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Move the decision logic whether it's a good idea to split a critical edge to clients. Also fixed an erroneous check. An edge is only a back edge when the from and to blocks are in the same loop.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@111256 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng
2010-08-17 17:43:50 +00:00
parent fc8042a122
commit e008384508
3 changed files with 15 additions and 13 deletions
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10
lib/CodeGen/MachineBasicBlock.cpp
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@@ -439,14 +439,6 @@ MachineBasicBlock::SplitCriticalEdge(MachineBasicBlock *Succ, Pass *P) {
if (TII->AnalyzeBranch(*this, TBB, FBB, Cond))
return NULL;
// Avoid splitting backedges of loops. It would introduce small out-of-line
// blocks into the loop which is very bad for code placement.
if (this == Succ)
return NULL;
MachineLoopInfo *MLI = P->getAnalysisIfAvailable<MachineLoopInfo>();
if (MLI->isLoopHeader(Succ))
return NULL;
MachineBasicBlock *NMBB = MF->CreateMachineBasicBlock();
MF->insert(llvm::next(MachineFunction::iterator(this)), NMBB);
DEBUG(dbgs() << "Splitting critical edge:"
@@ -479,7 +471,7 @@ MachineBasicBlock::SplitCriticalEdge(MachineBasicBlock *Succ, Pass *P) {
P->getAnalysisIfAvailable<MachineDominatorTree>())
MDT->addNewBlock(NMBB, this);
if (MLI)
if (MachineLoopInfo *MLI = P->getAnalysisIfAvailable<MachineLoopInfo>())
if (MachineLoop *TIL = MLI->getLoopFor(this)) {
// If one or the other blocks were not in a loop, the new block is not
// either, and thus LI doesn't need to be updated.