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//===- LoopPass.cpp - Loop Pass and Loop Pass Manager ---------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements LoopPass and LPPassManager. All loop optimization
// and transformation passes are derived from LoopPass. LPPassManager is
// responsible for managing LoopPasses.
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/LoopPass.h"
using namespace llvm;
//===----------------------------------------------------------------------===//
// LPPassManager
//
char LPPassManager::ID = 0;
/// LPPassManager manages FPPassManagers and CalLGraphSCCPasses.
LPPassManager::LPPassManager(int Depth)
: FunctionPass(&ID), PMDataManager(Depth) {
skipThisLoop = false;
redoThisLoop = false;
LI = NULL;
CurrentLoop = NULL;
}
/// Delete loop from the loop queue and loop hierarchy (LoopInfo).
void LPPassManager::deleteLoopFromQueue(Loop *L) {
if (Loop *ParentLoop = L->getParentLoop()) { // Not a top-level loop.
// Reparent all of the blocks in this loop. Since BBLoop had a parent,
// they are now all in it.
for (Loop::block_iterator I = L->block_begin(), E = L->block_end();
I != E; ++I)
if (LI->getLoopFor(*I) == L) // Don't change blocks in subloops.
LI->changeLoopFor(*I, ParentLoop);
// Remove the loop from its parent loop.
for (Loop::iterator I = ParentLoop->begin(), E = ParentLoop->end();;
++I) {
assert(I != E && "Couldn't find loop");
if (*I == L) {
ParentLoop->removeChildLoop(I);
break;
}
}
// Move all subloops into the parent loop.
while (!L->empty())
ParentLoop->addChildLoop(L->removeChildLoop(L->end()-1));
} else {
// Reparent all of the blocks in this loop. Since BBLoop had no parent,
// they no longer in a loop at all.
for (unsigned i = 0; i != L->getBlocks().size(); ++i) {
// Don't change blocks in subloops.
if (LI->getLoopFor(L->getBlocks()[i]) == L) {
LI->removeBlock(L->getBlocks()[i]);
--i;
}
}
// Remove the loop from the top-level LoopInfo object.
for (LoopInfo::iterator I = LI->begin(), E = LI->end();; ++I) {
assert(I != E && "Couldn't find loop");
if (*I == L) {
LI->removeLoop(I);
break;
}
}
// Move all of the subloops to the top-level.
while (!L->empty())
LI->addTopLevelLoop(L->removeChildLoop(L->end()-1));
}
delete L;
// If L is current loop then skip rest of the passes and let
// runOnFunction remove L from LQ. Otherwise, remove L from LQ now
// and continue applying other passes on CurrentLoop.
if (CurrentLoop == L) {
skipThisLoop = true;
return;
}
for (std::deque<Loop *>::iterator I = LQ.begin(),
E = LQ.end(); I != E; ++I) {
if (*I == L) {
LQ.erase(I);
break;
}
}
}
// Inset loop into loop nest (LoopInfo) and loop queue (LQ).
void LPPassManager::insertLoop(Loop *L, Loop *ParentLoop) {
assert (CurrentLoop != L && "Cannot insert CurrentLoop");
// Insert into loop nest
if (ParentLoop)
ParentLoop->addChildLoop(L);
else
LI->addTopLevelLoop(L);
// Insert L into loop queue
if (L == CurrentLoop)
redoLoop(L);
else if (!ParentLoop)
// This is top level loop.
LQ.push_front(L);
else {
// Insert L after ParentLoop
for (std::deque<Loop *>::iterator I = LQ.begin(),
E = LQ.end(); I != E; ++I) {
if (*I == ParentLoop) {
// deque does not support insert after.
++I;
LQ.insert(I, 1, L);
break;
}
}
}
}
// Reoptimize this loop. LPPassManager will re-insert this loop into the
// queue. This allows LoopPass to change loop nest for the loop. This
// utility may send LPPassManager into infinite loops so use caution.
void LPPassManager::redoLoop(Loop *L) {
assert (CurrentLoop == L && "Can redo only CurrentLoop");
redoThisLoop = true;
}
/// cloneBasicBlockSimpleAnalysis - Invoke cloneBasicBlockAnalysis hook for
/// all loop passes.
void LPPassManager::cloneBasicBlockSimpleAnalysis(BasicBlock *From,
BasicBlock *To, Loop *L) {
for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
Pass *P = getContainedPass(Index);
LoopPass *LP = dynamic_cast<LoopPass *>(P);
LP->cloneBasicBlockAnalysis(From, To, L);
}
}
/// deleteSimpleAnalysisValue - Invoke deleteAnalysisValue hook for all passes.
void LPPassManager::deleteSimpleAnalysisValue(Value *V, Loop *L) {
for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
Pass *P = getContainedPass(Index);
LoopPass *LP = dynamic_cast<LoopPass *>(P);
LP->deleteAnalysisValue(V, L);
}
}
// Recurse through all subloops and all loops into LQ.
static void addLoopIntoQueue(Loop *L, std::deque<Loop *> &LQ) {
LQ.push_back(L);
for (Loop::iterator I = L->begin(), E = L->end(); I != E; ++I)
addLoopIntoQueue(*I, LQ);
}
/// Pass Manager itself does not invalidate any analysis info.
void LPPassManager::getAnalysisUsage(AnalysisUsage &Info) const {
// LPPassManager needs LoopInfo. In the long term LoopInfo class will
// become part of LPPassManager.
Info.addRequired<LoopInfo>();
Info.setPreservesAll();
}
/// run - Execute all of the passes scheduled for execution. Keep track of
/// whether any of the passes modifies the function, and if so, return true.
bool LPPassManager::runOnFunction(Function &F) {
LI = &getAnalysis<LoopInfo>();
bool Changed = false;
// Collect inherited analysis from Module level pass manager.
populateInheritedAnalysis(TPM->activeStack);
// Populate Loop Queue
for (LoopInfo::iterator I = LI->begin(), E = LI->end(); I != E; ++I)
addLoopIntoQueue(*I, LQ);
// Initialization
for (std::deque<Loop *>::const_iterator I = LQ.begin(), E = LQ.end();
I != E; ++I) {
Loop *L = *I;
for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
Pass *P = getContainedPass(Index);
LoopPass *LP = dynamic_cast<LoopPass *>(P);
if (LP)
Changed |= LP->doInitialization(L, *this);
}
}
// Walk Loops
while (!LQ.empty()) {
CurrentLoop = LQ.back();
skipThisLoop = false;
redoThisLoop = false;
// Run all passes on current SCC
for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
Pass *P = getContainedPass(Index);
dumpPassInfo(P, EXECUTION_MSG, ON_LOOP_MSG, "");
dumpRequiredSet(P);
initializeAnalysisImpl(P);
LoopPass *LP = dynamic_cast<LoopPass *>(P);
{
PassManagerPrettyStackEntry X(LP, *CurrentLoop->getHeader());
StartPassTimer(P);
assert(LP && "Invalid LPPassManager member");
Changed |= LP->runOnLoop(CurrentLoop, *this);
StopPassTimer(P);
}
if (Changed)
dumpPassInfo(P, MODIFICATION_MSG, ON_LOOP_MSG, "");
dumpPreservedSet(P);
verifyPreservedAnalysis(LP);
removeNotPreservedAnalysis(P);
recordAvailableAnalysis(P);
removeDeadPasses(P, "", ON_LOOP_MSG);
// If dominator information is available then verify the info if requested.
verifyDomInfo(*LP, F);
if (skipThisLoop)
// Do not run other passes on this loop.
break;
}
// Pop the loop from queue after running all passes.
LQ.pop_back();
if (redoThisLoop)
LQ.push_back(CurrentLoop);
}
// Finalization
for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
Pass *P = getContainedPass(Index);
LoopPass *LP = dynamic_cast <LoopPass *>(P);
if (LP)
Changed |= LP->doFinalization();
}
return Changed;
}
/// Print passes managed by this manager
void LPPassManager::dumpPassStructure(unsigned Offset) {
llvm::cerr << std::string(Offset*2, ' ') << "Loop Pass Manager\n";
for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
Pass *P = getContainedPass(Index);
P->dumpPassStructure(Offset + 1);
dumpLastUses(P, Offset+1);
}
}
//===----------------------------------------------------------------------===//
// LoopPass
// Check if this pass is suitable for the current LPPassManager, if
// available. This pass P is not suitable for a LPPassManager if P
// is not preserving higher level analysis info used by other
// LPPassManager passes. In such case, pop LPPassManager from the
// stack. This will force assignPassManager() to create new
// LPPassManger as expected.
void LoopPass::preparePassManager(PMStack &PMS) {
// Find LPPassManager
while (!PMS.empty() &&
PMS.top()->getPassManagerType() > PMT_LoopPassManager)
PMS.pop();
LPPassManager *LPPM = dynamic_cast<LPPassManager *>(PMS.top());
// If this pass is destroying high level information that is used
// by other passes that are managed by LPM then do not insert
// this pass in current LPM. Use new LPPassManager.
if (LPPM && !LPPM->preserveHigherLevelAnalysis(this))
PMS.pop();
}
/// Assign pass manager to manage this pass.
void LoopPass::assignPassManager(PMStack &PMS,
PassManagerType PreferredType) {
// Find LPPassManager
while (!PMS.empty() &&
PMS.top()->getPassManagerType() > PMT_LoopPassManager)
PMS.pop();
LPPassManager *LPPM = dynamic_cast<LPPassManager *>(PMS.top());
// Create new Loop Pass Manager if it does not exist.
if (!LPPM) {
assert (!PMS.empty() && "Unable to create Loop Pass Manager");
PMDataManager *PMD = PMS.top();
// [1] Create new Call Graph Pass Manager
LPPM = new LPPassManager(PMD->getDepth() + 1);
LPPM->populateInheritedAnalysis(PMS);
// [2] Set up new manager's top level manager
PMTopLevelManager *TPM = PMD->getTopLevelManager();
TPM->addIndirectPassManager(LPPM);
// [3] Assign manager to manage this new manager. This may create
// and push new managers into PMS
Pass *P = dynamic_cast<Pass *>(LPPM);
TPM->schedulePass(P);
// [4] Push new manager into PMS
PMS.push(LPPM);
}
LPPM->add(this);
}
|