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Properly update MachineDominators when splitting critical edge.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@111574 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng
2010-08-19 23:32:47 +00:00
parent 45c3b65eb7
commit 19708923be
1 changed files with 25 additions and 2 deletions
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27
lib/CodeGen/MachineBasicBlock.cpp
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@ -468,8 +468,31 @@ MachineBasicBlock::SplitCriticalEdge(MachineBasicBlock *Succ, Pass *P) {
LV->addNewBlock(NMBB, this, Succ); LV->addNewBlock(NMBB, this, Succ);
if (MachineDominatorTree *MDT = if (MachineDominatorTree *MDT =
P->getAnalysisIfAvailable<MachineDominatorTree>()) P->getAnalysisIfAvailable<MachineDominatorTree>()) {
MDT->addNewBlock(NMBB, this); // Update dominator information.
MachineDomTreeNode *SucccDTNode = MDT->getNode(Succ);
bool IsNewIDom = true;
for (const_pred_iterator PI = Succ->pred_begin(), E = Succ->pred_end();
PI != E; ++PI) {
MachineBasicBlock *PredBB = *PI;
if (PredBB == NMBB)
continue;
if (!MDT->dominates(SucccDTNode, MDT->getNode(PredBB))) {
IsNewIDom = false;
break;
}
}
// We know "this" dominates the newly created basic block.
MachineDomTreeNode *NewDTNode = MDT->addNewBlock(NMBB, this);
// If all the other predecessors of "Succ" are dominated by "Succ" itself
// then the new block is the new immediate dominator of "Succ". Otherwise,
// the new block doesn't dominate anything.
if (IsNewIDom)
MDT->changeImmediateDominator(SucccDTNode, NewDTNode);
}
if (MachineLoopInfo *MLI = P->getAnalysisIfAvailable<MachineLoopInfo>()) if (MachineLoopInfo *MLI = P->getAnalysisIfAvailable<MachineLoopInfo>())
if (MachineLoop *TIL = MLI->getLoopFor(this)) { if (MachineLoop *TIL = MLI->getLoopFor(this)) {