+ if (NewBBDominatesDestBB) {
+ DominanceFrontier::iterator I = DF->find(DestBB);
+ if (I != DF->end()) {
+ DF->addBasicBlock(NewBB, I->second);
+
+ if (I->second.count(DestBB)) {
+ // However NewBB's frontier does not include DestBB.
+ DominanceFrontier::iterator NF = DF->find(NewBB);
+ DF->removeFromFrontier(NF, DestBB);
+ }
+ }
+ else
+ DF->addBasicBlock(NewBB, DominanceFrontier::DomSetType());
+ } else {
+ DominanceFrontier::DomSetType NewDFSet;
+ NewDFSet.insert(DestBB);
+ DF->addBasicBlock(NewBB, NewDFSet);
+ }
+ }
+
+ // Update LoopInfo if it is around.
+ if (LI) {
+ if (Loop *TIL = LI->getLoopFor(TIBB)) {
+ // 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.
+ if (Loop *DestLoop = LI->getLoopFor(DestBB)) {
+ if (TIL == DestLoop) {
+ // Both in the same loop, the NewBB joins loop.
+ DestLoop->addBasicBlockToLoop(NewBB, LI->getBase());
+ } else if (TIL->contains(DestLoop)) {
+ // Edge from an outer loop to an inner loop. Add to the outer loop.
+ TIL->addBasicBlockToLoop(NewBB, LI->getBase());
+ } else if (DestLoop->contains(TIL)) {
+ // Edge from an inner loop to an outer loop. Add to the outer loop.
+ DestLoop->addBasicBlockToLoop(NewBB, LI->getBase());
+ } else {
+ // Edge from two loops with no containment relation. Because these
+ // are natural loops, we know that the destination block must be the
+ // header of its loop (adding a branch into a loop elsewhere would
+ // create an irreducible loop).
+ assert(DestLoop->getHeader() == DestBB &&
+ "Should not create irreducible loops!");
+ if (Loop *P = DestLoop->getParentLoop())
+ P->addBasicBlockToLoop(NewBB, LI->getBase());
+ }
+ }
+ // If TIBB is in a loop and DestBB is outside of that loop, split the
+ // other exit blocks of the loop that also have predecessors outside
+ // the loop, to maintain a LoopSimplify guarantee.
+ if (!TIL->contains(DestBB) &&
+ P->mustPreserveAnalysisID(LoopSimplifyID)) {
+ assert(!TIL->contains(NewBB) &&
+ "Split point for loop exit is contained in loop!");
+
+ // Update LCSSA form in the newly created exit block.
+ if (P->mustPreserveAnalysisID(LCSSAID)) {
+ SmallVector<BasicBlock *, 1> OrigPred;
+ OrigPred.push_back(TIBB);
+ CreatePHIsForSplitLoopExit(OrigPred, NewBB, DestBB);
+ }
+
+ // For each unique exit block...
+ SmallVector<BasicBlock *, 4> ExitBlocks;
+ TIL->getExitBlocks(ExitBlocks);
+ for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i) {
+ // Collect all the preds that are inside the loop, and note
+ // whether there are any preds outside the loop.
+ SmallVector<BasicBlock *, 4> Preds;
+ bool HasPredOutsideOfLoop = false;
+ BasicBlock *Exit = ExitBlocks[i];
+ for (pred_iterator I = pred_begin(Exit), E = pred_end(Exit);
+ I != E; ++I) {
+ BasicBlock *P = *I;
+ if (TIL->contains(P))
+ Preds.push_back(P);
+ else
+ HasPredOutsideOfLoop = true;
+ }
+ // If there are any preds not in the loop, we'll need to split
+ // the edges. The Preds.empty() check is needed because a block
+ // may appear multiple times in the list. We can't use
+ // getUniqueExitBlocks above because that depends on LoopSimplify
+ // form, which we're in the process of restoring!
+ if (!Preds.empty() && HasPredOutsideOfLoop) {
+ BasicBlock *NewExitBB =
+ SplitBlockPredecessors(Exit, Preds.data(), Preds.size(),
+ "split", P);
+ if (P->mustPreserveAnalysisID(LCSSAID))
+ CreatePHIsForSplitLoopExit(Preds, NewExitBB, Exit);
+ }
+ }
+ }
+ // LCSSA form was updated above for the case where LoopSimplify is
+ // available, which means that all predecessors of loop exit blocks
+ // are within the loop. Without LoopSimplify form, it would be
+ // necessary to insert a new phi.
+ assert((!P->mustPreserveAnalysisID(LCSSAID) ||
+ P->mustPreserveAnalysisID(LoopSimplifyID)) &&
+ "SplitCriticalEdge doesn't know how to update LCCSA form "
+ "without LoopSimplify!");
+ }