RegAllocLocal.cpp

  MF = &Fn;
  TM = &Fn.getTarget();
  TRI = TM->getRegisterInfo();
  TII = TM->getInstrInfo();

  PhysRegsUsed.assign(TRI->getNumRegs(), -1);
  
  // At various places we want to efficiently check to see whether a register
  // is allocatable.  To handle this, we mark all unallocatable registers as
  // being pinned down, permanently.
  {
    BitVector Allocable = TRI->getAllocatableSet(Fn);
    for (unsigned i = 0, e = Allocable.size(); i != e; ++i)
      if (!Allocable[i])
        PhysRegsUsed[i] = -2;  // Mark the reg unallocable.
  }

  // initialize the virtual->physical register map to have a 'null'
  // mapping for all virtual registers
  unsigned LastVirtReg = MF->getRegInfo().getLastVirtReg();
  StackSlotForVirtReg.grow(LastVirtReg);
  Virt2PhysRegMap.grow(LastVirtReg);
  Virt2LastUseMap.grow(LastVirtReg);
  VirtRegModified.resize(LastVirtReg+1-TargetRegisterInfo::FirstVirtualRegister);
  UsedInMultipleBlocks.resize(LastVirtReg+1-TargetRegisterInfo::FirstVirtualRegister);
 
  // Loop over all of the basic blocks, eliminating virtual register references
  for (MachineFunction::iterator MBB = Fn.begin(), MBBe = Fn.end();
       MBB != MBBe; ++MBB)
    AllocateBasicBlock(*MBB);

  StackSlotForVirtReg.clear();
  PhysRegsUsed.clear();
  VirtRegModified.clear();
  UsedInMultipleBlocks.clear();
  Virt2PhysRegMap.clear();
  Virt2LastUseMap.clear();
  return true;
}

FunctionPass *llvm::createLocalRegisterAllocator() {
  return new RALocal();
}