-//===- 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
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/LoopInfo.h"
+#include "llvm/Constants.h"
+#include "llvm/Instructions.h"
#include "llvm/Analysis/Dominators.h"
+#include "llvm/Assembly/Writer.h"
#include "llvm/Support/CFG.h"
-#include "Support/DepthFirstIterator.h"
+#include "llvm/Support/Streams.h"
+#include "llvm/ADT/DepthFirstIterator.h"
+#include "llvm/ADT/SmallPtrSet.h"
#include <algorithm>
+#include <ostream>
+using namespace llvm;
-AnalysisID cfg::LoopInfo::ID(AnalysisID::create<cfg::LoopInfo>());
+char LoopInfo::ID = 0;
+static RegisterPass<LoopInfo>
+X("loops", "Natural Loop Construction", true, true);
//===----------------------------------------------------------------------===//
-// cfg::Loop implementation
+// Loop implementation
//
-bool cfg::Loop::contains(BasicBlock *BB) const {
- return find(Blocks.begin(), Blocks.end(), BB) != Blocks.end();
-}
-
-void cfg::LoopInfo::releaseMemory() {
- for (std::vector<Loop*>::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();
-}
+/// getNumBackEdges - Calculate the number of back edges to the loop header.
+///
//===----------------------------------------------------------------------===//
-// cfg::LoopInfo implementation
+// LoopInfo implementation
//
-bool cfg::LoopInfo::runOnFunction(Function *F) {
+bool LoopInfo::runOnFunction(Function &) {
releaseMemory();
- Calculate(getAnalysis<DominatorSet>()); // Update
+ LI->Calculate(getAnalysis<DominatorTree>().getBase()); // Update
return false;
}
-void cfg::LoopInfo::Calculate(const DominatorSet &DS) {
- BasicBlock *RootNode = DS.getRoot();
-
- for (df_iterator<BasicBlock*> 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 cfg::LoopInfo::getAnalysisUsage(AnalysisUsage &AU) const {
+void LoopInfo::getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
- AU.addRequired(DominatorSet::ID);
- AU.addProvided(ID);
-}
-
-
-cfg::Loop *cfg::LoopInfo::ConsiderForLoop(BasicBlock *BB,
- const DominatorSet &DS) {
- if (BBMap.find(BB) != BBMap.end()) return 0; // Havn't processed this node?
-
- std::vector<BasicBlock *> 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<BasicBlock*>::reverse_iterator I = L->Blocks.rbegin(),
- E = L->Blocks.rend(); I != E; ++I) {
-
- // Check to see if this block starts a new loop
- if (Loop *NewLoop = ConsiderForLoop(*I, DS)) {
- L->SubLoops.push_back(NewLoop);
- NewLoop->ParentLoop = L;
- }
-
- if (BBMap.find(*I) == BBMap.end())
- BBMap.insert(std::make_pair(*I, L));
- }
-
- return L;
+ AU.addRequired<DominatorTree>();
}