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[ARM] Stop gluing ALU nodes to branches / selects #116970

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Merged
merged 6 commits into from
Nov 30, 2024
Merged

[ARM] Stop gluing ALU nodes to branches / selects #116970

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2487cff
[ARM] Stop gluing ALU nodes to branches / selects
s-barannikov Nov 17, 2024
44688af
clang-format
s-barannikov Nov 20, 2024
b2cfc51
Comment out-of-line patterns
s-barannikov Nov 20, 2024
4add488
Merge branch 'main' into sdag/arm-glue
s-barannikov Nov 25, 2024
486d07f
Update the test added in the previous PR
s-barannikov Nov 25, 2024
6c3c0d1
Merge branch 'main' into sdag/arm-glue
s-barannikov Nov 29, 2024
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53 changes: 18 additions & 35 deletions llvm/lib/Target/ARM/ARMISelDAGToDAG.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -111,13 +111,6 @@ class ARMDAGToDAGISel : public SelectionDAGISel {
bool SelectAddrModeImm12(SDValue N, SDValue &Base, SDValue &OffImm);
bool SelectLdStSOReg(SDValue N, SDValue &Base, SDValue &Offset, SDValue &Opc);

bool SelectCMOVPred(SDValue N, SDValue &Pred, SDValue &Reg) {
const ConstantSDNode *CN = cast<ConstantSDNode>(N);
Pred = CurDAG->getTargetConstant(CN->getZExtValue(), SDLoc(N), MVT::i32);
Reg = CurDAG->getRegister(ARM::CPSR, MVT::i32);
return true;
}

bool SelectAddrMode2OffsetReg(SDNode *Op, SDValue N,
SDValue &Offset, SDValue &Opc);
bool SelectAddrMode2OffsetImm(SDNode *Op, SDValue N,
Expand Down Expand Up @@ -4123,17 +4116,15 @@ void ARMDAGToDAGISel::Select(SDNode *N) {
SDValue Chain = N->getOperand(0);
SDValue N1 = N->getOperand(1);
SDValue N2 = N->getOperand(2);
SDValue N3 = N->getOperand(3);
SDValue InGlue = N->getOperand(4);
SDValue Flags = N->getOperand(3);
assert(N1.getOpcode() == ISD::BasicBlock);
assert(N2.getOpcode() == ISD::Constant);
assert(N3.getOpcode() == ISD::Register);

unsigned CC = (unsigned)N2->getAsZExtVal();

if (InGlue.getOpcode() == ARMISD::CMPZ) {
if (InGlue.getOperand(0).getOpcode() == ISD::INTRINSIC_W_CHAIN) {
SDValue Int = InGlue.getOperand(0);
if (Flags.getOpcode() == ARMISD::CMPZ) {
if (Flags.getOperand(0).getOpcode() == ISD::INTRINSIC_W_CHAIN) {
SDValue Int = Flags.getOperand(0);
uint64_t ID = Int->getConstantOperandVal(1);

// Handle low-overhead loops.
Expand All @@ -4155,15 +4146,15 @@ void ARMDAGToDAGISel::Select(SDNode *N) {

ReplaceUses(N, LoopEnd);
CurDAG->RemoveDeadNode(N);
CurDAG->RemoveDeadNode(InGlue.getNode());
CurDAG->RemoveDeadNode(Flags.getNode());
CurDAG->RemoveDeadNode(Int.getNode());
return;
}
}

bool SwitchEQNEToPLMI;
SelectCMPZ(InGlue.getNode(), SwitchEQNEToPLMI);
InGlue = N->getOperand(4);
SelectCMPZ(Flags.getNode(), SwitchEQNEToPLMI);
Flags = N->getOperand(3);

if (SwitchEQNEToPLMI) {
switch ((ARMCC::CondCodes)CC) {
Expand All @@ -4179,25 +4170,18 @@ void ARMDAGToDAGISel::Select(SDNode *N) {
}

SDValue Tmp2 = CurDAG->getTargetConstant(CC, dl, MVT::i32);
SDValue Ops[] = { N1, Tmp2, N3, Chain, InGlue };
SDNode *ResNode = CurDAG->getMachineNode(Opc, dl, MVT::Other,
MVT::Glue, Ops);
Chain = SDValue(ResNode, 0);
if (N->getNumValues() == 2) {
InGlue = SDValue(ResNode, 1);
ReplaceUses(SDValue(N, 1), InGlue);
}
ReplaceUses(SDValue(N, 0),
SDValue(Chain.getNode(), Chain.getResNo()));
CurDAG->RemoveDeadNode(N);
Chain = CurDAG->getCopyToReg(Chain, dl, ARM::CPSR, Flags, SDValue());
SDValue Ops[] = {N1, Tmp2, CurDAG->getRegister(ARM::CPSR, MVT::i32), Chain,
Chain.getValue(1)};
CurDAG->SelectNodeTo(N, Opc, MVT::Other, Ops);
return;
}

case ARMISD::CMPZ: {
// select (CMPZ X, #-C) -> (CMPZ (ADDS X, #C), #0)
// This allows us to avoid materializing the expensive negative constant.
// The CMPZ #0 is useless and will be peepholed away but we need to keep it
// for its glue output.
// The CMPZ #0 is useless and will be peepholed away but we need to keep
// it for its flags output.
SDValue X = N->getOperand(0);
auto *C = dyn_cast<ConstantSDNode>(N->getOperand(1).getNode());
if (C && C->getSExtValue() < 0 && Subtarget->isThumb()) {
Expand All @@ -4224,19 +4208,19 @@ void ARMDAGToDAGISel::Select(SDNode *N) {
}
if (Add) {
SDValue Ops2[] = {SDValue(Add, 0), CurDAG->getConstant(0, dl, MVT::i32)};
CurDAG->MorphNodeTo(N, ARMISD::CMPZ, CurDAG->getVTList(MVT::Glue), Ops2);
CurDAG->MorphNodeTo(N, ARMISD::CMPZ, N->getVTList(), Ops2);
}
}
// Other cases are autogenerated.
break;
}

case ARMISD::CMOV: {
SDValue InGlue = N->getOperand(4);
SDValue Flags = N->getOperand(3);

if (InGlue.getOpcode() == ARMISD::CMPZ) {
if (Flags.getOpcode() == ARMISD::CMPZ) {
bool SwitchEQNEToPLMI;
SelectCMPZ(InGlue.getNode(), SwitchEQNEToPLMI);
SelectCMPZ(Flags.getNode(), SwitchEQNEToPLMI);

if (SwitchEQNEToPLMI) {
SDValue ARMcc = N->getOperand(2);
Expand All @@ -4253,10 +4237,9 @@ void ARMDAGToDAGISel::Select(SDNode *N) {
}
SDValue NewARMcc = CurDAG->getConstant((unsigned)CC, dl, MVT::i32);
SDValue Ops[] = {N->getOperand(0), N->getOperand(1), NewARMcc,
N->getOperand(3), N->getOperand(4)};
N->getOperand(3)};
CurDAG->MorphNodeTo(N, ARMISD::CMOV, N->getVTList(), Ops);
}

}
// Other cases are autogenerated.
break;
Expand Down
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