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

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Merged
merged 5 commits into from
Mar 18, 2024
Merged

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

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fac4e97
Add m_Neg and m_Not pattern matcher and update DAGCombiner
ZiCong-Wang Mar 14, 2024
556b164
Apply getNOT helper and reschedule operands in m_Not
ZiCong-Wang Mar 15, 2024
904c9a9
Add EXPECT_FALSE test
ZiCong-Wang Mar 15, 2024
699fd72
Amend EXPECT_FALSE test
ZiCong-Wang Mar 16, 2024
727b973
Update llvm/include/llvm/CodeGen/SDPatternMatch.h
ZiCong-Wang Mar 16, 2024
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12 changes: 12 additions & 0 deletions llvm/include/llvm/CodeGen/SDPatternMatch.h
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Original file line number Diff line number Diff line change
Expand Up @@ -705,6 +705,18 @@ 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
6 changes: 3 additions & 3 deletions llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand Down Expand Up @@ -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));

Expand Down
10 changes: 10 additions & 0 deletions llvm/unittests/CodeGen/SelectionDAGPatternMatchTest.cpp
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Expand Up @@ -174,10 +174,20 @@ 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) {
Expand Down