ARMBaseRegisterInfo.h

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//===-- ARMBaseRegisterInfo.h - ARM Register Information Impl ---*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains the base ARM implementation of TargetRegisterInfo class.
//
//===----------------------------------------------------------------------===//

#ifndef ARMBASEREGISTERINFO_H
#define ARMBASEREGISTERINFO_H

#include "ARM.h"
#include "llvm/Target/TargetRegisterInfo.h"

#define GET_REGINFO_HEADER
#include "ARMGenRegisterInfo.inc"

namespace llvm {
  class ARMSubtarget;
  class ARMBaseInstrInfo;
  class Type;

/// Register allocation hints.
namespace ARMRI {
  enum {
    RegPairOdd  = 1,
    RegPairEven = 2
  };
}

/// isARMArea1Register - Returns true if the register is a low register (r0-r7)
/// or a stack/pc register that we should push/pop.
static inline bool isARMArea1Register(unsigned Reg, bool isIOS) {
  using namespace ARM;
  switch (Reg) {
    case R0:  case R1:  case R2:  case R3:
    case R4:  case R5:  case R6:  case R7:
    case LR:  case SP:  case PC:
      return true;
    case R8:  case R9:  case R10: case R11:
      // For iOS we want r7 and lr to be next to each other.
      return !isIOS;
    default:
      return false;
  }
}

static inline bool isARMArea2Register(unsigned Reg, bool isIOS) {
  using namespace ARM;
  switch (Reg) {
    case R8: case R9: case R10: case R11:
      // iOS has this second area.
      return isIOS;
    default:
      return false;
  }
}

static inline bool isARMArea3Register(unsigned Reg, bool isIOS) {
  using namespace ARM;
  switch (Reg) {
    case D15: case D14: case D13: case D12:
    case D11: case D10: case D9:  case D8:
      return true;
    default:
      return false;
  }
}

class ARMBaseRegisterInfo : public ARMGenRegisterInfo {
protected:
  const ARMSubtarget &STI;

  /// FramePtr - ARM physical register used as frame ptr.
  unsigned FramePtr;

  /// BasePtr - ARM physical register used as a base ptr in complex stack
  /// frames. I.e., when we need a 3rd base, not just SP and FP, due to
  /// variable size stack objects.
  unsigned BasePtr;

  // Can be only subclassed.
  explicit ARMBaseRegisterInfo(const ARMSubtarget &STI);

  // Return the opcode that implements 'Op', or 0 if no opcode
  unsigned getOpcode(int Op) const;

public:
  /// Code Generation virtual methods...
  const uint16_t *getCalleeSavedRegs(const MachineFunction *MF = 0) const;
  const uint32_t *getCallPreservedMask(CallingConv::ID) const;
  const uint32_t *getNoPreservedMask() const;

  /// getThisReturnPreservedMask - Returns a call preserved mask specific to the
  /// case that 'returned' is on an i32 first argument if the calling convention
  /// is one that can (partially) model this attribute with a preserved mask
  /// (i.e. it is a calling convention that uses the same register for the first
  /// i32 argument and an i32 return value)
  ///
  /// Should return NULL in the case that the calling convention does not have
  /// this property
  const uint32_t *getThisReturnPreservedMask(CallingConv::ID) const;
  
  BitVector getReservedRegs(const MachineFunction &MF) const;

  const TargetRegisterClass*
  getPointerRegClass(const MachineFunction &MF, unsigned Kind = 0) const;
  const TargetRegisterClass*
  getCrossCopyRegClass(const TargetRegisterClass *RC) const;

  const TargetRegisterClass*
  getLargestLegalSuperClass(const TargetRegisterClass *RC) const;

  unsigned getRegPressureLimit(const TargetRegisterClass *RC,
                               MachineFunction &MF) const;

  void getRegAllocationHints(unsigned VirtReg,
                             ArrayRef<MCPhysReg> Order,
                             SmallVectorImpl<MCPhysReg> &Hints,
                             const MachineFunction &MF,
                             const VirtRegMap *VRM) const;

  void UpdateRegAllocHint(unsigned Reg, unsigned NewReg,
                          MachineFunction &MF) const;

  virtual bool avoidWriteAfterWrite(const TargetRegisterClass *RC) const;

  bool hasBasePointer(const MachineFunction &MF) const;

  bool canRealignStack(const MachineFunction &MF) const;
  bool needsStackRealignment(const MachineFunction &MF) const;
  int64_t getFrameIndexInstrOffset(const MachineInstr *MI, int Idx) const;
  bool needsFrameBaseReg(MachineInstr *MI, int64_t Offset) const;
  void materializeFrameBaseRegister(MachineBasicBlock *MBB,
                                    unsigned BaseReg, int FrameIdx,
                                    int64_t Offset) const;
  void resolveFrameIndex(MachineBasicBlock::iterator I,
                         unsigned BaseReg, int64_t Offset) const;
  bool isFrameOffsetLegal(const MachineInstr *MI, int64_t Offset) const;

  bool cannotEliminateFrame(const MachineFunction &MF) const;

  // Debug information queries.
  unsigned getFrameRegister(const MachineFunction &MF) const;
  unsigned getBaseRegister() const { return BasePtr; }

  bool isLowRegister(unsigned Reg) const;


  /// emitLoadConstPool - Emits a load from constpool to materialize the
  /// specified immediate.
  virtual void emitLoadConstPool(MachineBasicBlock &MBB,
                                 MachineBasicBlock::iterator &MBBI,
                                 DebugLoc dl,
                                 unsigned DestReg, unsigned SubIdx,
                                 int Val,
                                 ARMCC::CondCodes Pred = ARMCC::AL,
                                 unsigned PredReg = 0,
                                 unsigned MIFlags = MachineInstr::NoFlags)const;

  /// Code Generation virtual methods...
  virtual bool requiresRegisterScavenging(const MachineFunction &MF) const;

  virtual bool trackLivenessAfterRegAlloc(const MachineFunction &MF) const;

  virtual bool requiresFrameIndexScavenging(const MachineFunction &MF) const;

  virtual bool requiresVirtualBaseRegisters(const MachineFunction &MF) const;

  virtual void eliminateFrameIndex(MachineBasicBlock::iterator II,
                                   int SPAdj, unsigned FIOperandNum,
                                   RegScavenger *RS = NULL) const;
};

} // end namespace llvm

#endif