LLVM API Documentation
00001 //===- LoopInfo.cpp - Natural Loop Calculator -----------------------------===// 00002 // 00003 // The LLVM Compiler Infrastructure 00004 // 00005 // This file was developed by the LLVM research group and is distributed under 00006 // the University of Illinois Open Source License. See LICENSE.TXT for details. 00007 // 00008 //===----------------------------------------------------------------------===// 00009 // 00010 // This file defines the LoopInfo class that is used to identify natural loops 00011 // and determine the loop depth of various nodes of the CFG. Note that the 00012 // loops identified may actually be several natural loops that share the same 00013 // header node... not just a single natural loop. 00014 // 00015 //===----------------------------------------------------------------------===// 00016 00017 #include "llvm/Analysis/LoopInfo.h" 00018 #include "llvm/Constants.h" 00019 #include "llvm/Instructions.h" 00020 #include "llvm/Analysis/Dominators.h" 00021 #include "llvm/Assembly/Writer.h" 00022 #include "llvm/Support/CFG.h" 00023 #include "llvm/ADT/DepthFirstIterator.h" 00024 #include <algorithm> 00025 #include <iostream> 00026 using namespace llvm; 00027 00028 static RegisterAnalysis<LoopInfo> 00029 X("loops", "Natural Loop Construction", true); 00030 00031 //===----------------------------------------------------------------------===// 00032 // Loop implementation 00033 // 00034 bool Loop::contains(const BasicBlock *BB) const { 00035 return std::find(Blocks.begin(), Blocks.end(), BB) != Blocks.end(); 00036 } 00037 00038 bool Loop::isLoopExit(const BasicBlock *BB) const { 00039 for (succ_const_iterator SI = succ_begin(BB), SE = succ_end(BB); 00040 SI != SE; ++SI) { 00041 if (!contains(*SI)) 00042 return true; 00043 } 00044 return false; 00045 } 00046 00047 /// getNumBackEdges - Calculate the number of back edges to the loop header. 00048 /// 00049 unsigned Loop::getNumBackEdges() const { 00050 unsigned NumBackEdges = 0; 00051 BasicBlock *H = getHeader(); 00052 00053 for (pred_iterator I = pred_begin(H), E = pred_end(H); I != E; ++I) 00054 if (contains(*I)) 00055 ++NumBackEdges; 00056 00057 return NumBackEdges; 00058 } 00059 00060 /// isLoopInvariant - Return true if the specified value is loop invariant 00061 /// 00062 bool Loop::isLoopInvariant(Value *V) const { 00063 if (Instruction *I = dyn_cast<Instruction>(V)) 00064 return !contains(I->getParent()); 00065 return true; // All non-instructions are loop invariant 00066 } 00067 00068 void Loop::print(std::ostream &OS, unsigned Depth) const { 00069 OS << std::string(Depth*2, ' ') << "Loop Containing: "; 00070 00071 for (unsigned i = 0; i < getBlocks().size(); ++i) { 00072 if (i) OS << ","; 00073 WriteAsOperand(OS, getBlocks()[i], false); 00074 } 00075 OS << "\n"; 00076 00077 for (iterator I = begin(), E = end(); I != E; ++I) 00078 (*I)->print(OS, Depth+2); 00079 } 00080 00081 void Loop::dump() const { 00082 print(std::cerr); 00083 } 00084 00085 00086 //===----------------------------------------------------------------------===// 00087 // LoopInfo implementation 00088 // 00089 bool LoopInfo::runOnFunction(Function &) { 00090 releaseMemory(); 00091 Calculate(getAnalysis<ETForest>()); // Update 00092 return false; 00093 } 00094 00095 void LoopInfo::releaseMemory() { 00096 for (std::vector<Loop*>::iterator I = TopLevelLoops.begin(), 00097 E = TopLevelLoops.end(); I != E; ++I) 00098 delete *I; // Delete all of the loops... 00099 00100 BBMap.clear(); // Reset internal state of analysis 00101 TopLevelLoops.clear(); 00102 } 00103 00104 00105 void LoopInfo::Calculate(ETForest &EF) { 00106 BasicBlock *RootNode = EF.getRoot(); 00107 00108 for (df_iterator<BasicBlock*> NI = df_begin(RootNode), 00109 NE = df_end(RootNode); NI != NE; ++NI) 00110 if (Loop *L = ConsiderForLoop(*NI, EF)) 00111 TopLevelLoops.push_back(L); 00112 } 00113 00114 void LoopInfo::getAnalysisUsage(AnalysisUsage &AU) const { 00115 AU.setPreservesAll(); 00116 AU.addRequired<ETForest>(); 00117 } 00118 00119 void LoopInfo::print(std::ostream &OS, const Module* ) const { 00120 for (unsigned i = 0; i < TopLevelLoops.size(); ++i) 00121 TopLevelLoops[i]->print(OS); 00122 #if 0 00123 for (std::map<BasicBlock*, Loop*>::const_iterator I = BBMap.begin(), 00124 E = BBMap.end(); I != E; ++I) 00125 OS << "BB '" << I->first->getName() << "' level = " 00126 << I->second->getLoopDepth() << "\n"; 00127 #endif 00128 } 00129 00130 static bool isNotAlreadyContainedIn(Loop *SubLoop, Loop *ParentLoop) { 00131 if (SubLoop == 0) return true; 00132 if (SubLoop == ParentLoop) return false; 00133 return isNotAlreadyContainedIn(SubLoop->getParentLoop(), ParentLoop); 00134 } 00135 00136 Loop *LoopInfo::ConsiderForLoop(BasicBlock *BB, ETForest &EF) { 00137 if (BBMap.find(BB) != BBMap.end()) return 0; // Haven't processed this node? 00138 00139 std::vector<BasicBlock *> TodoStack; 00140 00141 // Scan the predecessors of BB, checking to see if BB dominates any of 00142 // them. This identifies backedges which target this node... 00143 for (pred_iterator I = pred_begin(BB), E = pred_end(BB); I != E; ++I) 00144 if (EF.dominates(BB, *I)) // If BB dominates it's predecessor... 00145 TodoStack.push_back(*I); 00146 00147 if (TodoStack.empty()) return 0; // No backedges to this block... 00148 00149 // Create a new loop to represent this basic block... 00150 Loop *L = new Loop(BB); 00151 BBMap[BB] = L; 00152 00153 BasicBlock *EntryBlock = &BB->getParent()->getEntryBlock(); 00154 00155 while (!TodoStack.empty()) { // Process all the nodes in the loop 00156 BasicBlock *X = TodoStack.back(); 00157 TodoStack.pop_back(); 00158 00159 if (!L->contains(X) && // As of yet unprocessed?? 00160 EF.dominates(EntryBlock, X)) { // X is reachable from entry block? 00161 // Check to see if this block already belongs to a loop. If this occurs 00162 // then we have a case where a loop that is supposed to be a child of the 00163 // current loop was processed before the current loop. When this occurs, 00164 // this child loop gets added to a part of the current loop, making it a 00165 // sibling to the current loop. We have to reparent this loop. 00166 if (Loop *SubLoop = const_cast<Loop*>(getLoopFor(X))) 00167 if (SubLoop->getHeader() == X && isNotAlreadyContainedIn(SubLoop, L)) { 00168 // Remove the subloop from it's current parent... 00169 assert(SubLoop->ParentLoop && SubLoop->ParentLoop != L); 00170 Loop *SLP = SubLoop->ParentLoop; // SubLoopParent 00171 std::vector<Loop*>::iterator I = 00172 std::find(SLP->SubLoops.begin(), SLP->SubLoops.end(), SubLoop); 00173 assert(I != SLP->SubLoops.end() && "SubLoop not a child of parent?"); 00174 SLP->SubLoops.erase(I); // Remove from parent... 00175 00176 // Add the subloop to THIS loop... 00177 SubLoop->ParentLoop = L; 00178 L->SubLoops.push_back(SubLoop); 00179 } 00180 00181 // Normal case, add the block to our loop... 00182 L->Blocks.push_back(X); 00183 00184 // Add all of the predecessors of X to the end of the work stack... 00185 TodoStack.insert(TodoStack.end(), pred_begin(X), pred_end(X)); 00186 } 00187 } 00188 00189 // If there are any loops nested within this loop, create them now! 00190 for (std::vector<BasicBlock*>::iterator I = L->Blocks.begin(), 00191 E = L->Blocks.end(); I != E; ++I) 00192 if (Loop *NewLoop = ConsiderForLoop(*I, EF)) { 00193 L->SubLoops.push_back(NewLoop); 00194 NewLoop->ParentLoop = L; 00195 } 00196 00197 // Add the basic blocks that comprise this loop to the BBMap so that this 00198 // loop can be found for them. 00199 // 00200 for (std::vector<BasicBlock*>::iterator I = L->Blocks.begin(), 00201 E = L->Blocks.end(); I != E; ++I) { 00202 std::map<BasicBlock*, Loop*>::iterator BBMI = BBMap.lower_bound(*I); 00203 if (BBMI == BBMap.end() || BBMI->first != *I) // Not in map yet... 00204 BBMap.insert(BBMI, std::make_pair(*I, L)); // Must be at this level 00205 } 00206 00207 // Now that we have a list of all of the child loops of this loop, check to 00208 // see if any of them should actually be nested inside of each other. We can 00209 // accidentally pull loops our of their parents, so we must make sure to 00210 // organize the loop nests correctly now. 00211 { 00212 std::map<BasicBlock*, Loop*> ContainingLoops; 00213 for (unsigned i = 0; i != L->SubLoops.size(); ++i) { 00214 Loop *Child = L->SubLoops[i]; 00215 assert(Child->getParentLoop() == L && "Not proper child loop?"); 00216 00217 if (Loop *ContainingLoop = ContainingLoops[Child->getHeader()]) { 00218 // If there is already a loop which contains this loop, move this loop 00219 // into the containing loop. 00220 MoveSiblingLoopInto(Child, ContainingLoop); 00221 --i; // The loop got removed from the SubLoops list. 00222 } else { 00223 // This is currently considered to be a top-level loop. Check to see if 00224 // any of the contained blocks are loop headers for subloops we have 00225 // already processed. 00226 for (unsigned b = 0, e = Child->Blocks.size(); b != e; ++b) { 00227 Loop *&BlockLoop = ContainingLoops[Child->Blocks[b]]; 00228 if (BlockLoop == 0) { // Child block not processed yet... 00229 BlockLoop = Child; 00230 } else if (BlockLoop != Child) { 00231 Loop *SubLoop = BlockLoop; 00232 // Reparent all of the blocks which used to belong to BlockLoops 00233 for (unsigned j = 0, e = SubLoop->Blocks.size(); j != e; ++j) 00234 ContainingLoops[SubLoop->Blocks[j]] = Child; 00235 00236 // There is already a loop which contains this block, that means 00237 // that we should reparent the loop which the block is currently 00238 // considered to belong to to be a child of this loop. 00239 MoveSiblingLoopInto(SubLoop, Child); 00240 --i; // We just shrunk the SubLoops list. 00241 } 00242 } 00243 } 00244 } 00245 } 00246 00247 return L; 00248 } 00249 00250 /// MoveSiblingLoopInto - This method moves the NewChild loop to live inside of 00251 /// the NewParent Loop, instead of being a sibling of it. 00252 void LoopInfo::MoveSiblingLoopInto(Loop *NewChild, Loop *NewParent) { 00253 Loop *OldParent = NewChild->getParentLoop(); 00254 assert(OldParent && OldParent == NewParent->getParentLoop() && 00255 NewChild != NewParent && "Not sibling loops!"); 00256 00257 // Remove NewChild from being a child of OldParent 00258 std::vector<Loop*>::iterator I = 00259 std::find(OldParent->SubLoops.begin(), OldParent->SubLoops.end(), NewChild); 00260 assert(I != OldParent->SubLoops.end() && "Parent fields incorrect??"); 00261 OldParent->SubLoops.erase(I); // Remove from parent's subloops list 00262 NewChild->ParentLoop = 0; 00263 00264 InsertLoopInto(NewChild, NewParent); 00265 } 00266 00267 /// InsertLoopInto - This inserts loop L into the specified parent loop. If the 00268 /// parent loop contains a loop which should contain L, the loop gets inserted 00269 /// into L instead. 00270 void LoopInfo::InsertLoopInto(Loop *L, Loop *Parent) { 00271 BasicBlock *LHeader = L->getHeader(); 00272 assert(Parent->contains(LHeader) && "This loop should not be inserted here!"); 00273 00274 // Check to see if it belongs in a child loop... 00275 for (unsigned i = 0, e = Parent->SubLoops.size(); i != e; ++i) 00276 if (Parent->SubLoops[i]->contains(LHeader)) { 00277 InsertLoopInto(L, Parent->SubLoops[i]); 00278 return; 00279 } 00280 00281 // If not, insert it here! 00282 Parent->SubLoops.push_back(L); 00283 L->ParentLoop = Parent; 00284 } 00285 00286 /// changeLoopFor - Change the top-level loop that contains BB to the 00287 /// specified loop. This should be used by transformations that restructure 00288 /// the loop hierarchy tree. 00289 void LoopInfo::changeLoopFor(BasicBlock *BB, Loop *L) { 00290 Loop *&OldLoop = BBMap[BB]; 00291 assert(OldLoop && "Block not in a loop yet!"); 00292 OldLoop = L; 00293 } 00294 00295 /// changeTopLevelLoop - Replace the specified loop in the top-level loops 00296 /// list with the indicated loop. 00297 void LoopInfo::changeTopLevelLoop(Loop *OldLoop, Loop *NewLoop) { 00298 std::vector<Loop*>::iterator I = std::find(TopLevelLoops.begin(), 00299 TopLevelLoops.end(), OldLoop); 00300 assert(I != TopLevelLoops.end() && "Old loop not at top level!"); 00301 *I = NewLoop; 00302 assert(NewLoop->ParentLoop == 0 && OldLoop->ParentLoop == 0 && 00303 "Loops already embedded into a subloop!"); 00304 } 00305 00306 /// removeLoop - This removes the specified top-level loop from this loop info 00307 /// object. The loop is not deleted, as it will presumably be inserted into 00308 /// another loop. 00309 Loop *LoopInfo::removeLoop(iterator I) { 00310 assert(I != end() && "Cannot remove end iterator!"); 00311 Loop *L = *I; 00312 assert(L->getParentLoop() == 0 && "Not a top-level loop!"); 00313 TopLevelLoops.erase(TopLevelLoops.begin() + (I-begin())); 00314 return L; 00315 } 00316 00317 /// removeBlock - This method completely removes BB from all data structures, 00318 /// including all of the Loop objects it is nested in and our mapping from 00319 /// BasicBlocks to loops. 00320 void LoopInfo::removeBlock(BasicBlock *BB) { 00321 std::map<BasicBlock *, Loop*>::iterator I = BBMap.find(BB); 00322 if (I != BBMap.end()) { 00323 for (Loop *L = I->second; L; L = L->getParentLoop()) 00324 L->removeBlockFromLoop(BB); 00325 00326 BBMap.erase(I); 00327 } 00328 } 00329 00330 00331 //===----------------------------------------------------------------------===// 00332 // APIs for simple analysis of the loop. 00333 // 00334 00335 /// getExitBlocks - Return all of the successor blocks of this loop. These 00336 /// are the blocks _outside of the current loop_ which are branched to. 00337 /// 00338 void Loop::getExitBlocks(std::vector<BasicBlock*> &ExitBlocks) const { 00339 for (std::vector<BasicBlock*>::const_iterator BI = Blocks.begin(), 00340 BE = Blocks.end(); BI != BE; ++BI) 00341 for (succ_iterator I = succ_begin(*BI), E = succ_end(*BI); I != E; ++I) 00342 if (!contains(*I)) // Not in current loop? 00343 ExitBlocks.push_back(*I); // It must be an exit block... 00344 } 00345 00346 00347 /// getLoopPreheader - If there is a preheader for this loop, return it. A 00348 /// loop has a preheader if there is only one edge to the header of the loop 00349 /// from outside of the loop. If this is the case, the block branching to the 00350 /// header of the loop is the preheader node. 00351 /// 00352 /// This method returns null if there is no preheader for the loop. 00353 /// 00354 BasicBlock *Loop::getLoopPreheader() const { 00355 // Keep track of nodes outside the loop branching to the header... 00356 BasicBlock *Out = 0; 00357 00358 // Loop over the predecessors of the header node... 00359 BasicBlock *Header = getHeader(); 00360 for (pred_iterator PI = pred_begin(Header), PE = pred_end(Header); 00361 PI != PE; ++PI) 00362 if (!contains(*PI)) { // If the block is not in the loop... 00363 if (Out && Out != *PI) 00364 return 0; // Multiple predecessors outside the loop 00365 Out = *PI; 00366 } 00367 00368 // Make sure there is only one exit out of the preheader. 00369 assert(Out && "Header of loop has no predecessors from outside loop?"); 00370 succ_iterator SI = succ_begin(Out); 00371 ++SI; 00372 if (SI != succ_end(Out)) 00373 return 0; // Multiple exits from the block, must not be a preheader. 00374 00375 // If there is exactly one preheader, return it. If there was zero, then Out 00376 // is still null. 00377 return Out; 00378 } 00379 00380 /// getLoopLatch - If there is a latch block for this loop, return it. A 00381 /// latch block is the canonical backedge for a loop. A loop header in normal 00382 /// form has two edges into it: one from a preheader and one from a latch 00383 /// block. 00384 BasicBlock *Loop::getLoopLatch() const { 00385 BasicBlock *Header = getHeader(); 00386 pred_iterator PI = pred_begin(Header), PE = pred_end(Header); 00387 if (PI == PE) return 0; // no preds? 00388 00389 BasicBlock *Latch = 0; 00390 if (contains(*PI)) 00391 Latch = *PI; 00392 ++PI; 00393 if (PI == PE) return 0; // only one pred? 00394 00395 if (contains(*PI)) { 00396 if (Latch) return 0; // multiple backedges 00397 Latch = *PI; 00398 } 00399 ++PI; 00400 if (PI != PE) return 0; // more than two preds 00401 00402 return Latch; 00403 } 00404 00405 /// getCanonicalInductionVariable - Check to see if the loop has a canonical 00406 /// induction variable: an integer recurrence that starts at 0 and increments by 00407 /// one each time through the loop. If so, return the phi node that corresponds 00408 /// to it. 00409 /// 00410 PHINode *Loop::getCanonicalInductionVariable() const { 00411 BasicBlock *H = getHeader(); 00412 00413 BasicBlock *Incoming = 0, *Backedge = 0; 00414 pred_iterator PI = pred_begin(H); 00415 assert(PI != pred_end(H) && "Loop must have at least one backedge!"); 00416 Backedge = *PI++; 00417 if (PI == pred_end(H)) return 0; // dead loop 00418 Incoming = *PI++; 00419 if (PI != pred_end(H)) return 0; // multiple backedges? 00420 00421 if (contains(Incoming)) { 00422 if (contains(Backedge)) 00423 return 0; 00424 std::swap(Incoming, Backedge); 00425 } else if (!contains(Backedge)) 00426 return 0; 00427 00428 // Loop over all of the PHI nodes, looking for a canonical indvar. 00429 for (BasicBlock::iterator I = H->begin(); isa<PHINode>(I); ++I) { 00430 PHINode *PN = cast<PHINode>(I); 00431 if (Instruction *Inc = 00432 dyn_cast<Instruction>(PN->getIncomingValueForBlock(Backedge))) 00433 if (Inc->getOpcode() == Instruction::Add && Inc->getOperand(0) == PN) 00434 if (ConstantInt *CI = dyn_cast<ConstantInt>(Inc->getOperand(1))) 00435 if (CI->equalsInt(1)) 00436 return PN; 00437 } 00438 return 0; 00439 } 00440 00441 /// getCanonicalInductionVariableIncrement - Return the LLVM value that holds 00442 /// the canonical induction variable value for the "next" iteration of the loop. 00443 /// This always succeeds if getCanonicalInductionVariable succeeds. 00444 /// 00445 Instruction *Loop::getCanonicalInductionVariableIncrement() const { 00446 if (PHINode *PN = getCanonicalInductionVariable()) { 00447 bool P1InLoop = contains(PN->getIncomingBlock(1)); 00448 return cast<Instruction>(PN->getIncomingValue(P1InLoop)); 00449 } 00450 return 0; 00451 } 00452 00453 /// getTripCount - Return a loop-invariant LLVM value indicating the number of 00454 /// times the loop will be executed. Note that this means that the backedge of 00455 /// the loop executes N-1 times. If the trip-count cannot be determined, this 00456 /// returns null. 00457 /// 00458 Value *Loop::getTripCount() const { 00459 // Canonical loops will end with a 'setne I, V', where I is the incremented 00460 // canonical induction variable and V is the trip count of the loop. 00461 Instruction *Inc = getCanonicalInductionVariableIncrement(); 00462 if (Inc == 0) return 0; 00463 PHINode *IV = cast<PHINode>(Inc->getOperand(0)); 00464 00465 BasicBlock *BackedgeBlock = 00466 IV->getIncomingBlock(contains(IV->getIncomingBlock(1))); 00467 00468 if (BranchInst *BI = dyn_cast<BranchInst>(BackedgeBlock->getTerminator())) 00469 if (BI->isConditional()) 00470 if (SetCondInst *SCI = dyn_cast<SetCondInst>(BI->getCondition())) 00471 if (SCI->getOperand(0) == Inc) 00472 if (BI->getSuccessor(0) == getHeader()) { 00473 if (SCI->getOpcode() == Instruction::SetNE) 00474 return SCI->getOperand(1); 00475 } else if (SCI->getOpcode() == Instruction::SetEQ) { 00476 return SCI->getOperand(1); 00477 } 00478 00479 return 0; 00480 } 00481 00482 /// isLCSSAForm - Return true if the Loop is in LCSSA form 00483 bool Loop::isLCSSAForm() const { 00484 for (Loop::block_iterator BB = block_begin(), E = block_end(); 00485 BB != E; ++BB) { 00486 for (BasicBlock::iterator I = (*BB)->begin(), E = (*BB)->end(); I != E; ++I) 00487 for (Value::use_iterator UI = I->use_begin(), E = I->use_end(); UI != E; 00488 ++UI) { 00489 BasicBlock *UserBB = cast<Instruction>(*UI)->getParent(); 00490 if (PHINode* p = dyn_cast<PHINode>(*UI)) { 00491 unsigned OperandNo = UI.getOperandNo(); 00492 UserBB = p->getIncomingBlock(OperandNo/2); 00493 } 00494 00495 if (!contains(UserBB)) { 00496 return false; 00497 } 00498 } 00499 } 00500 00501 return true; 00502 } 00503 00504 //===-------------------------------------------------------------------===// 00505 // APIs for updating loop information after changing the CFG 00506 // 00507 00508 /// addBasicBlockToLoop - This function is used by other analyses to update loop 00509 /// information. NewBB is set to be a new member of the current loop. Because 00510 /// of this, it is added as a member of all parent loops, and is added to the 00511 /// specified LoopInfo object as being in the current basic block. It is not 00512 /// valid to replace the loop header with this method. 00513 /// 00514 void Loop::addBasicBlockToLoop(BasicBlock *NewBB, LoopInfo &LI) { 00515 assert((Blocks.empty() || LI[getHeader()] == this) && 00516 "Incorrect LI specified for this loop!"); 00517 assert(NewBB && "Cannot add a null basic block to the loop!"); 00518 assert(LI[NewBB] == 0 && "BasicBlock already in the loop!"); 00519 00520 // Add the loop mapping to the LoopInfo object... 00521 LI.BBMap[NewBB] = this; 00522 00523 // Add the basic block to this loop and all parent loops... 00524 Loop *L = this; 00525 while (L) { 00526 L->Blocks.push_back(NewBB); 00527 L = L->getParentLoop(); 00528 } 00529 } 00530 00531 /// replaceChildLoopWith - This is used when splitting loops up. It replaces 00532 /// the OldChild entry in our children list with NewChild, and updates the 00533 /// parent pointers of the two loops as appropriate. 00534 void Loop::replaceChildLoopWith(Loop *OldChild, Loop *NewChild) { 00535 assert(OldChild->ParentLoop == this && "This loop is already broken!"); 00536 assert(NewChild->ParentLoop == 0 && "NewChild already has a parent!"); 00537 std::vector<Loop*>::iterator I = std::find(SubLoops.begin(), SubLoops.end(), 00538 OldChild); 00539 assert(I != SubLoops.end() && "OldChild not in loop!"); 00540 *I = NewChild; 00541 OldChild->ParentLoop = 0; 00542 NewChild->ParentLoop = this; 00543 } 00544 00545 /// addChildLoop - Add the specified loop to be a child of this loop. 00546 /// 00547 void Loop::addChildLoop(Loop *NewChild) { 00548 assert(NewChild->ParentLoop == 0 && "NewChild already has a parent!"); 00549 NewChild->ParentLoop = this; 00550 SubLoops.push_back(NewChild); 00551 } 00552 00553 template<typename T> 00554 static void RemoveFromVector(std::vector<T*> &V, T *N) { 00555 typename std::vector<T*>::iterator I = std::find(V.begin(), V.end(), N); 00556 assert(I != V.end() && "N is not in this list!"); 00557 V.erase(I); 00558 } 00559 00560 /// removeChildLoop - This removes the specified child from being a subloop of 00561 /// this loop. The loop is not deleted, as it will presumably be inserted 00562 /// into another loop. 00563 Loop *Loop::removeChildLoop(iterator I) { 00564 assert(I != SubLoops.end() && "Cannot remove end iterator!"); 00565 Loop *Child = *I; 00566 assert(Child->ParentLoop == this && "Child is not a child of this loop!"); 00567 SubLoops.erase(SubLoops.begin()+(I-begin())); 00568 Child->ParentLoop = 0; 00569 return Child; 00570 } 00571 00572 00573 /// removeBlockFromLoop - This removes the specified basic block from the 00574 /// current loop, updating the Blocks and ExitBlocks lists as appropriate. This 00575 /// does not update the mapping in the LoopInfo class. 00576 void Loop::removeBlockFromLoop(BasicBlock *BB) { 00577 RemoveFromVector(Blocks, BB); 00578 } 00579 00580 // Ensure this file gets linked when LoopInfo.h is used. 00581 DEFINING_FILE_FOR(LoopInfo)