LoopPass.cpp revision 198090
1145132Sanholt//===- LoopPass.cpp - Loop Pass and Loop Pass Manager ---------------------===// 2145132Sanholt// 3145132Sanholt// The LLVM Compiler Infrastructure 4145132Sanholt// 5145132Sanholt// This file is distributed under the University of Illinois Open Source 6145132Sanholt// License. See LICENSE.TXT for details. 7145132Sanholt// 8145132Sanholt//===----------------------------------------------------------------------===// 9145132Sanholt// 10145132Sanholt// This file implements LoopPass and LPPassManager. All loop optimization 11145132Sanholt// and transformation passes are derived from LoopPass. LPPassManager is 12145132Sanholt// responsible for managing LoopPasses. 13145132Sanholt// 14145132Sanholt//===----------------------------------------------------------------------===// 15145132Sanholt 16145132Sanholt#include "llvm/Analysis/LoopPass.h" 17145132Sanholtusing namespace llvm; 18145132Sanholt 19145132Sanholt//===----------------------------------------------------------------------===// 20145132Sanholt// LPPassManager 21145132Sanholt// 22145132Sanholt 23145132Sanholtchar LPPassManager::ID = 0; 24152909Sanholt 25152909SanholtLPPassManager::LPPassManager(int Depth) 26152909Sanholt : FunctionPass(&ID), PMDataManager(Depth) { 27182080Srnoland skipThisLoop = false; 28182080Srnoland redoThisLoop = false; 29182080Srnoland LI = NULL; 30182080Srnoland CurrentLoop = NULL; 31182080Srnoland} 32145132Sanholt 33145132Sanholt/// Delete loop from the loop queue and loop hierarchy (LoopInfo). 34145132Sanholtvoid LPPassManager::deleteLoopFromQueue(Loop *L) { 35145132Sanholt 36145132Sanholt if (Loop *ParentLoop = L->getParentLoop()) { // Not a top-level loop. 37145132Sanholt // Reparent all of the blocks in this loop. Since BBLoop had a parent, 38145132Sanholt // they are now all in it. 39145132Sanholt for (Loop::block_iterator I = L->block_begin(), E = L->block_end(); 40145132Sanholt I != E; ++I) 41194759Srnoland if (LI->getLoopFor(*I) == L) // Don't change blocks in subloops. 42145132Sanholt LI->changeLoopFor(*I, ParentLoop); 43145132Sanholt 44145132Sanholt // Remove the loop from its parent loop. 45145132Sanholt for (Loop::iterator I = ParentLoop->begin(), E = ParentLoop->end();; 46145132Sanholt ++I) { 47145132Sanholt assert(I != E && "Couldn't find loop"); 48145132Sanholt if (*I == L) { 49145132Sanholt ParentLoop->removeChildLoop(I); 50145132Sanholt break; 51194759Srnoland } 52145132Sanholt } 53145132Sanholt 54145132Sanholt // Move all subloops into the parent loop. 55145132Sanholt while (!L->empty()) 56145132Sanholt ParentLoop->addChildLoop(L->removeChildLoop(L->end()-1)); 57145132Sanholt } else { 58145132Sanholt // Reparent all of the blocks in this loop. Since BBLoop had no parent, 59145132Sanholt // they no longer in a loop at all. 60182080Srnoland 61145132Sanholt for (unsigned i = 0; i != L->getBlocks().size(); ++i) { 62145132Sanholt // Don't change blocks in subloops. 63145132Sanholt if (LI->getLoopFor(L->getBlocks()[i]) == L) { 64145132Sanholt LI->removeBlock(L->getBlocks()[i]); 65145132Sanholt --i; 66145132Sanholt } 67183833Srnoland } 68145132Sanholt 69145132Sanholt // Remove the loop from the top-level LoopInfo object. 70145132Sanholt for (LoopInfo::iterator I = LI->begin(), E = LI->end();; ++I) { 71145132Sanholt assert(I != E && "Couldn't find loop"); 72145132Sanholt if (*I == L) { 73145132Sanholt LI->removeLoop(I); 74145132Sanholt break; 75145132Sanholt } 76145132Sanholt } 77145132Sanholt 78145132Sanholt // Move all of the subloops to the top-level. 79145132Sanholt while (!L->empty()) 80145132Sanholt LI->addTopLevelLoop(L->removeChildLoop(L->end()-1)); 81145132Sanholt } 82145132Sanholt 83145132Sanholt delete L; 84145132Sanholt 85145132Sanholt // If L is current loop then skip rest of the passes and let 86145132Sanholt // runOnFunction remove L from LQ. Otherwise, remove L from LQ now 87145132Sanholt // and continue applying other passes on CurrentLoop. 88145132Sanholt if (CurrentLoop == L) { 89145132Sanholt skipThisLoop = true; 90145132Sanholt return; 91145132Sanholt } 92145132Sanholt 93145132Sanholt for (std::deque<Loop *>::iterator I = LQ.begin(), 94145132Sanholt E = LQ.end(); I != E; ++I) { 95145132Sanholt if (*I == L) { 96145132Sanholt LQ.erase(I); 97145132Sanholt break; 98220979Skib } 99145132Sanholt } 100145132Sanholt} 101145132Sanholt 102145132Sanholt// Inset loop into loop nest (LoopInfo) and loop queue (LQ). 103145132Sanholtvoid LPPassManager::insertLoop(Loop *L, Loop *ParentLoop) { 104145132Sanholt 105145132Sanholt assert (CurrentLoop != L && "Cannot insert CurrentLoop"); 106145132Sanholt 107145132Sanholt // Insert into loop nest 108145132Sanholt if (ParentLoop) 109145132Sanholt ParentLoop->addChildLoop(L); 110145132Sanholt else 111145132Sanholt LI->addTopLevelLoop(L); 112145132Sanholt 113145132Sanholt insertLoopIntoQueue(L); 114182080Srnoland} 115145132Sanholt 116145132Sanholtvoid LPPassManager::insertLoopIntoQueue(Loop *L) { 117145132Sanholt // Insert L into loop queue 118145132Sanholt if (L == CurrentLoop) 119183833Srnoland redoLoop(L); 120145132Sanholt else if (!L->getParentLoop()) 121145132Sanholt // This is top level loop. 122145132Sanholt LQ.push_front(L); 123145132Sanholt else { 124145132Sanholt // Insert L after the parent loop. 125145132Sanholt for (std::deque<Loop *>::iterator I = LQ.begin(), 126145132Sanholt E = LQ.end(); I != E; ++I) { 127145132Sanholt if (*I == L->getParentLoop()) { 128145132Sanholt // deque does not support insert after. 129145132Sanholt ++I; 130145132Sanholt LQ.insert(I, 1, L); 131145132Sanholt break; 132145132Sanholt } 133145132Sanholt } 134145132Sanholt } 135182080Srnoland} 136145132Sanholt 137145132Sanholt// Reoptimize this loop. LPPassManager will re-insert this loop into the 138145132Sanholt// queue. This allows LoopPass to change loop nest for the loop. This 139145132Sanholt// utility may send LPPassManager into infinite loops so use caution. 140183573Srnolandvoid LPPassManager::redoLoop(Loop *L) { 141145132Sanholt assert (CurrentLoop == L && "Can redo only CurrentLoop"); 142145132Sanholt redoThisLoop = true; 143145132Sanholt} 144145132Sanholt 145145132Sanholt/// cloneBasicBlockSimpleAnalysis - Invoke cloneBasicBlockAnalysis hook for 146145132Sanholt/// all loop passes. 147145132Sanholtvoid LPPassManager::cloneBasicBlockSimpleAnalysis(BasicBlock *From, 148145132Sanholt BasicBlock *To, Loop *L) { 149145132Sanholt for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) { 150145132Sanholt Pass *P = getContainedPass(Index); 151145132Sanholt LoopPass *LP = dynamic_cast<LoopPass *>(P); 152145132Sanholt LP->cloneBasicBlockAnalysis(From, To, L); 153145132Sanholt } 154145132Sanholt} 155145132Sanholt 156145132Sanholt/// deleteSimpleAnalysisValue - Invoke deleteAnalysisValue hook for all passes. 157145132Sanholtvoid LPPassManager::deleteSimpleAnalysisValue(Value *V, Loop *L) { 158145132Sanholt if (BasicBlock *BB = dyn_cast<BasicBlock>(V)) { 159145132Sanholt for (BasicBlock::iterator BI = BB->begin(), BE = BB->end(); BI != BE; 160182080Srnoland ++BI) { 161145132Sanholt Instruction &I = *BI; 162145132Sanholt deleteSimpleAnalysisValue(&I, L); 163145132Sanholt } 164145132Sanholt } 165145132Sanholt for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) { 166145132Sanholt Pass *P = getContainedPass(Index); 167145132Sanholt LoopPass *LP = dynamic_cast<LoopPass *>(P); 168145132Sanholt LP->deleteAnalysisValue(V, L); 169145132Sanholt } 170145132Sanholt} 171145132Sanholt 172145132Sanholt 173145132Sanholt// Recurse through all subloops and all loops into LQ. 174145132Sanholtstatic void addLoopIntoQueue(Loop *L, std::deque<Loop *> &LQ) { 175145132Sanholt LQ.push_back(L); 176145132Sanholt for (Loop::iterator I = L->begin(), E = L->end(); I != E; ++I) 177183833Srnoland addLoopIntoQueue(*I, LQ); 178183833Srnoland} 179145132Sanholt 180145132Sanholt/// Pass Manager itself does not invalidate any analysis info. 181145132Sanholtvoid LPPassManager::getAnalysisUsage(AnalysisUsage &Info) const { 182145132Sanholt // LPPassManager needs LoopInfo. In the long term LoopInfo class will 183145132Sanholt // become part of LPPassManager. 184145132Sanholt Info.addRequired<LoopInfo>(); 185145132Sanholt Info.setPreservesAll(); 186145132Sanholt} 187145132Sanholt 188145132Sanholt/// run - Execute all of the passes scheduled for execution. Keep track of 189145132Sanholt/// whether any of the passes modifies the function, and if so, return true. 190189562Srnolandbool LPPassManager::runOnFunction(Function &F) { 191207066Srnoland LI = &getAnalysis<LoopInfo>(); 192145132Sanholt bool Changed = false; 193145132Sanholt 194145132Sanholt // Collect inherited analysis from Module level pass manager. 195145132Sanholt populateInheritedAnalysis(TPM->activeStack); 196145132Sanholt 197145132Sanholt // Populate Loop Queue 198145132Sanholt for (LoopInfo::iterator I = LI->begin(), E = LI->end(); I != E; ++I) 199145132Sanholt addLoopIntoQueue(*I, LQ); 200145132Sanholt 201145132Sanholt if (LQ.empty()) // No loops, skip calling finalizers 202145132Sanholt return false; 203145132Sanholt 204145132Sanholt // Initialization 205145132Sanholt for (std::deque<Loop *>::const_iterator I = LQ.begin(), E = LQ.end(); 206145132Sanholt I != E; ++I) { 207207066Srnoland Loop *L = *I; 208207066Srnoland for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) { 209207066Srnoland Pass *P = getContainedPass(Index); 210207066Srnoland LoopPass *LP = dynamic_cast<LoopPass *>(P); 211207066Srnoland if (LP) 212145132Sanholt Changed |= LP->doInitialization(L, *this); 213145132Sanholt } 214145132Sanholt } 215145132Sanholt 216183833Srnoland // Walk Loops 217145132Sanholt while (!LQ.empty()) { 218145132Sanholt 219145132Sanholt CurrentLoop = LQ.back(); 220145132Sanholt skipThisLoop = false; 221145132Sanholt redoThisLoop = false; 222182080Srnoland 223145132Sanholt // Run all passes on the current Loop. 224145132Sanholt for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) { 225145132Sanholt Pass *P = getContainedPass(Index); 226145132Sanholt 227145132Sanholt dumpPassInfo(P, EXECUTION_MSG, ON_LOOP_MSG, 228145132Sanholt CurrentLoop->getHeader()->getNameStr()); 229145132Sanholt dumpRequiredSet(P); 230145132Sanholt 231145132Sanholt initializeAnalysisImpl(P); 232145132Sanholt 233145132Sanholt LoopPass *LP = dynamic_cast<LoopPass *>(P); 234145132Sanholt assert(LP && "Invalid LPPassManager member"); 235145132Sanholt { 236145132Sanholt PassManagerPrettyStackEntry X(LP, *CurrentLoop->getHeader()); 237145132Sanholt Timer *T = StartPassTimer(P); 238145132Sanholt Changed |= LP->runOnLoop(CurrentLoop, *this); 239145132Sanholt StopPassTimer(P, T); 240183833Srnoland } 241183833Srnoland 242145132Sanholt if (Changed) 243145132Sanholt dumpPassInfo(P, MODIFICATION_MSG, ON_LOOP_MSG, 244145132Sanholt skipThisLoop ? "<deleted>" : 245145132Sanholt CurrentLoop->getHeader()->getNameStr()); 246145132Sanholt dumpPreservedSet(P); 247145132Sanholt 248145132Sanholt if (!skipThisLoop) { 249145132Sanholt // Manually check that this loop is still healthy. This is done 250145132Sanholt // instead of relying on LoopInfo::verifyLoop since LoopInfo 251145132Sanholt // is a function pass and it's really expensive to verify every 252145132Sanholt // loop in the function every time. That level of checking can be 253145132Sanholt // enabled with the -verify-loop-info option. 254145132Sanholt Timer *T = StartPassTimer(LI); 255145132Sanholt CurrentLoop->verifyLoop(); 256145132Sanholt StopPassTimer(LI, T); 257145132Sanholt 258145132Sanholt // Then call the regular verifyAnalysis functions. 259145132Sanholt verifyPreservedAnalysis(LP); 260145132Sanholt } 261145132Sanholt 262215367Snwhitehorn removeNotPreservedAnalysis(P); 263145132Sanholt recordAvailableAnalysis(P); 264145132Sanholt removeDeadPasses(P, 265145132Sanholt skipThisLoop ? "<deleted>" : 266145132Sanholt CurrentLoop->getHeader()->getNameStr(), 267145132Sanholt ON_LOOP_MSG); 268145132Sanholt 269145132Sanholt if (skipThisLoop) 270145132Sanholt // Do not run other passes on this loop. 271145132Sanholt break; 272145132Sanholt } 273183833Srnoland 274145132Sanholt // If the loop was deleted, release all the loop passes. This frees up 275145132Sanholt // some memory, and avoids trouble with the pass manager trying to call 276145132Sanholt // verifyAnalysis on them. 277145132Sanholt if (skipThisLoop) 278145132Sanholt for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) { 279182080Srnoland Pass *P = getContainedPass(Index); 280183573Srnoland freePass(P, "<deleted>", ON_LOOP_MSG); 281145132Sanholt } 282145132Sanholt 283145132Sanholt // Pop the loop from queue after running all passes. 284145132Sanholt LQ.pop_back(); 285145132Sanholt 286145132Sanholt if (redoThisLoop) 287145132Sanholt LQ.push_back(CurrentLoop); 288145132Sanholt } 289145132Sanholt 290145132Sanholt // Finalization 291183833Srnoland for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) { 292183833Srnoland Pass *P = getContainedPass(Index); 293145132Sanholt LoopPass *LP = dynamic_cast <LoopPass *>(P); 294145132Sanholt if (LP) 295145132Sanholt Changed |= LP->doFinalization(); 296145132Sanholt } 297145132Sanholt 298145132Sanholt return Changed; 299145132Sanholt} 300145132Sanholt 301145132Sanholt/// Print passes managed by this manager 302145132Sanholtvoid LPPassManager::dumpPassStructure(unsigned Offset) { 303196465Srnoland errs().indent(Offset*2) << "Loop Pass Manager\n"; 304196465Srnoland for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) { 305145132Sanholt Pass *P = getContainedPass(Index); 306145132Sanholt P->dumpPassStructure(Offset + 1); 307196465Srnoland dumpLastUses(P, Offset+1); 308145132Sanholt } 309196465Srnoland} 310145132Sanholt 311145132Sanholt 312145132Sanholt//===----------------------------------------------------------------------===// 313145132Sanholt// LoopPass 314145132Sanholt 315145132Sanholt// Check if this pass is suitable for the current LPPassManager, if 316145132Sanholt// available. This pass P is not suitable for a LPPassManager if P 317145132Sanholt// is not preserving higher level analysis info used by other 318183833Srnoland// LPPassManager passes. In such case, pop LPPassManager from the 319145132Sanholt// stack. This will force assignPassManager() to create new 320145132Sanholt// LPPassManger as expected. 321194759Srnolandvoid LoopPass::preparePassManager(PMStack &PMS) { 322194759Srnoland 323194759Srnoland // Find LPPassManager 324194759Srnoland while (!PMS.empty() && 325194759Srnoland PMS.top()->getPassManagerType() > PMT_LoopPassManager) 326194759Srnoland PMS.pop(); 327194759Srnoland 328194759Srnoland LPPassManager *LPPM = dynamic_cast<LPPassManager *>(PMS.top()); 329194759Srnoland 330194759Srnoland // If this pass is destroying high level information that is used 331194759Srnoland // by other passes that are managed by LPM then do not insert 332194759Srnoland // this pass in current LPM. Use new LPPassManager. 333194759Srnoland if (LPPM && !LPPM->preserveHigherLevelAnalysis(this)) 334194759Srnoland PMS.pop(); 335194759Srnoland} 336194759Srnoland 337194759Srnoland/// Assign pass manager to manage this pass. 338194759Srnolandvoid LoopPass::assignPassManager(PMStack &PMS, 339194759Srnoland PassManagerType PreferredType) { 340194759Srnoland // Find LPPassManager 341194759Srnoland while (!PMS.empty() && 342194759Srnoland PMS.top()->getPassManagerType() > PMT_LoopPassManager) 343 PMS.pop(); 344 345 LPPassManager *LPPM = dynamic_cast<LPPassManager *>(PMS.top()); 346 347 // Create new Loop Pass Manager if it does not exist. 348 if (!LPPM) { 349 350 assert (!PMS.empty() && "Unable to create Loop Pass Manager"); 351 PMDataManager *PMD = PMS.top(); 352 353 // [1] Create new Call Graph Pass Manager 354 LPPM = new LPPassManager(PMD->getDepth() + 1); 355 LPPM->populateInheritedAnalysis(PMS); 356 357 // [2] Set up new manager's top level manager 358 PMTopLevelManager *TPM = PMD->getTopLevelManager(); 359 TPM->addIndirectPassManager(LPPM); 360 361 // [3] Assign manager to manage this new manager. This may create 362 // and push new managers into PMS 363 Pass *P = dynamic_cast<Pass *>(LPPM); 364 TPM->schedulePass(P); 365 366 // [4] Push new manager into PMS 367 PMS.push(LPPM); 368 } 369 370 LPPM->add(this); 371} 372