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/DebugInfoProbe.h"
18 #include "llvm/Assembly/PrintModulePass.h"
19 #include "llvm/Support/Debug.h"
20 #include "llvm/Support/ManagedStatic.h"
21 #include "llvm/Support/Timer.h"
26 /// PrintLoopPass - Print a Function corresponding to a Loop.
28 class PrintLoopPass : public LoopPass {
31 raw_ostream &Out; // raw_ostream to print on.
35 PrintLoopPass(const std::string &B, raw_ostream &o)
36 : LoopPass(ID), Banner(B), Out(o) {}
38 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
42 bool runOnLoop(Loop *L, LPPassManager &) {
44 for (Loop::block_iterator b = L->block_begin(), be = L->block_end();
53 char PrintLoopPass::ID = 0;
56 //===----------------------------------------------------------------------===//
59 static DebugInfoProbeInfo *TheDebugProbe;
60 static void createDebugInfoProbe() {
61 if (TheDebugProbe) return;
63 // Constructed the first time this is called. This guarantees that the
64 // object will be constructed, if -enable-debug-info-probe is set,
65 // before static globals, thus it will be destroyed before them.
66 static ManagedStatic<DebugInfoProbeInfo> DIP;
67 TheDebugProbe = &*DIP;
70 //===----------------------------------------------------------------------===//
74 char LPPassManager::ID = 0;
76 LPPassManager::LPPassManager()
77 : FunctionPass(ID), PMDataManager() {
84 /// Delete loop from the loop queue and loop hierarchy (LoopInfo).
85 void LPPassManager::deleteLoopFromQueue(Loop *L) {
89 // If L is current loop then skip rest of the passes and let
90 // runOnFunction remove L from LQ. Otherwise, remove L from LQ now
91 // and continue applying other passes on CurrentLoop.
100 for (std::deque<Loop *>::iterator I = LQ.begin(),
101 E = LQ.end(); I != E; ++I) {
109 // Inset loop into loop nest (LoopInfo) and loop queue (LQ).
110 void LPPassManager::insertLoop(Loop *L, Loop *ParentLoop) {
112 assert (CurrentLoop != L && "Cannot insert CurrentLoop");
114 // Insert into loop nest
116 ParentLoop->addChildLoop(L);
118 LI->addTopLevelLoop(L);
120 insertLoopIntoQueue(L);
123 void LPPassManager::insertLoopIntoQueue(Loop *L) {
124 // Insert L into loop queue
125 if (L == CurrentLoop)
127 else if (!L->getParentLoop())
128 // This is top level loop.
131 // Insert L after the parent loop.
132 for (std::deque<Loop *>::iterator I = LQ.begin(),
133 E = LQ.end(); I != E; ++I) {
134 if (*I == L->getParentLoop()) {
135 // deque does not support insert after.
144 // Reoptimize this loop. LPPassManager will re-insert this loop into the
145 // queue. This allows LoopPass to change loop nest for the loop. This
146 // utility may send LPPassManager into infinite loops so use caution.
147 void LPPassManager::redoLoop(Loop *L) {
148 assert (CurrentLoop == L && "Can redo only CurrentLoop");
152 /// cloneBasicBlockSimpleAnalysis - Invoke cloneBasicBlockAnalysis hook for
154 void LPPassManager::cloneBasicBlockSimpleAnalysis(BasicBlock *From,
155 BasicBlock *To, Loop *L) {
156 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
157 LoopPass *LP = getContainedPass(Index);
158 LP->cloneBasicBlockAnalysis(From, To, L);
162 /// deleteSimpleAnalysisValue - Invoke deleteAnalysisValue hook for all passes.
163 void LPPassManager::deleteSimpleAnalysisValue(Value *V, Loop *L) {
164 if (BasicBlock *BB = dyn_cast<BasicBlock>(V)) {
165 for (BasicBlock::iterator BI = BB->begin(), BE = BB->end(); BI != BE;
167 Instruction &I = *BI;
168 deleteSimpleAnalysisValue(&I, L);
171 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
172 LoopPass *LP = getContainedPass(Index);
173 LP->deleteAnalysisValue(V, L);
178 // Recurse through all subloops and all loops into LQ.
179 static void addLoopIntoQueue(Loop *L, std::deque<Loop *> &LQ) {
181 for (Loop::iterator I = L->begin(), E = L->end(); I != E; ++I)
182 addLoopIntoQueue(*I, LQ);
185 /// Pass Manager itself does not invalidate any analysis info.
186 void LPPassManager::getAnalysisUsage(AnalysisUsage &Info) const {
187 // LPPassManager needs LoopInfo. In the long term LoopInfo class will
188 // become part of LPPassManager.
189 Info.addRequired<LoopInfo>();
190 Info.setPreservesAll();
193 /// run - Execute all of the passes scheduled for execution. Keep track of
194 /// whether any of the passes modifies the function, and if so, return true.
195 bool LPPassManager::runOnFunction(Function &F) {
196 LI = &getAnalysis<LoopInfo>();
197 bool Changed = false;
198 createDebugInfoProbe();
200 // Collect inherited analysis from Module level pass manager.
201 populateInheritedAnalysis(TPM->activeStack);
203 // Populate Loop Queue
204 for (LoopInfo::iterator I = LI->begin(), E = LI->end(); I != E; ++I)
205 addLoopIntoQueue(*I, LQ);
207 if (LQ.empty()) // No loops, skip calling finalizers
211 for (std::deque<Loop *>::const_iterator I = LQ.begin(), E = LQ.end();
214 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
215 LoopPass *P = getContainedPass(Index);
216 Changed |= P->doInitialization(L, *this);
221 while (!LQ.empty()) {
223 CurrentLoop = LQ.back();
224 skipThisLoop = false;
225 redoThisLoop = false;
227 // Run all passes on the current Loop.
228 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
229 LoopPass *P = getContainedPass(Index);
230 dumpPassInfo(P, EXECUTION_MSG, ON_LOOP_MSG,
231 CurrentLoop->getHeader()->getName());
234 initializeAnalysisImpl(P);
236 TheDebugProbe->initialize(P, F);
238 PassManagerPrettyStackEntry X(P, *CurrentLoop->getHeader());
239 TimeRegion PassTimer(getPassTimer(P));
241 Changed |= P->runOnLoop(CurrentLoop, *this);
244 TheDebugProbe->finalize(P, F);
247 dumpPassInfo(P, MODIFICATION_MSG, ON_LOOP_MSG,
248 skipThisLoop ? "<deleted>" :
249 CurrentLoop->getHeader()->getName());
253 // Manually check that this loop is still healthy. This is done
254 // instead of relying on LoopInfo::verifyLoop since LoopInfo
255 // is a function pass and it's really expensive to verify every
256 // loop in the function every time. That level of checking can be
257 // enabled with the -verify-loop-info option.
259 TimeRegion PassTimer(getPassTimer(LI));
260 CurrentLoop->verifyLoop();
263 // Then call the regular verifyAnalysis functions.
264 verifyPreservedAnalysis(P);
267 removeNotPreservedAnalysis(P);
268 recordAvailableAnalysis(P);
270 skipThisLoop ? "<deleted>" :
271 CurrentLoop->getHeader()->getName(),
275 // Do not run other passes on this loop.
279 // If the loop was deleted, release all the loop passes. This frees up
280 // some memory, and avoids trouble with the pass manager trying to call
281 // verifyAnalysis on them.
283 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
284 Pass *P = getContainedPass(Index);
285 freePass(P, "<deleted>", ON_LOOP_MSG);
288 // Pop the loop from queue after running all passes.
292 LQ.push_back(CurrentLoop);
296 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
297 LoopPass *P = getContainedPass(Index);
298 Changed |= P->doFinalization();
304 /// Print passes managed by this manager
305 void LPPassManager::dumpPassStructure(unsigned Offset) {
306 errs().indent(Offset*2) << "Loop Pass Manager\n";
307 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
308 Pass *P = getContainedPass(Index);
309 P->dumpPassStructure(Offset + 1);
310 dumpLastUses(P, Offset+1);
315 //===----------------------------------------------------------------------===//
318 Pass *LoopPass::createPrinterPass(raw_ostream &O,
319 const std::string &Banner) const {
320 return new PrintLoopPass(Banner, O);
323 // Check if this pass is suitable for the current LPPassManager, if
324 // available. This pass P is not suitable for a LPPassManager if P
325 // is not preserving higher level analysis info used by other
326 // LPPassManager passes. In such case, pop LPPassManager from the
327 // stack. This will force assignPassManager() to create new
328 // LPPassManger as expected.
329 void LoopPass::preparePassManager(PMStack &PMS) {
331 // Find LPPassManager
332 while (!PMS.empty() &&
333 PMS.top()->getPassManagerType() > PMT_LoopPassManager)
336 // If this pass is destroying high level information that is used
337 // by other passes that are managed by LPM then do not insert
338 // this pass in current LPM. Use new LPPassManager.
339 if (PMS.top()->getPassManagerType() == PMT_LoopPassManager &&
340 !PMS.top()->preserveHigherLevelAnalysis(this))
344 /// Assign pass manager to manage this pass.
345 void LoopPass::assignPassManager(PMStack &PMS,
346 PassManagerType PreferredType) {
347 // Find LPPassManager
348 while (!PMS.empty() &&
349 PMS.top()->getPassManagerType() > PMT_LoopPassManager)
353 if (PMS.top()->getPassManagerType() == PMT_LoopPassManager)
354 LPPM = (LPPassManager*)PMS.top();
356 // Create new Loop Pass Manager if it does not exist.
357 assert (!PMS.empty() && "Unable to create Loop Pass Manager");
358 PMDataManager *PMD = PMS.top();
360 // [1] Create new Loop Pass Manager
361 LPPM = new LPPassManager();
362 LPPM->populateInheritedAnalysis(PMS);
364 // [2] Set up new manager's top level manager
365 PMTopLevelManager *TPM = PMD->getTopLevelManager();
366 TPM->addIndirectPassManager(LPPM);
368 // [3] Assign manager to manage this new manager. This may create
369 // and push new managers into PMS
370 Pass *P = LPPM->getAsPass();
371 TPM->schedulePass(P);
373 // [4] Push new manager into PMS