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 // Reoptimize this loop. LPPassManager will re-insert this loop into the
101 // queue. This allows LoopPass to change loop nest for the loop. This
102 // utility may send LPPassManager into infinite loops so use caution.
103 void LPPassManager::redoLoop(Loop *L) {
107 // Recurse through all subloops and all loops into LQ.
108 static void addLoopIntoQueue(Loop *L, std::deque<Loop *> &LQ) {
109 for (Loop::iterator I = L->begin(), E = L->end(); I != E; ++I)
110 addLoopIntoQueue(*I, LQ);
114 /// run - Execute all of the passes scheduled for execution. Keep track of
115 /// whether any of the passes modifies the function, and if so, return true.
116 bool LPPassManager::runOnFunction(Function &F) {
117 LoopInfo &LI = getAnalysis<LoopInfo>();
118 bool Changed = false;
120 // Populate Loop Queue
121 for (LoopInfo::iterator I = LI.begin(), E = LI.end(); I != E; ++I)
122 addLoopIntoQueue(*I, LQ);
125 for (std::deque<Loop *>::const_iterator I = LQ.begin(), E = LQ.end();
128 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
129 Pass *P = getContainedPass(Index);
130 LoopPass *LP = dynamic_cast<LoopPass *>(P);
132 Changed |= LP->doInitialization(L, *this);
137 while (!LQ.empty()) {
139 CurrentLoop = LQ.back();
140 skipThisLoop = false;
141 redoThisLoop = false;
143 // Run all passes on current SCC
144 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
146 Pass *P = getContainedPass(Index);
147 AnalysisUsage AnUsage;
148 P->getAnalysisUsage(AnUsage);
150 dumpPassInfo(P, EXECUTION_MSG, ON_LOOP_MSG, "");
151 dumpAnalysisSetInfo("Required", P, AnUsage.getRequiredSet());
153 initializeAnalysisImpl(P);
156 LoopPass *LP = dynamic_cast<LoopPass *>(P);
157 assert (LP && "Invalid LPPassManager member");
158 LP->runOnLoop(CurrentLoop, *this);
162 dumpPassInfo(P, MODIFICATION_MSG, ON_LOOP_MSG, "");
163 dumpAnalysisSetInfo("Preserved", P, AnUsage.getPreservedSet());
165 removeNotPreservedAnalysis(P);
166 recordAvailableAnalysis(P);
167 removeDeadPasses(P, "", ON_LOOP_MSG);
170 // Do not run other passes on this loop.
174 // Pop the loop from queue after running all passes.
178 LQ.push_back(CurrentLoop);
182 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
183 Pass *P = getContainedPass(Index);
184 LoopPass *LP = dynamic_cast <LoopPass *>(P);
186 Changed |= LP->doFinalization();
193 //===----------------------------------------------------------------------===//
196 // Check if this pass is suitable for the current LPPassManager, if
197 // available. This pass P is not suitable for a LPPassManager if P
198 // is not preserving higher level analysis info used by other
199 // LPPassManager passes. In such case, pop LPPassManager from the
200 // stack. This will force assignPassManager() to create new
201 // LPPassManger as expected.
202 void LoopPass::preparePassManager(PMStack &PMS) {
204 // Find LPPassManager
205 while (!PMS.empty()) {
206 if (PMS.top()->getPassManagerType() > PMT_LoopPassManager)
212 LPPassManager *LPPM = dynamic_cast<LPPassManager *>(PMS.top());
214 // If this pass is destroying high level information that is used
215 // by other passes that are managed by LPM then do not insert
216 // this pass in current LPM. Use new LPPassManager.
217 if (LPPM && !LPPM->preserveHigherLevelAnalysis(this))
221 /// Assign pass manager to manage this pass.
222 void LoopPass::assignPassManager(PMStack &PMS,
223 PassManagerType PreferredType) {
224 // Find LPPassManager
225 while (!PMS.empty()) {
226 if (PMS.top()->getPassManagerType() > PMT_LoopPassManager)
232 LPPassManager *LPPM = dynamic_cast<LPPassManager *>(PMS.top());
234 // Create new Loop Pass Manager if it does not exist.
237 assert (!PMS.empty() && "Unable to create Loop Pass Manager");
238 PMDataManager *PMD = PMS.top();
240 // [1] Create new Call Graph Pass Manager
241 LPPM = new LPPassManager(PMD->getDepth() + 1);
243 // [2] Set up new manager's top level manager
244 PMTopLevelManager *TPM = PMD->getTopLevelManager();
245 TPM->addIndirectPassManager(LPPM);
247 // [3] Assign manager to manage this new manager. This may create
248 // and push new managers into PMS
249 Pass *P = dynamic_cast<Pass *>(LPPM);
250 P->assignPassManager(PMS);
252 // [4] Push new manager into PMS