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[RISCV][VLOpt] Minor worklist invariant cleanup [NFC] #123989

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Merged
merged 1 commit into from
Jan 22, 2025
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[RISCV][VLOpt] Minor worklist invariant cleanup [NFC] #123989

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15 changes: 7 additions & 8 deletions llvm/lib/Target/RISCV/RISCVVLOptimizer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1189,6 +1189,10 @@ bool RISCVVLOptimizer::isCandidate(const MachineInstr &MI) const {
return false;
}

assert(MI.getOperand(0).isReg() &&
isVectorRegClass(MI.getOperand(0).getReg(), MRI) &&
"All supported instructions produce a vector register result");

LLVM_DEBUG(dbgs() << "Found a candidate for VL reduction: " << MI << "\n");
return true;
}
Expand Down Expand Up @@ -1295,9 +1299,6 @@ std::optional<MachineOperand> RISCVVLOptimizer::checkUsers(MachineInstr &MI) {
bool RISCVVLOptimizer::tryReduceVL(MachineInstr &MI) {
LLVM_DEBUG(dbgs() << "Trying to reduce VL for " << MI << "\n");

if (!isVectorRegClass(MI.getOperand(0).getReg(), MRI))
return false;

auto CommonVL = checkUsers(MI);
if (!CommonVL)
return false;
Expand Down Expand Up @@ -1347,14 +1348,11 @@ bool RISCVVLOptimizer::runOnMachineFunction(MachineFunction &MF) {
auto PushOperands = [this, &Worklist](MachineInstr &MI,
bool IgnoreSameBlock) {
for (auto &Op : MI.operands()) {
if (!Op.isReg() || !Op.isUse() || !Op.getReg().isVirtual())
continue;

if (!isVectorRegClass(Op.getReg(), MRI))
if (!Op.isReg() || !Op.isUse() || !Op.getReg().isVirtual() ||
!isVectorRegClass(Op.getReg(), MRI))
continue;

MachineInstr *DefMI = MRI->getVRegDef(Op.getReg());

if (!isCandidate(*DefMI))
continue;

Expand Down Expand Up @@ -1388,6 +1386,7 @@ bool RISCVVLOptimizer::runOnMachineFunction(MachineFunction &MF) {
while (!Worklist.empty()) {
assert(MadeChange);
MachineInstr &MI = *Worklist.pop_back_val();
assert(isCandidate(MI));
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Is this assert redundant? isCandidate explicitly blocks insertion to the Worklist in PushOperands. That being said, isCandidate is cheap, so I don't have a strong objection.

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I can drop it if you want. Personally, I find it helpful to have the assertion at the point of extraction from a worklist. This is particular true when there's more than one insert point though - which doesn't apply here. Happy to defer to your preference.

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We can keep it. It is cheap.

if (!tryReduceVL(MI))
continue;
PushOperands(MI, /*IgnoreSameBlock*/ false);
Expand Down
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