MachineLoopInfo.cpp revision d04a8d4b33ff316ca4cf961e06c9e312eff8e64f 
1//===- MachineLoopInfo.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 MachineLoopInfo class that is used to identify natural
11// loops and determine the loop depth of various nodes of the CFG.  Note that
12// the loops identified may actually be several natural loops that share the
13// same header node... not just a single natural loop.
14//
15//===----------------------------------------------------------------------===//
16
17#include "llvm/CodeGen/MachineLoopInfo.h"
18#include "llvm/Analysis/LoopInfoImpl.h"
19#include "llvm/CodeGen/MachineDominators.h"
20#include "llvm/CodeGen/Passes.h"
21#include "llvm/Support/Debug.h"
22using namespace llvm;
23
24// Explicitly instantiate methods in LoopInfoImpl.h for MI-level Loops.
25template class llvm::LoopBase<MachineBasicBlock, MachineLoop>;
26template class llvm::LoopInfoBase<MachineBasicBlock, MachineLoop>;
27
28char MachineLoopInfo::ID = 0;
29INITIALIZE_PASS_BEGIN(MachineLoopInfo, "machine-loops",
30                "Machine Natural Loop Construction", true, true)
31INITIALIZE_PASS_DEPENDENCY(MachineDominatorTree)
32INITIALIZE_PASS_END(MachineLoopInfo, "machine-loops",
33                "Machine Natural Loop Construction", true, true)
34
35char &llvm::MachineLoopInfoID = MachineLoopInfo::ID;
36
37bool MachineLoopInfo::runOnMachineFunction(MachineFunction &) {
38  releaseMemory();
39  LI.Analyze(getAnalysis<MachineDominatorTree>().getBase());
40  return false;
41}
42
43void MachineLoopInfo::getAnalysisUsage(AnalysisUsage &AU) const {
44  AU.setPreservesAll();
45  AU.addRequired<MachineDominatorTree>();
46  MachineFunctionPass::getAnalysisUsage(AU);
47}
48
49MachineBasicBlock *MachineLoop::getTopBlock() {
50  MachineBasicBlock *TopMBB = getHeader();
51  MachineFunction::iterator Begin = TopMBB->getParent()->begin();
52  if (TopMBB != Begin) {
53    MachineBasicBlock *PriorMBB = prior(MachineFunction::iterator(TopMBB));
54    while (contains(PriorMBB)) {
55      TopMBB = PriorMBB;
56      if (TopMBB == Begin) break;
57      PriorMBB = prior(MachineFunction::iterator(TopMBB));
58    }
59  }
60  return TopMBB;
61}
62
63MachineBasicBlock *MachineLoop::getBottomBlock() {
64  MachineBasicBlock *BotMBB = getHeader();
65  MachineFunction::iterator End = BotMBB->getParent()->end();
66  if (BotMBB != prior(End)) {
67    MachineBasicBlock *NextMBB = llvm::next(MachineFunction::iterator(BotMBB));
68    while (contains(NextMBB)) {
69      BotMBB = NextMBB;
70      if (BotMBB == llvm::next(MachineFunction::iterator(BotMBB))) break;
71      NextMBB = llvm::next(MachineFunction::iterator(BotMBB));
72    }
73  }
74  return BotMBB;
75}
76
77#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
78void MachineLoop::dump() const {
79  print(dbgs());
80}
81#endif
82