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 41 bool MachineLoopInfo::runOnMachineFunction(MachineFunction &) { 42 releaseMemory(); 43 LI.Calculate(getAnalysis<MachineDominatorTree>().getBase()); // Update 44 return false; 45 } 46 47 void MachineLoopInfo::getAnalysisUsage(AnalysisUsage &AU) const { 48 AU.setPreservesAll(); 49 AU.addRequired<MachineDominatorTree>(); 50 MachineFunctionPass::getAnalysisUsage(AU); 51 } 52 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 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 81 void MachineLoop::dump() const { 82 print(dbgs()); 83 } 84
