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[DAG] Add SDPatternMatch::m_Load #145481

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Merged
abhishek-kaushik22 merged 4 commits into from
Jun 26, 2025
Merged

[DAG] Add SDPatternMatch::m_Load #145481

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ac69bb3
[DAG] Add `SDPatternMatch::m_Load`
abhishek-kaushik22 Jun 24, 2025
b931000
Fix formatting
abhishek-kaushik22 Jun 24, 2025
a95c9f9
Update SelectionDAGPatternMatchTest.cpp
abhishek-kaushik22 Jun 26, 2025
c961ba3
Use m_Result to match only the loaded value
abhishek-kaushik22 Jun 26, 2025
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6 changes: 6 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 @@ -513,6 +513,12 @@ m_VSelect(const T0_P &Cond, const T1_P &T, const T2_P &F) {
return TernaryOpc_match<T0_P, T1_P, T2_P>(ISD::VSELECT, Cond, T, F);
}

template <typename T0_P, typename T1_P, typename T2_P>
inline TernaryOpc_match<T0_P, T1_P, T2_P>
m_Load(const T0_P &Ch, const T1_P &Ptr, const T2_P &Offset) {
return TernaryOpc_match<T0_P, T1_P, T2_P>(ISD::LOAD, Ch, Ptr, Offset);
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@RKSimon RKSimon Jun 24, 2025

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Should this match for both Load.getValue(0) (the loaded value) and Load.getValue(1) (the out chain)? Or should we have a template/run arg to match?

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@mshockwave mshockwave Jun 24, 2025

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I think having a way to distinguish which (SDValue) result to match would indeed be helpful. For instance, to match a SDNode with optional input chain, we can't tell if operand 0 is a chain or not, other than something like m_AllOf(m_SpecificVT(MVT::Other), <matcher for operand 0>) or using a matching class that uses EffectiveOperand, which skips over chains and glues (but not every matching classes use it).

Not necessary for this patch, but we might want a more general solution, for instance m_Result<0>(m_Load(...)) for matching the first result of a load.

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@RKSimon RKSimon Jun 25, 2025

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OK - for now let's just match against ResNo == 0 as that's what most people will expect from m_Load

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@RKSimon RKSimon Jun 26, 2025

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When #145775 lands this will need to be:

return m_Result<0>(TernaryOpc_match<T0_P, T1_P, T2_P>(ISD::LOAD, Ch, Ptr, Offset));

}

template <typename T0_P, typename T1_P, typename T2_P>
inline TernaryOpc_match<T0_P, T1_P, T2_P>
m_InsertElt(const T0_P &Vec, const T1_P &Val, const T2_P &Idx) {
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13 changes: 13 additions & 0 deletions llvm/unittests/CodeGen/SelectionDAGPatternMatchTest.cpp
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Expand Up @@ -178,6 +178,12 @@ TEST_F(SelectionDAGPatternMatchTest, matchTernaryOp) {
SDValue ExtractELT =
DAG->getNode(ISD::EXTRACT_VECTOR_ELT, DL, Int32VT, V1, Op3);

SDValue Ch = DAG->getEntryNode();
SDValue BasePtr = DAG->getRegister(1, MVT::i64);
SDValue Offset = DAG->getUNDEF(MVT::i64);
MachinePointerInfo PtrInfo;
SDValue Load = DAG->getLoad(MVT::i32, DL, Ch, BasePtr, PtrInfo);

using namespace SDPatternMatch;
ISD::CondCode CC;
EXPECT_TRUE(sd_match(ICMP_UGT, m_SetCC(m_Value(), m_Value(),
Expand Down Expand Up @@ -230,6 +236,13 @@ TEST_F(SelectionDAGPatternMatchTest, matchTernaryOp) {
EXPECT_FALSE(sd_match(
InsertSubvector,
m_InsertSubvector(m_Specific(V2), m_Specific(V3), m_SpecificInt(3))));

EXPECT_TRUE(sd_match(
Load, m_Load(m_Specific(Ch), m_Specific(BasePtr), m_Specific(Offset))));

EXPECT_TRUE(
sd_match(Load.getValue(1), m_Load(m_Specific(Ch), m_Specific(BasePtr),
m_Specific(Offset))));
}

TEST_F(SelectionDAGPatternMatchTest, matchBinaryOp) {
Expand Down