path: root/lib/CodeGen/VirtRegMap.cpp

//===-- llvm/CodeGen/VirtRegMap.cpp - Virtual Register Map ----------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the VirtRegMap class.
//
// It also contains implementations of the the Spiller interface, which, given a
// virtual register map and a machine function, eliminates all virtual
// references by replacing them with physical register references - adding spill
// code as necessary.
//
//===----------------------------------------------------------------------===//

#define DEBUG_TYPE "spiller"
#include "VirtRegMap.h"
#include "llvm/Function.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/SSARegMap.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/Compiler.h"
#include "llvm/ADT/BitVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallSet.h"
#include <algorithm>
using namespace llvm;

STATISTIC(NumSpills, "Number of register spills");
STATISTIC(NumReMats, "Number of re-materialization");
STATISTIC(NumDRM   , "Number of re-materializable defs elided");
STATISTIC(NumStores, "Number of stores added");
STATISTIC(NumLoads , "Number of loads added");
STATISTIC(NumReused, "Number of values reused");
STATISTIC(NumDSE   , "Number of dead stores elided");
STATISTIC(NumDCE   , "Number of copies elided");

namespace {
  enum SpillerName { simple, local };

  static cl::opt<SpillerName>
  SpillerOpt("spiller",
             cl::desc("Spiller to use: (default: local)"),
             cl::Prefix,
             cl::values(clEnumVal(simple, "  simple spiller"),
                        clEnumVal(local,  "  local spiller"),
                        clEnumValEnd),
             cl::init(local));
}

//===----------------------------------------------------------------------===//
//  VirtRegMap implementation
//===----------------------------------------------------------------------===//

VirtRegMap::VirtRegMap(MachineFunction &mf)
  : TII(*mf.getTarget().getInstrInfo()), MF(mf), 
    Virt2PhysMap(NO_PHYS_REG), Virt2StackSlotMap(NO_STACK_SLOT),
    Virt2ReMatIdMap(NO_STACK_SLOT), ReMatMap(NULL),
    ReMatId(MAX_STACK_SLOT+1) {
  grow();
}

void VirtRegMap::grow() {
  unsigned LastVirtReg = MF.getSSARegMap()->getLastVirtReg();
  Virt2PhysMap.grow(LastVirtReg);
  Virt2StackSlotMap.grow(LastVirtReg);
  Virt2ReMatIdMap.grow(LastVirtReg);
  ReMatMap.grow(LastVirtReg);
}

int VirtRegMap::assignVirt2StackSlot(unsigned virtReg) {
  assert(MRegisterInfo::isVirtualRegister(virtReg));
  assert(Virt2StackSlotMap[virtReg] == NO_STACK_SLOT &&
         "attempt to assign stack slot to already spilled register");
  const TargetRegisterClass* RC = MF.getSSARegMap()->getRegClass(virtReg);
  int frameIndex = MF.getFrameInfo()->CreateStackObject(RC->getSize(),
                                                        RC->getAlignment());
  Virt2StackSlotMap[virtReg] = frameIndex;
  ++NumSpills;
  return frameIndex;
}

void VirtRegMap::assignVirt2StackSlot(unsigned