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 using namespace llvm;
  21
  22 #define MLB class LoopBase<MachineBasicBlock, MachineLoop>
  23 TEMPLATE_INSTANTIATION(MLB);
  24 #undef MLB
  25 #define MLIB class LoopInfoBase<MachineBasicBlock, MachineLoop>
  26 TEMPLATE_INSTANTIATION(MLIB);
  27 #undef MLIB
  28
  29 char MachineLoopInfo::ID = 0;
  30 static RegisterPass<MachineLoopInfo>
  31 X("machine-loops", "Machine Natural Loop Construction", true);
  32
  33 const PassInfo *const llvm::MachineLoopInfoID = &X;
  34
  35 bool MachineLoopInfo::runOnMachineFunction(MachineFunction &) {
  36   releaseMemory();
  37   LI.Calculate(getAnalysis<MachineDominatorTree>().getBase());    // Update
  38   return false;
  39 }
  40
  41 void MachineLoopInfo::getAnalysisUsage(AnalysisUsage &AU) const {
  42   AU.setPreservesAll();
  43   AU.addRequired<MachineDominatorTree>();
  44   MachineFunctionPass::getAnalysisUsage(AU);
  45 }