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[RISCV] Stop passing the merge opcode around in RISCVMoveMerger. NFC #153687

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Merged
merged 2 commits into from
Aug 15, 2025
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[RISCV] Stop passing the merge opcode around in RISCVMoveMerger. NFC #153687

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392c07b
[RISCV] Stop passing the merge opcode around in RISCVMoveMerger. NFC
topperc Aug 14, 2025
6e31656
[RISCV] Fix backwards naming.
topperc Aug 14, 2025
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86 changes: 31 additions & 55 deletions llvm/lib/Target/RISCV/RISCVMoveMerger.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,7 @@ struct RISCVMoveMerge : public MachineFunctionPass {

RISCVMoveMerge() : MachineFunctionPass(ID) {}

const RISCVSubtarget *ST;
const RISCVInstrInfo *TII;
const TargetRegisterInfo *TRI;

Expand All @@ -37,15 +38,15 @@ struct RISCVMoveMerge : public MachineFunctionPass {
// Merge the two instructions indicated into a single pair instruction.
MachineBasicBlock::iterator
mergePairedInsns(MachineBasicBlock::iterator I,
MachineBasicBlock::iterator Paired, unsigned Opcode);
MachineBasicBlock::iterator Paired, bool MoveFromSToA);

// Look for C.MV instruction that can be combined with
// the given instruction into CM.MVA01S or CM.MVSA01. Return the matching
// instruction if one exists.
MachineBasicBlock::iterator
findMatchingInst(MachineBasicBlock::iterator &MBBI, unsigned InstOpcode,
findMatchingInst(MachineBasicBlock::iterator &MBBI, bool MoveFromSToA,
const DestSourcePair &RegPair);
bool mergeMoveSARegPair(const RISCVSubtarget &STI, MachineBasicBlock &MBB);
bool mergeMoveSARegPair(MachineBasicBlock &MBB);
bool runOnMachineFunction(MachineFunction &Fn) override;

StringRef getPassName() const override { return RISCV_MOVE_MERGE_NAME; }
Expand All @@ -58,41 +59,21 @@ char RISCVMoveMerge::ID = 0;
INITIALIZE_PASS(RISCVMoveMerge, "riscv-move-merge", RISCV_MOVE_MERGE_NAME,
false, false)

static bool isMoveFromAToS(unsigned Opcode) {
switch (Opcode) {
case RISCV::CM_MVA01S:
case RISCV::QC_CM_MVA01S:
return true;
default:
return false;
}
}

static unsigned getMoveFromAToSOpcode(const RISCVSubtarget &STI) {
if (STI.hasStdExtZcmp())
static unsigned getMoveFromSToAOpcode(const RISCVSubtarget &ST) {
if (ST.hasStdExtZcmp())
return RISCV::CM_MVA01S;

if (STI.hasVendorXqccmp())
if (ST.hasVendorXqccmp())
return RISCV::QC_CM_MVA01S;

llvm_unreachable("Unhandled subtarget with paired A to S move.");
}

static bool isMoveFromSToA(unsigned Opcode) {
switch (Opcode) {
case RISCV::CM_MVSA01:
case RISCV::QC_CM_MVSA01:
return true;
default:
return false;
}
}

static unsigned getMoveFromSToAOpcode(const RISCVSubtarget &STI) {
if (STI.hasStdExtZcmp())
static unsigned getMoveFromAToSOpcode(const RISCVSubtarget &ST) {
if (ST.hasStdExtZcmp())
return RISCV::CM_MVSA01;

if (STI.hasVendorXqccmp())
if (ST.hasVendorXqccmp())
return RISCV::QC_CM_MVSA01;

llvm_unreachable("Unhandled subtarget with paired S to A move");
Expand Down Expand Up @@ -123,21 +104,20 @@ bool RISCVMoveMerge::isCandidateToMergeMVSA01(const DestSourcePair &RegPair) {
MachineBasicBlock::iterator
RISCVMoveMerge::mergePairedInsns(MachineBasicBlock::iterator I,
MachineBasicBlock::iterator Paired,
unsigned Opcode) {
bool MoveFromSToA) {
const MachineOperand *Sreg1, *Sreg2;
MachineBasicBlock::iterator E = I->getParent()->end();
MachineBasicBlock::iterator NextI = next_nodbg(I, E);
DestSourcePair FirstPair = TII->isCopyInstrImpl(*I).value();
DestSourcePair PairedRegs = TII->isCopyInstrImpl(*Paired).value();
Register ARegInFirstPair = isMoveFromAToS(Opcode)
? FirstPair.Destination->getReg()
: FirstPair.Source->getReg();
Register ARegInFirstPair = MoveFromSToA ? FirstPair.Destination->getReg()
: FirstPair.Source->getReg();

if (NextI == Paired)
NextI = next_nodbg(NextI, E);
DebugLoc DL = I->getDebugLoc();

// Make a copy so we can update the kill flag in the MoveFromAToS case. The
// Make a copy so we can update the kill flag in the MoveFromSToA case. The
// copied operand needs to be scoped outside the if since we make a pointer
// to it.
MachineOperand PairedSource = *PairedRegs.Source;
Expand All @@ -151,17 +131,20 @@ RISCVMoveMerge::mergePairedInsns(MachineBasicBlock::iterator I,
// mv a0, s2
// mv a1, s1 => cm.mva01s s2,s1
bool StartWithX10 = ARegInFirstPair == RISCV::X10;
if (isMoveFromAToS(Opcode)) {
unsigned Opcode;
if (MoveFromSToA) {
// We are moving one of the copies earlier so its kill flag may become
// invalid. Clear the copied kill flag if there are any reads of the
// register between the new location and the old location.
for (auto It = std::next(I); It != Paired && PairedSource.isKill(); ++It)
if (It->readsRegister(PairedSource.getReg(), TRI))
PairedSource.setIsKill(false);

Opcode = getMoveFromSToAOpcode(*ST);
Sreg1 = StartWithX10 ? FirstPair.Source : &PairedSource;
Sreg2 = StartWithX10 ? &PairedSource : FirstPair.Source;
} else {
Opcode = getMoveFromAToSOpcode(*ST);
Sreg1 = StartWithX10 ? FirstPair.Destination : PairedRegs.Destination;
Sreg2 = StartWithX10 ? PairedRegs.Destination : FirstPair.Destination;
}
Expand All @@ -175,7 +158,7 @@ RISCVMoveMerge::mergePairedInsns(MachineBasicBlock::iterator I,

MachineBasicBlock::iterator
RISCVMoveMerge::findMatchingInst(MachineBasicBlock::iterator &MBBI,
unsigned InstOpcode,
bool MoveFromSToA,
const DestSourcePair &RegPair) {
MachineBasicBlock::iterator E = MBBI->getParent()->end();

Expand All @@ -193,7 +176,7 @@ RISCVMoveMerge::findMatchingInst(MachineBasicBlock::iterator &MBBI,
Register SourceReg = SecondPair->Source->getReg();
Register DestReg = SecondPair->Destination->getReg();

if (isMoveFromAToS(InstOpcode) && isCandidateToMergeMVA01S(*SecondPair)) {
if (MoveFromSToA && isCandidateToMergeMVA01S(*SecondPair)) {
// If register pair is valid and destination registers are different.
if ((RegPair.Destination->getReg() == DestReg))
return E;
Expand All @@ -207,8 +190,7 @@ RISCVMoveMerge::findMatchingInst(MachineBasicBlock::iterator &MBBI,
return E;

return I;
} else if (isMoveFromSToA(InstOpcode) &&
isCandidateToMergeMVSA01(*SecondPair)) {
} else if (!MoveFromSToA && isCandidateToMergeMVSA01(*SecondPair)) {
if ((RegPair.Source->getReg() == SourceReg) ||
(RegPair.Destination->getReg() == DestReg))
return E;
Expand All @@ -229,8 +211,7 @@ RISCVMoveMerge::findMatchingInst(MachineBasicBlock::iterator &MBBI,

// Finds instructions, which could be represented as C.MV instructions and
// merged into CM.MVA01S or CM.MVSA01.
bool RISCVMoveMerge::mergeMoveSARegPair(const RISCVSubtarget &STI,
MachineBasicBlock &MBB) {
bool RISCVMoveMerge::mergeMoveSARegPair(MachineBasicBlock &MBB) {
bool Modified = false;

for (MachineBasicBlock::iterator MBBI = MBB.begin(), E = MBB.end();
Expand All @@ -239,22 +220,17 @@ bool RISCVMoveMerge::mergeMoveSARegPair(const RISCVSubtarget &STI,
// can, return Dest/Src register pair.
auto RegPair = TII->isCopyInstrImpl(*MBBI);
if (RegPair.has_value()) {
unsigned Opcode = 0;

if (isCandidateToMergeMVA01S(*RegPair))
Opcode = getMoveFromAToSOpcode(STI);
else if (isCandidateToMergeMVSA01(*RegPair))
Opcode = getMoveFromSToAOpcode(STI);
else {
bool MoveFromSToA = isCandidateToMergeMVA01S(*RegPair);
if (!MoveFromSToA && !isCandidateToMergeMVSA01(*RegPair)) {
++MBBI;
continue;
}

MachineBasicBlock::iterator Paired =
findMatchingInst(MBBI, Opcode, RegPair.value());
findMatchingInst(MBBI, MoveFromSToA, RegPair.value());
// If matching instruction can be found merge them.
if (Paired != E) {
MBBI = mergePairedInsns(MBBI, Paired, Opcode);
MBBI = mergePairedInsns(MBBI, Paired, MoveFromSToA);
Modified = true;
continue;
}
Expand All @@ -268,20 +244,20 @@ bool RISCVMoveMerge::runOnMachineFunction(MachineFunction &Fn) {
if (skipFunction(Fn.getFunction()))
return false;

const RISCVSubtarget *Subtarget = &Fn.getSubtarget<RISCVSubtarget>();
if (!(Subtarget->hasStdExtZcmp() || Subtarget->hasVendorXqccmp()))
ST = &Fn.getSubtarget<RISCVSubtarget>();
if (!ST->hasStdExtZcmp() && !ST->hasVendorXqccmp())
return false;

TII = Subtarget->getInstrInfo();
TRI = Subtarget->getRegisterInfo();
TII = ST->getInstrInfo();
TRI = ST->getRegisterInfo();
// Resize the modified and used register unit trackers. We do this once
// per function and then clear the register units each time we optimize a
// move.
ModifiedRegUnits.init(*TRI);
UsedRegUnits.init(*TRI);
bool Modified = false;
for (auto &MBB : Fn)
Modified |= mergeMoveSARegPair(*Subtarget, MBB);
Modified |= mergeMoveSARegPair(MBB);
return Modified;
}

Expand Down