lib/CodeGen/MachineLoopInfo.cpp

   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 }