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More progress on StrongPHIElimination. Now we actually USE the DomForest!

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@44877 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Owen Anderson 2007-12-11 20:12:11 +00:00
parent 12ebf14048
commit d525f664c9
1 changed files with 89 additions and 0 deletions
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89
lib/CodeGen/StrongPHIElimination.cpp
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@ -97,6 +97,9 @@ namespace {
void processBlock(MachineBasicBlock* MBB);
std::vector<DomForestNode*> computeDomForest(std::set<unsigned>& instrs);
void processPHIUnion(MachineInstr* Inst,
std::set<unsigned>& PHIUnion,
std::vector<StrongPHIElimination::DomForestNode*>& DF);
void breakCriticalEdges(MachineFunction &Fn);
};
@ -303,6 +306,92 @@ void StrongPHIElimination::processBlock(MachineBasicBlock* MBB) {
}
}
void StrongPHIElimination::processPHIUnion(MachineInstr* Inst,
std::set<unsigned>& PHIUnion,
std::vector<StrongPHIElimination::DomForestNode*>& DF) {
std::vector<DomForestNode*> worklist(DF.begin(), DF.end());
SmallPtrSet<DomForestNode*, 4> visited;
LiveVariables& LV = getAnalysis<LiveVariables>();
unsigned DestReg = Inst->getOperand(0).getReg();
while (!worklist.empty()) {
DomForestNode* DFNode = worklist.back();
LiveVariables::VarInfo& Info = LV.getVarInfo(DFNode->getReg());
visited.insert(DFNode);
bool inserted = false;
SmallPtrSet<DomForestNode*, 4> interferences;
for (DomForestNode::iterator CI = DFNode->begin(), CE = DFNode->end();
CI != CE; ++CI) {
DomForestNode* child = *CI;
LiveVariables::VarInfo& CInfo = LV.getVarInfo(child->getReg());
if (isLiveOut(Info, CInfo.DefInst->getParent())) {
interferences.insert(child);
} else if (isLiveIn(Info, CInfo.DefInst->getParent()) ||
Info.DefInst->getParent() == CInfo.DefInst->getParent()) {
// FIXME: Add (p, c) to possible local interferences
}
if (!visited.count(child)) {
worklist.push_back(child);
inserted = true;
}
}
if (interferences.size() == 1) {
DomForestNode* child = *interferences.begin();
unsigned numParentCopies = 0;
unsigned numChildCopies = 0;
for (int i = Inst->getNumOperands() - 1; i >= 2; i-=2) {
unsigned SrcReg = Inst->getOperand(i-1).getReg();
if (SrcReg == DFNode->getReg()) numParentCopies++;
else if (SrcReg == child->getReg()) numChildCopies++;
}
if (numParentCopies < numChildCopies) {
// Insert copies for child
for (int i = Inst->getNumOperands() - 1; i >= 2; i-=2) {
if (Inst->getOperand(i-1).getReg() == child->getReg()) {
unsigned SrcReg = Inst->getOperand(i-1).getReg();
MachineBasicBlock* From = Inst->getOperand(i).getMBB();
Waiting[From].push_back(std::make_pair(SrcReg, DestReg));
}
}
// FIXME: Make child's children parent's children
} else {
// Insert copies for parent
for (int i = Inst->getNumOperands() - 1; i >= 2; i-=2) {
if (Inst->getOperand(i-1).getReg() == DFNode->getReg()) {
unsigned SrcReg = Inst->getOperand(i-1).getReg();
MachineBasicBlock* From = Inst->getOperand(i).getMBB();
Waiting[From].push_back(std::make_pair(SrcReg, DestReg));
}
}
}
} else if (interferences.size() > 1) {
// Insert copies for parent
for (int i = Inst->getNumOperands() - 1; i >= 2; i-=2) {
if (Inst->getOperand(i-1).getReg() == DFNode->getReg()) {
unsigned SrcReg = Inst->getOperand(i-1).getReg();
MachineBasicBlock* From = Inst->getOperand(i).getMBB();
Waiting[From].push_back(std::make_pair(SrcReg, DestReg));
}
}
}
if (!inserted) worklist.pop_back();
}
}
/// breakCriticalEdges - Break critical edges coming into blocks with PHI
/// nodes, preserving dominator and livevariable info.
void StrongPHIElimination::breakCriticalEdges(MachineFunction &Fn) {