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