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[MachineLateInstrsCleanup] Minor fixing (NFC). #117816

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Merged
merged 1 commit into from
Nov 27, 2024
+7 −11
Merged

[MachineLateInstrsCleanup] Minor fixing (NFC). #117816

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18 changes: 7 additions & 11 deletions llvm/lib/CodeGen/MachineLateInstrsCleanup.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -57,7 +57,6 @@ class MachineLateInstrsCleanup : public MachineFunctionPass {

void removeRedundantDef(MachineInstr *MI);
void clearKillsForDef(Register Reg, MachineBasicBlock *MBB,
MachineBasicBlock::iterator I,
BitVector &VisitedPreds);

public:
Expand Down Expand Up @@ -110,14 +109,11 @@ bool MachineLateInstrsCleanup::runOnMachineFunction(MachineFunction &MF) {
return Changed;
}

// Clear any previous kill flag on Reg found before I in MBB. Walk backwards
// in MBB and if needed continue in predecessors until a use/def of Reg is
// encountered. This seems to be faster in practice than tracking kill flags
// in a map.
void MachineLateInstrsCleanup::
clearKillsForDef(Register Reg, MachineBasicBlock *MBB,
MachineBasicBlock::iterator I,
BitVector &VisitedPreds) {
// Clear any preceding kill flag on Reg after removing a redundant
// definition.
void MachineLateInstrsCleanup::clearKillsForDef(Register Reg,
MachineBasicBlock *MBB,
BitVector &VisitedPreds) {
VisitedPreds.set(MBB->getNumber());

// Kill flag in MBB
Expand All @@ -137,13 +133,13 @@ clearKillsForDef(Register Reg, MachineBasicBlock *MBB,
assert(!MBB->pred_empty() && "Predecessor def not found!");
for (MachineBasicBlock *Pred : MBB->predecessors())
if (!VisitedPreds.test(Pred->getNumber()))
clearKillsForDef(Reg, Pred, Pred->end(), VisitedPreds);
clearKillsForDef(Reg, Pred, VisitedPreds);
}

void MachineLateInstrsCleanup::removeRedundantDef(MachineInstr *MI) {
Register Reg = MI->getOperand(0).getReg();
BitVector VisitedPreds(MI->getMF()->getNumBlockIDs());
clearKillsForDef(Reg, MI->getParent(), MI->getIterator(), VisitedPreds);
clearKillsForDef(Reg, MI->getParent(), VisitedPreds);
MI->eraseFromParent();
++NumRemoved;
}
Expand Down