+
+ // If TIBB is in a loop and DestBB is outside of that loop, we may need
+ // to update LoopSimplify form and LCSSA form.
+ if (!TIL->contains(DestBB)) {
+ assert(!TIL->contains(NewBB) &&
+ "Split point for loop exit is contained in loop!");
+
+ // Update LCSSA form in the newly created exit block.
+ if (Options.PreserveLCSSA) {
+ createPHIsForSplitLoopExit(TIBB, NewBB, DestBB);
+ }
+
+ // The only that we can break LoopSimplify form by splitting a critical
+ // edge is if after the split there exists some edge from TIL to DestBB
+ // *and* the only edge into DestBB from outside of TIL is that of
+ // NewBB. If the first isn't true, then LoopSimplify still holds, NewBB
+ // is the new exit block and it has no non-loop predecessors. If the
+ // second isn't true, then DestBB was not in LoopSimplify form prior to
+ // the split as it had a non-loop predecessor. In both of these cases,
+ // the predecessor must be directly in TIL, not in a subloop, or again
+ // LoopSimplify doesn't hold.
+ SmallVector<BasicBlock *, 4> LoopPreds;
+ for (pred_iterator I = pred_begin(DestBB), E = pred_end(DestBB); I != E;
+ ++I) {
+ BasicBlock *P = *I;
+ if (P == NewBB)
+ continue; // The new block is known.
+ if (LI->getLoopFor(P) != TIL) {
+ // No need to re-simplify, it wasn't to start with.
+ LoopPreds.clear();
+ break;
+ }
+ LoopPreds.push_back(P);
+ }
+ if (!LoopPreds.empty()) {
+ assert(!DestBB->isLandingPad() &&
+ "We don't split edges to landing pads!");
+ BasicBlock *NewExitBB = SplitBlockPredecessors(
+ DestBB, LoopPreds, "split", AA, DT, LI, Options.PreserveLCSSA);
+ if (Options.PreserveLCSSA)
+ createPHIsForSplitLoopExit(LoopPreds, NewExitBB, DestBB);
+ }
+ }
+ }