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[RISCV] Use sd_match in trySignedBitfieldInsertInMask #154152

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Merged
merged 2 commits into from
Aug 19, 2025
Merged

[RISCV] Use sd_match in trySignedBitfieldInsertInMask #154152

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a5f1e7a
[RISCV] Use sd_match in trySignedBitfieldInsertInMask
svs-quic Aug 18, 2025
81e8c62
Merge branch 'main' into sdmatch_inmask
svs-quic Aug 19, 2025
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31 changes: 12 additions & 19 deletions llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -682,39 +682,32 @@ bool RISCVDAGToDAGISel::trySignedBitfieldInsertInMask(SDNode *Node) {
if (!Subtarget->hasVendorXqcibm())
return false;

auto *N1C = dyn_cast<ConstantSDNode>(Node->getOperand(1));
if (!N1C)
return false;
using namespace SDPatternMatch;

int32_t C1 = N1C->getSExtValue();
if (!isShiftedMask_32(C1) || isInt<12>(C1))
SDValue X;
APInt MaskImm;
if (!sd_match(Node, m_Or(m_OneUse(m_Value(X)), m_ConstInt(MaskImm))))
return false;

// INSBI will clobber the input register in N0. Bail out if we need a copy to
// preserve this value.
SDValue N0 = Node->getOperand(0);
if (!N0.hasOneUse())
unsigned ShAmt, Width;
if (!MaskImm.isShiftedMask(ShAmt, Width) || MaskImm.isSignedIntN(12))
return false;

// If C1 is a shifted mask (but can't be formed as an ORI),
// use a bitfield insert of -1.
// Transform (or x, C1)
// -> (qc.insbi x, -1, width, shift)
const unsigned Leading = llvm::countl_zero((uint32_t)C1);
const unsigned Trailing = llvm::countr_zero((uint32_t)C1);
const unsigned Width = 32 - Leading - Trailing;

// If Zbs is enabled and it is a single bit set we can use BSETI which
// can be compressed to C_BSETI when Xqcibm in enabled.
if (Width == 1 && Subtarget->hasStdExtZbs())
return false;

// If C1 is a shifted mask (but can't be formed as an ORI),
// use a bitfield insert of -1.
// Transform (or x, C1)
// -> (qc.insbi x, -1, width, shift)
SDLoc DL(Node);
MVT VT = Node->getSimpleValueType(0);

SDValue Ops[] = {N0, CurDAG->getSignedTargetConstant(-1, DL, VT),
SDValue Ops[] = {X, CurDAG->getSignedTargetConstant(-1, DL, VT),
CurDAG->getTargetConstant(Width, DL, VT),
CurDAG->getTargetConstant(Trailing, DL, VT)};
CurDAG->getTargetConstant(ShAmt, DL, VT)};
SDNode *BitIns = CurDAG->getMachineNode(RISCV::QC_INSBI, DL, VT, Ops);
ReplaceNode(Node, BitIns);
return true;
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