[InstCombine] Add one use checks to or/and->xnor folding

topperc · topperc · commit 0de5e6a72932 · 2017-06-22T16:12:02.000Z
If the components of the and/or had multiple uses, this transform created an additional instruction. This patch makes sure we remove one of the components. Differential Revision: https://reviews.llvm.org/D34498 llvm-svn: 306027
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -1230,9 +1230,10 @@ static Instruction *foldAndToXor(BinaryOperator &I,
   // (A | ~B) & (B | ~A) --> ~(A ^ B)
   // (~B | A) & (~A | B) --> ~(A ^ B)
   // (~B | A) & (B | ~A) --> ~(A ^ B)
-  if (match(Op0, m_c_Or(m_Value(A), m_Not(m_Value(B)))) &&
-      match(Op1, m_c_Or(m_Not(m_Specific(A)), m_Specific(B))))
-    return BinaryOperator::CreateNot(Builder.CreateXor(A, B));
+  if (Op0->hasOneUse() || Op1->hasOneUse())
+    if (match(Op0, m_c_Or(m_Value(A), m_Not(m_Value(B)))) &&
+        match(Op1, m_c_Or(m_Not(m_Specific(A)), m_Specific(B))))
+      return BinaryOperator::CreateNot(Builder.CreateXor(A, B));
 
   return nullptr;
 }
@@ -1247,9 +1248,10 @@ static Instruction *foldOrToXor(BinaryOperator &I,
   // Operand complexity canonicalization guarantees that the 'and' is Op0.
   // (A & B) | ~(A | B) --> ~(A ^ B)
   // (A & B) | ~(B | A) --> ~(A ^ B)
-  if (match(Op0, m_And(m_Value(A), m_Value(B))) &&
-      match(Op1, m_Not(m_c_Or(m_Specific(A), m_Specific(B)))))
-    return BinaryOperator::CreateNot(Builder.CreateXor(A, B));
+  if (Op0->hasOneUse() || Op1->hasOneUse())
+    if (match(Op0, m_And(m_Value(A), m_Value(B))) &&
+        match(Op1, m_Not(m_c_Or(m_Specific(A), m_Specific(B)))))
+      return BinaryOperator::CreateNot(Builder.CreateXor(A, B));
 
   // (A & ~B) | (~A & B) --> A ^ B
   // (A & ~B) | (B & ~A) --> A ^ B
diff --git a/llvm/test/Transforms/InstCombine/and-or-not.ll b/llvm/test/Transforms/InstCombine/and-or-not.ll
@@ -527,8 +527,7 @@ define i32 @and_to_nxor_multiuse(float %fa, float %fb) {
 ; CHECK-NEXT:    [[NOTB:%.*]] = xor i32 [[B]], -1
 ; CHECK-NEXT:    [[OR1:%.*]] = or i32 [[NOTA]], [[B]]
 ; CHECK-NEXT:    [[OR2:%.*]] = or i32 [[NOTB]], [[A]]
-; CHECK-NEXT:    [[TMP1:%.*]] = xor i32 [[B]], [[A]]
-; CHECK-NEXT:    [[AND:%.*]] = xor i32 [[TMP1]], -1
+; CHECK-NEXT:    [[AND:%.*]] = and i32 [[OR1]], [[OR2]]
 ; CHECK-NEXT:    [[MUL1:%.*]] = mul i32 [[OR1]], [[OR2]]
 ; CHECK-NEXT:    [[MUL2:%.*]] = mul i32 [[MUL1]], [[AND]]
 ; CHECK-NEXT:    ret i32 [[MUL2]]
@@ -552,8 +551,7 @@ define i32 @or_to_nxor_multiuse(i32 %a, i32 %b) {
 ; CHECK-NEXT:    [[AND:%.*]] = and i32 [[A:%.*]], [[B:%.*]]
 ; CHECK-NEXT:    [[OR:%.*]] = or i32 [[A]], [[B]]
 ; CHECK-NEXT:    [[NOTOR:%.*]] = xor i32 [[OR]], -1
-; CHECK-NEXT:    [[TMP1:%.*]] = xor i32 [[A]], [[B]]
-; CHECK-NEXT:    [[OR2:%.*]] = xor i32 [[TMP1]], -1
+; CHECK-NEXT:    [[OR2:%.*]] = or i32 [[AND]], [[NOTOR]]
 ; CHECK-NEXT:    [[MUL1:%.*]] = mul i32 [[AND]], [[NOTOR]]
 ; CHECK-NEXT:    [[MUL2:%.*]] = mul i32 [[MUL1]], [[OR2]]
 ; CHECK-NEXT:    ret i32 [[MUL2]]
