1 //===- LoopPass.cpp - Loop Pass and Loop Pass Manager ---------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by Devang Patel and is distributed under
6 // the University of Illinois Open Source 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"
19 //===----------------------------------------------------------------------===//
22 /// LPPassManager manages FPPassManagers and CalLGraphSCCPasses.
24 LPPassManager::LPPassManager(int Depth) : PMDataManager(Depth) {
31 /// Delete loop from the loop queue and loop hierarcy (LoopInfo).
32 void LPPassManager::deleteLoopFromQueue(Loop *L) {
34 if (Loop *ParentLoop = L->getParentLoop()) { // Not a top-level loop.
35 // Reparent all of the blocks in this loop. Since BBLoop had a parent,
36 // they are now all in it.
37 for (Loop::block_iterator I = L->block_begin(), E = L->block_end();
39 if (LI->getLoopFor(*I) == L) // Don't change blocks in subloops.
40 LI->changeLoopFor(*I, ParentLoop);
42 // Remove the loop from its parent loop.
43 for (Loop::iterator I = ParentLoop->begin(), E = ParentLoop->end();;
45 assert(I != E && "Couldn't find loop");
47 ParentLoop->removeChildLoop(I);
52 // Move all subloops into the parent loop.
53 while (L->begin() != L->end())
54 ParentLoop->addChildLoop(L->removeChildLoop(L->end()-1));
56 // Reparent all of the blocks in this loop. Since BBLoop had no parent,
57 // they no longer in a loop at all.
59 for (unsigned i = 0; i != L->getBlocks().size(); ++i) {
60 // Don't change blocks in subloops.
61 if (LI->getLoopFor(L->getBlocks()[i]) == L) {
62 LI->removeBlock(L->getBlocks()[i]);
67 // Remove the loop from the top-level LoopInfo object.
68 for (LoopInfo::iterator I = LI->begin(), E = LI->end();; ++I) {
69 assert(I != E && "Couldn't find loop");
76 // Move all of the subloops to the top-level.
77 while (L->begin() != L->end())
78 LI->addTopLevelLoop(L->removeChildLoop(L->end()-1));
83 // If L is current loop then skip rest of the passes and let
84 // runOnFunction remove L from LQ. Otherwise, remove L from LQ now
85 // and continue applying other passes on CurrentLoop.
86 if (CurrentLoop == L) {
91 for (std::deque<Loop *>::iterator I = LQ.begin(),
92 E = LQ.end(); I != E; ++I) {
100 // Inset loop into loop nest (LoopInfo) and loop queue (LQ).
101 void LPPassManager::insertLoop(Loop *L, Loop *ParentLoop) {
103 assert (CurrentLoop != L && "Cannot insert CurrentLoop");
105 // Insert into loop nest
107 ParentLoop->addChildLoop(L);
109 LI->addTopLevelLoop(L);
111 // Insert L into loop queue
112 if (L == CurrentLoop)
114 else if (!ParentLoop)
115 // This is top level loop.
118 // Insert L after ParentLoop
119 for (std::deque<Loop *>::iterator I = LQ.begin(),
120 E = LQ.end(); I != E; ++I) {
121 if (*I == ParentLoop) {
122 // deque does not support insert after.
131 // Reoptimize this loop. LPPassManager will re-insert this loop into the
132 // queue. This allows LoopPass to change loop nest for the loop. This
133 // utility may send LPPassManager into infinite loops so use caution.
134 void LPPassManager::redoLoop(Loop *L) {
135 assert (CurrentLoop != L && "Can redo only CurrentLoop");
139 // Recurse through all subloops and all loops into LQ.
140 static void addLoopIntoQueue(Loop *L, std::deque<Loop *> &LQ) {
141 for (Loop::iterator I = L->begin(), E = L->end(); I != E; ++I)
142 addLoopIntoQueue(*I, LQ);
146 /// run - Execute all of the passes scheduled for execution. Keep track of
147 /// whether any of the passes modifies the function, and if so, return true.
148 bool LPPassManager::runOnFunction(Function &F) {
149 LoopInfo &LI = getAnalysis<LoopInfo>();
150 bool Changed = false;
152 // Populate Loop Queue
153 for (LoopInfo::iterator I = LI.begin(), E = LI.end(); I != E; ++I)
154 addLoopIntoQueue(*I, LQ);
157 for (std::deque<Loop *>::const_iterator I = LQ.begin(), E = LQ.end();
160 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
161 Pass *P = getContainedPass(Index);
162 LoopPass *LP = dynamic_cast<LoopPass *>(P);
164 Changed |= LP->doInitialization(L, *this);
169 while (!LQ.empty()) {
171 CurrentLoop = LQ.back();
172 skipThisLoop = false;
173 redoThisLoop = false;
175 // Run all passes on current SCC
176 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
178 Pass *P = getContainedPass(Index);
179 AnalysisUsage AnUsage;
180 P->getAnalysisUsage(AnUsage);
182 dumpPassInfo(P, EXECUTION_MSG, ON_LOOP_MSG, "");
183 dumpAnalysisSetInfo("Required", P, AnUsage.getRequiredSet());
185 initializeAnalysisImpl(P);
188 LoopPass *LP = dynamic_cast<LoopPass *>(P);
189 assert (LP && "Invalid LPPassManager member");
190 LP->runOnLoop(CurrentLoop, *this);
194 dumpPassInfo(P, MODIFICATION_MSG, ON_LOOP_MSG, "");
195 dumpAnalysisSetInfo("Preserved", P, AnUsage.getPreservedSet());
197 removeNotPreservedAnalysis(P);
198 recordAvailableAnalysis(P);
199 removeDeadPasses(P, "", ON_LOOP_MSG);
202 // Do not run other passes on this loop.
206 // Pop the loop from queue after running all passes.
210 LQ.push_back(CurrentLoop);
214 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
215 Pass *P = getContainedPass(Index);
216 LoopPass *LP = dynamic_cast <LoopPass *>(P);
218 Changed |= LP->doFinalization();
225 //===----------------------------------------------------------------------===//
228 // Check if this pass is suitable for the current LPPassManager, if
229 // available. This pass P is not suitable for a LPPassManager if P
230 // is not preserving higher level analysis info used by other
231 // LPPassManager passes. In such case, pop LPPassManager from the
232 // stack. This will force assignPassManager() to create new
233 // LPPassManger as expected.
234 void LoopPass::preparePassManager(PMStack &PMS) {
236 // Find LPPassManager
237 while (!PMS.empty()) {
238 if (PMS.top()->getPassManagerType() > PMT_LoopPassManager)
244 LPPassManager *LPPM = dynamic_cast<LPPassManager *>(PMS.top());
246 // If this pass is destroying high level information that is used
247 // by other passes that are managed by LPM then do not insert
248 // this pass in current LPM. Use new LPPassManager.
249 if (LPPM && !LPPM->preserveHigherLevelAnalysis(this))
253 /// Assign pass manager to manage this pass.
254 void LoopPass::assignPassManager(PMStack &PMS,
255 PassManagerType PreferredType) {
256 // Find LPPassManager
257 while (!PMS.empty()) {
258 if (PMS.top()->getPassManagerType() > PMT_LoopPassManager)
264 LPPassManager *LPPM = dynamic_cast<LPPassManager *>(PMS.top());
266 // Create new Loop Pass Manager if it does not exist.
269 assert (!PMS.empty() && "Unable to create Loop Pass Manager");
270 PMDataManager *PMD = PMS.top();
272 // [1] Create new Call Graph Pass Manager
273 LPPM = new LPPassManager(PMD->getDepth() + 1);
275 // [2] Set up new manager's top level manager
276 PMTopLevelManager *TPM = PMD->getTopLevelManager();
277 TPM->addIndirectPassManager(LPPM);
279 // [3] Assign manager to manage this new manager. This may create
280 // and push new managers into PMS
281 Pass *P = dynamic_cast<Pass *>(LPPM);
282 P->assignPassManager(PMS);
284 // [4] Push new manager into PMS