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"
22 #include "llvm/Support/raw_ostream.h"
23 using namespace llvm;
24
25 // Explicitly instantiate methods in LoopInfoImpl.h for MI-level Loops.
26 template class llvm::LoopBase<MachineBasicBlock, MachineLoop>;
27 template class llvm::LoopInfoBase<MachineBasicBlock, MachineLoop>;
28
29 char MachineLoopInfo::ID = 0;
30 INITIALIZE_PASS_BEGIN(MachineLoopInfo, "machine-loops",
31 "Machine Natural Loop Construction", true, true)
32 INITIALIZE_PASS_DEPENDENCY(MachineDominatorTree)
33 INITIALIZE_PASS_END(MachineLoopInfo, "machine-loops",
34 "Machine Natural Loop Construction", true, true)
35
36 char &llvm::MachineLoopInfoID = MachineLoopInfo::ID;
37
runOnMachineFunction(MachineFunction &)38 bool MachineLoopInfo::runOnMachineFunction(MachineFunction &) {
39 releaseMemory();
40 LI.analyze(getAnalysis<MachineDominatorTree>().getBase());
41 return false;
42 }
43
getAnalysisUsage(AnalysisUsage & AU) const44 void MachineLoopInfo::getAnalysisUsage(AnalysisUsage &AU) const {
45 AU.setPreservesAll();
46 AU.addRequired<MachineDominatorTree>();
47 MachineFunctionPass::getAnalysisUsage(AU);
48 }
49
getTopBlock()50 MachineBasicBlock *MachineLoop::getTopBlock() {
51 MachineBasicBlock *TopMBB = getHeader();
52 MachineFunction::iterator Begin = TopMBB->getParent()->begin();
53 if (TopMBB != Begin) {
54 MachineBasicBlock *PriorMBB = &*std::prev(TopMBB->getIterator());
55 while (contains(PriorMBB)) {
56 TopMBB = PriorMBB;
57 if (TopMBB == Begin) break;
58 PriorMBB = &*std::prev(TopMBB->getIterator());
59 }
60 }
61 return TopMBB;
62 }
63
getBottomBlock()64 MachineBasicBlock *MachineLoop::getBottomBlock() {
65 MachineBasicBlock *BotMBB = getHeader();
66 MachineFunction::iterator End = BotMBB->getParent()->end();
67 if (BotMBB != std::prev(End)) {
68 MachineBasicBlock *NextMBB = &*std::next(BotMBB->getIterator());
69 while (contains(NextMBB)) {
70 BotMBB = NextMBB;
71 if (BotMBB == &*std::next(BotMBB->getIterator()))
72 break;
73 NextMBB = &*std::next(BotMBB->getIterator());
74 }
75 }
76 return BotMBB;
77 }
78
79 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
dump() const80 void MachineLoop::dump() const {
81 print(dbgs());
82 }
83 #endif
84