Transforms/Utils/BreakCriticalEdges.cpp

82 /// is the new loop exit block, and DestBB is the old loop exit, now the
86                                        BasicBlock *DestBB) {
92   for (BasicBlock::iterator I = DestBB->begin();
141   BasicBlock *DestBB = TI->getSuccessor(SuccNum);
145   if (DestBB->isEHPad()) return nullptr;
149                       TIBB->getName() + "." + DestBB->getName() + "_crit_edge");
151   BranchInst *NewBI = BranchInst::Create(DestBB, NewBB);
162   // If there are any PHI nodes in DestBB, we need to update them so that they
166     for (BasicBlock::iterator I = DestBB->begin(); isa<PHINode>(I); ++I) {
183   // If there are any other edges from TIBB to DestBB, update those to go
185   // reducing the number of phi entries in the DestBB if relevant).
188       if (TI->getSuccessor(i) != DestBB) continue;
190       // Remove an entry for TIBB from DestBB phi nodes.
191       DestBB->removePredecessor(TIBB, Options.DontDeleteUselessPHIs);
193       // We found another edge to DestBB, go to NewBB instead.
206   // anything, as there are other successors of DestBB.  However, if all other
207   // predecessors of DestBB are already dominated by DestBB (e.g. DestBB is a
208   // loop header) then NewBB dominates DestBB.
213   if (PHINode *PN = dyn_cast<PHINode>(DestBB->begin())) {
218     for (pred_iterator I = pred_begin(DestBB), E = pred_end(DestBB);
241         DestBBNode = DT->getNode(DestBB);
250       // If NewBBDominatesDestBB, then NewBB dominates DestBB, otherwise it
253         if (!DestBBNode) DestBBNode = DT->getNode(DestBB);
264       if (Loop *DestLoop = LI->getLoopFor(DestBB)) {
279           assert(DestLoop->getHeader() == DestBB &&
286       // If TIBB is in a loop and DestBB is outside of that loop, we may need
288       if (!TIL->contains(DestBB)) {
294           createPHIsForSplitLoopExit(TIBB, NewBB, DestBB);
298         // edge is if after the split there exists some edge from TIL to DestBB
299         // *and* the only edge into DestBB from outside of TIL is that of
302         // second isn't true, then DestBB was not in LoopSimplify form prior to
307         for (pred_iterator I = pred_begin(DestBB), E = pred_end(DestBB); I != E;
320           assert(!DestBB->isEHPad() && "We don't split edges to EH pads!");
322               DestBB, LoopPreds, "split", DT, LI, Options.PreserveLCSSA);
324             createPHIsForSplitLoopExit(LoopPreds, NewExitBB, DestBB);