]
-; CHECK-NEXT:    [[XOR2:%.*]] = xor i1 [[AND]], [[B]]
-; CHECK-NEXT:    [[OR:%.*]] = or i1 [[XOR1]], [[XOR2]]
+; CHECK-NEXT:    [[OR:%.*]] = xor i1 [[A:%.*]], [[B:%.*]]
 ; CHECK-NEXT:    ret i1 [[OR]]
 ;
   %and = and i1 %a, %b
@@ -20,10 +17,7 @@
 
 define i1 @or_xor_xor_normal_variant2(i1 %a, i1 %b) {
 ; CHECK-LABEL: @or_xor_xor_normal_variant2(
-; CHECK-NEXT:    [[AND:%.*]] = and i1 [[A:%.*]], [[B:%.*]]
-; CHECK-NEXT:    [[XOR1:%.*]] = xor i1 [[AND]], [[B]]
-; CHECK-NEXT:    [[XOR2:%.*]] = xor i1 [[AND]], [[A]]
-; CHECK-NEXT:    [[OR:%.*]] = or i1 [[XOR1]], [[XOR2]]
+; CHECK-NEXT:    [[OR:%.*]] = xor i1 [[A:%.*]], [[B:%.*]]
 ; CHECK-NEXT:    ret i1 [[OR]]
 ;
   %and = and i1 %a, %b
@@ -35,10 +29,7 @@
 
 define <3 x i1> @or_xor_xor_normal_vector(<3 x i1> %a, <3 x i1> %b) {
 ; CHECK-LABEL: @or_xor_xor_normal_vector(
-; CHECK-NEXT:    [[AND:%.*]] = and <3 x i1> [[A:%.*]], [[B:%.*]]
-; CHECK-NEXT:    [[XOR1:%.*]] = xor <3 x i1> [[AND]], [[B]]
-; CHECK-NEXT:    [[XOR2:%.*]] = xor <3 x i1> [[AND]], [[A]]
-; CHECK-NEXT:    [[OR:%.*]] = or <3 x i1> [[XOR1]], [[XOR2]]
+; CHECK-NEXT:    [[OR:%.*]] = xor <3 x i1> [[A:%.*]], [[B:%.*]]
 ; CHECK-NEXT:    ret <3 x i1> [[OR]]
 ;
   %and = and <3 x i1> %a, %b
@@ -52,9 +43,7 @@
 ; CHECK-LABEL: @or_xor_xor_normal_multiple_uses_and(
 ; CHECK-NEXT:    [[AND:%.*]] = and i1 [[A:%.*]], [[B:%.*]]
 ; CHECK-NEXT:    call void @use(i1 [[AND]])
-; CHECK-NEXT:    [[XOR1:%.*]] = xor i1 [[AND]], [[B]]
-; CHECK-NEXT:    [[XOR2:%.*]] = xor i1 [[AND]], [[A]]
-; CHECK-NEXT:    [[OR:%.*]] = or i1 [[XOR1]], [[XOR2]]
+; CHECK-NEXT:    [[OR:%.*]] = xor i1 [[A]], [[B]]
 ; CHECK-NEXT:    ret i1 [[OR]]
 ;
   %and = and i1 %a, %b
Index: llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
===================================================================
--- llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -3650,6 +3650,24 @@
     }
   }
 
+  {
+    // ((A & B) ^ A) | ((A & B) ^ B) -> A ^ B
+    if (match(Op0,
+              m_OneUse(m_Xor(m_And(m_Value(A), m_Value(B)), m_Deferred(A)))) &&
+        match(Op1, m_OneUse(m_Xor(m_And(m_Specific(A), m_Specific(B)),
+                                  m_Deferred(B))))) {
+      return BinaryOperator::CreateXor(A, B);
+    }
+
+    // ((A & B) ^ B) | ((A & B) ^ A) -> A ^ B
+    if (match(Op0,
+              m_OneUse(m_Xor(m_And(m_Value(A), m_Value(B)), m_Deferred(B)))) &&
+        match(Op1, m_OneUse(m_Xor(m_And(m_Specific(A), m_Specific(B)),
+                                  m_Deferred(A))))) {
+      return BinaryOperator::CreateXor(A, B);
+    }
+  }
+
   if (Instruction *V =
           canonicalizeCondSignextOfHighBitExtractToSignextHighBitExtract(I))
     return V;


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