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Flesh out the Briggs implementation a little bit more, fix a few FIXMEs.

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llvm-svn: 45347
This commit is contained in:
Owen Anderson 2007-12-24 22:12:23 +00:00
parent 7e1e1f2933
commit 1064e276a9
1 changed files with 35 additions and 11 deletions
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46
lib/CodeGen/StrongPHIElimination.cpp
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@ -102,7 +102,8 @@ namespace {
std::set<unsigned>& PHIUnion,
std::vector<StrongPHIElimination::DomForestNode*>& DF,
std::vector<std::pair<unsigned, unsigned> >& locals);
void ScheduleCopies(MachineBasicBlock* MBB);
void ScheduleCopies(MachineBasicBlock* MBB, std::set<unsigned>& pushed);
void InsertCopies(MachineBasicBlock* MBB);
};
char StrongPHIElimination::ID = 0;
@ -514,7 +515,8 @@ void StrongPHIElimination::processPHIUnion(MachineInstr* Inst,
///
/// Based on "Practical Improvements to the Construction and Destruction
/// of Static Single Assignment Form" by Briggs, et al.
void StrongPHIElimination::ScheduleCopies(MachineBasicBlock* MBB) {
void StrongPHIElimination::ScheduleCopies(MachineBasicBlock* MBB,
std::set<unsigned>& pushed) {
std::map<unsigned, unsigned>& copy_set= Waiting[MBB];
std::map<unsigned, unsigned> worklist;
@ -549,6 +551,7 @@ void StrongPHIElimination::ScheduleCopies(MachineBasicBlock* MBB) {
if (isLiveOut(LV.getVarInfo(curr.second), MBB)) {
// Insert copy from curr.second to a temporary
// Push temporary on Stacks
// Insert temporary in pushed
}
// Insert copy from map[curr.first] to curr.second
@ -583,6 +586,34 @@ void StrongPHIElimination::ScheduleCopies(MachineBasicBlock* MBB) {
}
}
/// InsertCopies - insert copies into MBB and all of its successors
void StrongPHIElimination::InsertCopies(MachineBasicBlock* MBB) {
std::set<unsigned> pushed;
// Rewrite register uses from Stacks
for (MachineBasicBlock::iterator I = MBB->begin(), E = MBB->end();
I != E; ++I)
for (unsigned i = 0; i < I->getNumOperands(); ++i)
if (I->getOperand(i).isRegister() &&
Stacks[I->getOperand(i).getReg()].size()) {
I->getOperand(i).setReg(Stacks[I->getOperand(i).getReg()].back());
}
// Schedule the copies for this block
ScheduleCopies(MBB, pushed);
// Recur to our successors
for (GraphTraits<MachineBasicBlock*>::ChildIteratorType I =
GraphTraits<MachineBasicBlock*>::child_begin(MBB), E =
GraphTraits<MachineBasicBlock*>::child_end(MBB); I != E; ++I)
InsertCopies(*I);
// As we exit this block, pop the names we pushed while processing it
for (std::set<unsigned>::iterator I = pushed.begin(),
E = pushed.end(); I != E; ++I)
Stacks[*I].pop_back();
}
bool StrongPHIElimination::runOnMachineFunction(MachineFunction &Fn) {
// Compute DFS numbers of each block
computeDFS(Fn);
@ -594,15 +625,8 @@ bool StrongPHIElimination::runOnMachineFunction(MachineFunction &Fn) {
processBlock(I);
// Insert copies
MachineDominatorTree& MDT = getAnalysis<MachineDominatorTree>();
for (df_iterator<MachineDomTreeNode*> DI = df_begin(MDT.getRootNode()),
DE = df_end(MDT.getRootNode()); DI != DE; ++DI) {
MachineBasicBlock* block = DI->getBlock();
// FIXME: Do rewriting with Stacks
ScheduleCopies(block);
}
// FIXME: This process should probably preserve LiveVariables
InsertCopies(Fn.begin());
// FIXME: Perform renaming