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 static RegisterPass<MachineLoopInfo>
  34 X("machine-loops", "Machine Natural Loop Construction", true);
  35
  36 const PassInfo *const llvm::MachineLoopInfoID = &X;
  37
  38 bool MachineLoopInfo::runOnMachineFunction(MachineFunction &) {
  39   releaseMemory();
  40   LI.Calculate(getAnalysis<MachineDominatorTree>().getBase());    // Update
  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 = prior(MachineFunction::iterator(TopMBB));
  55     while (contains(PriorMBB)) {
  56       TopMBB = PriorMBB;
  57       if (TopMBB == Begin) break;
  58       PriorMBB = prior(MachineFunction::iterator(TopMBB));
  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 != prior(End)) {
  68     MachineBasicBlock *NextMBB = llvm::next(MachineFunction::iterator(BotMBB));
  69     while (contains(NextMBB)) {
  70       BotMBB = NextMBB;
  71       if (BotMBB == llvm::next(MachineFunction::iterator(BotMBB))) break;
  72       NextMBB = llvm::next(MachineFunction::iterator(BotMBB));
  73     }
  74   }
  75   return BotMBB;
  76 }
  77
  78 void MachineLoop::dump() const {
  79   print(dbgs());
  80 }