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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" | |
970d7e83 | 18 | #include "llvm/Analysis/LoopInfoImpl.h" |
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19 | #include "llvm/CodeGen/MachineDominators.h" |
20 | #include "llvm/CodeGen/Passes.h" | |
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21 | #include "llvm/Support/Debug.h" |
22 | using namespace llvm; | |
23 | ||
24 | // Explicitly instantiate methods in LoopInfoImpl.h for MI-level Loops. | |
25 | template class llvm::LoopBase<MachineBasicBlock, MachineLoop>; | |
26 | template class llvm::LoopInfoBase<MachineBasicBlock, MachineLoop>; | |
27 | ||
28 | char MachineLoopInfo::ID = 0; | |
29 | INITIALIZE_PASS_BEGIN(MachineLoopInfo, "machine-loops", | |
30 | "Machine Natural Loop Construction", true, true) | |
31 | INITIALIZE_PASS_DEPENDENCY(MachineDominatorTree) | |
32 | INITIALIZE_PASS_END(MachineLoopInfo, "machine-loops", | |
33 | "Machine Natural Loop Construction", true, true) | |
34 | ||
35 | char &llvm::MachineLoopInfoID = MachineLoopInfo::ID; | |
36 | ||
37 | bool MachineLoopInfo::runOnMachineFunction(MachineFunction &) { | |
38 | releaseMemory(); | |
39 | LI.Analyze(getAnalysis<MachineDominatorTree>().getBase()); | |
40 | return false; | |
41 | } | |
42 | ||
43 | void MachineLoopInfo::getAnalysisUsage(AnalysisUsage &AU) const { | |
44 | AU.setPreservesAll(); | |
45 | AU.addRequired<MachineDominatorTree>(); | |
46 | MachineFunctionPass::getAnalysisUsage(AU); | |
47 | } | |
48 | ||
49 | MachineBasicBlock *MachineLoop::getTopBlock() { | |
50 | MachineBasicBlock *TopMBB = getHeader(); | |
51 | MachineFunction::iterator Begin = TopMBB->getParent()->begin(); | |
52 | if (TopMBB != Begin) { | |
1a4d82fc | 53 | MachineBasicBlock *PriorMBB = std::prev(MachineFunction::iterator(TopMBB)); |
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54 | while (contains(PriorMBB)) { |
55 | TopMBB = PriorMBB; | |
56 | if (TopMBB == Begin) break; | |
1a4d82fc | 57 | PriorMBB = std::prev(MachineFunction::iterator(TopMBB)); |
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58 | } |
59 | } | |
60 | return TopMBB; | |
61 | } | |
62 | ||
63 | MachineBasicBlock *MachineLoop::getBottomBlock() { | |
64 | MachineBasicBlock *BotMBB = getHeader(); | |
65 | MachineFunction::iterator End = BotMBB->getParent()->end(); | |
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66 | if (BotMBB != std::prev(End)) { |
67 | MachineBasicBlock *NextMBB = std::next(MachineFunction::iterator(BotMBB)); | |
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68 | while (contains(NextMBB)) { |
69 | BotMBB = NextMBB; | |
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70 | if (BotMBB == std::next(MachineFunction::iterator(BotMBB))) break; |
71 | NextMBB = std::next(MachineFunction::iterator(BotMBB)); | |
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72 | } |
73 | } | |
74 | return BotMBB; | |
75 | } | |
76 | ||
77 | #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) | |
78 | void MachineLoop::dump() const { | |
79 | print(dbgs()); | |
80 | } | |
81 | #endif |