[llvm-commits] [llvm] r132814 - /llvm/trunk/lib/CodeGen/TailDuplication.cpp
Rafael Espindola
rafael.espindola at gmail.com
Thu Jun 9 15:53:48 PDT 2011
Author: rafael
Date: Thu Jun 9 17:53:47 2011
New Revision: 132814
URL: http://llvm.org/viewvc/llvm-project?rev=132814&view=rev
Log:
Also consider phi nodes when deciding if a register is live out.
Modified:
llvm/trunk/lib/CodeGen/TailDuplication.cpp
Modified: llvm/trunk/lib/CodeGen/TailDuplication.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/TailDuplication.cpp?rev=132814&r1=132813&r2=132814&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/TailDuplication.cpp (original)
+++ llvm/trunk/lib/CodeGen/TailDuplication.cpp Thu Jun 9 17:53:47 2011
@@ -81,12 +81,14 @@
void ProcessPHI(MachineInstr *MI, MachineBasicBlock *TailBB,
MachineBasicBlock *PredBB,
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,
MachineBasicBlock *TailBB,
MachineBasicBlock *PredBB,
MachineFunction &MF,
- DenseMap<unsigned, unsigned> &LocalVRMap);
+ DenseMap<unsigned, unsigned> &LocalVRMap,
+ const DenseSet<unsigned> &UsedByPhi);
void UpdateSuccessorsPHIs(MachineBasicBlock *FromBB, bool isDead,
SmallVector<MachineBasicBlock*, 8> &TDBBs,
SmallSetVector<MachineBasicBlock*, 8> &Succs);
@@ -293,6 +295,24 @@
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
/// SSA update.
void TailDuplicatePass::AddSSAUpdateEntry(unsigned OrigReg, unsigned NewReg,
@@ -315,7 +335,8 @@
MachineBasicBlock *TailBB,
MachineBasicBlock *PredBB,
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 SrcOpIdx = getPHISrcRegOpIdx(MI, PredBB);
assert(SrcOpIdx && "Unable to find matching PHI source?");
@@ -327,7 +348,7 @@
// available value liveout of the block.
unsigned NewDef = MRI->createVirtualRegister(RC);
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);
// Remove PredBB from the PHI node.
@@ -343,7 +364,8 @@
MachineBasicBlock *TailBB,
MachineBasicBlock *PredBB,
MachineFunction &MF,
- DenseMap<unsigned, unsigned> &LocalVRMap) {
+ DenseMap<unsigned, unsigned> &LocalVRMap,
+ const DenseSet<unsigned> &UsedByPhi) {
MachineInstr *NewMI = TII->duplicate(MI, MF);
for (unsigned i = 0, e = NewMI->getNumOperands(); i != e; ++i) {
MachineOperand &MO = NewMI->getOperand(i);
@@ -357,7 +379,7 @@
unsigned NewReg = MRI->createVirtualRegister(RC);
MO.setReg(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);
} else {
DenseMap<unsigned, unsigned>::iterator VI = LocalVRMap.find(Reg);
@@ -531,6 +553,8 @@
bool Changed = false;
SmallSetVector<MachineBasicBlock*, 8> Preds(TailBB->pred_begin(),
TailBB->pred_end());
+ DenseSet<unsigned> UsedByPhi;
+ getRegsUsedByPHIs(*TailBB, &UsedByPhi);
for (SmallSetVector<MachineBasicBlock *, 8>::iterator PI = Preds.begin(),
PE = Preds.end(); PI != PE; ++PI) {
MachineBasicBlock *PredBB = *PI;
@@ -570,11 +594,11 @@
if (MI->isPHI()) {
// Replace the uses of the def of the PHI with the register coming
// from PredBB.
- ProcessPHI(MI, TailBB, PredBB, LocalVRMap, CopyInfos);
+ ProcessPHI(MI, TailBB, PredBB, LocalVRMap, CopyInfos, UsedByPhi);
} else {
// Replace def of virtual registers with new registers, and update
// 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();
@@ -620,7 +644,7 @@
// Replace the uses of the def of the PHI with the register coming
// from PredBB.
MachineInstr *MI = &*I++;
- ProcessPHI(MI, TailBB, PrevBB, LocalVRMap, CopyInfos);
+ ProcessPHI(MI, TailBB, PrevBB, LocalVRMap, CopyInfos, UsedByPhi);
if (MI->getParent())
MI->eraseFromParent();
}
@@ -630,7 +654,7 @@
// Replace def of virtual registers with new registers, and update
// uses with PHI source register or the new registers.
MachineInstr *MI = &*I++;
- DuplicateInstruction(MI, TailBB, PrevBB, MF, LocalVRMap);
+ DuplicateInstruction(MI, TailBB, PrevBB, MF, LocalVRMap, UsedByPhi);
MI->eraseFromParent();
}
MachineBasicBlock::iterator Loc = PrevBB->getFirstTerminator();
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