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) {
142 for (Loop::iterator I = L->begin(), E = L->end(); I != E; ++I)
143 addLoopIntoQueue(*I, LQ);
146 /// Pass Manager itself does not invalidate any analysis info.
147 void LPPassManager::getAnalysisUsage(AnalysisUsage &Info) const {
148 // LPPassManager needs LoopInfo. In the long term LoopInfo class will
149 // become part of LPPassManager.
150 Info.addRequired<LoopInfo>();
151 Info.setPreservesAll();
154 /// run - Execute all of the passes scheduled for execution. Keep track of
155 /// whether any of the passes modifies the function, and if so, return true.
156 bool LPPassManager::runOnFunction(Function &F) {
157 LI = &getAnalysis<LoopInfo>();
158 bool Changed = false;
160 // Populate Loop Queue
161 for (LoopInfo::iterator I = LI->begin(), E = LI->end(); I != E; ++I)
162 addLoopIntoQueue(*I, LQ);
165 for (std::deque<Loop *>::const_iterator I = LQ.begin(), E = LQ.end();
168 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
169 Pass *P = getContainedPass(Index);
170 LoopPass *LP = dynamic_cast<LoopPass *>(P);
172 Changed |= LP->doInitialization(L, *this);
177 while (!LQ.empty()) {
179 CurrentLoop = LQ.back();
180 skipThisLoop = false;
181 redoThisLoop = false;
183 // Run all passes on current SCC
184 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
186 Pass *P = getContainedPass(Index);
187 AnalysisUsage AnUsage;
188 P->getAnalysisUsage(AnUsage);
190 dumpPassInfo(P, EXECUTION_MSG, ON_LOOP_MSG, "");
191 dumpAnalysisSetInfo("Required", P, AnUsage.getRequiredSet());
193 initializeAnalysisImpl(P);
196 LoopPass *LP = dynamic_cast<LoopPass *>(P);
197 assert (LP && "Invalid LPPassManager member");
198 LP->runOnLoop(CurrentLoop, *this);
202 dumpPassInfo(P, MODIFICATION_MSG, ON_LOOP_MSG, "");
203 dumpAnalysisSetInfo("Preserved", P, AnUsage.getPreservedSet());
205 removeNotPreservedAnalysis(P);
206 recordAvailableAnalysis(P);
207 removeDeadPasses(P, "", ON_LOOP_MSG);
210 // Do not run other passes on this loop.
214 // Pop the loop from queue after running all passes.
218 LQ.push_back(CurrentLoop);
222 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
223 Pass *P = getContainedPass(Index);
224 LoopPass *LP = dynamic_cast <LoopPass *>(P);
226 Changed |= LP->doFinalization();
233 //===----------------------------------------------------------------------===//
236 // Check if this pass is suitable for the current LPPassManager, if
237 // available. This pass P is not suitable for a LPPassManager if P
238 // is not preserving higher level analysis info used by other
239 // LPPassManager passes. In such case, pop LPPassManager from the
240 // stack. This will force assignPassManager() to create new
241 // LPPassManger as expected.
242 void LoopPass::preparePassManager(PMStack &PMS) {
244 // Find LPPassManager
245 while (!PMS.empty()) {
246 if (PMS.top()->getPassManagerType() > PMT_LoopPassManager)
252 LPPassManager *LPPM = dynamic_cast<LPPassManager *>(PMS.top());
254 // If this pass is destroying high level information that is used
255 // by other passes that are managed by LPM then do not insert
256 // this pass in current LPM. Use new LPPassManager.
257 if (LPPM && !LPPM->preserveHigherLevelAnalysis(this))
261 /// Assign pass manager to manage this pass.
262 void LoopPass::assignPassManager(PMStack &PMS,
263 PassManagerType PreferredType) {
264 // Find LPPassManager
265 while (!PMS.empty()) {
266 if (PMS.top()->getPassManagerType() > PMT_LoopPassManager)
272 LPPassManager *LPPM = dynamic_cast<LPPassManager *>(PMS.top());
274 // Create new Loop Pass Manager if it does not exist.
277 assert (!PMS.empty() && "Unable to create Loop Pass Manager");
278 PMDataManager *PMD = PMS.top();
280 // [1] Create new Call Graph Pass Manager
281 LPPM = new LPPassManager(PMD->getDepth() + 1);
283 // [2] Set up new manager's top level manager
284 PMTopLevelManager *TPM = PMD->getTopLevelManager();
285 TPM->addIndirectPassManager(LPPM);
287 // [3] Assign manager to manage this new manager. This may create
288 // and push new managers into PMS
289 Pass *P = dynamic_cast<Pass *>(LPPM);
290 TPM->schedulePass(P);
292 // [4] Push new manager into PMS