Author: dpatel
Date: Fri Aug 17 19:00:32 2007
New Revision: 41148
URL: http://llvm.org/viewvc/llvm-project?rev=41148&view=rev
Log:
Avoid spliting loops where two split condition branches are not independent.
Modified:
llvm/trunk/lib/Transforms/Scalar/LoopIndexSplit.cpp
Modified: llvm/trunk/lib/Transforms/Scalar/LoopIndexSplit.cpp
URL:
http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/LoopIndexSplit.cpp?rev=41148&r1=41147&r2=41148&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/LoopIndexSplit.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/LoopIndexSplit.cpp Fri Aug 17 19:00:32 2007
@@ -711,12 +711,22 @@
|| Latch == SplitTerminator->getSuccessor(1)))
return false;
-
+ // If one of the split condition branch is post dominating other then loop
+ // index split is not appropriate.
BasicBlock *Succ0 = SplitTerminator->getSuccessor(0);
BasicBlock *Succ1 = SplitTerminator->getSuccessor(1);
if (DT->dominates(Succ0, Latch) || DT->dominates(Succ1, Latch))
return false;
+ // If one of the split condition branch is a predecessor of the other
+ // split condition branch head then do not split loop on this condition.
+ for(pred_iterator PI = pred_begin(Succ0), PE = pred_end(Succ0); PI != PE;
++PI)
+ if (Succ1 == *PI)
+ return false;
+ for(pred_iterator PI = pred_begin(Succ1), PE = pred_end(Succ1); PI != PE;
++PI)
+ if (Succ0 == *PI)
+ return false;
+
// True loop is original loop. False loop is cloned loop.
bool SignedPredicate = ExitCondition->isSignedPredicate();
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