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/Analysis/LoopAnalysisManager.h"
18 #include "llvm/IR/Dominators.h"
19 #include "llvm/IR/IRPrintingPasses.h"
20 #include "llvm/IR/LLVMContext.h"
21 #include "llvm/IR/OptBisect.h"
22 #include "llvm/IR/PassManager.h"
23 #include "llvm/Support/Debug.h"
24 #include "llvm/Support/Timer.h"
25 #include "llvm/Support/raw_ostream.h"
28 #define DEBUG_TYPE "loop-pass-manager"
32 /// PrintLoopPass - Print a Function corresponding to a Loop.
34 class PrintLoopPassWrapper : public LoopPass {
40 PrintLoopPassWrapper() : LoopPass(ID), OS(dbgs()) {}
41 PrintLoopPassWrapper(raw_ostream &OS, const std::string &Banner)
42 : LoopPass(ID), OS(OS), Banner(Banner) {}
44 void getAnalysisUsage(AnalysisUsage &AU) const override {
48 bool runOnLoop(Loop *L, LPPassManager &) override {
49 auto BBI = llvm::find_if(L->blocks(), [](BasicBlock *BB) { return BB; });
50 if (BBI != L->blocks().end() &&
51 isFunctionInPrintList((*BBI)->getParent()->getName())) {
52 printLoop(*L, OS, Banner);
57 StringRef getPassName() const override { return "Print Loop IR"; }
60 char PrintLoopPassWrapper::ID = 0;
63 //===----------------------------------------------------------------------===//
67 char LPPassManager::ID = 0;
69 LPPassManager::LPPassManager()
70 : FunctionPass(ID), PMDataManager() {
72 CurrentLoop = nullptr;
75 // Insert loop into loop nest (LoopInfo) and loop queue (LQ).
76 void LPPassManager::addLoop(Loop &L) {
77 if (!L.getParentLoop()) {
78 // This is the top level loop.
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.
94 /// cloneBasicBlockSimpleAnalysis - Invoke cloneBasicBlockAnalysis hook for
96 void LPPassManager::cloneBasicBlockSimpleAnalysis(BasicBlock *From,
97 BasicBlock *To, Loop *L) {
98 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
99 LoopPass *LP = getContainedPass(Index);
100 LP->cloneBasicBlockAnalysis(From, To, L);
104 /// deleteSimpleAnalysisValue - Invoke deleteAnalysisValue hook for all passes.
105 void LPPassManager::deleteSimpleAnalysisValue(Value *V, Loop *L) {
106 if (BasicBlock *BB = dyn_cast<BasicBlock>(V)) {
107 for (Instruction &I : *BB) {
108 deleteSimpleAnalysisValue(&I, L);
111 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
112 LoopPass *LP = getContainedPass(Index);
113 LP->deleteAnalysisValue(V, L);
117 /// Invoke deleteAnalysisLoop hook for all passes.
118 void LPPassManager::deleteSimpleAnalysisLoop(Loop *L) {
119 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
120 LoopPass *LP = getContainedPass(Index);
121 LP->deleteAnalysisLoop(L);
126 // Recurse through all subloops and all loops into LQ.
127 static void addLoopIntoQueue(Loop *L, std::deque<Loop *> &LQ) {
129 for (Loop *I : reverse(*L))
130 addLoopIntoQueue(I, LQ);
133 /// Pass Manager itself does not invalidate any analysis info.
134 void LPPassManager::getAnalysisUsage(AnalysisUsage &Info) const {
135 // LPPassManager needs LoopInfo. In the long term LoopInfo class will
136 // become part of LPPassManager.
137 Info.addRequired<LoopInfoWrapperPass>();
138 Info.addRequired<DominatorTreeWrapperPass>();
139 Info.setPreservesAll();
142 void LPPassManager::markLoopAsDeleted(Loop &L) {
143 assert((&L == CurrentLoop || CurrentLoop->contains(&L)) &&
144 "Must not delete loop outside the current loop tree!");
145 if (&L == CurrentLoop)
146 CurrentLoopDeleted = true;
149 /// run - Execute all of the passes scheduled for execution. Keep track of
150 /// whether any of the passes modifies the function, and if so, return true.
151 bool LPPassManager::runOnFunction(Function &F) {
152 auto &LIWP = getAnalysis<LoopInfoWrapperPass>();
153 LI = &LIWP.getLoopInfo();
154 DominatorTree *DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
155 bool Changed = false;
157 // Collect inherited analysis from Module level pass manager.
158 populateInheritedAnalysis(TPM->activeStack);
160 // Populate the loop queue in reverse program order. There is no clear need to
161 // process sibling loops in either forward or reverse order. There may be some
162 // advantage in deleting uses in a later loop before optimizing the
163 // definitions in an earlier loop. If we find a clear reason to process in
164 // forward order, then a forward variant of LoopPassManager should be created.
166 // Note that LoopInfo::iterator visits loops in reverse program
167 // order. Here, reverse_iterator gives us a forward order, and the LoopQueue
168 // reverses the order a third time by popping from the back.
169 for (Loop *L : reverse(*LI))
170 addLoopIntoQueue(L, LQ);
172 if (LQ.empty()) // No loops, skip calling finalizers
177 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
178 LoopPass *P = getContainedPass(Index);
179 Changed |= P->doInitialization(L, *this);
184 while (!LQ.empty()) {
185 CurrentLoopDeleted = false;
186 CurrentLoop = LQ.back();
188 // Run all passes on the current Loop.
189 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
190 LoopPass *P = getContainedPass(Index);
192 dumpPassInfo(P, EXECUTION_MSG, ON_LOOP_MSG,
193 CurrentLoop->getHeader()->getName());
196 initializeAnalysisImpl(P);
199 PassManagerPrettyStackEntry X(P, *CurrentLoop->getHeader());
200 TimeRegion PassTimer(getPassTimer(P));
202 Changed |= P->runOnLoop(CurrentLoop, *this);
206 dumpPassInfo(P, MODIFICATION_MSG, ON_LOOP_MSG,
207 CurrentLoopDeleted ? "<deleted loop>"
208 : CurrentLoop->getName());
211 if (CurrentLoopDeleted) {
212 // Notify passes that the loop is being deleted.
213 deleteSimpleAnalysisLoop(CurrentLoop);
215 // Manually check that this loop is still healthy. This is done
216 // instead of relying on LoopInfo::verifyLoop since LoopInfo
217 // is a function pass and it's really expensive to verify every
218 // loop in the function every time. That level of checking can be
219 // enabled with the -verify-loop-info option.
221 TimeRegion PassTimer(getPassTimer(&LIWP));
222 CurrentLoop->verifyLoop();
224 // Here we apply same reasoning as in the above case. Only difference
225 // is that LPPassManager might run passes which do not require LCSSA
226 // form (LoopPassPrinter for example). We should skip verification for
228 if (mustPreserveAnalysisID(LCSSAVerificationPass::ID))
229 CurrentLoop->isRecursivelyLCSSAForm(*DT, *LI);
231 // Then call the regular verifyAnalysis functions.
232 verifyPreservedAnalysis(P);
234 F.getContext().yield();
237 removeNotPreservedAnalysis(P);
238 recordAvailableAnalysis(P);
240 CurrentLoopDeleted ? "<deleted>"
241 : CurrentLoop->getHeader()->getName(),
244 if (CurrentLoopDeleted)
245 // Do not run other passes on this loop.
249 // If the loop was deleted, release all the loop passes. This frees up
250 // some memory, and avoids trouble with the pass manager trying to call
251 // verifyAnalysis on them.
252 if (CurrentLoopDeleted) {
253 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
254 Pass *P = getContainedPass(Index);
255 freePass(P, "<deleted>", ON_LOOP_MSG);
259 // Pop the loop from queue after running all passes.
264 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
265 LoopPass *P = getContainedPass(Index);
266 Changed |= P->doFinalization();
272 /// Print passes managed by this manager
273 void LPPassManager::dumpPassStructure(unsigned Offset) {
274 errs().indent(Offset*2) << "Loop Pass Manager\n";
275 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
276 Pass *P = getContainedPass(Index);
277 P->dumpPassStructure(Offset + 1);
278 dumpLastUses(P, Offset+1);
283 //===----------------------------------------------------------------------===//
286 Pass *LoopPass::createPrinterPass(raw_ostream &O,
287 const std::string &Banner) const {
288 return new PrintLoopPassWrapper(O, Banner);
291 // Check if this pass is suitable for the current LPPassManager, if
292 // available. This pass P is not suitable for a LPPassManager if P
293 // is not preserving higher level analysis info used by other
294 // LPPassManager passes. In such case, pop LPPassManager from the
295 // stack. This will force assignPassManager() to create new
296 // LPPassManger as expected.
297 void LoopPass::preparePassManager(PMStack &PMS) {
299 // Find LPPassManager
300 while (!PMS.empty() &&
301 PMS.top()->getPassManagerType() > PMT_LoopPassManager)
304 // If this pass is destroying high level information that is used
305 // by other passes that are managed by LPM then do not insert
306 // this pass in current LPM. Use new LPPassManager.
307 if (PMS.top()->getPassManagerType() == PMT_LoopPassManager &&
308 !PMS.top()->preserveHigherLevelAnalysis(this))
312 /// Assign pass manager to manage this pass.
313 void LoopPass::assignPassManager(PMStack &PMS,
314 PassManagerType PreferredType) {
315 // Find LPPassManager
316 while (!PMS.empty() &&
317 PMS.top()->getPassManagerType() > PMT_LoopPassManager)
321 if (PMS.top()->getPassManagerType() == PMT_LoopPassManager)
322 LPPM = (LPPassManager*)PMS.top();
324 // Create new Loop Pass Manager if it does not exist.
325 assert (!PMS.empty() && "Unable to create Loop Pass Manager");
326 PMDataManager *PMD = PMS.top();
328 // [1] Create new Loop Pass Manager
329 LPPM = new LPPassManager();
330 LPPM->populateInheritedAnalysis(PMS);
332 // [2] Set up new manager's top level manager
333 PMTopLevelManager *TPM = PMD->getTopLevelManager();
334 TPM->addIndirectPassManager(LPPM);
336 // [3] Assign manager to manage this new manager. This may create
337 // and push new managers into PMS
338 Pass *P = LPPM->getAsPass();
339 TPM->schedulePass(P);
341 // [4] Push new manager into PMS
348 bool LoopPass::skipLoop(const Loop *L) const {
349 const Function *F = L->getHeader()->getParent();
352 // Check the opt bisect limit.
353 LLVMContext &Context = F->getContext();
354 if (!Context.getOptBisect().shouldRunPass(this, *L))
356 // Check for the OptimizeNone attribute.
357 if (F->hasFnAttribute(Attribute::OptimizeNone)) {
358 // FIXME: Report this to dbgs() only once per function.
359 DEBUG(dbgs() << "Skipping pass '" << getPassName()
360 << "' in function " << F->getName() << "\n");
361 // FIXME: Delete loop from pass manager's queue?
367 char LCSSAVerificationPass::ID = 0;
368 INITIALIZE_PASS(LCSSAVerificationPass, "lcssa-verification", "LCSSA Verifier",