MachineLoopInfo.cpp revision 2ab36d350293c77fc8941ce1023e4899df7e3a82 
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"
20#include "llvm/Support/Debug.h"
21using namespace llvm;
22
23namespace llvm {
24#define MLB class LoopBase<MachineBasicBlock, MachineLoop>
25TEMPLATE_INSTANTIATION(MLB);
26#undef MLB
27#define MLIB class LoopInfoBase<MachineBasicBlock, MachineLoop>
28TEMPLATE_INSTANTIATION(MLIB);
29#undef MLIB
30}
31
32char MachineLoopInfo::ID = 0;
33INITIALIZE_PASS_BEGIN(MachineLoopInfo, "machine-loops",
34                "Machine Natural Loop Construction", true, true)
35INITIALIZE_PASS_DEPENDENCY(MachineDominatorTree)
36INITIALIZE_PASS_END(MachineLoopInfo, "machine-loops",
37                "Machine Natural Loop Construction", true, true)
38
39char &llvm::MachineLoopInfoID = MachineLoopInfo::ID;
40
41bool MachineLoopInfo::runOnMachineFunction(MachineFunction &) {
42  releaseMemory();
43  LI.Calculate(getAnalysis<MachineDominatorTree>().getBase());    // Update
44  return false;
45}
46
47void MachineLoopInfo::getAnalysisUsage(AnalysisUsage &AU) const {
48  AU.setPreservesAll();
49  AU.addRequired<MachineDominatorTree>();
50  MachineFunctionPass::getAnalysisUsage(AU);
51}
52
53MachineBasicBlock *MachineLoop::getTopBlock() {
54  MachineBasicBlock *TopMBB = getHeader();
55  MachineFunction::iterator Begin = TopMBB->getParent()->begin();
56  if (TopMBB != Begin) {
57    MachineBasicBlock *PriorMBB = prior(MachineFunction::iterator(TopMBB));
58    while (contains(PriorMBB)) {
59      TopMBB = PriorMBB;
60      if (TopMBB == Begin) break;
61      PriorMBB = prior(MachineFunction::iterator(TopMBB));
62    }
63  }
64  return TopMBB;
65}
66
67MachineBasicBlock *MachineLoop::getBottomBlock() {
68  MachineBasicBlock *BotMBB = getHeader();
69  MachineFunction::iterator End = BotMBB->getParent()->end();
70  if (BotMBB != prior(End)) {
71    MachineBasicBlock *NextMBB = llvm::next(MachineFunction::iterator(BotMBB));
72    while (contains(NextMBB)) {
73      BotMBB = NextMBB;
74      if (BotMBB == llvm::next(MachineFunction::iterator(BotMBB))) break;
75      NextMBB = llvm::next(MachineFunction::iterator(BotMBB));
76    }
77  }
78  return BotMBB;
79}
80
81void MachineLoop::dump() const {
82  print(dbgs());
83}
84