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 char LoopInfo::ID = 0;
31 static RegisterPass<LoopInfo>
32 X("loops", "Natural Loop Construction", true);
34 //===----------------------------------------------------------------------===//
35 // Loop implementation
37 bool Loop::contains(const BasicBlock *BB) const {
38 return std::find(Blocks.begin(), Blocks.end(), BB) != Blocks.end();
41 bool Loop::isLoopExit(const BasicBlock *BB) const {
42 for (succ_const_iterator SI = succ_begin(BB), SE = succ_end(BB);
50 /// getNumBackEdges - Calculate the number of back edges to the loop header.
52 unsigned Loop::getNumBackEdges() const {
53 unsigned NumBackEdges = 0;
54 BasicBlock *H = getHeader();
56 for (pred_iterator I = pred_begin(H), E = pred_end(H); I != E; ++I)
63 /// isLoopInvariant - Return true if the specified value is loop invariant
65 bool Loop::isLoopInvariant(Value *V) const {
66 if (Instruction *I = dyn_cast<Instruction>(V))
67 return !contains(I->getParent());
68 return true; // All non-instructions are loop invariant
71 void Loop::print(std::ostream &OS, unsigned Depth) const {
72 OS << std::string(Depth*2, ' ') << "Loop Containing: ";
74 for (unsigned i = 0; i < getBlocks().size(); ++i) {
76 WriteAsOperand(OS, getBlocks()[i], false);
80 for (iterator I = begin(), E = end(); I != E; ++I)
81 (*I)->print(OS, Depth+2);
84 /// verifyLoop - Verify loop structure
85 void Loop::verifyLoop() const {
87 assert (getHeader() && "Loop header is missing");
88 assert (getLoopPreheader() && "Loop preheader is missing");
89 assert (getLoopLatch() && "Loop latch is missing");
90 for (std::vector<Loop*>::const_iterator I = SubLoops.begin(), E = SubLoops.end();
96 void Loop::dump() const {
101 //===----------------------------------------------------------------------===//
102 // LoopInfo implementation
104 bool LoopInfo::runOnFunction(Function &) {
106 Calculate(getAnalysis<DominatorTree>()); // Update
110 void LoopInfo::releaseMemory() {
111 for (std::vector<Loop*>::iterator I = TopLevelLoops.begin(),
112 E = TopLevelLoops.end(); I != E; ++I)
113 delete *I; // Delete all of the loops...
115 BBMap.clear(); // Reset internal state of analysis
116 TopLevelLoops.clear();
119 void LoopInfo::Calculate(DominatorTree &DT) {
120 BasicBlock *RootNode = DT.getRootNode()->getBlock();
122 for (df_iterator<BasicBlock*> NI = df_begin(RootNode),
123 NE = df_end(RootNode); NI != NE; ++NI)
124 if (Loop *L = ConsiderForLoop(*NI, DT))
125 TopLevelLoops.push_back(L);
128 void LoopInfo::getAnalysisUsage(AnalysisUsage &AU) const {
129 AU.setPreservesAll();
130 AU.addRequired<DominatorTree>();
133 void LoopInfo::print(std::ostream &OS, const Module* ) const {
134 for (unsigned i = 0; i < TopLevelLoops.size(); ++i)
135 TopLevelLoops[i]->print(OS);
137 for (std::map<BasicBlock*, Loop*>::const_iterator I = BBMap.begin(),
138 E = BBMap.end(); I != E; ++I)
139 OS << "BB '" << I->first->getName() << "' level = "
140 << I->second->getLoopDepth() << "\n";
144 static bool isNotAlreadyContainedIn(Loop *SubLoop, Loop *ParentLoop) {
145 if (SubLoop == 0) return true;
146 if (SubLoop == ParentLoop) return false;
147 return isNotAlreadyContainedIn(SubLoop->getParentLoop(), ParentLoop);
150 Loop *LoopInfo::ConsiderForLoop(BasicBlock *BB, DominatorTree &DT) {
151 if (BBMap.find(BB) != BBMap.end()) return 0; // Haven't processed this node?
153 std::vector<BasicBlock *> TodoStack;
155 // Scan the predecessors of BB, checking to see if BB dominates any of
156 // them. This identifies backedges which target this node...
157 for (pred_iterator I = pred_begin(BB), E = pred_end(BB); I != E; ++I)
158 if (DT.dominates(BB, *I)) // If BB dominates it's predecessor...
159 TodoStack.push_back(*I);
161 if (TodoStack.empty()) return 0; // No backedges to this block...
163 // Create a new loop to represent this basic block...
164 Loop *L = new Loop(BB);
167 BasicBlock *EntryBlock = &BB->getParent()->getEntryBlock();
169 while (!TodoStack.empty()) { // Process all the nodes in the loop
170 BasicBlock *X = TodoStack.back();
171 TodoStack.pop_back();
173 if (!L->contains(X) && // As of yet unprocessed??
174 DT.dominates(EntryBlock, X)) { // X is reachable from entry block?
175 // Check to see if this block already belongs to a loop. If this occurs
176 // then we have a case where a loop that is supposed to be a child of the
177 // current loop was processed before the current loop. When this occurs,
178 // this child loop gets added to a part of the current loop, making it a
179 // sibling to the current loop. We have to reparent this loop.
180 if (Loop *SubLoop = const_cast<Loop*>(getLoopFor(X)))
181 if (SubLoop->getHeader() == X && isNotAlreadyContainedIn(SubLoop, L)) {
182 // Remove the subloop from it's current parent...
183 assert(SubLoop->ParentLoop && SubLoop->ParentLoop != L);
184 Loop *SLP = SubLoop->ParentLoop; // SubLoopParent
185 std::vector<Loop*>::iterator I =
186 std::find(SLP->SubLoops.begin(), SLP->SubLoops.end(), SubLoop);
187 assert(I != SLP->SubLoops.end() && "SubLoop not a child of parent?");
188 SLP->SubLoops.erase(I); // Remove from parent...
190 // Add the subloop to THIS loop...
191 SubLoop->ParentLoop = L;
192 L->SubLoops.push_back(SubLoop);
195 // Normal case, add the block to our loop...
196 L->Blocks.push_back(X);
198 // Add all of the predecessors of X to the end of the work stack...
199 TodoStack.insert(TodoStack.end(), pred_begin(X), pred_end(X));
203 // If there are any loops nested within this loop, create them now!
204 for (std::vector<BasicBlock*>::iterator I = L->Blocks.begin(),
205 E = L->Blocks.end(); I != E; ++I)
206 if (Loop *NewLoop = ConsiderForLoop(*I, DT)) {
207 L->SubLoops.push_back(NewLoop);
208 NewLoop->ParentLoop = L;
211 // Add the basic blocks that comprise this loop to the BBMap so that this
212 // loop can be found for them.
214 for (std::vector<BasicBlock*>::iterator I = L->Blocks.begin(),
215 E = L->Blocks.end(); I != E; ++I) {
216 std::map<BasicBlock*, Loop*>::iterator BBMI = BBMap.lower_bound(*I);
217 if (BBMI == BBMap.end() || BBMI->first != *I) // Not in map yet...
218 BBMap.insert(BBMI, std::make_pair(*I, L)); // Must be at this level
221 // Now that we have a list of all of the child loops of this loop, check to
222 // see if any of them should actually be nested inside of each other. We can
223 // accidentally pull loops our of their parents, so we must make sure to
224 // organize the loop nests correctly now.
226 std::map<BasicBlock*, Loop*> ContainingLoops;
227 for (unsigned i = 0; i != L->SubLoops.size(); ++i) {
228 Loop *Child = L->SubLoops[i];
229 assert(Child->getParentLoop() == L && "Not proper child loop?");
231 if (Loop *ContainingLoop = ContainingLoops[Child->getHeader()]) {
232 // If there is already a loop which contains this loop, move this loop
233 // into the containing loop.
234 MoveSiblingLoopInto(Child, ContainingLoop);
235 --i; // The loop got removed from the SubLoops list.
237 // This is currently considered to be a top-level loop. Check to see if
238 // any of the contained blocks are loop headers for subloops we have
239 // already processed.
240 for (unsigned b = 0, e = Child->Blocks.size(); b != e; ++b) {
241 Loop *&BlockLoop = ContainingLoops[Child->Blocks[b]];
242 if (BlockLoop == 0) { // Child block not processed yet...
244 } else if (BlockLoop != Child) {
245 Loop *SubLoop = BlockLoop;
246 // Reparent all of the blocks which used to belong to BlockLoops
247 for (unsigned j = 0, e = SubLoop->Blocks.size(); j != e; ++j)
248 ContainingLoops[SubLoop->Blocks[j]] = Child;
250 // There is already a loop which contains this block, that means
251 // that we should reparent the loop which the block is currently
252 // considered to belong to to be a child of this loop.
253 MoveSiblingLoopInto(SubLoop, Child);
254 --i; // We just shrunk the SubLoops list.
264 /// MoveSiblingLoopInto - This method moves the NewChild loop to live inside of
265 /// the NewParent Loop, instead of being a sibling of it.
266 void LoopInfo::MoveSiblingLoopInto(Loop *NewChild, Loop *NewParent) {
267 Loop *OldParent = NewChild->getParentLoop();
268 assert(OldParent && OldParent == NewParent->getParentLoop() &&
269 NewChild != NewParent && "Not sibling loops!");
271 // Remove NewChild from being a child of OldParent
272 std::vector<Loop*>::iterator I =
273 std::find(OldParent->SubLoops.begin(), OldParent->SubLoops.end(), NewChild);
274 assert(I != OldParent->SubLoops.end() && "Parent fields incorrect??");
275 OldParent->SubLoops.erase(I); // Remove from parent's subloops list
276 NewChild->ParentLoop = 0;
278 InsertLoopInto(NewChild, NewParent);
281 /// InsertLoopInto - This inserts loop L into the specified parent loop. If the
282 /// parent loop contains a loop which should contain L, the loop gets inserted
284 void LoopInfo::InsertLoopInto(Loop *L, Loop *Parent) {
285 BasicBlock *LHeader = L->getHeader();
286 assert(Parent->contains(LHeader) && "This loop should not be inserted here!");
288 // Check to see if it belongs in a child loop...
289 for (unsigned i = 0, e = Parent->SubLoops.size(); i != e; ++i)
290 if (Parent->SubLoops[i]->contains(LHeader)) {
291 InsertLoopInto(L, Parent->SubLoops[i]);
295 // If not, insert it here!
296 Parent->SubLoops.push_back(L);
297 L->ParentLoop = Parent;
300 /// changeLoopFor - Change the top-level loop that contains BB to the
301 /// specified loop. This should be used by transformations that restructure
302 /// the loop hierarchy tree.
303 void LoopInfo::changeLoopFor(BasicBlock *BB, Loop *L) {
304 Loop *&OldLoop = BBMap[BB];
305 assert(OldLoop && "Block not in a loop yet!");
309 /// changeTopLevelLoop - Replace the specified loop in the top-level loops
310 /// list with the indicated loop.
311 void LoopInfo::changeTopLevelLoop(Loop *OldLoop, Loop *NewLoop) {
312 std::vector<Loop*>::iterator I = std::find(TopLevelLoops.begin(),
313 TopLevelLoops.end(), OldLoop);
314 assert(I != TopLevelLoops.end() && "Old loop not at top level!");
316 assert(NewLoop->ParentLoop == 0 && OldLoop->ParentLoop == 0 &&
317 "Loops already embedded into a subloop!");
320 /// removeLoop - This removes the specified top-level loop from this loop info
321 /// object. The loop is not deleted, as it will presumably be inserted into
323 Loop *LoopInfo::removeLoop(iterator I) {
324 assert(I != end() && "Cannot remove end iterator!");
326 assert(L->getParentLoop() == 0 && "Not a top-level loop!");
327 TopLevelLoops.erase(TopLevelLoops.begin() + (I-begin()));
331 /// removeBlock - This method completely removes BB from all data structures,
332 /// including all of the Loop objects it is nested in and our mapping from
333 /// BasicBlocks to loops.
334 void LoopInfo::removeBlock(BasicBlock *BB) {
335 std::map<BasicBlock *, Loop*>::iterator I = BBMap.find(BB);
336 if (I != BBMap.end()) {
337 for (Loop *L = I->second; L; L = L->getParentLoop())
338 L->removeBlockFromLoop(BB);
345 //===----------------------------------------------------------------------===//
346 // APIs for simple analysis of the loop.
349 /// getExitingBlocks - Return all blocks inside the loop that have successors
350 /// outside of the loop. These are the blocks _inside of the current loop_
351 /// which branch out. The returned list is always unique.
353 void Loop::getExitingBlocks(SmallVectorImpl<BasicBlock*> &ExitingBlocks) const {
354 // Sort the blocks vector so that we can use binary search to do quick
356 SmallVector<BasicBlock*, 128> LoopBBs(block_begin(), block_end());
357 std::sort(LoopBBs.begin(), LoopBBs.end());
359 for (std::vector<BasicBlock*>::const_iterator BI = Blocks.begin(),
360 BE = Blocks.end(); BI != BE; ++BI)
361 for (succ_iterator I = succ_begin(*BI), E = succ_end(*BI); I != E; ++I)
362 if (!std::binary_search(LoopBBs.begin(), LoopBBs.end(), *I)) {
363 // Not in current loop? It must be an exit block.
364 ExitingBlocks.push_back(*BI);
369 /// getExitBlocks - Return all of the successor blocks of this loop. These
370 /// are the blocks _outside of the current loop_ which are branched to.
372 void Loop::getExitBlocks(SmallVectorImpl<BasicBlock*> &ExitBlocks) const {
373 // Sort the blocks vector so that we can use binary search to do quick
375 SmallVector<BasicBlock*, 128> LoopBBs(block_begin(), block_end());
376 std::sort(LoopBBs.begin(), LoopBBs.end());
378 for (std::vector<BasicBlock*>::const_iterator BI = Blocks.begin(),
379 BE = Blocks.end(); BI != BE; ++BI)
380 for (succ_iterator I = succ_begin(*BI), E = succ_end(*BI); I != E; ++I)
381 if (!std::binary_search(LoopBBs.begin(), LoopBBs.end(), *I))
382 // Not in current loop? It must be an exit block.
383 ExitBlocks.push_back(*I);
386 /// getUniqueExitBlocks - Return all unique successor blocks of this loop. These
387 /// are the blocks _outside of the current loop_ which are branched to. This
388 /// assumes that loop is in canonical form.
390 void Loop::getUniqueExitBlocks(SmallVectorImpl<BasicBlock*> &ExitBlocks) const {
391 // Sort the blocks vector so that we can use binary search to do quick
393 SmallVector<BasicBlock*, 128> LoopBBs(block_begin(), block_end());
394 std::sort(LoopBBs.begin(), LoopBBs.end());
396 std::vector<BasicBlock*> switchExitBlocks;
398 for (std::vector<BasicBlock*>::const_iterator BI = Blocks.begin(),
399 BE = Blocks.end(); BI != BE; ++BI) {
401 BasicBlock *current = *BI;
402 switchExitBlocks.clear();
404 for (succ_iterator I = succ_begin(*BI), E = succ_end(*BI); I != E; ++I) {
405 if (std::binary_search(LoopBBs.begin(), LoopBBs.end(), *I))
406 // If block is inside the loop then it is not a exit block.
409 pred_iterator PI = pred_begin(*I);
410 BasicBlock *firstPred = *PI;
412 // If current basic block is this exit block's first predecessor
413 // then only insert exit block in to the output ExitBlocks vector.
414 // This ensures that same exit block is not inserted twice into
415 // ExitBlocks vector.
416 if (current != firstPred)
419 // If a terminator has more then two successors, for example SwitchInst,
420 // then it is possible that there are multiple edges from current block
421 // to one exit block.
422 if (current->getTerminator()->getNumSuccessors() <= 2) {
423 ExitBlocks.push_back(*I);
427 // In case of multiple edges from current block to exit block, collect
428 // only one edge in ExitBlocks. Use switchExitBlocks to keep track of
430 if (std::find(switchExitBlocks.begin(), switchExitBlocks.end(), *I)
431 == switchExitBlocks.end()) {
432 switchExitBlocks.push_back(*I);
433 ExitBlocks.push_back(*I);
440 /// getLoopPreheader - If there is a preheader for this loop, return it. A
441 /// loop has a preheader if there is only one edge to the header of the loop
442 /// from outside of the loop. If this is the case, the block branching to the
443 /// header of the loop is the preheader node.
445 /// This method returns null if there is no preheader for the loop.
447 BasicBlock *Loop::getLoopPreheader() const {
448 // Keep track of nodes outside the loop branching to the header...
451 // Loop over the predecessors of the header node...
452 BasicBlock *Header = getHeader();
453 for (pred_iterator PI = pred_begin(Header), PE = pred_end(Header);
455 if (!contains(*PI)) { // If the block is not in the loop...
456 if (Out && Out != *PI)
457 return 0; // Multiple predecessors outside the loop
461 // Make sure there is only one exit out of the preheader.
462 assert(Out && "Header of loop has no predecessors from outside loop?");
463 succ_iterator SI = succ_begin(Out);
465 if (SI != succ_end(Out))
466 return 0; // Multiple exits from the block, must not be a preheader.
468 // If there is exactly one preheader, return it. If there was zero, then Out
473 /// getLoopLatch - If there is a latch block for this loop, return it. A
474 /// latch block is the canonical backedge for a loop. A loop header in normal
475 /// form has two edges into it: one from a preheader and one from a latch
477 BasicBlock *Loop::getLoopLatch() const {
478 BasicBlock *Header = getHeader();
479 pred_iterator PI = pred_begin(Header), PE = pred_end(Header);
480 if (PI == PE) return 0; // no preds?
482 BasicBlock *Latch = 0;
486 if (PI == PE) return 0; // only one pred?
489 if (Latch) return 0; // multiple backedges
493 if (PI != PE) return 0; // more than two preds
498 /// getCanonicalInductionVariable - Check to see if the loop has a canonical
499 /// induction variable: an integer recurrence that starts at 0 and increments by
500 /// one each time through the loop. If so, return the phi node that corresponds
503 PHINode *Loop::getCanonicalInductionVariable() const {
504 BasicBlock *H = getHeader();
506 BasicBlock *Incoming = 0, *Backedge = 0;
507 pred_iterator PI = pred_begin(H);
508 assert(PI != pred_end(H) && "Loop must have at least one backedge!");
510 if (PI == pred_end(H)) return 0; // dead loop
512 if (PI != pred_end(H)) return 0; // multiple backedges?
514 if (contains(Incoming)) {
515 if (contains(Backedge))
517 std::swap(Incoming, Backedge);
518 } else if (!contains(Backedge))
521 // Loop over all of the PHI nodes, looking for a canonical indvar.
522 for (BasicBlock::iterator I = H->begin(); isa<PHINode>(I); ++I) {
523 PHINode *PN = cast<PHINode>(I);
524 if (Instruction *Inc =
525 dyn_cast<Instruction>(PN->getIncomingValueForBlock(Backedge)))
526 if (Inc->getOpcode() == Instruction::Add && Inc->getOperand(0) == PN)
527 if (ConstantInt *CI = dyn_cast<ConstantInt>(Inc->getOperand(1)))
528 if (CI->equalsInt(1))
534 /// getCanonicalInductionVariableIncrement - Return the LLVM value that holds
535 /// the canonical induction variable value for the "next" iteration of the loop.
536 /// This always succeeds if getCanonicalInductionVariable succeeds.
538 Instruction *Loop::getCanonicalInductionVariableIncrement() const {
539 if (PHINode *PN = getCanonicalInductionVariable()) {
540 bool P1InLoop = contains(PN->getIncomingBlock(1));
541 return cast<Instruction>(PN->getIncomingValue(P1InLoop));
546 /// getTripCount - Return a loop-invariant LLVM value indicating the number of
547 /// times the loop will be executed. Note that this means that the backedge of
548 /// the loop executes N-1 times. If the trip-count cannot be determined, this
551 Value *Loop::getTripCount() const {
552 // Canonical loops will end with a 'cmp ne I, V', where I is the incremented
553 // canonical induction variable and V is the trip count of the loop.
554 Instruction *Inc = getCanonicalInductionVariableIncrement();
555 if (Inc == 0) return 0;
556 PHINode *IV = cast<PHINode>(Inc->getOperand(0));
558 BasicBlock *BackedgeBlock =
559 IV->getIncomingBlock(contains(IV->getIncomingBlock(1)));
561 if (BranchInst *BI = dyn_cast<BranchInst>(BackedgeBlock->getTerminator()))
562 if (BI->isConditional()) {
563 if (ICmpInst *ICI = dyn_cast<ICmpInst>(BI->getCondition())) {
564 if (ICI->getOperand(0) == Inc)
565 if (BI->getSuccessor(0) == getHeader()) {
566 if (ICI->getPredicate() == ICmpInst::ICMP_NE)
567 return ICI->getOperand(1);
568 } else if (ICI->getPredicate() == ICmpInst::ICMP_EQ) {
569 return ICI->getOperand(1);
577 /// isLCSSAForm - Return true if the Loop is in LCSSA form
578 bool Loop::isLCSSAForm() const {
579 // Sort the blocks vector so that we can use binary search to do quick
581 SmallPtrSet<BasicBlock*, 16> LoopBBs(block_begin(), block_end());
583 for (block_iterator BI = block_begin(), E = block_end(); BI != E; ++BI) {
584 BasicBlock *BB = *BI;
585 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
586 for (Value::use_iterator UI = I->use_begin(), E = I->use_end(); UI != E;
588 BasicBlock *UserBB = cast<Instruction>(*UI)->getParent();
589 if (PHINode *P = dyn_cast<PHINode>(*UI)) {
590 unsigned OperandNo = UI.getOperandNo();
591 UserBB = P->getIncomingBlock(OperandNo/2);
594 // Check the current block, as a fast-path. Most values are used in the
595 // same block they are defined in.
596 if (UserBB != BB && !LoopBBs.count(UserBB))
604 //===-------------------------------------------------------------------===//
605 // APIs for updating loop information after changing the CFG
608 /// addBasicBlockToLoop - This function is used by other analyses to update loop
609 /// information. NewBB is set to be a new member of the current loop. Because
610 /// of this, it is added as a member of all parent loops, and is added to the
611 /// specified LoopInfo object as being in the current basic block. It is not
612 /// valid to replace the loop header with this method.
614 void Loop::addBasicBlockToLoop(BasicBlock *NewBB, LoopInfo &LI) {
615 assert((Blocks.empty() || LI[getHeader()] == this) &&
616 "Incorrect LI specified for this loop!");
617 assert(NewBB && "Cannot add a null basic block to the loop!");
618 assert(LI[NewBB] == 0 && "BasicBlock already in the loop!");
620 // Add the loop mapping to the LoopInfo object...
621 LI.BBMap[NewBB] = this;
623 // Add the basic block to this loop and all parent loops...
626 L->Blocks.push_back(NewBB);
627 L = L->getParentLoop();
631 /// replaceChildLoopWith - This is used when splitting loops up. It replaces
632 /// the OldChild entry in our children list with NewChild, and updates the
633 /// parent pointers of the two loops as appropriate.
634 void Loop::replaceChildLoopWith(Loop *OldChild, Loop *NewChild) {
635 assert(OldChild->ParentLoop == this && "This loop is already broken!");
636 assert(NewChild->ParentLoop == 0 && "NewChild already has a parent!");
637 std::vector<Loop*>::iterator I = std::find(SubLoops.begin(), SubLoops.end(),
639 assert(I != SubLoops.end() && "OldChild not in loop!");
641 OldChild->ParentLoop = 0;
642 NewChild->ParentLoop = this;
645 /// addChildLoop - Add the specified loop to be a child of this loop.
647 void Loop::addChildLoop(Loop *NewChild) {
648 assert(NewChild->ParentLoop == 0 && "NewChild already has a parent!");
649 NewChild->ParentLoop = this;
650 SubLoops.push_back(NewChild);
654 static void RemoveFromVector(std::vector<T*> &V, T *N) {
655 typename std::vector<T*>::iterator I = std::find(V.begin(), V.end(), N);
656 assert(I != V.end() && "N is not in this list!");
660 /// removeChildLoop - This removes the specified child from being a subloop of
661 /// this loop. The loop is not deleted, as it will presumably be inserted
662 /// into another loop.
663 Loop *Loop::removeChildLoop(iterator I) {
664 assert(I != SubLoops.end() && "Cannot remove end iterator!");
666 assert(Child->ParentLoop == this && "Child is not a child of this loop!");
667 SubLoops.erase(SubLoops.begin()+(I-begin()));
668 Child->ParentLoop = 0;
673 /// removeBlockFromLoop - This removes the specified basic block from the
674 /// current loop, updating the Blocks and ExitBlocks lists as appropriate. This
675 /// does not update the mapping in the LoopInfo class.
676 void Loop::removeBlockFromLoop(BasicBlock *BB) {
677 RemoveFromVector(Blocks, BB);
680 // Ensure this file gets linked when LoopInfo.h is used.
681 DEFINING_FILE_FOR(LoopInfo)