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/IR/IRPrintingPasses.h"
18 #include "llvm/IR/LLVMContext.h"
19 #include "llvm/IR/PassManager.h"
20 #include "llvm/Support/Debug.h"
21 #include "llvm/Support/Timer.h"
22 #include "llvm/Support/raw_ostream.h"
25 #define DEBUG_TYPE "loop-pass-manager"
29 /// PrintLoopPass - Print a Function corresponding to a Loop.
31 class PrintLoopPassWrapper : public LoopPass {
36 PrintLoopPassWrapper() : LoopPass(ID) {}
37 PrintLoopPassWrapper(raw_ostream &OS, const std::string &Banner)
38 : LoopPass(ID), P(OS, Banner) {}
40 void getAnalysisUsage(AnalysisUsage &AU) const override {
44 bool runOnLoop(Loop *L, LPPassManager &) override {
45 auto BBI = find_if(L->blocks().begin(), L->blocks().end(),
46 [](BasicBlock *BB) { return BB; });
47 if (BBI != L->blocks().end() &&
48 isFunctionInPrintList((*BBI)->getParent()->getName()))
54 char PrintLoopPassWrapper::ID = 0;
57 //===----------------------------------------------------------------------===//
61 char LPPassManager::ID = 0;
63 LPPassManager::LPPassManager()
64 : FunctionPass(ID), PMDataManager() {
66 CurrentLoop = nullptr;
69 // Inset loop into loop nest (LoopInfo) and loop queue (LQ).
70 Loop &LPPassManager::addLoop(Loop *ParentLoop) {
71 // Create a new loop. LI will take ownership.
74 // Insert into the loop nest and the loop queue.
76 // This is the top level loop.
77 LI->addTopLevelLoop(L);
82 ParentLoop->addChildLoop(L);
83 // Insert L into the loop queue after the parent loop.
84 for (auto I = LQ.begin(), E = LQ.end(); I != E; ++I) {
85 if (*I == L->getParentLoop()) {
86 // deque does not support insert after.
95 /// cloneBasicBlockSimpleAnalysis - Invoke cloneBasicBlockAnalysis hook for
97 void LPPassManager::cloneBasicBlockSimpleAnalysis(BasicBlock *From,
98 BasicBlock *To, Loop *L) {
99 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
100 LoopPass *LP = getContainedPass(Index);
101 LP->cloneBasicBlockAnalysis(From, To, L);
105 /// deleteSimpleAnalysisValue - Invoke deleteAnalysisValue hook for all passes.
106 void LPPassManager::deleteSimpleAnalysisValue(Value *V, Loop *L) {
107 if (BasicBlock *BB = dyn_cast<BasicBlock>(V)) {
108 for (BasicBlock::iterator BI = BB->begin(), BE = BB->end(); BI != BE;
110 Instruction &I = *BI;
111 deleteSimpleAnalysisValue(&I, L);
114 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
115 LoopPass *LP = getContainedPass(Index);
116 LP->deleteAnalysisValue(V, L);
120 /// Invoke deleteAnalysisLoop hook for all passes.
121 void LPPassManager::deleteSimpleAnalysisLoop(Loop *L) {
122 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
123 LoopPass *LP = getContainedPass(Index);
124 LP->deleteAnalysisLoop(L);
129 // Recurse through all subloops and all loops into LQ.
130 static void addLoopIntoQueue(Loop *L, std::deque<Loop *> &LQ) {
132 for (Loop::reverse_iterator I = L->rbegin(), E = L->rend(); I != E; ++I)
133 addLoopIntoQueue(*I, LQ);
136 /// Pass Manager itself does not invalidate any analysis info.
137 void LPPassManager::getAnalysisUsage(AnalysisUsage &Info) const {
138 // LPPassManager needs LoopInfo. In the long term LoopInfo class will
139 // become part of LPPassManager.
140 Info.addRequired<LoopInfoWrapperPass>();
141 Info.setPreservesAll();
144 /// run - Execute all of the passes scheduled for execution. Keep track of
145 /// whether any of the passes modifies the function, and if so, return true.
146 bool LPPassManager::runOnFunction(Function &F) {
147 auto &LIWP = getAnalysis<LoopInfoWrapperPass>();
148 LI = &LIWP.getLoopInfo();
149 bool Changed = false;
151 // Collect inherited analysis from Module level pass manager.
152 populateInheritedAnalysis(TPM->activeStack);
154 // Populate the loop queue in reverse program order. There is no clear need to
155 // process sibling loops in either forward or reverse order. There may be some
156 // advantage in deleting uses in a later loop before optimizing the
157 // definitions in an earlier loop. If we find a clear reason to process in
158 // forward order, then a forward variant of LoopPassManager should be created.
160 // Note that LoopInfo::iterator visits loops in reverse program
161 // order. Here, reverse_iterator gives us a forward order, and the LoopQueue
162 // reverses the order a third time by popping from the back.
163 for (LoopInfo::reverse_iterator I = LI->rbegin(), E = LI->rend(); I != E; ++I)
164 addLoopIntoQueue(*I, LQ);
166 if (LQ.empty()) // No loops, skip calling finalizers
170 for (std::deque<Loop *>::const_iterator I = LQ.begin(), E = LQ.end();
173 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
174 LoopPass *P = getContainedPass(Index);
175 Changed |= P->doInitialization(L, *this);
180 while (!LQ.empty()) {
182 CurrentLoop = LQ.back();
183 // Run all passes on the current Loop.
184 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
185 LoopPass *P = getContainedPass(Index);
187 dumpPassInfo(P, EXECUTION_MSG, ON_LOOP_MSG,
188 CurrentLoop->getHeader()->getName());
191 initializeAnalysisImpl(P);
194 PassManagerPrettyStackEntry X(P, *CurrentLoop->getHeader());
195 TimeRegion PassTimer(getPassTimer(P));
197 Changed |= P->runOnLoop(CurrentLoop, *this);
201 dumpPassInfo(P, MODIFICATION_MSG, ON_LOOP_MSG,
202 CurrentLoop->isUnloop()
204 : CurrentLoop->getHeader()->getName());
207 if (CurrentLoop->isUnloop()) {
208 // Notify passes that the loop is being deleted.
209 deleteSimpleAnalysisLoop(CurrentLoop);
211 // Manually check that this loop is still healthy. This is done
212 // instead of relying on LoopInfo::verifyLoop since LoopInfo
213 // is a function pass and it's really expensive to verify every
214 // loop in the function every time. That level of checking can be
215 // enabled with the -verify-loop-info option.
217 TimeRegion PassTimer(getPassTimer(&LIWP));
218 CurrentLoop->verifyLoop();
221 // Then call the regular verifyAnalysis functions.
222 verifyPreservedAnalysis(P);
224 F.getContext().yield();
227 removeNotPreservedAnalysis(P);
228 recordAvailableAnalysis(P);
229 removeDeadPasses(P, CurrentLoop->isUnloop()
231 : CurrentLoop->getHeader()->getName(),
234 if (CurrentLoop->isUnloop())
235 // Do not run other passes on this loop.
239 // If the loop was deleted, release all the loop passes. This frees up
240 // some memory, and avoids trouble with the pass manager trying to call
241 // verifyAnalysis on them.
242 if (CurrentLoop->isUnloop()) {
243 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
244 Pass *P = getContainedPass(Index);
245 freePass(P, "<deleted>", ON_LOOP_MSG);
250 // Pop the loop from queue after running all passes.
255 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
256 LoopPass *P = getContainedPass(Index);
257 Changed |= P->doFinalization();
263 /// Print passes managed by this manager
264 void LPPassManager::dumpPassStructure(unsigned Offset) {
265 errs().indent(Offset*2) << "Loop Pass Manager\n";
266 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
267 Pass *P = getContainedPass(Index);
268 P->dumpPassStructure(Offset + 1);
269 dumpLastUses(P, Offset+1);
274 //===----------------------------------------------------------------------===//
277 Pass *LoopPass::createPrinterPass(raw_ostream &O,
278 const std::string &Banner) const {
279 return new PrintLoopPassWrapper(O, Banner);
282 // Check if this pass is suitable for the current LPPassManager, if
283 // available. This pass P is not suitable for a LPPassManager if P
284 // is not preserving higher level analysis info used by other
285 // LPPassManager passes. In such case, pop LPPassManager from the
286 // stack. This will force assignPassManager() to create new
287 // LPPassManger as expected.
288 void LoopPass::preparePassManager(PMStack &PMS) {
290 // Find LPPassManager
291 while (!PMS.empty() &&
292 PMS.top()->getPassManagerType() > PMT_LoopPassManager)
295 // If this pass is destroying high level information that is used
296 // by other passes that are managed by LPM then do not insert
297 // this pass in current LPM. Use new LPPassManager.
298 if (PMS.top()->getPassManagerType() == PMT_LoopPassManager &&
299 !PMS.top()->preserveHigherLevelAnalysis(this))
303 /// Assign pass manager to manage this pass.
304 void LoopPass::assignPassManager(PMStack &PMS,
305 PassManagerType PreferredType) {
306 // Find LPPassManager
307 while (!PMS.empty() &&
308 PMS.top()->getPassManagerType() > PMT_LoopPassManager)
312 if (PMS.top()->getPassManagerType() == PMT_LoopPassManager)
313 LPPM = (LPPassManager*)PMS.top();
315 // Create new Loop Pass Manager if it does not exist.
316 assert (!PMS.empty() && "Unable to create Loop Pass Manager");
317 PMDataManager *PMD = PMS.top();
319 // [1] Create new Loop Pass Manager
320 LPPM = new LPPassManager();
321 LPPM->populateInheritedAnalysis(PMS);
323 // [2] Set up new manager's top level manager
324 PMTopLevelManager *TPM = PMD->getTopLevelManager();
325 TPM->addIndirectPassManager(LPPM);
327 // [3] Assign manager to manage this new manager. This may create
328 // and push new managers into PMS
329 Pass *P = LPPM->getAsPass();
330 TPM->schedulePass(P);
332 // [4] Push new manager into PMS
339 // Containing function has Attribute::OptimizeNone and transformation
340 // passes should skip it.
341 bool LoopPass::skipOptnoneFunction(const Loop *L) const {
342 const Function *F = L->getHeader()->getParent();
343 if (F && F->hasFnAttribute(Attribute::OptimizeNone)) {
344 // FIXME: Report this to dbgs() only once per function.
345 DEBUG(dbgs() << "Skipping pass '" << getPassName()
346 << "' in function " << F->getName() << "\n");
347 // FIXME: Delete loop from pass manager's queue?