VirtRegMap.h

//===-- llvm/CodeGen/VirtRegMap.h - Virtual Register Map -*- C++ -*--------===//
//
//                     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 a virtual register map. This maps virtual registers to
// physical registers and virtual registers to stack slots. It is created and
// updated by a register allocator and then used by a machine code rewriter that
// adds spill code and rewrites virtual into physical register references.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_CODEGEN_VIRTREGMAP_H
#define LLVM_CODEGEN_VIRTREGMAP_H

#include "llvm/Target/MRegisterInfo.h"
#include "llvm/ADT/DenseMap.h"
#include <map>

namespace llvm {
  class MachineInstr;

  class VirtRegMap {
  public:
    typedef DenseMap<unsigned, VirtReg2IndexFunctor> Virt2PhysMap;
    typedef DenseMap<int, VirtReg2IndexFunctor> Virt2StackSlotMap;
    typedef std::multimap<MachineInstr*, unsigned> MI2VirtMap;

  private:
    MachineFunction* mf_;
    Virt2PhysMap v2pMap_;
    Virt2StackSlotMap v2ssMap_;
    MI2VirtMap mi2vMap_;
    
    VirtRegMap(const VirtRegMap&);     // DO NOT IMPLEMENT
    void operator=(const VirtRegMap&); // DO NOT IMPLEMENT

    enum {
      NO_PHYS_REG = 0,
      NO_STACK_SLOT = ~0 >> 1
    };

  public:
    VirtRegMap(MachineFunction& mf)
      : mf_(&mf), v2pMap_(NO_PHYS_REG), v2ssMap_(NO_STACK_SLOT) {
      grow();
    }

    void grow();

    bool hasPhys(unsigned virtReg) const {
      return getPhys(virtReg) != NO_PHYS_REG;
    }

    unsigned getPhys(unsigned virtReg) const {
      assert(MRegisterInfo::isVirtualRegister(virtReg));
      return v2pMap_[virtReg];
    }

    void assignVirt2Phys(unsigned virtReg, unsigned physReg) {
      assert(MRegisterInfo::isVirtualRegister(virtReg) &&
             MRegisterInfo::isPhysicalRegister(physReg));
      assert(v2pMap_[virtReg] == NO_PHYS_REG &&
             "attempt to assign physical register to already mapped "
             "virtual register");
      v2pMap_[virtReg] = physReg;
    }

    void clearVirt(unsigned virtReg) {
      assert(MRegisterInfo::isVirtualRegister(virtReg));
      assert(v2pMap_[virtReg] != NO_PHYS_REG &&
             "attempt to clear a not assigned virtual register");
      v2pMap_[virtReg] = NO_PHYS_REG;
    }

    void clearAllVirt() {
      v2pMap_.clear();
      grow();
    }

    bool hasStackSlot(unsigned virtReg) const {
      return getStackSlot(virtReg) != NO_STACK_SLOT;
    }

    int getStackSlot(unsigned virtReg) const {
      assert(MRegisterInfo::isVirtualRegister(virtReg));
      return v2ssMap_[virtReg];
    }

    int assignVirt2StackSlot(unsigned virtReg);
    void assignVirt2StackSlot(unsigned virtReg, int frameIndex);

    void virtFolded(unsigned virtReg, MachineInstr* oldMI,
                    MachineInstr* newMI);

    std::pair<MI2VirtMap::const_iterator, MI2VirtMap::const_iterator>
    getFoldedVirts(MachineInstr* MI) const {
      return mi2vMap_.equal_range(MI);
    }

    void print(std::ostream &OS) const;
    void dump() const;
  };

  inline std::ostream &operator<<(std::ostream &OS, const VirtRegMap &VRM) {
    VRM.print(OS);
    return OS;
  }

  /// Spiller interface: Implementations of this interface assign spilled
  /// virtual registers to stack slots, rewriting the code.
  struct Spiller {
    virtual ~Spiller();
    virtual bool runOnMachineFunction(MachineFunction &MF,
                                      const VirtRegMap &VRM) = 0;
  };

  /// createSpiller - Create an return a spiller object, as specified on the
  /// command line.
  Spiller* createSpiller();

} // End llvm namespace

#endif