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Add some more of StrongPHIElim.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@43805 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Owen Anderson 2007-11-07 05:17:15 +00:00
parent d96b159fe3
commit 60a877d713
1 changed files with 74 additions and 12 deletions
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86
lib/CodeGen/StrongPHIElimination.cpp
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@ -89,7 +89,7 @@ namespace {
void computeDFS(MachineFunction& MF);
void processPHI(MachineInstr* P);
void processBlock(MachineBasicBlock* MBB);
std::vector<DomForestNode*> computeDomForest(std::set<unsigned>& instrs);
@ -219,23 +219,85 @@ StrongPHIElimination::computeDomForest(std::set<unsigned>& regs) {
return ret;
}
/// processPHI - Eliminate the given PHI node
void StrongPHIElimination::processPHI(MachineInstr* P) {
/// isLiveIn - helper method that determines, from a VarInfo, if a register
/// is live into a block
bool isLiveIn(LiveVariables::VarInfo& V, MachineBasicBlock* MBB) {
if (V.AliveBlocks.test(MBB->getNumber()))
return true;
for (std::vector<MachineInstr*>::iterator I = V.Kills.begin(),
E = V.Kills.end(); I != E; ++I)
if ((*I)->getParent() == MBB)
return true;
return false;
}
/// isLiveOut - help method that determines, from a VarInfo, if a register is
/// live out of a block.
bool isLiveOut(LiveVariables::VarInfo& V, MachineBasicBlock* MBB) {
if (V.AliveBlocks.test(MBB->getNumber()))
return true;
if (V.DefInst->getParent() == MBB)
return true;
return false;
}
/// processBlock - Eliminate PHIs in the given block
void StrongPHIElimination::processBlock(MachineBasicBlock* MBB) {
LiveVariables& LV = getAnalysis<LiveVariables>();
// Holds names that have been added to a set in any PHI within this block
// before the current one.
std::set<unsigned> ProcessedNames;
MachineBasicBlock::iterator P = MBB->begin();
while (P->getOpcode() == TargetInstrInfo::PHI) {
LiveVariables::VarInfo& PHIInfo = LV.getVarInfo(P->getOperand(0).getReg());
// Hold the names that are currently in the candidate set.
std::set<unsigned> PHIUnion;
std::set<MachineBasicBlock*> UnionedBlocks;
for (int i = P->getNumOperands() - 1; i >= 2; i-=2) {
unsigned SrcReg = P->getOperand(i-1).getReg();
LiveVariables::VarInfo& SrcInfo = LV.getVarInfo(SrcReg);
if (isLiveIn(SrcInfo, P->getParent())) {
// add a copy from a_i to p in Waiting[From[a_i]]
} else if (isLiveOut(PHIInfo, SrcInfo.DefInst->getParent())) {
// add a copy to Waiting[From[a_i]]
} else if (PHIInfo.DefInst->getOpcode() == TargetInstrInfo::PHI &&
isLiveIn(PHIInfo, SrcInfo.DefInst->getParent())) {
// add a copy to Waiting[From[a_i]]
} else if (ProcessedNames.count(SrcReg)) {
// add a copy to Waiting[From[a_i]]
} else if (UnionedBlocks.count(SrcInfo.DefInst->getParent())) {
// add a copy to Waiting[From[a_i]]
} else {
PHIUnion.insert(SrcReg);
UnionedBlocks.insert(SrcInfo.DefInst->getParent());
// DO STUFF HERE
}
ProcessedNames.insert(PHIUnion.begin(), PHIUnion.end());
}
++P;
}
}
bool StrongPHIElimination::runOnMachineFunction(MachineFunction &Fn) {
computeDFS(Fn);
for (MachineFunction::iterator I = Fn.begin(), E = Fn.end(); I != E; ++I) {
for (MachineBasicBlock::iterator BI = I->begin(), BE = I->end(); BI != BE;
++BI) {
if (BI->getOpcode() == TargetInstrInfo::PHI)
processPHI(BI);
else
break;
}
}
for (MachineFunction::iterator I = Fn.begin(), E = Fn.end(); I != E; ++I)
if (!I->empty() &&
I->begin()->getOpcode() == TargetInstrInfo::PHI)
processBlock(I);
return false;
}