MachineLoopInfo.cpp revision f32616e0bd5995e5e8053d4fc2b0a1da22fa68f6 
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/CodeGen/MachineDominators.h"
19#include "llvm/CodeGen/Passes.h"
20using namespace llvm;
21
22namespace llvm {
23#define MLB class LoopBase<MachineBasicBlock, MachineLoop>
24TEMPLATE_INSTANTIATION(MLB);
25#undef MLB
26#define MLIB class LoopInfoBase<MachineBasicBlock, MachineLoop>
27TEMPLATE_INSTANTIATION(MLIB);
28#undef MLIB
29}
30
31char MachineLoopInfo::ID = 0;
32static RegisterPass<MachineLoopInfo>
33X("machine-loops", "Machine Natural Loop Construction", true);
34
35const PassInfo *const llvm::MachineLoopInfoID = &X;
36
37bool MachineLoopInfo::runOnMachineFunction(MachineFunction &) {
38  releaseMemory();
39  LI.Calculate(getAnalysis<MachineDominatorTree>().getBase());    // Update
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