1 //===- LoopPass.cpp - Loop Pass and Loop Pass Manager ---------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements LoopPass and LPPassManager. All loop optimization
11 // and transformation passes are derived from LoopPass. LPPassManager is
12 // responsible for managing LoopPasses.
14 //===----------------------------------------------------------------------===//
16 #include "llvm/Analysis/LoopPass.h"
17 #include "llvm/Support/Timer.h"
20 //===----------------------------------------------------------------------===//
24 char LPPassManager::ID = 0;
26 LPPassManager::LPPassManager(int Depth)
27 : FunctionPass(&ID), PMDataManager(Depth) {
34 /// Delete loop from the loop queue and loop hierarchy (LoopInfo).
35 void LPPassManager::deleteLoopFromQueue(Loop *L) {
37 if (Loop *ParentLoop = L->getParentLoop()) { // Not a top-level loop.
38 // Reparent all of the blocks in this loop. Since BBLoop had a parent,
39 // they are now all in it.
40 for (Loop::block_iterator I = L->block_begin(), E = L->block_end();
42 if (LI->getLoopFor(*I) == L) // Don't change blocks in subloops.
43 LI->changeLoopFor(*I, ParentLoop);
45 // Remove the loop from its parent loop.
46 for (Loop::iterator I = ParentLoop->begin(), E = ParentLoop->end();;
48 assert(I != E && "Couldn't find loop");
50 ParentLoop->removeChildLoop(I);
55 // Move all subloops into the parent loop.
57 ParentLoop->addChildLoop(L->removeChildLoop(L->end()-1));
59 // Reparent all of the blocks in this loop. Since BBLoop had no parent,
60 // they no longer in a loop at all.
62 for (unsigned i = 0; i != L->getBlocks().size(); ++i) {
63 // Don't change blocks in subloops.
64 if (LI->getLoopFor(L->getBlocks()[i]) == L) {
65 LI->removeBlock(L->getBlocks()[i]);
70 // Remove the loop from the top-level LoopInfo object.
71 for (LoopInfo::iterator I = LI->begin(), E = LI->end();; ++I) {
72 assert(I != E && "Couldn't find loop");
79 // Move all of the subloops to the top-level.
81 LI->addTopLevelLoop(L->removeChildLoop(L->end()-1));
86 // If L is current loop then skip rest of the passes and let
87 // runOnFunction remove L from LQ. Otherwise, remove L from LQ now
88 // and continue applying other passes on CurrentLoop.
89 if (CurrentLoop == L) {
94 for (std::deque<Loop *>::iterator I = LQ.begin(),
95 E = LQ.end(); I != E; ++I) {
103 // Inset loop into loop nest (LoopInfo) and loop queue (LQ).
104 void LPPassManager::insertLoop(Loop *L, Loop *ParentLoop) {
106 assert (CurrentLoop != L && "Cannot insert CurrentLoop");
108 // Insert into loop nest
110 ParentLoop->addChildLoop(L);
112 LI->addTopLevelLoop(L);
114 insertLoopIntoQueue(L);
117 void LPPassManager::insertLoopIntoQueue(Loop *L) {
118 // Insert L into loop queue
119 if (L == CurrentLoop)
121 else if (!L->getParentLoop())
122 // This is top level loop.
125 // Insert L after the parent loop.
126 for (std::deque<Loop *>::iterator I = LQ.begin(),
127 E = LQ.end(); I != E; ++I) {
128 if (*I == L->getParentLoop()) {
129 // deque does not support insert after.
138 // Reoptimize this loop. LPPassManager will re-insert this loop into the
139 // queue. This allows LoopPass to change loop nest for the loop. This
140 // utility may send LPPassManager into infinite loops so use caution.
141 void LPPassManager::redoLoop(Loop *L) {
142 assert (CurrentLoop == L && "Can redo only CurrentLoop");
146 /// cloneBasicBlockSimpleAnalysis - Invoke cloneBasicBlockAnalysis hook for
148 void LPPassManager::cloneBasicBlockSimpleAnalysis(BasicBlock *From,
149 BasicBlock *To, Loop *L) {
150 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
151 LoopPass *LP = (LoopPass *)getContainedPass(Index);
152 LP->cloneBasicBlockAnalysis(From, To, L);
156 /// deleteSimpleAnalysisValue - Invoke deleteAnalysisValue hook for all passes.
157 void LPPassManager::deleteSimpleAnalysisValue(Value *V, Loop *L) {
158 if (BasicBlock *BB = dyn_cast<BasicBlock>(V)) {
159 for (BasicBlock::iterator BI = BB->begin(), BE = BB->end(); BI != BE;
161 Instruction &I = *BI;
162 deleteSimpleAnalysisValue(&I, L);
165 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
166 LoopPass *LP = (LoopPass *)getContainedPass(Index);
167 LP->deleteAnalysisValue(V, L);
172 // Recurse through all subloops and all loops into LQ.
173 static void addLoopIntoQueue(Loop *L, std::deque<Loop *> &LQ) {
175 for (Loop::iterator I = L->begin(), E = L->end(); I != E; ++I)
176 addLoopIntoQueue(*I, LQ);
179 /// Pass Manager itself does not invalidate any analysis info.
180 void LPPassManager::getAnalysisUsage(AnalysisUsage &Info) const {
181 // LPPassManager needs LoopInfo. In the long term LoopInfo class will
182 // become part of LPPassManager.
183 Info.addRequired<LoopInfo>();
184 Info.setPreservesAll();
187 /// run - Execute all of the passes scheduled for execution. Keep track of
188 /// whether any of the passes modifies the function, and if so, return true.
189 bool LPPassManager::runOnFunction(Function &F) {
190 LI = &getAnalysis<LoopInfo>();
191 bool Changed = false;
193 // Collect inherited analysis from Module level pass manager.
194 populateInheritedAnalysis(TPM->activeStack);
196 // Populate Loop Queue
197 for (LoopInfo::iterator I = LI->begin(), E = LI->end(); I != E; ++I)
198 addLoopIntoQueue(*I, LQ);
200 if (LQ.empty()) // No loops, skip calling finalizers
204 for (std::deque<Loop *>::const_iterator I = LQ.begin(), E = LQ.end();
207 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
208 LoopPass *P = (LoopPass*)getContainedPass(Index);
209 Changed |= P->doInitialization(L, *this);
214 while (!LQ.empty()) {
216 CurrentLoop = LQ.back();
217 skipThisLoop = false;
218 redoThisLoop = false;
220 // Run all passes on the current Loop.
221 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
222 LoopPass *P = (LoopPass*)getContainedPass(Index);
224 dumpPassInfo(P, EXECUTION_MSG, ON_LOOP_MSG,
225 CurrentLoop->getHeader()->getName());
228 initializeAnalysisImpl(P);
231 PassManagerPrettyStackEntry X(P, *CurrentLoop->getHeader());
232 TimeRegion PassTimer(getPassTimer(P));
234 Changed |= P->runOnLoop(CurrentLoop, *this);
238 dumpPassInfo(P, MODIFICATION_MSG, ON_LOOP_MSG,
239 skipThisLoop ? "<deleted>" :
240 CurrentLoop->getHeader()->getName());
244 // Manually check that this loop is still healthy. This is done
245 // instead of relying on LoopInfo::verifyLoop since LoopInfo
246 // is a function pass and it's really expensive to verify every
247 // loop in the function every time. That level of checking can be
248 // enabled with the -verify-loop-info option.
250 TimeRegion PassTimer(getPassTimer(LI));
251 CurrentLoop->verifyLoop();
254 // Then call the regular verifyAnalysis functions.
255 verifyPreservedAnalysis(P);
258 removeNotPreservedAnalysis(P);
259 recordAvailableAnalysis(P);
261 skipThisLoop ? "<deleted>" :
262 CurrentLoop->getHeader()->getName(),
266 // Do not run other passes on this loop.
270 // If the loop was deleted, release all the loop passes. This frees up
271 // some memory, and avoids trouble with the pass manager trying to call
272 // verifyAnalysis on them.
274 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
275 Pass *P = getContainedPass(Index);
276 freePass(P, "<deleted>", ON_LOOP_MSG);
279 // Pop the loop from queue after running all passes.
283 LQ.push_back(CurrentLoop);
287 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
288 LoopPass *P = (LoopPass *)getContainedPass(Index);
289 Changed |= P->doFinalization();
295 /// Print passes managed by this manager
296 void LPPassManager::dumpPassStructure(unsigned Offset) {
297 errs().indent(Offset*2) << "Loop Pass Manager\n";
298 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
299 Pass *P = getContainedPass(Index);
300 P->dumpPassStructure(Offset + 1);
301 dumpLastUses(P, Offset+1);
306 //===----------------------------------------------------------------------===//
309 // Check if this pass is suitable for the current LPPassManager, if
310 // available. This pass P is not suitable for a LPPassManager if P
311 // is not preserving higher level analysis info used by other
312 // LPPassManager passes. In such case, pop LPPassManager from the
313 // stack. This will force assignPassManager() to create new
314 // LPPassManger as expected.
315 void LoopPass::preparePassManager(PMStack &PMS) {
317 // Find LPPassManager
318 while (!PMS.empty() &&
319 PMS.top()->getPassManagerType() > PMT_LoopPassManager)
322 // If this pass is destroying high level information that is used
323 // by other passes that are managed by LPM then do not insert
324 // this pass in current LPM. Use new LPPassManager.
325 if (PMS.top()->getPassManagerType() == PMT_LoopPassManager &&
326 !PMS.top()->preserveHigherLevelAnalysis(this))
330 /// Assign pass manager to manage this pass.
331 void LoopPass::assignPassManager(PMStack &PMS,
332 PassManagerType PreferredType) {
333 // Find LPPassManager
334 while (!PMS.empty() &&
335 PMS.top()->getPassManagerType() > PMT_LoopPassManager)
339 if (PMS.top()->getPassManagerType() == PMT_LoopPassManager)
340 LPPM = (LPPassManager*)PMS.top();
342 // Create new Loop Pass Manager if it does not exist.
343 assert (!PMS.empty() && "Unable to create Loop Pass Manager");
344 PMDataManager *PMD = PMS.top();
346 // [1] Create new Call Graph Pass Manager
347 LPPM = new LPPassManager(PMD->getDepth() + 1);
348 LPPM->populateInheritedAnalysis(PMS);
350 // [2] Set up new manager's top level manager
351 PMTopLevelManager *TPM = PMD->getTopLevelManager();
352 TPM->addIndirectPassManager(LPPM);
354 // [3] Assign manager to manage this new manager. This may create
355 // and push new managers into PMS
356 Pass *P = LPPM->getAsPass();
357 TPM->schedulePass(P);
359 // [4] Push new manager into PMS