LoopInfo.cpp revision 193323 
1//===- LoopInfo.cpp - Natural Loop Calculator -----------------------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file defines the LoopInfo class that is used to identify natural loops
11// and determine the loop depth of various nodes of the CFG.  Note that the
12// loops identified may actually be several natural loops that share the same
13// header node... not just a single natural loop.
14//
15//===----------------------------------------------------------------------===//
16
17#include "llvm/Analysis/LoopInfo.h"
18#include "llvm/Constants.h"
19#include "llvm/Instructions.h"
20#include "llvm/Analysis/Dominators.h"
21#include "llvm/Assembly/Writer.h"
22#include "llvm/Support/CFG.h"
23#include "llvm/Support/Streams.h"
24#include "llvm/ADT/DepthFirstIterator.h"
25#include "llvm/ADT/SmallPtrSet.h"
26#include <algorithm>
27#include <ostream>
28using namespace llvm;
29
30char LoopInfo::ID = 0;
31static RegisterPass<LoopInfo>
32X("loops", "Natural Loop Information", true, true);
33
34//===----------------------------------------------------------------------===//
35// Loop implementation
36//
37
38//===----------------------------------------------------------------------===//
39// LoopInfo implementation
40//
41bool LoopInfo::runOnFunction(Function &) {
42  releaseMemory();
43  LI->Calculate(getAnalysis<DominatorTree>().getBase());    // Update
44  return false;
45}
46
47void LoopInfo::getAnalysisUsage(AnalysisUsage &AU) const {
48  AU.setPreservesAll();
49  AU.addRequired<DominatorTree>();
50}
51