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Also consider phi nodes when deciding if a register is live out. 

llvm-svn: 132814
This commit is contained in:
Rafael Espindola 2011-06-09 22:53:47 +00:00
parent c3ae1cefc0
commit 81512fc1bb
1 changed files with 34 additions and 10 deletions
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44
llvm/lib/CodeGen/TailDuplication.cpp
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@ -81,12 +81,14 @@ namespace {
void ProcessPHI(MachineInstr *MI, MachineBasicBlock *TailBB, void ProcessPHI(MachineInstr *MI, MachineBasicBlock *TailBB,
MachineBasicBlock *PredBB, MachineBasicBlock *PredBB,
DenseMap<unsigned, unsigned> &LocalVRMap, DenseMap<unsigned, unsigned> &LocalVRMap,
SmallVector<std::pair<unsigned,unsigned>, 4> &Copies); SmallVector<std::pair<unsigned,unsigned>, 4> &Copies,
const DenseSet<unsigned> &UsedByPhi);
void DuplicateInstruction(MachineInstr *MI, void DuplicateInstruction(MachineInstr *MI,
MachineBasicBlock *TailBB, MachineBasicBlock *TailBB,
MachineBasicBlock *PredBB, MachineBasicBlock *PredBB,
MachineFunction &MF, MachineFunction &MF,
DenseMap<unsigned, unsigned> &LocalVRMap); DenseMap<unsigned, unsigned> &LocalVRMap,
const DenseSet<unsigned> &UsedByPhi);
void UpdateSuccessorsPHIs(MachineBasicBlock *FromBB, bool isDead, void UpdateSuccessorsPHIs(MachineBasicBlock *FromBB, bool isDead,
SmallVector<MachineBasicBlock*, 8> &TDBBs, SmallVector<MachineBasicBlock*, 8> &TDBBs,
SmallSetVector<MachineBasicBlock*, 8> &Succs); SmallSetVector<MachineBasicBlock*, 8> &Succs);
@ -293,6 +295,24 @@ static unsigned getPHISrcRegOpIdx(MachineInstr *MI, MachineBasicBlock *SrcBB) {
return 0; return 0;
} }
// Remember which registers are used by phis in this block. This is
// used to determine which registers are liveout while modifying the
// block (which is why we need to copy the information).
static void getRegsUsedByPHIs(const MachineBasicBlock &BB,
DenseSet<unsigned> *UsedByPhi) {
for(MachineBasicBlock::const_iterator I = BB.begin(), E = BB.end();
I != E; ++I) {
const MachineInstr &MI = *I;
if (!MI.isPHI())
break;
for (unsigned i = 1, e = MI.getNumOperands(); i != e; i += 2) {
unsigned SrcReg = MI.getOperand(i).getReg();
UsedByPhi->insert(SrcReg);
}
}
}
/// AddSSAUpdateEntry - Add a definition and source virtual registers pair for /// AddSSAUpdateEntry - Add a definition and source virtual registers pair for
/// SSA update. /// SSA update.
void TailDuplicatePass::AddSSAUpdateEntry(unsigned OrigReg, unsigned NewReg, void TailDuplicatePass::AddSSAUpdateEntry(unsigned OrigReg, unsigned NewReg,
@ -315,7 +335,8 @@ void TailDuplicatePass::ProcessPHI(MachineInstr *MI,
MachineBasicBlock *TailBB, MachineBasicBlock *TailBB,
MachineBasicBlock *PredBB, MachineBasicBlock *PredBB,
DenseMap<unsigned, unsigned> &LocalVRMap, DenseMap<unsigned, unsigned> &LocalVRMap,
SmallVector<std::pair<unsigned,unsigned>, 4> &Copies) { SmallVector<std::pair<unsigned,unsigned>, 4> &Copies,
const DenseSet<unsigned> &RegsUsedByPhi) {
unsigned DefReg = MI->getOperand(0).getReg(); unsigned DefReg = MI->getOperand(0).getReg();
unsigned SrcOpIdx = getPHISrcRegOpIdx(MI, PredBB); unsigned SrcOpIdx = getPHISrcRegOpIdx(MI, PredBB);
assert(SrcOpIdx && "Unable to find matching PHI source?"); assert(SrcOpIdx && "Unable to find matching PHI source?");
@ -327,7 +348,7 @@ void TailDuplicatePass::ProcessPHI(MachineInstr *MI,
// available value liveout of the block. // available value liveout of the block.
unsigned NewDef = MRI->createVirtualRegister(RC); unsigned NewDef = MRI->createVirtualRegister(RC);
Copies.push_back(std::make_pair(NewDef, SrcReg)); Copies.push_back(std::make_pair(NewDef, SrcReg));
if (isDefLiveOut(DefReg, TailBB, MRI)) if (isDefLiveOut(DefReg, TailBB, MRI) || RegsUsedByPhi.count(DefReg))
AddSSAUpdateEntry(DefReg, NewDef, PredBB); AddSSAUpdateEntry(DefReg, NewDef, PredBB);
// Remove PredBB from the PHI node. // Remove PredBB from the PHI node.
@ -343,7 +364,8 @@ void TailDuplicatePass::DuplicateInstruction(MachineInstr *MI,
MachineBasicBlock *TailBB, MachineBasicBlock *TailBB,
MachineBasicBlock *PredBB, MachineBasicBlock *PredBB,
MachineFunction &MF, MachineFunction &MF,
DenseMap<unsigned, unsigned> &LocalVRMap) { DenseMap<unsigned, unsigned> &LocalVRMap,
const DenseSet<unsigned> &UsedByPhi) {
MachineInstr *NewMI = TII->duplicate(MI, MF); MachineInstr *NewMI = TII->duplicate(MI, MF);
for (unsigned i = 0, e = NewMI->getNumOperands(); i != e; ++i) { for (unsigned i = 0, e = NewMI->getNumOperands(); i != e; ++i) {
MachineOperand &MO = NewMI->getOperand(i); MachineOperand &MO = NewMI->getOperand(i);
@ -357,7 +379,7 @@ void TailDuplicatePass::DuplicateInstruction(MachineInstr *MI,
unsigned NewReg = MRI->createVirtualRegister(RC); unsigned NewReg = MRI->createVirtualRegister(RC);
MO.setReg(NewReg); MO.setReg(NewReg);
LocalVRMap.insert(std::make_pair(Reg, NewReg)); LocalVRMap.insert(std::make_pair(Reg, NewReg));
if (isDefLiveOut(Reg, TailBB, MRI)) if (isDefLiveOut(Reg, TailBB, MRI) || UsedByPhi.count(Reg))
AddSSAUpdateEntry(Reg, NewReg, PredBB); AddSSAUpdateEntry(Reg, NewReg, PredBB);
} else { } else {
DenseMap<unsigned, unsigned>::iterator VI = LocalVRMap.find(Reg); DenseMap<unsigned, unsigned>::iterator VI = LocalVRMap.find(Reg);
@ -531,6 +553,8 @@ TailDuplicatePass::TailDuplicate(MachineBasicBlock *TailBB, MachineFunction &MF,
bool Changed = false; bool Changed = false;
SmallSetVector<MachineBasicBlock*, 8> Preds(TailBB->pred_begin(), SmallSetVector<MachineBasicBlock*, 8> Preds(TailBB->pred_begin(),
TailBB->pred_end()); TailBB->pred_end());
DenseSet<unsigned> UsedByPhi;
getRegsUsedByPHIs(*TailBB, &UsedByPhi);
for (SmallSetVector<MachineBasicBlock *, 8>::iterator PI = Preds.begin(), for (SmallSetVector<MachineBasicBlock *, 8>::iterator PI = Preds.begin(),
PE = Preds.end(); PI != PE; ++PI) { PE = Preds.end(); PI != PE; ++PI) {
MachineBasicBlock *PredBB = *PI; MachineBasicBlock *PredBB = *PI;
@ -570,11 +594,11 @@ TailDuplicatePass::TailDuplicate(MachineBasicBlock *TailBB, MachineFunction &MF,
if (MI->isPHI()) { if (MI->isPHI()) {
// Replace the uses of the def of the PHI with the register coming // Replace the uses of the def of the PHI with the register coming
// from PredBB. // from PredBB.
ProcessPHI(MI, TailBB, PredBB, LocalVRMap, CopyInfos); ProcessPHI(MI, TailBB, PredBB, LocalVRMap, CopyInfos, UsedByPhi);
} else { } else {
// Replace def of virtual registers with new registers, and update // Replace def of virtual registers with new registers, and update
// uses with PHI source register or the new registers. // uses with PHI source register or the new registers.
DuplicateInstruction(MI, TailBB, PredBB, MF, LocalVRMap); DuplicateInstruction(MI, TailBB, PredBB, MF, LocalVRMap, UsedByPhi);
} }
} }
MachineBasicBlock::iterator Loc = PredBB->getFirstTerminator(); MachineBasicBlock::iterator Loc = PredBB->getFirstTerminator();
@ -620,7 +644,7 @@ TailDuplicatePass::TailDuplicate(MachineBasicBlock *TailBB, MachineFunction &MF,
// Replace the uses of the def of the PHI with the register coming // Replace the uses of the def of the PHI with the register coming
// from PredBB. // from PredBB.
MachineInstr *MI = &*I++; MachineInstr *MI = &*I++;
ProcessPHI(MI, TailBB, PrevBB, LocalVRMap, CopyInfos); ProcessPHI(MI, TailBB, PrevBB, LocalVRMap, CopyInfos, UsedByPhi);
if (MI->getParent()) if (MI->getParent())
MI->eraseFromParent(); MI->eraseFromParent();
} }
@ -630,7 +654,7 @@ TailDuplicatePass::TailDuplicate(MachineBasicBlock *TailBB, MachineFunction &MF,
// Replace def of virtual registers with new registers, and update // Replace def of virtual registers with new registers, and update
// uses with PHI source register or the new registers. // uses with PHI source register or the new registers.
MachineInstr *MI = &*I++; MachineInstr *MI = &*I++;
DuplicateInstruction(MI, TailBB, PrevBB, MF, LocalVRMap); DuplicateInstruction(MI, TailBB, PrevBB, MF, LocalVRMap, UsedByPhi);
MI->eraseFromParent(); MI->eraseFromParent();
} }
MachineBasicBlock::iterator Loc = PrevBB->getFirstTerminator(); MachineBasicBlock::iterator Loc = PrevBB->getFirstTerminator();