1 //===- LoopInfo.cpp - Natural Loop Calculator -----------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines the LoopInfo class that is used to identify natural loops
11 // and determine the loop depth of various nodes of the CFG. Note that the
12 // loops identified may actually be several natural loops that share the same
13 // header node... not just a single natural loop.
15 //===----------------------------------------------------------------------===//
17 #include "llvm/Analysis/LoopInfo.h"
18 #include "llvm/Constants.h"
19 #include "llvm/Instructions.h"
20 #include "llvm/Analysis/Dominators.h"
21 #include "llvm/Assembly/Writer.h"
22 #include "llvm/Support/CFG.h"
23 #include "llvm/Support/Streams.h"
24 #include "llvm/ADT/DepthFirstIterator.h"
25 #include "llvm/ADT/SmallPtrSet.h"
30 static RegisterPass<LoopInfo>
31 X("loops", "Natural Loop Construction", true);
33 //===----------------------------------------------------------------------===//
34 // Loop implementation
36 bool Loop::contains(const BasicBlock *BB) const {
37 return std::find(Blocks.begin(), Blocks.end(), BB) != Blocks.end();
40 bool Loop::isLoopExit(const BasicBlock *BB) const {
41 for (succ_const_iterator SI = succ_begin(BB), SE = succ_end(BB);
49 /// getNumBackEdges - Calculate the number of back edges to the loop header.
51 unsigned Loop::getNumBackEdges() const {
52 unsigned NumBackEdges = 0;
53 BasicBlock *H = getHeader();
55 for (pred_iterator I = pred_begin(H), E = pred_end(H); I != E; ++I)
62 /// isLoopInvariant - Return true if the specified value is loop invariant
64 bool Loop::isLoopInvariant(Value *V) const {
65 if (Instruction *I = dyn_cast<Instruction>(V))
66 return !contains(I->getParent());
67 return true; // All non-instructions are loop invariant
70 void Loop::print(std::ostream &OS, unsigned Depth) const {
71 OS << std::string(Depth*2, ' ') << "Loop Containing: ";
73 for (unsigned i = 0; i < getBlocks().size(); ++i) {
75 WriteAsOperand(OS, getBlocks()[i], false);
79 for (iterator I = begin(), E = end(); I != E; ++I)
80 (*I)->print(OS, Depth+2);
83 void Loop::dump() const {
88 //===----------------------------------------------------------------------===//
89 // LoopInfo implementation
91 bool LoopInfo::runOnFunction(Function &) {
93 Calculate(getAnalysis<ETForest>()); // Update
97 void LoopInfo::releaseMemory() {
98 for (std::vector<Loop*>::iterator I = TopLevelLoops.begin(),
99 E = TopLevelLoops.end(); I != E; ++I)
100 delete *I; // Delete all of the loops...
102 BBMap.clear(); // Reset internal state of analysis
103 TopLevelLoops.clear();
107 void LoopInfo::Calculate(ETForest &EF) {
108 BasicBlock *RootNode = EF.getRoot();
110 for (df_iterator<BasicBlock*> NI = df_begin(RootNode),
111 NE = df_end(RootNode); NI != NE; ++NI)
112 if (Loop *L = ConsiderForLoop(*NI, EF))
113 TopLevelLoops.push_back(L);
116 void LoopInfo::getAnalysisUsage(AnalysisUsage &AU) const {
117 AU.setPreservesAll();
118 AU.addRequired<ETForest>();
121 void LoopInfo::print(std::ostream &OS, const Module* ) const {
122 for (unsigned i = 0; i < TopLevelLoops.size(); ++i)
123 TopLevelLoops[i]->print(OS);
125 for (std::map<BasicBlock*, Loop*>::const_iterator I = BBMap.begin(),
126 E = BBMap.end(); I != E; ++I)
127 OS << "BB '" << I->first->getName() << "' level = "
128 << I->second->getLoopDepth() << "\n";
132 static bool isNotAlreadyContainedIn(Loop *SubLoop, Loop *ParentLoop) {
133 if (SubLoop == 0) return true;
134 if (SubLoop == ParentLoop) return false;
135 return isNotAlreadyContainedIn(SubLoop->getParentLoop(), ParentLoop);
138 Loop *LoopInfo::ConsiderForLoop(BasicBlock *BB, ETForest &EF) {
139 if (BBMap.find(BB) != BBMap.end()) return 0; // Haven't processed this node?
141 std::vector<BasicBlock *> TodoStack;
143 // Scan the predecessors of BB, checking to see if BB dominates any of
144 // them. This identifies backedges which target this node...
145 for (pred_iterator I = pred_begin(BB), E = pred_end(BB); I != E; ++I)
146 if (EF.dominates(BB, *I)) // If BB dominates it's predecessor...
147 TodoStack.push_back(*I);
149 if (TodoStack.empty()) return 0; // No backedges to this block...
151 // Create a new loop to represent this basic block...
152 Loop *L = new Loop(BB);
155 BasicBlock *EntryBlock = &BB->getParent()->getEntryBlock();
157 while (!TodoStack.empty()) { // Process all the nodes in the loop
158 BasicBlock *X = TodoStack.back();
159 TodoStack.pop_back();
161 if (!L->contains(X) && // As of yet unprocessed??
162 EF.dominates(EntryBlock, X)) { // X is reachable from entry block?
163 // Check to see if this block already belongs to a loop. If this occurs
164 // then we have a case where a loop that is supposed to be a child of the
165 // current loop was processed before the current loop. When this occurs,
166 // this child loop gets added to a part of the current loop, making it a
167 // sibling to the current loop. We have to reparent this loop.
168 if (Loop *SubLoop = const_cast<Loop*>(getLoopFor(X)))
169 if (SubLoop->getHeader() == X && isNotAlreadyContainedIn(SubLoop, L)) {
170 // Remove the subloop from it's current parent...
171 assert(SubLoop->ParentLoop && SubLoop->ParentLoop != L);
172 Loop *SLP = SubLoop->ParentLoop; // SubLoopParent
173 std::vector<Loop*>::iterator I =
174 std::find(SLP->SubLoops.begin(), SLP->SubLoops.end(), SubLoop);
175 assert(I != SLP->SubLoops.end() && "SubLoop not a child of parent?");
176 SLP->SubLoops.erase(I); // Remove from parent...
178 // Add the subloop to THIS loop...
179 SubLoop->ParentLoop = L;
180 L->SubLoops.push_back(SubLoop);
183 // Normal case, add the block to our loop...
184 L->Blocks.push_back(X);
186 // Add all of the predecessors of X to the end of the work stack...
187 TodoStack.insert(TodoStack.end(), pred_begin(X), pred_end(X));
191 // If there are any loops nested within this loop, create them now!
192 for (std::vector<BasicBlock*>::iterator I = L->Blocks.begin(),
193 E = L->Blocks.end(); I != E; ++I)
194 if (Loop *NewLoop = ConsiderForLoop(*I, EF)) {
195 L->SubLoops.push_back(NewLoop);
196 NewLoop->ParentLoop = L;
199 // Add the basic blocks that comprise this loop to the BBMap so that this
200 // loop can be found for them.
202 for (std::vector<BasicBlock*>::iterator I = L->Blocks.begin(),
203 E = L->Blocks.end(); I != E; ++I) {
204 std::map<BasicBlock*, Loop*>::iterator BBMI = BBMap.lower_bound(*I);
205 if (BBMI == BBMap.end() || BBMI->first != *I) // Not in map yet...
206 BBMap.insert(BBMI, std::make_pair(*I, L)); // Must be at this level
209 // Now that we have a list of all of the child loops of this loop, check to
210 // see if any of them should actually be nested inside of each other. We can
211 // accidentally pull loops our of their parents, so we must make sure to
212 // organize the loop nests correctly now.
214 std::map<BasicBlock*, Loop*> ContainingLoops;
215 for (unsigned i = 0; i != L->SubLoops.size(); ++i) {
216 Loop *Child = L->SubLoops[i];
217 assert(Child->getParentLoop() == L && "Not proper child loop?");
219 if (Loop *ContainingLoop = ContainingLoops[Child->getHeader()]) {
220 // If there is already a loop which contains this loop, move this loop
221 // into the containing loop.
222 MoveSiblingLoopInto(Child, ContainingLoop);
223 --i; // The loop got removed from the SubLoops list.
225 // This is currently considered to be a top-level loop. Check to see if
226 // any of the contained blocks are loop headers for subloops we have
227 // already processed.
228 for (unsigned b = 0, e = Child->Blocks.size(); b != e; ++b) {
229 Loop *&BlockLoop = ContainingLoops[Child->Blocks[b]];
230 if (BlockLoop == 0) { // Child block not processed yet...
232 } else if (BlockLoop != Child) {
233 Loop *SubLoop = BlockLoop;
234 // Reparent all of the blocks which used to belong to BlockLoops
235 for (unsigned j = 0, e = SubLoop->Blocks.size(); j != e; ++j)
236 ContainingLoops[SubLoop->Blocks[j]] = Child;
238 // There is already a loop which contains this block, that means
239 // that we should reparent the loop which the block is currently
240 // considered to belong to to be a child of this loop.
241 MoveSiblingLoopInto(SubLoop, Child);
242 --i; // We just shrunk the SubLoops list.
252 /// MoveSiblingLoopInto - This method moves the NewChild loop to live inside of
253 /// the NewParent Loop, instead of being a sibling of it.
254 void LoopInfo::MoveSiblingLoopInto(Loop *NewChild, Loop *NewParent) {
255 Loop *OldParent = NewChild->getParentLoop();
256 assert(OldParent && OldParent == NewParent->getParentLoop() &&
257 NewChild != NewParent && "Not sibling loops!");
259 // Remove NewChild from being a child of OldParent
260 std::vector<Loop*>::iterator I =
261 std::find(OldParent->SubLoops.begin(), OldParent->SubLoops.end(), NewChild);
262 assert(I != OldParent->SubLoops.end() && "Parent fields incorrect??");
263 OldParent->SubLoops.erase(I); // Remove from parent's subloops list
264 NewChild->ParentLoop = 0;
266 InsertLoopInto(NewChild, NewParent);
269 /// InsertLoopInto - This inserts loop L into the specified parent loop. If the
270 /// parent loop contains a loop which should contain L, the loop gets inserted
272 void LoopInfo::InsertLoopInto(Loop *L, Loop *Parent) {
273 BasicBlock *LHeader = L->getHeader();
274 assert(Parent->contains(LHeader) && "This loop should not be inserted here!");
276 // Check to see if it belongs in a child loop...
277 for (unsigned i = 0, e = Parent->SubLoops.size(); i != e; ++i)
278 if (Parent->SubLoops[i]->contains(LHeader)) {
279 InsertLoopInto(L, Parent->SubLoops[i]);
283 // If not, insert it here!
284 Parent->SubLoops.push_back(L);
285 L->ParentLoop = Parent;
288 /// changeLoopFor - Change the top-level loop that contains BB to the
289 /// specified loop. This should be used by transformations that restructure
290 /// the loop hierarchy tree.
291 void LoopInfo::changeLoopFor(BasicBlock *BB, Loop *L) {
292 Loop *&OldLoop = BBMap[BB];
293 assert(OldLoop && "Block not in a loop yet!");
297 /// changeTopLevelLoop - Replace the specified loop in the top-level loops
298 /// list with the indicated loop.
299 void LoopInfo::changeTopLevelLoop(Loop *OldLoop, Loop *NewLoop) {
300 std::vector<Loop*>::iterator I = std::find(TopLevelLoops.begin(),
301 TopLevelLoops.end(), OldLoop);
302 assert(I != TopLevelLoops.end() && "Old loop not at top level!");
304 assert(NewLoop->ParentLoop == 0 && OldLoop->ParentLoop == 0 &&
305 "Loops already embedded into a subloop!");
308 /// removeLoop - This removes the specified top-level loop from this loop info
309 /// object. The loop is not deleted, as it will presumably be inserted into
311 Loop *LoopInfo::removeLoop(iterator I) {
312 assert(I != end() && "Cannot remove end iterator!");
314 assert(L->getParentLoop() == 0 && "Not a top-level loop!");
315 TopLevelLoops.erase(TopLevelLoops.begin() + (I-begin()));
319 /// removeBlock - This method completely removes BB from all data structures,
320 /// including all of the Loop objects it is nested in and our mapping from
321 /// BasicBlocks to loops.
322 void LoopInfo::removeBlock(BasicBlock *BB) {
323 std::map<BasicBlock *, Loop*>::iterator I = BBMap.find(BB);
324 if (I != BBMap.end()) {
325 for (Loop *L = I->second; L; L = L->getParentLoop())
326 L->removeBlockFromLoop(BB);
333 //===----------------------------------------------------------------------===//
334 // APIs for simple analysis of the loop.
337 /// getExitingBlocks - Return all blocks inside the loop that have successors
338 /// outside of the loop. These are the blocks _inside of the current loop_
339 /// which branch out. The returned list is always unique.
341 void Loop::getExitingBlocks(std::vector<BasicBlock*> &ExitingBlocks) const {
342 // Sort the blocks vector so that we can use binary search to do quick
344 std::vector<BasicBlock*> LoopBBs(block_begin(), block_end());
345 std::sort(LoopBBs.begin(), LoopBBs.end());
347 for (std::vector<BasicBlock*>::const_iterator BI = Blocks.begin(),
348 BE = Blocks.end(); BI != BE; ++BI)
349 for (succ_iterator I = succ_begin(*BI), E = succ_end(*BI); I != E; ++I)
350 if (!std::binary_search(LoopBBs.begin(), LoopBBs.end(), *I)) {
351 // Not in current loop? It must be an exit block.
352 ExitingBlocks.push_back(*BI);
357 /// getExitBlocks - Return all of the successor blocks of this loop. These
358 /// are the blocks _outside of the current loop_ which are branched to.
360 void Loop::getExitBlocks(std::vector<BasicBlock*> &ExitBlocks) const {
361 // Sort the blocks vector so that we can use binary search to do quick
363 std::vector<BasicBlock*> LoopBBs(block_begin(), block_end());
364 std::sort(LoopBBs.begin(), LoopBBs.end());
366 for (std::vector<BasicBlock*>::const_iterator BI = Blocks.begin(),
367 BE = Blocks.end(); BI != BE; ++BI)
368 for (succ_iterator I = succ_begin(*BI), E = succ_end(*BI); I != E; ++I)
369 if (!std::binary_search(LoopBBs.begin(), LoopBBs.end(), *I))
370 // Not in current loop? It must be an exit block.
371 ExitBlocks.push_back(*I);
374 /// getUniqueExitBlocks - Return all unique successor blocks of this loop. These
375 /// are the blocks _outside of the current loop_ which are branched to. This
376 /// assumes that loop is in canonical form.
378 void Loop::getUniqueExitBlocks(std::vector<BasicBlock*> &ExitBlocks) const {
379 // Sort the blocks vector so that we can use binary search to do quick
381 std::vector<BasicBlock*> LoopBBs(block_begin(), block_end());
382 std::sort(LoopBBs.begin(), LoopBBs.end());
384 std::vector<BasicBlock*> switchExitBlocks;
386 for (std::vector<BasicBlock*>::const_iterator BI = Blocks.begin(),
387 BE = Blocks.end(); BI != BE; ++BI) {
389 BasicBlock *current = *BI;
390 switchExitBlocks.clear();
392 for (succ_iterator I = succ_begin(*BI), E = succ_end(*BI); I != E; ++I) {
393 if (std::binary_search(LoopBBs.begin(), LoopBBs.end(), *I))
394 // If block is inside the loop then it is not a exit block.
397 pred_iterator PI = pred_begin(*I);
398 BasicBlock *firstPred = *PI;
400 // If current basic block is this exit block's first predecessor
401 // then only insert exit block in to the output ExitBlocks vector.
402 // This ensures that same exit block is not inserted twice into
403 // ExitBlocks vector.
404 if (current != firstPred)
407 // If a terminator has more then two successors, for example SwitchInst,
408 // then it is possible that there are multiple edges from current block
409 // to one exit block.
410 if (current->getTerminator()->getNumSuccessors() <= 2) {
411 ExitBlocks.push_back(*I);
415 // In case of multiple edges from current block to exit block, collect
416 // only one edge in ExitBlocks. Use switchExitBlocks to keep track of
418 if (std::find(switchExitBlocks.begin(), switchExitBlocks.end(), *I)
419 == switchExitBlocks.end()) {
420 switchExitBlocks.push_back(*I);
421 ExitBlocks.push_back(*I);
428 /// getLoopPreheader - If there is a preheader for this loop, return it. A
429 /// loop has a preheader if there is only one edge to the header of the loop
430 /// from outside of the loop. If this is the case, the block branching to the
431 /// header of the loop is the preheader node.
433 /// This method returns null if there is no preheader for the loop.
435 BasicBlock *Loop::getLoopPreheader() const {
436 // Keep track of nodes outside the loop branching to the header...
439 // Loop over the predecessors of the header node...
440 BasicBlock *Header = getHeader();
441 for (pred_iterator PI = pred_begin(Header), PE = pred_end(Header);
443 if (!contains(*PI)) { // If the block is not in the loop...
444 if (Out && Out != *PI)
445 return 0; // Multiple predecessors outside the loop
449 // Make sure there is only one exit out of the preheader.
450 assert(Out && "Header of loop has no predecessors from outside loop?");
451 succ_iterator SI = succ_begin(Out);
453 if (SI != succ_end(Out))
454 return 0; // Multiple exits from the block, must not be a preheader.
456 // If there is exactly one preheader, return it. If there was zero, then Out
461 /// getLoopLatch - If there is a latch block for this loop, return it. A
462 /// latch block is the canonical backedge for a loop. A loop header in normal
463 /// form has two edges into it: one from a preheader and one from a latch
465 BasicBlock *Loop::getLoopLatch() const {
466 BasicBlock *Header = getHeader();
467 pred_iterator PI = pred_begin(Header), PE = pred_end(Header);
468 if (PI == PE) return 0; // no preds?
470 BasicBlock *Latch = 0;
474 if (PI == PE) return 0; // only one pred?
477 if (Latch) return 0; // multiple backedges
481 if (PI != PE) return 0; // more than two preds
486 /// getCanonicalInductionVariable - Check to see if the loop has a canonical
487 /// induction variable: an integer recurrence that starts at 0 and increments by
488 /// one each time through the loop. If so, return the phi node that corresponds
491 PHINode *Loop::getCanonicalInductionVariable() const {
492 BasicBlock *H = getHeader();
494 BasicBlock *Incoming = 0, *Backedge = 0;
495 pred_iterator PI = pred_begin(H);
496 assert(PI != pred_end(H) && "Loop must have at least one backedge!");
498 if (PI == pred_end(H)) return 0; // dead loop
500 if (PI != pred_end(H)) return 0; // multiple backedges?
502 if (contains(Incoming)) {
503 if (contains(Backedge))
505 std::swap(Incoming, Backedge);
506 } else if (!contains(Backedge))
509 // Loop over all of the PHI nodes, looking for a canonical indvar.
510 for (BasicBlock::iterator I = H->begin(); isa<PHINode>(I); ++I) {
511 PHINode *PN = cast<PHINode>(I);
512 if (Instruction *Inc =
513 dyn_cast<Instruction>(PN->getIncomingValueForBlock(Backedge)))
514 if (Inc->getOpcode() == Instruction::Add && Inc->getOperand(0) == PN)
515 if (ConstantInt *CI = dyn_cast<ConstantInt>(Inc->getOperand(1)))
516 if (CI->equalsInt(1))
522 /// getCanonicalInductionVariableIncrement - Return the LLVM value that holds
523 /// the canonical induction variable value for the "next" iteration of the loop.
524 /// This always succeeds if getCanonicalInductionVariable succeeds.
526 Instruction *Loop::getCanonicalInductionVariableIncrement() const {
527 if (PHINode *PN = getCanonicalInductionVariable()) {
528 bool P1InLoop = contains(PN->getIncomingBlock(1));
529 return cast<Instruction>(PN->getIncomingValue(P1InLoop));
534 /// getTripCount - Return a loop-invariant LLVM value indicating the number of
535 /// times the loop will be executed. Note that this means that the backedge of
536 /// the loop executes N-1 times. If the trip-count cannot be determined, this
539 Value *Loop::getTripCount() const {
540 // Canonical loops will end with a 'cmp ne I, V', where I is the incremented
541 // canonical induction variable and V is the trip count of the loop.
542 Instruction *Inc = getCanonicalInductionVariableIncrement();
543 if (Inc == 0) return 0;
544 PHINode *IV = cast<PHINode>(Inc->getOperand(0));
546 BasicBlock *BackedgeBlock =
547 IV->getIncomingBlock(contains(IV->getIncomingBlock(1)));
549 if (BranchInst *BI = dyn_cast<BranchInst>(BackedgeBlock->getTerminator()))
550 if (BI->isConditional()) {
551 if (ICmpInst *ICI = dyn_cast<ICmpInst>(BI->getCondition())) {
552 if (ICI->getOperand(0) == Inc)
553 if (BI->getSuccessor(0) == getHeader()) {
554 if (ICI->getPredicate() == ICmpInst::ICMP_NE)
555 return ICI->getOperand(1);
556 } else if (ICI->getPredicate() == ICmpInst::ICMP_EQ) {
557 return ICI->getOperand(1);
565 /// isLCSSAForm - Return true if the Loop is in LCSSA form
566 bool Loop::isLCSSAForm() const {
567 // Sort the blocks vector so that we can use binary search to do quick
569 SmallPtrSet<BasicBlock*, 16> LoopBBs(block_begin(), block_end());
571 for (block_iterator BI = block_begin(), E = block_end(); BI != E; ++BI) {
572 BasicBlock *BB = *BI;
573 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
574 for (Value::use_iterator UI = I->use_begin(), E = I->use_end(); UI != E;
576 BasicBlock *UserBB = cast<Instruction>(*UI)->getParent();
577 if (PHINode *P = dyn_cast<PHINode>(*UI)) {
578 unsigned OperandNo = UI.getOperandNo();
579 UserBB = P->getIncomingBlock(OperandNo/2);
582 // Check the current block, as a fast-path. Most values are used in the
583 // same block they are defined in.
584 if (UserBB != BB && !LoopBBs.count(UserBB))
592 //===-------------------------------------------------------------------===//
593 // APIs for updating loop information after changing the CFG
596 /// addBasicBlockToLoop - This function is used by other analyses to update loop
597 /// information. NewBB is set to be a new member of the current loop. Because
598 /// of this, it is added as a member of all parent loops, and is added to the
599 /// specified LoopInfo object as being in the current basic block. It is not
600 /// valid to replace the loop header with this method.
602 void Loop::addBasicBlockToLoop(BasicBlock *NewBB, LoopInfo &LI) {
603 assert((Blocks.empty() || LI[getHeader()] == this) &&
604 "Incorrect LI specified for this loop!");
605 assert(NewBB && "Cannot add a null basic block to the loop!");
606 assert(LI[NewBB] == 0 && "BasicBlock already in the loop!");
608 // Add the loop mapping to the LoopInfo object...
609 LI.BBMap[NewBB] = this;
611 // Add the basic block to this loop and all parent loops...
614 L->Blocks.push_back(NewBB);
615 L = L->getParentLoop();
619 /// replaceChildLoopWith - This is used when splitting loops up. It replaces
620 /// the OldChild entry in our children list with NewChild, and updates the
621 /// parent pointers of the two loops as appropriate.
622 void Loop::replaceChildLoopWith(Loop *OldChild, Loop *NewChild) {
623 assert(OldChild->ParentLoop == this && "This loop is already broken!");
624 assert(NewChild->ParentLoop == 0 && "NewChild already has a parent!");
625 std::vector<Loop*>::iterator I = std::find(SubLoops.begin(), SubLoops.end(),
627 assert(I != SubLoops.end() && "OldChild not in loop!");
629 OldChild->ParentLoop = 0;
630 NewChild->ParentLoop = this;
633 /// addChildLoop - Add the specified loop to be a child of this loop.
635 void Loop::addChildLoop(Loop *NewChild) {
636 assert(NewChild->ParentLoop == 0 && "NewChild already has a parent!");
637 NewChild->ParentLoop = this;
638 SubLoops.push_back(NewChild);
642 static void RemoveFromVector(std::vector<T*> &V, T *N) {
643 typename std::vector<T*>::iterator I = std::find(V.begin(), V.end(), N);
644 assert(I != V.end() && "N is not in this list!");
648 /// removeChildLoop - This removes the specified child from being a subloop of
649 /// this loop. The loop is not deleted, as it will presumably be inserted
650 /// into another loop.
651 Loop *Loop::removeChildLoop(iterator I) {
652 assert(I != SubLoops.end() && "Cannot remove end iterator!");
654 assert(Child->ParentLoop == this && "Child is not a child of this loop!");
655 SubLoops.erase(SubLoops.begin()+(I-begin()));
656 Child->ParentLoop = 0;
661 /// removeBlockFromLoop - This removes the specified basic block from the
662 /// current loop, updating the Blocks and ExitBlocks lists as appropriate. This
663 /// does not update the mapping in the LoopInfo class.
664 void Loop::removeBlockFromLoop(BasicBlock *BB) {
665 RemoveFromVector(Blocks, BB);
668 // Ensure this file gets linked when LoopInfo.h is used.
669 DEFINING_FILE_FOR(LoopInfo)