[SelectionDAG] Add m_Neg and m_Not pattern matcher and update DAGCombiner (llvm#85365)

Resolves llvm#85065

---------

Co-authored-by: Matt Arsenault <[email protected]>

Author: ZiCong-Wang

llvm/include/llvm/CodeGen/SDPatternMatch.h

@@ -725,6 +725,18 @@ inline auto m_False() {
       },
       m_Value()};
 }
+
+/// Match a negate as a sub(0, v)
+template <typename ValTy>
+inline BinaryOpc_match<SpecificInt_match, ValTy> m_Neg(const ValTy &V) {
+  return m_Sub(m_Zero(), V);
+}
+
+/// Match a Not as a xor(v, -1) or xor(-1, v)
+template <typename ValTy>
+inline BinaryOpc_match<ValTy, SpecificInt_match, true> m_Not(const ValTy &V) {
+  return m_Xor(V, m_AllOnes());
+}
 } // namespace SDPatternMatch
 } // namespace llvm
 #endif

llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

@@ -2703,11 +2703,11 @@ SDValue DAGCombiner::visitADDLike(SDNode *N) {
   SDValue A, B, C;
 
   // fold ((0-A) + B) -> B-A
-  if (sd_match(N0, m_Sub(m_Zero(), m_Value(A))))
+  if (sd_match(N0, m_Neg(m_Value(A))))
     return DAG.getNode(ISD::SUB, DL, VT, N1, A);
 
   // fold (A + (0-B)) -> A-B
-  if (sd_match(N1, m_Sub(m_Zero(), m_Value(B))))
+  if (sd_match(N1, m_Neg(m_Value(B))))
     return DAG.getNode(ISD::SUB, DL, VT, N0, B);
 
   // fold (A+(B-A)) -> B
@@ -3812,7 +3812,7 @@ SDValue DAGCombiner::visitSUB(SDNode *N) {
     return DAG.getNode(ISD::AND, DL, VT, N0, DAG.getNOT(DL, B, VT));
 
   // fold (A - (-B * C)) -> (A + (B * C))
-  if (sd_match(N1, m_OneUse(m_Mul(m_Sub(m_Zero(), m_Value(B)), m_Value(C)))))
+  if (sd_match(N1, m_OneUse(m_Mul(m_Neg(m_Value(B)), m_Value(C)))))
     return DAG.getNode(ISD::ADD, DL, VT, N0,
                        DAG.getNode(ISD::MUL, DL, VT, B, C));
 

llvm/unittests/CodeGen/SelectionDAGPatternMatchTest.cpp

@@ -187,10 +187,20 @@ TEST_F(SelectionDAGPatternMatchTest, matchUnaryOp) {
   SDValue SExt = DAG->getNode(ISD::SIGN_EXTEND, DL, Int64VT, Op0);
   SDValue Trunc = DAG->getNode(ISD::TRUNCATE, DL, Int32VT, Op1);
 
+  SDValue Sub = DAG->getNode(ISD::SUB, DL, Int32VT, Trunc, Op0);
+  SDValue Neg = DAG->getNegative(Op0, DL, Int32VT);
+  SDValue Not = DAG->getNOT(DL, Op0, Int32VT);
+
   using namespace SDPatternMatch;
   EXPECT_TRUE(sd_match(ZExt, m_UnaryOp(ISD::ZERO_EXTEND, m_Value())));
   EXPECT_TRUE(sd_match(SExt, m_SExt(m_Value())));
   EXPECT_TRUE(sd_match(Trunc, m_Trunc(m_Specific(Op1))));
+
+  EXPECT_TRUE(sd_match(Neg, m_Neg(m_Value())));
+  EXPECT_TRUE(sd_match(Not, m_Not(m_Value())));
+  EXPECT_FALSE(sd_match(ZExt, m_Neg(m_Value())));
+  EXPECT_FALSE(sd_match(Sub, m_Neg(m_Value())));
+  EXPECT_FALSE(sd_match(Neg, m_Not(m_Value())));
 }
 
 TEST_F(SelectionDAGPatternMatchTest, matchConstants) {