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"
21 using namespace llvm;
22
23 namespace llvm {
24 #define MLB class LoopBase<MachineBasicBlock, MachineLoop>
25 TEMPLATE_INSTANTIATION(MLB);
26 #undef MLB
27 #define MLIB class LoopInfoBase<MachineBasicBlock, MachineLoop>
28 TEMPLATE_INSTANTIATION(MLIB);
29 #undef MLIB
30 }
31
32 char MachineLoopInfo::ID = 0;
33 INITIALIZE_PASS_BEGIN(MachineLoopInfo, "machine-loops",
34 "Machine Natural Loop Construction", true, true)
35 INITIALIZE_PASS_DEPENDENCY(MachineDominatorTree)
36 INITIALIZE_PASS_END(MachineLoopInfo, "machine-loops",
37 "Machine Natural Loop Construction", true, true)
38
39 char &llvm::MachineLoopInfoID = MachineLoopInfo::ID;
40
runOnMachineFunction(MachineFunction &)41 bool MachineLoopInfo::runOnMachineFunction(MachineFunction &) {
42 releaseMemory();
43 LI.Calculate(getAnalysis<MachineDominatorTree>().getBase()); // Update
44 return false;
45 }
46
getAnalysisUsage(AnalysisUsage & AU) const47 void MachineLoopInfo::getAnalysisUsage(AnalysisUsage &AU) const {
48 AU.setPreservesAll();
49 AU.addRequired<MachineDominatorTree>();
50 MachineFunctionPass::getAnalysisUsage(AU);
51 }
52
getTopBlock()53 MachineBasicBlock *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
getBottomBlock()67 MachineBasicBlock *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
dump() const81 void MachineLoop::dump() const {
82 print(dbgs());
83 }
84