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.

llvm-svn: 111256

1 files changed, 1 insertions, 9 deletions

diff --git a/llvm/lib/CodeGen/MachineBasicBlock.cpp b/llvm/lib/CodeGen/MachineBasicBlock.cpp
index f506f12050a..d351db59e69 100644
--- a/llvm/lib/CodeGen/MachineBasicBlock.cpp
+++ b/llvm/lib/CodeGen/MachineBasicBlock.cpp
@@ -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.