LoopInfo.cpp revision 195340 
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>
27using namespace llvm;
28
29char LoopInfo::ID = 0;
30static RegisterPass<LoopInfo>
31X("loops", "Natural Loop Information", true, true);
32
33//===----------------------------------------------------------------------===//
34// Loop implementation
35//
36
37//===----------------------------------------------------------------------===//
38// LoopInfo implementation
39//
40bool LoopInfo::runOnFunction(Function &) {
41  releaseMemory();
42  LI.Calculate(getAnalysis<DominatorTree>().getBase());    // Update
43  return false;
44}
45
46void LoopInfo::getAnalysisUsage(AnalysisUsage &AU) const {
47  AU.setPreservesAll();
48  AU.addRequired<DominatorTree>();
49}
50