401 lines
12 KiB
C++
401 lines
12 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 is distributed under the University of Illinois Open Source
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// 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/IR/IRPrintingPasses.h"
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#include "llvm/IR/LLVMContext.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/Timer.h"
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using namespace llvm;
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#define DEBUG_TYPE "loop-pass-manager"
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namespace {
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/// PrintLoopPass - Print a Function corresponding to a Loop.
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///
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class PrintLoopPass : public LoopPass {
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private:
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std::string Banner;
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raw_ostream &Out; // raw_ostream to print on.
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public:
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static char ID;
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PrintLoopPass(const std::string &B, raw_ostream &o)
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: LoopPass(ID), Banner(B), Out(o) {}
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void getAnalysisUsage(AnalysisUsage &AU) const override {
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AU.setPreservesAll();
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}
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bool runOnLoop(Loop *L, LPPassManager &) override {
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Out << Banner;
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for (Loop::block_iterator b = L->block_begin(), be = L->block_end();
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b != be;
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++b) {
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if (*b)
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(*b)->print(Out);
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else
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Out << "Printing <null> block";
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}
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return false;
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}
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};
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char PrintLoopPass::ID = 0;
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}
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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::LPPassManager()
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: FunctionPass(ID), PMDataManager() {
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skipThisLoop = false;
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redoThisLoop = false;
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LI = nullptr;
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CurrentLoop = nullptr;
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}
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/// Delete loop from the loop queue and loop hierarchy (LoopInfo).
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void LPPassManager::deleteLoopFromQueue(Loop *L) {
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LI->updateUnloop(L);
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// Notify passes that the loop is being deleted.
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deleteSimpleAnalysisLoop(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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delete L;
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if (skipThisLoop)
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return;
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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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insertLoopIntoQueue(L);
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}
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void LPPassManager::insertLoopIntoQueue(Loop *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 (!L->getParentLoop())
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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 the parent loop.
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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->getParentLoop()) {
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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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/// cloneBasicBlockSimpleAnalysis - Invoke cloneBasicBlockAnalysis hook for
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/// all loop passes.
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void LPPassManager::cloneBasicBlockSimpleAnalysis(BasicBlock *From,
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BasicBlock *To, Loop *L) {
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for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
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LoopPass *LP = getContainedPass(Index);
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LP->cloneBasicBlockAnalysis(From, To, L);
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}
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}
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/// deleteSimpleAnalysisValue - Invoke deleteAnalysisValue hook for all passes.
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void LPPassManager::deleteSimpleAnalysisValue(Value *V, Loop *L) {
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if (BasicBlock *BB = dyn_cast<BasicBlock>(V)) {
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for (BasicBlock::iterator BI = BB->begin(), BE = BB->end(); BI != BE;
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++BI) {
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Instruction &I = *BI;
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deleteSimpleAnalysisValue(&I, L);
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}
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}
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for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
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LoopPass *LP = getContainedPass(Index);
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LP->deleteAnalysisValue(V, L);
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}
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}
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/// Invoke deleteAnalysisLoop hook for all passes.
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void LPPassManager::deleteSimpleAnalysisLoop(Loop *L) {
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for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
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LoopPass *LP = getContainedPass(Index);
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LP->deleteAnalysisLoop(L);
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}
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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::reverse_iterator I = L->rbegin(), E = L->rend(); 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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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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// Collect inherited analysis from Module level pass manager.
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populateInheritedAnalysis(TPM->activeStack);
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// Populate the loop queue in reverse program order. There is no clear need to
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// process sibling loops in either forward or reverse order. There may be some
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// advantage in deleting uses in a later loop before optimizing the
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// definitions in an earlier loop. If we find a clear reason to process in
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// forward order, then a forward variant of LoopPassManager should be created.
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//
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// Note that LoopInfo::iterator visits loops in reverse program
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// order. Here, reverse_iterator gives us a forward order, and the LoopQueue
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// reverses the order a third time by popping from the back.
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for (LoopInfo::reverse_iterator I = LI->rbegin(), E = LI->rend(); I != E; ++I)
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addLoopIntoQueue(*I, LQ);
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if (LQ.empty()) // No loops, skip calling finalizers
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return false;
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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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LoopPass *P = getContainedPass(Index);
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Changed |= P->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 the current Loop.
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for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
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LoopPass *P = getContainedPass(Index);
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dumpPassInfo(P, EXECUTION_MSG, ON_LOOP_MSG,
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CurrentLoop->getHeader()->getName());
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dumpRequiredSet(P);
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initializeAnalysisImpl(P);
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{
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PassManagerPrettyStackEntry X(P, *CurrentLoop->getHeader());
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TimeRegion PassTimer(getPassTimer(P));
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Changed |= P->runOnLoop(CurrentLoop, *this);
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}
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if (Changed)
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dumpPassInfo(P, MODIFICATION_MSG, ON_LOOP_MSG,
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skipThisLoop ? "<deleted>" :
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CurrentLoop->getHeader()->getName());
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dumpPreservedSet(P);
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if (!skipThisLoop) {
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// Manually check that this loop is still healthy. This is done
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// instead of relying on LoopInfo::verifyLoop since LoopInfo
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// is a function pass and it's really expensive to verify every
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// loop in the function every time. That level of checking can be
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// enabled with the -verify-loop-info option.
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{
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TimeRegion PassTimer(getPassTimer(LI));
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CurrentLoop->verifyLoop();
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}
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// Then call the regular verifyAnalysis functions.
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verifyPreservedAnalysis(P);
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F.getContext().yield();
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}
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removeNotPreservedAnalysis(P);
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recordAvailableAnalysis(P);
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removeDeadPasses(P,
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skipThisLoop ? "<deleted>" :
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CurrentLoop->getHeader()->getName(),
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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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// If the loop was deleted, release all the loop passes. This frees up
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// some memory, and avoids trouble with the pass manager trying to call
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// verifyAnalysis on them.
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if (skipThisLoop)
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for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
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Pass *P = getContainedPass(Index);
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freePass(P, "<deleted>", ON_LOOP_MSG);
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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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LoopPass *P = getContainedPass(Index);
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Changed |= P->doFinalization();
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}
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return Changed;
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}
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/// Print passes managed by this manager
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void LPPassManager::dumpPassStructure(unsigned Offset) {
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errs().indent(Offset*2) << "Loop Pass Manager\n";
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for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
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Pass *P = getContainedPass(Index);
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P->dumpPassStructure(Offset + 1);
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dumpLastUses(P, Offset+1);
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}
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}
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//===----------------------------------------------------------------------===//
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// LoopPass
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Pass *LoopPass::createPrinterPass(raw_ostream &O,
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const std::string &Banner) const {
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return new PrintLoopPass(Banner, O);
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}
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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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PMS.top()->getPassManagerType() > PMT_LoopPassManager)
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PMS.pop();
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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 (PMS.top()->getPassManagerType() == PMT_LoopPassManager &&
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!PMS.top()->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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PMS.top()->getPassManagerType() > PMT_LoopPassManager)
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PMS.pop();
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LPPassManager *LPPM;
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if (PMS.top()->getPassManagerType() == PMT_LoopPassManager)
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LPPM = (LPPassManager*)PMS.top();
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else {
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// Create new Loop Pass Manager if it does not exist.
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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 Loop Pass Manager
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LPPM = new LPPassManager();
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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 = LPPM->getAsPass();
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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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// Containing function has Attribute::OptimizeNone and transformation
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// passes should skip it.
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bool LoopPass::skipOptnoneFunction(const Loop *L) const {
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const Function *F = L->getHeader()->getParent();
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if (F && F->hasFnAttribute(Attribute::OptimizeNone)) {
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// FIXME: Report this to dbgs() only once per function.
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DEBUG(dbgs() << "Skipping pass '" << getPassName()
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<< "' in function " << F->getName() << "\n");
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// FIXME: Delete loop from pass manager's queue?
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return true;
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}
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return false;
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}
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