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 38 bool MachineLoopInfo::runOnMachineFunction(MachineFunction &) { 39 releaseMemory(); 40 LI.analyze(getAnalysis<MachineDominatorTree>().getBase()); 41 return false; 42 } 43 44 void MachineLoopInfo::getAnalysisUsage(AnalysisUsage &AU) const { 45 AU.setPreservesAll(); 46 AU.addRequired<MachineDominatorTree>(); 47 MachineFunctionPass::getAnalysisUsage(AU); 48 } 49 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 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) 80 void MachineLoop::dump() const { 81 print(dbgs()); 82 } 83 #endif 84