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 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) { 53 MachineBasicBlock *PriorMBB = std::prev(MachineFunction::iterator(TopMBB)); 54 while (contains(PriorMBB)) { 55 TopMBB = PriorMBB; 56 if (TopMBB == Begin) break; 57 PriorMBB = std::prev(MachineFunction::iterator(TopMBB)); 58 } 59 } 60 return TopMBB; 61 } 62 63 MachineBasicBlock *MachineLoop::getBottomBlock() { 64 MachineBasicBlock *BotMBB = getHeader(); 65 MachineFunction::iterator End = BotMBB->getParent()->end(); 66 if (BotMBB != std::prev(End)) { 67 MachineBasicBlock *NextMBB = std::next(MachineFunction::iterator(BotMBB)); 68 while (contains(NextMBB)) { 69 BotMBB = NextMBB; 70 if (BotMBB == std::next(MachineFunction::iterator(BotMBB))) break; 71 NextMBB = std::next(MachineFunction::iterator(BotMBB)); 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 82
