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[DAG] Add SpecificFP matcher #167438

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[DAG] Add SpecificFP matcher #167438

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21 changes: 21 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 @@ -1144,6 +1144,27 @@ inline SpecificInt_match m_SpecificInt(uint64_t V) {
return SpecificInt_match(APInt(64, V));
}

struct SpecificFP_match {
double Val;

explicit SpecificFP_match(double V) : Val(V) {}

template <typename MatchContext>
bool match(const MatchContext &Ctx, SDValue V) {
if (const auto *CFP = dyn_cast<ConstantFPSDNode>(V.getNode()))
if (CFP->isExactlyValue(Val))
return true;
return false;
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@RKSimon RKSimon Nov 11, 2025

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Is it possible to add splat handling as well?

}
};

/// Match a specific float constant.
inline SpecificFP_match m_SpecificFP(APFloat V) {
return SpecificFP_match(V.convertToDouble());
}

inline SpecificFP_match m_SpecificFP(double V) { return SpecificFP_match(V); }

struct Zero_match {
bool AllowUndefs;

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15 changes: 15 additions & 0 deletions llvm/unittests/CodeGen/SelectionDAGPatternMatchTest.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -354,6 +354,21 @@ TEST_F(SelectionDAGPatternMatchTest, matchBinaryOp) {
sd_match(InsertELT, m_InsertElt(m_Value(), m_Value(), m_SpecificInt(1))));
}

TEST_F(SelectionDAGPatternMatchTest, matchSpecificFpOp) {
SDLoc DL;
APFloat Value(1.5f);
auto Float32VT = EVT::getFloatingPointVT(32);
SDValue Op0 = DAG->getCopyFromReg(DAG->getEntryNode(), DL, 1, Float32VT);
SDValue Op1 = DAG->getConstantFP(Value, DL, Float32VT);
SDValue FAdd = DAG->getNode(ISD::FADD, DL, Float32VT, Op0, Op1);

using namespace SDPatternMatch;

EXPECT_TRUE(sd_match(Op0, m_SpecificFP(Value)));
EXPECT_TRUE(
sd_match(FAdd, m_BinOp(ISD::FADD, m_Specific(Op1), m_SpecificFP(Value))));
}

TEST_F(SelectionDAGPatternMatchTest, matchGenericTernaryOp) {
SDLoc DL;
auto Float32VT = EVT::getFloatingPointVT(32);
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