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//===- LoopPass.cpp - Loop Pass and Loop Pass Manager ---------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by Devang Patel and 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"
#include <queue>
using namespace llvm;
//===----------------------------------------------------------------------===//
// LoopQueue
namespace llvm {
// Compare Two loops based on their depth in loop nest.
class LoopCompare {
public:
bool operator()( Loop *L1, Loop *L2) const {
// Loops with highest depth has the highest priority.
return L1->getLoopDepth() < L2->getLoopDepth();
}
};
// Loop queue used by Loop Pass Manager. This is a wrapper class
// that hides implemenation detail (use of priority_queue) inside .cpp file.
class LoopQueue {
public:
inline void push(Loop *L) { LPQ.push(L); }
inline void pop() { LPQ.pop(); }
inline Loop *top() { return LPQ.top(); }
inline bool empty() { return LPQ.empty(); }
private:
std::priority_queue<Loop *, std::vector<Loop *>, LoopCompare> LPQ;
};
} // End of LLVM namespace
//===----------------------------------------------------------------------===//
// LPPassManager
//
/// LPPassManager manages FPPassManagers and CalLGraphSCCPasses.
LPPassManager::LPPassManager(int Depth) : PMDataManager(Depth) {
skipThisLoop = false;
redoThisLoop = false;
LQ = new LoopQueue();
}
LPPassManager::~LPPassManager() {
delete LQ;
}
/// Delete loop from the loop queue. This is used by Loop pass to inform
/// Loop Pass Manager that it should skip rest of the passes for this loop.
void LPPassManager::deleteLoopFromQueue(Loop *L) {
// Do not pop loop from LQ here. It will be done by runOnFunction while loop.
skipThisLoop = true;
}
// 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) {
redoThisLoop = true;
}
// Recurse through all subloops and all loops into LQ.
static void addLoopIntoQueue(Loop *L, LoopQueue *LQ) {
for (Loop::iterator I = L->begin(), E = L->end(); I != E; ++I)
addLoopIntoQueue(*I, LQ);
LQ->push(L);
}
/// 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) {
LoopInfo &LI = getAnalysis<LoopInfo>();
bool Changed = false;
// Populate Loop Queue
for (LoopInfo::iterator I = LI.begin(), E = LI.end(); I != E; ++I)
addLoopIntoQueue(*I, LQ);
std::string Msg1 = "Executing Pass '";
std::string Msg3 = "' Made Modification '";
// Walk Loops
while (!LQ->empty()) {
Loop *L = LQ->top();
skipThisLoop = false;
redoThisLoop = false;
// Run all passes on current SCC
for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
Pass *P = getContainedPass(Index);
AnalysisUsage AnUsage;
P->getAnalysisUsage(AnUsage);
std::string Msg2 = "' on Loop ...\n'";
dumpPassInfo(P, Msg1, Msg2);
dumpAnalysisSetInfo("Required", P, AnUsage.getRequiredSet());
initializeAnalysisImpl(P);
StartPassTimer(P);
LoopPass *LP = dynamic_cast<LoopPass *>(P);
assert (LP && "Invalid LPPassManager member");
LP->runOnLoop(L, *this);
StopPassTimer(P);
if (Changed)
dumpPassInfo(P, Msg3, Msg2);
dumpAnalysisSetInfo("Preserved", P, AnUsage.getPreservedSet());
removeNotPreservedAnalysis(P);
recordAvailableAnalysis(P);
removeDeadPasses(P, Msg2);
if (skipThisLoop)
// Do not run other passes on this loop.
break;
}
// Pop the loop from queue after running all passes.
LQ->pop();
if (redoThisLoop)
LQ->push(L);
}
return Changed;
}
//===----------------------------------------------------------------------===//
// LoopPass
/// Assign pass manager to manage this pass.
void LoopPass::assignPassManager(PMStack &PMS,
PassManagerType PreferredType) {
// Find LPPassManager
while (!PMS.empty()) {
if (PMS.top()->getPassManagerType() > PMT_LoopPassManager)
PMS.pop();
else;
break;
}
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);
// [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);
P->assignPassManager(PMS);
// [4] Push new manager into PMS
PMS.push(LPPM);
}
LPPM->add(this);
}
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