- // one predecessor.
- BasicBlock *ExitSplit = SplitCriticalEdge(L->getLoopLatch(), Exit, this);
- ExitSplit->moveBefore(Exit);
+ // one predecessor. Note that Exit could be an exit block for multiple
+ // nested loops, causing both of the edges to now be critical and need to
+ // be split.
+ SmallVector<BasicBlock *, 4> ExitPreds(pred_begin(Exit), pred_end(Exit));
+ bool SplitLatchEdge = false;
+ for (SmallVectorImpl<BasicBlock *>::iterator PI = ExitPreds.begin(),
+ PE = ExitPreds.end();
+ PI != PE; ++PI) {
+ // We only need to split loop exit edges.
+ Loop *PredLoop = LI->getLoopFor(*PI);
+ if (!PredLoop || PredLoop->contains(Exit))
+ continue;
+ if (isa<IndirectBrInst>((*PI)->getTerminator()))
+ continue;
+ SplitLatchEdge |= L->getLoopLatch() == *PI;
+ BasicBlock *ExitSplit = SplitCriticalEdge(
+ *PI, Exit, CriticalEdgeSplittingOptions(DT, LI).setPreserveLCSSA());
+ ExitSplit->moveBefore(Exit);
+ }
+ assert(SplitLatchEdge &&
+ "Despite splitting all preds, failed to split latch exit?");