LoopPass.cpp revision 206124
1193323Sed//===- LoopPass.cpp - Loop Pass and Loop Pass Manager ---------------------===// 2193323Sed// 3193323Sed// The LLVM Compiler Infrastructure 4193323Sed// 5193323Sed// This file is distributed under the University of Illinois Open Source 6193323Sed// License. See LICENSE.TXT for details. 7193323Sed// 8193323Sed//===----------------------------------------------------------------------===// 9193323Sed// 10193323Sed// This file implements LoopPass and LPPassManager. All loop optimization 11193323Sed// and transformation passes are derived from LoopPass. LPPassManager is 12193323Sed// responsible for managing LoopPasses. 13193323Sed// 14193323Sed//===----------------------------------------------------------------------===// 15193323Sed 16193323Sed#include "llvm/Analysis/LoopPass.h" 17206124Srdivacky#include "llvm/Assembly/PrintModulePass.h" 18206124Srdivacky#include "llvm/Support/Debug.h" 19206083Srdivacky#include "llvm/Support/Timer.h" 20193323Sedusing namespace llvm; 21193323Sed 22206124Srdivackynamespace { 23206124Srdivacky 24206124Srdivacky/// PrintLoopPass - Print a Function corresponding to a Loop. 25206124Srdivacky/// 26206124Srdivackyclass PrintLoopPass : public LoopPass { 27206124Srdivackyprivate: 28206124Srdivacky std::string Banner; 29206124Srdivacky raw_ostream &Out; // raw_ostream to print on. 30206124Srdivacky 31206124Srdivackypublic: 32206124Srdivacky static char ID; 33206124Srdivacky PrintLoopPass() : LoopPass(&ID), Out(dbgs()) {} 34206124Srdivacky PrintLoopPass(const std::string &B, raw_ostream &o) 35206124Srdivacky : LoopPass(&ID), Banner(B), Out(o) {} 36206124Srdivacky 37206124Srdivacky virtual void getAnalysisUsage(AnalysisUsage &AU) const { 38206124Srdivacky AU.setPreservesAll(); 39206124Srdivacky } 40206124Srdivacky 41206124Srdivacky bool runOnLoop(Loop *L, LPPassManager &) { 42206124Srdivacky Out << Banner; 43206124Srdivacky for (Loop::block_iterator b = L->block_begin(), be = L->block_end(); 44206124Srdivacky b != be; 45206124Srdivacky ++b) { 46206124Srdivacky (*b)->print(Out); 47206124Srdivacky } 48206124Srdivacky return false; 49206124Srdivacky } 50206124Srdivacky}; 51206124Srdivacky 52206124Srdivackychar PrintLoopPass::ID = 0; 53206124Srdivacky} 54206124Srdivacky 55193323Sed//===----------------------------------------------------------------------===// 56193323Sed// LPPassManager 57193323Sed// 58193323Sed 59193323Sedchar LPPassManager::ID = 0; 60193323Sed 61193323SedLPPassManager::LPPassManager(int Depth) 62193323Sed : FunctionPass(&ID), PMDataManager(Depth) { 63193323Sed skipThisLoop = false; 64193323Sed redoThisLoop = false; 65193323Sed LI = NULL; 66193323Sed CurrentLoop = NULL; 67193323Sed} 68193323Sed 69193323Sed/// Delete loop from the loop queue and loop hierarchy (LoopInfo). 70193323Sedvoid LPPassManager::deleteLoopFromQueue(Loop *L) { 71193323Sed 72193323Sed if (Loop *ParentLoop = L->getParentLoop()) { // Not a top-level loop. 73193323Sed // Reparent all of the blocks in this loop. Since BBLoop had a parent, 74193323Sed // they are now all in it. 75193323Sed for (Loop::block_iterator I = L->block_begin(), E = L->block_end(); 76193323Sed I != E; ++I) 77193323Sed if (LI->getLoopFor(*I) == L) // Don't change blocks in subloops. 78193323Sed LI->changeLoopFor(*I, ParentLoop); 79193323Sed 80193323Sed // Remove the loop from its parent loop. 81193323Sed for (Loop::iterator I = ParentLoop->begin(), E = ParentLoop->end();; 82193323Sed ++I) { 83193323Sed assert(I != E && "Couldn't find loop"); 84193323Sed if (*I == L) { 85193323Sed ParentLoop->removeChildLoop(I); 86193323Sed break; 87193323Sed } 88193323Sed } 89193323Sed 90193323Sed // Move all subloops into the parent loop. 91193323Sed while (!L->empty()) 92193323Sed ParentLoop->addChildLoop(L->removeChildLoop(L->end()-1)); 93193323Sed } else { 94193323Sed // Reparent all of the blocks in this loop. Since BBLoop had no parent, 95193323Sed // they no longer in a loop at all. 96193323Sed 97193323Sed for (unsigned i = 0; i != L->getBlocks().size(); ++i) { 98193323Sed // Don't change blocks in subloops. 99193323Sed if (LI->getLoopFor(L->getBlocks()[i]) == L) { 100193323Sed LI->removeBlock(L->getBlocks()[i]); 101193323Sed --i; 102193323Sed } 103193323Sed } 104193323Sed 105193323Sed // Remove the loop from the top-level LoopInfo object. 106193323Sed for (LoopInfo::iterator I = LI->begin(), E = LI->end();; ++I) { 107193323Sed assert(I != E && "Couldn't find loop"); 108193323Sed if (*I == L) { 109193323Sed LI->removeLoop(I); 110193323Sed break; 111193323Sed } 112193323Sed } 113193323Sed 114193323Sed // Move all of the subloops to the top-level. 115193323Sed while (!L->empty()) 116193323Sed LI->addTopLevelLoop(L->removeChildLoop(L->end()-1)); 117193323Sed } 118193323Sed 119193323Sed delete L; 120193323Sed 121193323Sed // If L is current loop then skip rest of the passes and let 122193323Sed // runOnFunction remove L from LQ. Otherwise, remove L from LQ now 123193323Sed // and continue applying other passes on CurrentLoop. 124193323Sed if (CurrentLoop == L) { 125193323Sed skipThisLoop = true; 126193323Sed return; 127193323Sed } 128193323Sed 129193323Sed for (std::deque<Loop *>::iterator I = LQ.begin(), 130193323Sed E = LQ.end(); I != E; ++I) { 131193323Sed if (*I == L) { 132193323Sed LQ.erase(I); 133193323Sed break; 134193323Sed } 135193323Sed } 136193323Sed} 137193323Sed 138193323Sed// Inset loop into loop nest (LoopInfo) and loop queue (LQ). 139193323Sedvoid LPPassManager::insertLoop(Loop *L, Loop *ParentLoop) { 140193323Sed 141193323Sed assert (CurrentLoop != L && "Cannot insert CurrentLoop"); 142193323Sed 143193323Sed // Insert into loop nest 144193323Sed if (ParentLoop) 145193323Sed ParentLoop->addChildLoop(L); 146193323Sed else 147193323Sed LI->addTopLevelLoop(L); 148193323Sed 149198090Srdivacky insertLoopIntoQueue(L); 150198090Srdivacky} 151198090Srdivacky 152198090Srdivackyvoid LPPassManager::insertLoopIntoQueue(Loop *L) { 153193323Sed // Insert L into loop queue 154193323Sed if (L == CurrentLoop) 155193323Sed redoLoop(L); 156198090Srdivacky else if (!L->getParentLoop()) 157193323Sed // This is top level loop. 158193323Sed LQ.push_front(L); 159193323Sed else { 160198090Srdivacky // Insert L after the parent loop. 161193323Sed for (std::deque<Loop *>::iterator I = LQ.begin(), 162193323Sed E = LQ.end(); I != E; ++I) { 163198090Srdivacky if (*I == L->getParentLoop()) { 164193323Sed // deque does not support insert after. 165193323Sed ++I; 166193323Sed LQ.insert(I, 1, L); 167193323Sed break; 168193323Sed } 169193323Sed } 170193323Sed } 171193323Sed} 172193323Sed 173193323Sed// Reoptimize this loop. LPPassManager will re-insert this loop into the 174193323Sed// queue. This allows LoopPass to change loop nest for the loop. This 175193323Sed// utility may send LPPassManager into infinite loops so use caution. 176193323Sedvoid LPPassManager::redoLoop(Loop *L) { 177193323Sed assert (CurrentLoop == L && "Can redo only CurrentLoop"); 178193323Sed redoThisLoop = true; 179193323Sed} 180193323Sed 181193323Sed/// cloneBasicBlockSimpleAnalysis - Invoke cloneBasicBlockAnalysis hook for 182193323Sed/// all loop passes. 183193323Sedvoid LPPassManager::cloneBasicBlockSimpleAnalysis(BasicBlock *From, 184193323Sed BasicBlock *To, Loop *L) { 185193323Sed for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) { 186202878Srdivacky LoopPass *LP = (LoopPass *)getContainedPass(Index); 187193323Sed LP->cloneBasicBlockAnalysis(From, To, L); 188193323Sed } 189193323Sed} 190193323Sed 191193323Sed/// deleteSimpleAnalysisValue - Invoke deleteAnalysisValue hook for all passes. 192193323Sedvoid LPPassManager::deleteSimpleAnalysisValue(Value *V, Loop *L) { 193193323Sed if (BasicBlock *BB = dyn_cast<BasicBlock>(V)) { 194193323Sed for (BasicBlock::iterator BI = BB->begin(), BE = BB->end(); BI != BE; 195193323Sed ++BI) { 196193323Sed Instruction &I = *BI; 197193323Sed deleteSimpleAnalysisValue(&I, L); 198193323Sed } 199193323Sed } 200193323Sed for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) { 201202878Srdivacky LoopPass *LP = (LoopPass *)getContainedPass(Index); 202193323Sed LP->deleteAnalysisValue(V, L); 203193323Sed } 204193323Sed} 205193323Sed 206193323Sed 207193323Sed// Recurse through all subloops and all loops into LQ. 208193323Sedstatic void addLoopIntoQueue(Loop *L, std::deque<Loop *> &LQ) { 209193323Sed LQ.push_back(L); 210193323Sed for (Loop::iterator I = L->begin(), E = L->end(); I != E; ++I) 211193323Sed addLoopIntoQueue(*I, LQ); 212193323Sed} 213193323Sed 214193323Sed/// Pass Manager itself does not invalidate any analysis info. 215193323Sedvoid LPPassManager::getAnalysisUsage(AnalysisUsage &Info) const { 216193323Sed // LPPassManager needs LoopInfo. In the long term LoopInfo class will 217193323Sed // become part of LPPassManager. 218193323Sed Info.addRequired<LoopInfo>(); 219193323Sed Info.setPreservesAll(); 220193323Sed} 221193323Sed 222193323Sed/// run - Execute all of the passes scheduled for execution. Keep track of 223193323Sed/// whether any of the passes modifies the function, and if so, return true. 224193323Sedbool LPPassManager::runOnFunction(Function &F) { 225193323Sed LI = &getAnalysis<LoopInfo>(); 226193323Sed bool Changed = false; 227193323Sed 228193323Sed // Collect inherited analysis from Module level pass manager. 229193323Sed populateInheritedAnalysis(TPM->activeStack); 230193323Sed 231193323Sed // Populate Loop Queue 232193323Sed for (LoopInfo::iterator I = LI->begin(), E = LI->end(); I != E; ++I) 233193323Sed addLoopIntoQueue(*I, LQ); 234193323Sed 235195340Sed if (LQ.empty()) // No loops, skip calling finalizers 236195340Sed return false; 237195340Sed 238193323Sed // Initialization 239193323Sed for (std::deque<Loop *>::const_iterator I = LQ.begin(), E = LQ.end(); 240193323Sed I != E; ++I) { 241193323Sed Loop *L = *I; 242193323Sed for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) { 243202878Srdivacky LoopPass *P = (LoopPass*)getContainedPass(Index); 244202878Srdivacky Changed |= P->doInitialization(L, *this); 245193323Sed } 246193323Sed } 247193323Sed 248193323Sed // Walk Loops 249193323Sed while (!LQ.empty()) { 250193323Sed 251193323Sed CurrentLoop = LQ.back(); 252193323Sed skipThisLoop = false; 253193323Sed redoThisLoop = false; 254193323Sed 255198090Srdivacky // Run all passes on the current Loop. 256193323Sed for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) { 257202878Srdivacky LoopPass *P = (LoopPass*)getContainedPass(Index); 258193323Sed 259198090Srdivacky dumpPassInfo(P, EXECUTION_MSG, ON_LOOP_MSG, 260206083Srdivacky CurrentLoop->getHeader()->getName()); 261193323Sed dumpRequiredSet(P); 262193323Sed 263193323Sed initializeAnalysisImpl(P); 264193323Sed 265193323Sed { 266202878Srdivacky PassManagerPrettyStackEntry X(P, *CurrentLoop->getHeader()); 267206083Srdivacky TimeRegion PassTimer(getPassTimer(P)); 268206083Srdivacky 269202878Srdivacky Changed |= P->runOnLoop(CurrentLoop, *this); 270193323Sed } 271193323Sed 272193323Sed if (Changed) 273198090Srdivacky dumpPassInfo(P, MODIFICATION_MSG, ON_LOOP_MSG, 274198090Srdivacky skipThisLoop ? "<deleted>" : 275206083Srdivacky CurrentLoop->getHeader()->getName()); 276193323Sed dumpPreservedSet(P); 277193323Sed 278198090Srdivacky if (!skipThisLoop) { 279198090Srdivacky // Manually check that this loop is still healthy. This is done 280198090Srdivacky // instead of relying on LoopInfo::verifyLoop since LoopInfo 281198090Srdivacky // is a function pass and it's really expensive to verify every 282198090Srdivacky // loop in the function every time. That level of checking can be 283198090Srdivacky // enabled with the -verify-loop-info option. 284206083Srdivacky { 285206083Srdivacky TimeRegion PassTimer(getPassTimer(LI)); 286206083Srdivacky CurrentLoop->verifyLoop(); 287206083Srdivacky } 288198090Srdivacky 289198090Srdivacky // Then call the regular verifyAnalysis functions. 290202878Srdivacky verifyPreservedAnalysis(P); 291198090Srdivacky } 292198090Srdivacky 293193323Sed removeNotPreservedAnalysis(P); 294193323Sed recordAvailableAnalysis(P); 295198090Srdivacky removeDeadPasses(P, 296198090Srdivacky skipThisLoop ? "<deleted>" : 297206083Srdivacky CurrentLoop->getHeader()->getName(), 298198090Srdivacky ON_LOOP_MSG); 299193323Sed 300193323Sed if (skipThisLoop) 301193323Sed // Do not run other passes on this loop. 302193323Sed break; 303193323Sed } 304193323Sed 305198090Srdivacky // If the loop was deleted, release all the loop passes. This frees up 306198090Srdivacky // some memory, and avoids trouble with the pass manager trying to call 307198090Srdivacky // verifyAnalysis on them. 308198090Srdivacky if (skipThisLoop) 309198090Srdivacky for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) { 310198090Srdivacky Pass *P = getContainedPass(Index); 311198090Srdivacky freePass(P, "<deleted>", ON_LOOP_MSG); 312198090Srdivacky } 313198090Srdivacky 314193323Sed // Pop the loop from queue after running all passes. 315193323Sed LQ.pop_back(); 316193323Sed 317193323Sed if (redoThisLoop) 318193323Sed LQ.push_back(CurrentLoop); 319193323Sed } 320193323Sed 321193323Sed // Finalization 322193323Sed for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) { 323202878Srdivacky LoopPass *P = (LoopPass *)getContainedPass(Index); 324202878Srdivacky Changed |= P->doFinalization(); 325193323Sed } 326193323Sed 327193323Sed return Changed; 328193323Sed} 329193323Sed 330193323Sed/// Print passes managed by this manager 331193323Sedvoid LPPassManager::dumpPassStructure(unsigned Offset) { 332198090Srdivacky errs().indent(Offset*2) << "Loop Pass Manager\n"; 333193323Sed for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) { 334193323Sed Pass *P = getContainedPass(Index); 335193323Sed P->dumpPassStructure(Offset + 1); 336193323Sed dumpLastUses(P, Offset+1); 337193323Sed } 338193323Sed} 339193323Sed 340193323Sed 341193323Sed//===----------------------------------------------------------------------===// 342193323Sed// LoopPass 343193323Sed 344206124SrdivackyPass *LoopPass::createPrinterPass(raw_ostream &O, 345206124Srdivacky const std::string &Banner) const { 346206124Srdivacky return new PrintLoopPass(Banner, O); 347206124Srdivacky} 348206124Srdivacky 349193323Sed// Check if this pass is suitable for the current LPPassManager, if 350193323Sed// available. This pass P is not suitable for a LPPassManager if P 351193323Sed// is not preserving higher level analysis info used by other 352193323Sed// LPPassManager passes. In such case, pop LPPassManager from the 353193323Sed// stack. This will force assignPassManager() to create new 354193323Sed// LPPassManger as expected. 355193323Sedvoid LoopPass::preparePassManager(PMStack &PMS) { 356193323Sed 357193323Sed // Find LPPassManager 358193323Sed while (!PMS.empty() && 359193323Sed PMS.top()->getPassManagerType() > PMT_LoopPassManager) 360193323Sed PMS.pop(); 361193323Sed 362193323Sed // If this pass is destroying high level information that is used 363193323Sed // by other passes that are managed by LPM then do not insert 364193323Sed // this pass in current LPM. Use new LPPassManager. 365202878Srdivacky if (PMS.top()->getPassManagerType() == PMT_LoopPassManager && 366202878Srdivacky !PMS.top()->preserveHigherLevelAnalysis(this)) 367193323Sed PMS.pop(); 368193323Sed} 369193323Sed 370193323Sed/// Assign pass manager to manage this pass. 371193323Sedvoid LoopPass::assignPassManager(PMStack &PMS, 372193323Sed PassManagerType PreferredType) { 373193323Sed // Find LPPassManager 374193323Sed while (!PMS.empty() && 375193323Sed PMS.top()->getPassManagerType() > PMT_LoopPassManager) 376193323Sed PMS.pop(); 377193323Sed 378202878Srdivacky LPPassManager *LPPM; 379202878Srdivacky if (PMS.top()->getPassManagerType() == PMT_LoopPassManager) 380202878Srdivacky LPPM = (LPPassManager*)PMS.top(); 381202878Srdivacky else { 382202878Srdivacky // Create new Loop Pass Manager if it does not exist. 383193323Sed assert (!PMS.empty() && "Unable to create Loop Pass Manager"); 384193323Sed PMDataManager *PMD = PMS.top(); 385193323Sed 386193323Sed // [1] Create new Call Graph Pass Manager 387193323Sed LPPM = new LPPassManager(PMD->getDepth() + 1); 388193323Sed LPPM->populateInheritedAnalysis(PMS); 389193323Sed 390193323Sed // [2] Set up new manager's top level manager 391193323Sed PMTopLevelManager *TPM = PMD->getTopLevelManager(); 392193323Sed TPM->addIndirectPassManager(LPPM); 393193323Sed 394193323Sed // [3] Assign manager to manage this new manager. This may create 395193323Sed // and push new managers into PMS 396202878Srdivacky Pass *P = LPPM->getAsPass(); 397193323Sed TPM->schedulePass(P); 398193323Sed 399193323Sed // [4] Push new manager into PMS 400193323Sed PMS.push(LPPM); 401193323Sed } 402193323Sed 403193323Sed LPPM->add(this); 404193323Sed} 405