X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FAnalysis%2FLoopInfo.cpp;h=275331b03a58f952f0298d7dde3fc7ec54fb4559;hb=b169426272b85ce28a9a56d13154e61b158fc47a;hp=70bf97caccd0d73edafeb56efcfa15411c5f8e1a;hpb=3a9a56e7b2f574b946edc0abb5dfa19e40f82ec1;p=oota-llvm.git diff --git a/lib/Analysis/LoopInfo.cpp b/lib/Analysis/LoopInfo.cpp index 70bf97caccd..275331b03a5 100644 --- a/lib/Analysis/LoopInfo.cpp +++ b/lib/Analysis/LoopInfo.cpp @@ -1,4 +1,11 @@ -//===- LoopInfo.cpp - Natural Loop Calculator -------------------------------=// +//===- LoopInfo.cpp - Natural Loop Calculator -----------------------------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// // // This file defines the LoopInfo class that is used to identify natural loops // and determine the loop depth of various nodes of the CFG. Note that the @@ -8,220 +15,36 @@ //===----------------------------------------------------------------------===// #include "llvm/Analysis/LoopInfo.h" +#include "llvm/Constants.h" +#include "llvm/Instructions.h" #include "llvm/Analysis/Dominators.h" -#include "llvm/Support/CFG.h" #include "llvm/Assembly/Writer.h" -#include "Support/DepthFirstIterator.h" +#include "llvm/Support/CFG.h" +#include "llvm/Support/Streams.h" +#include "llvm/ADT/DepthFirstIterator.h" +#include "llvm/ADT/SmallPtrSet.h" #include +#include +using namespace llvm; -static RegisterAnalysis -X("loops", "Natural Loop Construction", true); +char LoopInfo::ID = 0; +static RegisterPass +X("loops", "Natural Loop Construction", true, true); //===----------------------------------------------------------------------===// // Loop implementation // -bool Loop::contains(const BasicBlock *BB) const { - return find(Blocks.begin(), Blocks.end(), BB) != Blocks.end(); -} - -bool Loop::isLoopExit(const BasicBlock *BB) const { - for (BasicBlock::succ_const_iterator SI = succ_begin(BB), SE = succ_end(BB); - SI != SE; ++SI) { - if (! contains(*SI)) - return true; - } - return false; -} - -unsigned Loop::getNumBackEdges() const { - unsigned numBackEdges = 0; - BasicBlock *header = Blocks.front(); - - for (std::vector::const_iterator I = Blocks.begin(), - E = Blocks.end(); I != E; ++I) { - for (BasicBlock::succ_iterator SI = succ_begin(*I), SE = succ_end(*I); - SI != SE; ++SI) - if (header == *SI) - ++numBackEdges; - } - return numBackEdges; -} - -void Loop::print(std::ostream &OS) const { - OS << std::string(getLoopDepth()*2, ' ') << "Loop Containing: "; - - for (unsigned i = 0; i < getBlocks().size(); ++i) { - if (i) OS << ","; - WriteAsOperand(OS, (const Value*)getBlocks()[i]); - } - OS << "\n"; - - for (unsigned i = 0, e = getSubLoops().size(); i != e; ++i) - getSubLoops()[i]->print(OS); -} //===----------------------------------------------------------------------===// // LoopInfo implementation // -void LoopInfo::stub() {} - bool LoopInfo::runOnFunction(Function &) { releaseMemory(); - Calculate(getAnalysis()); // Update + LI->Calculate(getAnalysis().getBase()); // Update return false; } -void LoopInfo::releaseMemory() { - for (std::vector::iterator I = TopLevelLoops.begin(), - E = TopLevelLoops.end(); I != E; ++I) - delete *I; // Delete all of the loops... - - BBMap.clear(); // Reset internal state of analysis - TopLevelLoops.clear(); -} - - -void LoopInfo::Calculate(const DominatorSet &DS) { - BasicBlock *RootNode = DS.getRoot(); - - for (df_iterator NI = df_begin(RootNode), - NE = df_end(RootNode); NI != NE; ++NI) - if (Loop *L = ConsiderForLoop(*NI, DS)) - TopLevelLoops.push_back(L); - - for (unsigned i = 0; i < TopLevelLoops.size(); ++i) - TopLevelLoops[i]->setLoopDepth(1); -} - void LoopInfo::getAnalysisUsage(AnalysisUsage &AU) const { AU.setPreservesAll(); - AU.addRequired(); -} - -void LoopInfo::print(std::ostream &OS) const { - for (unsigned i = 0; i < TopLevelLoops.size(); ++i) - TopLevelLoops[i]->print(OS); -} - -Loop *LoopInfo::ConsiderForLoop(BasicBlock *BB, const DominatorSet &DS) { - if (BBMap.find(BB) != BBMap.end()) return 0; // Haven't processed this node? - - std::vector TodoStack; - - // Scan the predecessors of BB, checking to see if BB dominates any of - // them. - for (pred_iterator I = pred_begin(BB), E = pred_end(BB); I != E; ++I) - if (DS.dominates(BB, *I)) // If BB dominates it's predecessor... - TodoStack.push_back(*I); - - if (TodoStack.empty()) return 0; // Doesn't dominate any predecessors... - - // Create a new loop to represent this basic block... - Loop *L = new Loop(BB); - BBMap[BB] = L; - - while (!TodoStack.empty()) { // Process all the nodes in the loop - BasicBlock *X = TodoStack.back(); - TodoStack.pop_back(); - - if (!L->contains(X)) { // As of yet unprocessed?? - L->Blocks.push_back(X); - - // Add all of the predecessors of X to the end of the work stack... - TodoStack.insert(TodoStack.end(), pred_begin(X), pred_end(X)); - } - } - - // Add the basic blocks that comprise this loop to the BBMap so that this - // loop can be found for them. Also check subsidary basic blocks to see if - // they start subloops of their own. - // - for (std::vector::reverse_iterator I = L->Blocks.rbegin(), - E = L->Blocks.rend(); I != E; ++I) - - // Check to see if this block starts a new loop - if (*I != BB) - if (Loop *NewLoop = ConsiderForLoop(*I, DS)) { - L->SubLoops.push_back(NewLoop); - NewLoop->ParentLoop = L; - } else { - std::map::iterator BBMI = BBMap.lower_bound(*I); - if (BBMI == BBMap.end() || BBMI->first != *I) { // Not in map yet... - BBMap.insert(BBMI, std::make_pair(*I, L)); - } else { - // If this is already in the BBMap then this means that we already - // added a loop for it, but incorrectly added the loop to a higher - // level loop instead of the current loop we are creating. Fix this - // now by moving the loop into the correct subloop. - // - Loop *SubLoop = BBMI->second; - if (SubLoop->getHeader() == *I) { // Only do this once for the loop... - Loop *OldSubLoopParent = SubLoop->getParentLoop(); - if (OldSubLoopParent != L) { - // Remove SubLoop from OldSubLoopParent's list of subloops... - std::vector::iterator I = - std::find(OldSubLoopParent->SubLoops.begin(), - OldSubLoopParent->SubLoops.end(), SubLoop); - assert(I != OldSubLoopParent->SubLoops.end() - && "Loop parent doesn't contain loop?"); - OldSubLoopParent->SubLoops.erase(I); - SubLoop->ParentLoop = L; - L->SubLoops.push_back(SubLoop); - } - } - } - } - - return L; -} - -/// getLoopPreheader - If there is a preheader for this loop, return it. A -/// loop has a preheader if there is only one edge to the header of the loop -/// from outside of the loop. If this is the case, the block branching to the -/// header of the loop is the preheader node. The "preheaders" pass can be -/// "Required" to ensure that there is always a preheader node for every loop. -/// -/// This method returns null if there is no preheader for the loop (either -/// because the loop is dead or because multiple blocks branch to the header -/// node of this loop). -/// -BasicBlock *Loop::getLoopPreheader() const { - // Keep track of nodes outside the loop branching to the header... - BasicBlock *Out = 0; - - // Loop over the predecessors of the header node... - BasicBlock *Header = getHeader(); - for (pred_iterator PI = pred_begin(Header), PE = pred_end(Header); - PI != PE; ++PI) - if (!contains(*PI)) { // If the block is not in the loop... - if (Out && Out != *PI) - return 0; // Multiple predecessors outside the loop - Out = *PI; - } - - // If there is exactly one preheader, return it. If there was zero, then Out - // is still null. - return Out; -} - -/// addBasicBlockToLoop - This function is used by other analyses to update loop -/// information. NewBB is set to be a new member of the current loop. Because -/// of this, it is added as a member of all parent loops, and is added to the -/// specified LoopInfo object as being in the current basic block. It is not -/// valid to replace the loop header with this method. -/// -void Loop::addBasicBlockToLoop(BasicBlock *NewBB, LoopInfo &LI) { - assert(LI[getHeader()] == this && "Incorrect LI specified for this loop!"); - assert(NewBB && "Cannot add a null basic block to the loop!"); - assert(LI[NewBB] == 0 && "BasicBlock already in the loop!"); - - // Add the loop mapping to the LoopInfo object... - LI.BBMap[NewBB] = this; - - // Add the basic block to this loop and all parent loops... - Loop *L = this; - while (L) { - L->Blocks.push_back(NewBB); - L = L->getParentLoop(); - } + AU.addRequired(); }