runtime/mirror/var_handle.h - LeafOS-Project/android_art - Gitiles

 /*
  * Copyright (C) 2017 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #ifndef ART_RUNTIME_MIRROR_VAR_HANDLE_H_
 #define ART_RUNTIME_MIRROR_VAR_HANDLE_H_

 #include "handle.h"
 #include "interpreter/shadow_frame.h"
 #include "jvalue.h"
 #include "object.h"

 namespace art {

 template<class T> class Handle;
 class InstructionOperands;
 template<class T> class ObjPtr;

 enum class Intrinsics;

 struct VarHandleOffsets;
 struct FieldVarHandleOffsets;
 struct ArrayElementVarHandleOffsets;
 struct ByteArrayViewVarHandleOffsets;
 struct ByteBufferViewVarHandleOffsets;

 class ReflectiveValueVisitor;
 class ShadowFrameGetter;

 namespace mirror {

 class MethodType;
 class VarHandleTest;

 // C++ mirror of java.lang.invoke.VarHandle
 class MANAGED VarHandle : public Object {
  public:
   // The maximum number of parameters a VarHandle accessor method can
   // take. The Worst case is equivalent to a compare-and-swap
   // operation on an array element which requires four parameters
   // (array, index, old, new).
   static constexpr int kMaxAccessorParameters = 4;

   // The maximum number of VarType parameters a VarHandle accessor
   // method can take.
   static constexpr size_t kMaxVarTypeParameters = 2;

   // The minimum number of CoordinateType parameters a VarHandle acessor method may take.
   static constexpr size_t kMinCoordinateTypes = 0;

   // The maximum number of CoordinateType parameters a VarHandle acessor method may take.
   static constexpr size_t kMaxCoordinateTypes = 2;

   // Enumeration of the possible access modes. This mirrors the enum
   // in java.lang.invoke.VarHandle.
   enum class AccessMode : uint32_t {
     kGet,
     kSet,
     kGetVolatile,
     kSetVolatile,
     kGetAcquire,
     kSetRelease,
     kGetOpaque,
     kSetOpaque,
     kCompareAndSet,
     kCompareAndExchange,
     kCompareAndExchangeAcquire,
     kCompareAndExchangeRelease,
     kWeakCompareAndSetPlain,
     kWeakCompareAndSet,
     kWeakCompareAndSetAcquire,
     kWeakCompareAndSetRelease,
     kGetAndSet,
     kGetAndSetAcquire,
     kGetAndSetRelease,
     kGetAndAdd,
     kGetAndAddAcquire,
     kGetAndAddRelease,
     kGetAndBitwiseOr,
     kGetAndBitwiseOrRelease,
     kGetAndBitwiseOrAcquire,
     kGetAndBitwiseAnd,
     kGetAndBitwiseAndRelease,
     kGetAndBitwiseAndAcquire,
     kGetAndBitwiseXor,
     kGetAndBitwiseXorRelease,
     kGetAndBitwiseXorAcquire,
     kLast = kGetAndBitwiseXorAcquire,
   };
   constexpr static size_t kNumberOfAccessModes = static_cast<size_t>(AccessMode::kLast) + 1u;

   // Enumeration for describing the parameter and return types of an AccessMode.
   enum class AccessModeTemplate : uint32_t {
     kGet,                 // T Op(C0..CN)
     kSet,                 // void Op(C0..CN, T)
     kCompareAndSet,       // boolean Op(C0..CN, T, T)
     kCompareAndExchange,  // T Op(C0..CN, T, T)
     kGetAndUpdate,        // T Op(C0..CN, T)
   };

   // Returns true if the AccessMode specified is a supported operation.
   bool IsAccessModeSupported(AccessMode accessMode) REQUIRES_SHARED(Locks::mutator_lock_) {
     return (GetAccessModesBitMask() & (1u << static_cast<uint32_t>(accessMode))) != 0;
   }

   enum MatchKind : uint8_t {
     kNone,
     kWithConversions,
     kExact
   };

   // Returns match information on the compatability between the exact method type for
   // 'access_mode' and the provided 'method_type'.
   MatchKind GetMethodTypeMatchForAccessMode(AccessMode access_mode, ObjPtr<MethodType> method_type)
         REQUIRES_SHARED(Locks::mutator_lock_);

   // Allocates and returns the MethodType associated with the
   // AccessMode. No check is made for whether the AccessMode is a
   // supported operation so the MethodType can be used when raising a
   // WrongMethodTypeException exception.
   ObjPtr<MethodType> GetMethodTypeForAccessMode(Thread* self, AccessMode accessMode)
       REQUIRES_SHARED(Locks::mutator_lock_);

   // Returns a string representing the descriptor of the MethodType associated with
   // this AccessMode.
   std::string PrettyDescriptorForAccessMode(AccessMode access_mode)
       REQUIRES_SHARED(Locks::mutator_lock_);

   bool Access(AccessMode access_mode,
               ShadowFrame* shadow_frame,
               const InstructionOperands* const operands,
               JValue* result)
       REQUIRES_SHARED(Locks::mutator_lock_);

   // Gets the variable type that is operated on by this VarHandle instance.
   ObjPtr<Class> GetVarType() REQUIRES_SHARED(Locks::mutator_lock_);

   // Gets the return type descriptor for a named accessor method,
   // nullptr if accessor_method is not supported.
   static const char* GetReturnTypeDescriptor(const char* accessor_method);

   // Returns the AccessMode corresponding to a VarHandle accessor intrinsic.
   static AccessMode GetAccessModeByIntrinsic(Intrinsics ordinal);

   // Returns true and sets access_mode if method_name corresponds to a
   // VarHandle access method, such as "setOpaque". Returns false otherwise.
   static bool GetAccessModeByMethodName(const char* method_name, AccessMode* access_mode);

   // Returns the AccessModeTemplate for a given mode.
   static AccessModeTemplate GetAccessModeTemplate(AccessMode access_mode);

   // Returns the AccessModeTemplate corresponding to a VarHandle accessor intrinsic.
   static AccessModeTemplate GetAccessModeTemplateByIntrinsic(Intrinsics ordinal);

   // Returns the number of VarType parameters for an access mode template.
   static int32_t GetNumberOfVarTypeParameters(AccessModeTemplate access_mode_template);

   static MemberOffset VarTypeOffset() {
     return MemberOffset(OFFSETOF_MEMBER(VarHandle, var_type_));
   }

   static MemberOffset CoordinateType0Offset() {
     return MemberOffset(OFFSETOF_MEMBER(VarHandle, coordinate_type0_));
   }

   static MemberOffset CoordinateType1Offset() {
     return MemberOffset(OFFSETOF_MEMBER(VarHandle, coordinate_type1_));
   }

   static MemberOffset AccessModesBitMaskOffset() {
     return MemberOffset(OFFSETOF_MEMBER(VarHandle, access_modes_bit_mask_));
   }

  private:
   ObjPtr<Class> GetCoordinateType0() REQUIRES_SHARED(Locks::mutator_lock_);
   ObjPtr<Class> GetCoordinateType1() REQUIRES_SHARED(Locks::mutator_lock_);
   int32_t GetAccessModesBitMask() REQUIRES_SHARED(Locks::mutator_lock_);

   static ObjPtr<MethodType> GetMethodTypeForAccessMode(Thread* self,
                                                        ObjPtr<VarHandle> var_handle,
                                                        AccessMode access_mode)
       REQUIRES_SHARED(Locks::mutator_lock_);

   HeapReference<mirror::Class> coordinate_type0_;
   HeapReference<mirror::Class> coordinate_type1_;
   HeapReference<mirror::Class> var_type_;
   int32_t access_modes_bit_mask_;

   friend class VarHandleTest;  // for testing purposes
   friend struct art::VarHandleOffsets;  // for verifying offset information
   DISALLOW_IMPLICIT_CONSTRUCTORS(VarHandle);
 };

 // Represents a VarHandle to a static or instance field.
 // The corresponding managed class in libart java.lang.invoke.FieldVarHandle.
 class MANAGED FieldVarHandle : public VarHandle {
  public:
   bool Access(AccessMode access_mode,
               ShadowFrame* shadow_frame,
               const InstructionOperands* const operands,
               JValue* result)
       REQUIRES_SHARED(Locks::mutator_lock_);

   ArtField* GetField() REQUIRES_SHARED(Locks::mutator_lock_);

   // Used for updating var-handles to obsolete fields.
   void VisitTarget(ReflectiveValueVisitor* v) REQUIRES(Locks::mutator_lock_);

   static MemberOffset ArtFieldOffset() {
     return MemberOffset(OFFSETOF_MEMBER(FieldVarHandle, art_field_));
   }

  private:
   // ArtField instance corresponding to variable for accessors.
   int64_t art_field_;

   friend class VarHandleTest;  // for var_handle_test.
   friend struct art::FieldVarHandleOffsets;  // for verifying offset information
   DISALLOW_IMPLICIT_CONSTRUCTORS(FieldVarHandle);
 };

 // Represents a VarHandle providing accessors to an array.
 // The corresponding managed class in libart java.lang.invoke.ArrayElementVarHandle.
 class MANAGED ArrayElementVarHandle : public VarHandle {
  public:
     bool Access(AccessMode access_mode,
                 ShadowFrame* shadow_frame,
                 const InstructionOperands* const operands,
                 JValue* result)
       REQUIRES_SHARED(Locks::mutator_lock_);

  private:
   friend class VarHandleTest;
   DISALLOW_IMPLICIT_CONSTRUCTORS(ArrayElementVarHandle);
 };

 // Represents a VarHandle providing accessors to a view of a ByteArray.
 // The corresponding managed class in libart java.lang.invoke.ByteArrayViewVarHandle.
 class MANAGED ByteArrayViewVarHandle : public VarHandle {
  public:
   bool Access(AccessMode access_mode,
               ShadowFrame* shadow_frame,
               const InstructionOperands* const operands,
               JValue* result)
       REQUIRES_SHARED(Locks::mutator_lock_);

   bool GetNativeByteOrder() REQUIRES_SHARED(Locks::mutator_lock_);

  private:
   static MemberOffset NativeByteOrderOffset() {
     return MemberOffset(OFFSETOF_MEMBER(ByteArrayViewVarHandle, native_byte_order_));
   }

   // Flag indicating that accessors should use native byte-ordering.
   uint8_t native_byte_order_;

   friend class VarHandleTest;  // for var_handle_test.
   friend struct art::ByteArrayViewVarHandleOffsets;  // for verifying offset information
   DISALLOW_IMPLICIT_CONSTRUCTORS(ByteArrayViewVarHandle);
 };

 // Represents a VarHandle providing accessors to a view of a ByteBuffer
 // The corresponding managed class in libart java.lang.invoke.ByteBufferViewVarHandle.
 class MANAGED ByteBufferViewVarHandle : public VarHandle {
  public:
   bool Access(AccessMode access_mode,
               ShadowFrame* shadow_frame,
               const InstructionOperands* const operands,
               JValue* result)
       REQUIRES_SHARED(Locks::mutator_lock_);

   bool GetNativeByteOrder() REQUIRES_SHARED(Locks::mutator_lock_);

  private:
   bool AccessHeapBuffer(AccessMode access_mode,
                         ObjPtr<Object> byte_buffer,
                         int buffer_offset,
                         ObjPtr<ByteArray> heap_byte_array,
                         ShadowFrameGetter* getter,
                         JValue* result)
       REQUIRES_SHARED(Locks::mutator_lock_);

   bool AccessFixedMemory(AccessMode access_mode,
                          ObjPtr<Object> byte_buffer,
                          int buffer_offset,
                          ShadowFrameGetter* getter,
                          JValue* result)
       REQUIRES_SHARED(Locks::mutator_lock_);

   static MemberOffset NativeByteOrderOffset() {
     return MemberOffset(OFFSETOF_MEMBER(ByteBufferViewVarHandle, native_byte_order_));
   }

   // Flag indicating that accessors should use native byte-ordering.
   uint8_t native_byte_order_;

   friend class VarHandleTest;  // for var_handle_test.
   friend struct art::ByteBufferViewVarHandleOffsets;  // for verifying offset information
   DISALLOW_IMPLICIT_CONSTRUCTORS(ByteBufferViewVarHandle);
 };

 }  // namespace mirror
 }  // namespace art

 #endif  // ART_RUNTIME_MIRROR_VAR_HANDLE_H_
	/*
	* Copyright (C) 2017 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#ifndef ART_RUNTIME_MIRROR_VAR_HANDLE_H_
	#define ART_RUNTIME_MIRROR_VAR_HANDLE_H_

	#include "handle.h"
	#include "interpreter/shadow_frame.h"
	#include "jvalue.h"
	#include "object.h"

	namespace art {

	template<class T> class Handle;
	class InstructionOperands;
	template<class T> class ObjPtr;

	enum class Intrinsics;

	struct VarHandleOffsets;
	struct FieldVarHandleOffsets;
	struct ArrayElementVarHandleOffsets;
	struct ByteArrayViewVarHandleOffsets;
	struct ByteBufferViewVarHandleOffsets;

	class ReflectiveValueVisitor;
	class ShadowFrameGetter;

	namespace mirror {

	class MethodType;
	class VarHandleTest;

	// C++ mirror of java.lang.invoke.VarHandle
	class MANAGED VarHandle : public Object {
	public:
	// The maximum number of parameters a VarHandle accessor method can
	// take. The Worst case is equivalent to a compare-and-swap
	// operation on an array element which requires four parameters
	// (array, index, old, new).
	static constexpr int kMaxAccessorParameters = 4;

	// The maximum number of VarType parameters a VarHandle accessor
	// method can take.
	static constexpr size_t kMaxVarTypeParameters = 2;

	// The minimum number of CoordinateType parameters a VarHandle acessor method may take.
	static constexpr size_t kMinCoordinateTypes = 0;

	// The maximum number of CoordinateType parameters a VarHandle acessor method may take.
	static constexpr size_t kMaxCoordinateTypes = 2;

	// Enumeration of the possible access modes. This mirrors the enum
	// in java.lang.invoke.VarHandle.
	enum class AccessMode : uint32_t {
	kGet,
	kSet,
	kGetVolatile,
	kSetVolatile,
	kGetAcquire,
	kSetRelease,
	kGetOpaque,
	kSetOpaque,
	kCompareAndSet,
	kCompareAndExchange,
	kCompareAndExchangeAcquire,
	kCompareAndExchangeRelease,
	kWeakCompareAndSetPlain,
	kWeakCompareAndSet,
	kWeakCompareAndSetAcquire,
	kWeakCompareAndSetRelease,
	kGetAndSet,
	kGetAndSetAcquire,
	kGetAndSetRelease,
	kGetAndAdd,
	kGetAndAddAcquire,
	kGetAndAddRelease,
	kGetAndBitwiseOr,
	kGetAndBitwiseOrRelease,
	kGetAndBitwiseOrAcquire,
	kGetAndBitwiseAnd,
	kGetAndBitwiseAndRelease,
	kGetAndBitwiseAndAcquire,
	kGetAndBitwiseXor,
	kGetAndBitwiseXorRelease,
	kGetAndBitwiseXorAcquire,
	kLast = kGetAndBitwiseXorAcquire,
	};
	constexpr static size_t kNumberOfAccessModes = static_cast<size_t>(AccessMode::kLast) + 1u;

	// Enumeration for describing the parameter and return types of an AccessMode.
	enum class AccessModeTemplate : uint32_t {
	kGet, // T Op(C0..CN)
	kSet, // void Op(C0..CN, T)
	kCompareAndSet, // boolean Op(C0..CN, T, T)
	kCompareAndExchange, // T Op(C0..CN, T, T)
	kGetAndUpdate, // T Op(C0..CN, T)
	};

	// Returns true if the AccessMode specified is a supported operation.
	bool IsAccessModeSupported(AccessMode accessMode) REQUIRES_SHARED(Locks::mutator_lock_) {
	return (GetAccessModesBitMask() & (1u << static_cast<uint32_t>(accessMode))) != 0;
	}

	enum MatchKind : uint8_t {
	kNone,
	kWithConversions,
	kExact
	};

	// Returns match information on the compatability between the exact method type for
	// 'access_mode' and the provided 'method_type'.
	MatchKind GetMethodTypeMatchForAccessMode(AccessMode access_mode, ObjPtr<MethodType> method_type)
	REQUIRES_SHARED(Locks::mutator_lock_);

	// Allocates and returns the MethodType associated with the
	// AccessMode. No check is made for whether the AccessMode is a
	// supported operation so the MethodType can be used when raising a
	// WrongMethodTypeException exception.
	ObjPtr<MethodType> GetMethodTypeForAccessMode(Thread* self, AccessMode accessMode)
	REQUIRES_SHARED(Locks::mutator_lock_);

	// Returns a string representing the descriptor of the MethodType associated with
	// this AccessMode.
	std::string PrettyDescriptorForAccessMode(AccessMode access_mode)
	REQUIRES_SHARED(Locks::mutator_lock_);

	bool Access(AccessMode access_mode,
	ShadowFrame* shadow_frame,
	const InstructionOperands* const operands,
	JValue* result)
	REQUIRES_SHARED(Locks::mutator_lock_);

	// Gets the variable type that is operated on by this VarHandle instance.
	ObjPtr<Class> GetVarType() REQUIRES_SHARED(Locks::mutator_lock_);

	// Gets the return type descriptor for a named accessor method,
	// nullptr if accessor_method is not supported.
	static const char* GetReturnTypeDescriptor(const char* accessor_method);

	// Returns the AccessMode corresponding to a VarHandle accessor intrinsic.
	static AccessMode GetAccessModeByIntrinsic(Intrinsics ordinal);

	// Returns true and sets access_mode if method_name corresponds to a
	// VarHandle access method, such as "setOpaque". Returns false otherwise.
	static bool GetAccessModeByMethodName(const char* method_name, AccessMode* access_mode);

	// Returns the AccessModeTemplate for a given mode.
	static AccessModeTemplate GetAccessModeTemplate(AccessMode access_mode);

	// Returns the AccessModeTemplate corresponding to a VarHandle accessor intrinsic.
	static AccessModeTemplate GetAccessModeTemplateByIntrinsic(Intrinsics ordinal);

	// Returns the number of VarType parameters for an access mode template.
	static int32_t GetNumberOfVarTypeParameters(AccessModeTemplate access_mode_template);

	static MemberOffset VarTypeOffset() {
	return MemberOffset(OFFSETOF_MEMBER(VarHandle, var_type_));
	}

	static MemberOffset CoordinateType0Offset() {
	return MemberOffset(OFFSETOF_MEMBER(VarHandle, coordinate_type0_));
	}

	static MemberOffset CoordinateType1Offset() {
	return MemberOffset(OFFSETOF_MEMBER(VarHandle, coordinate_type1_));
	}

	static MemberOffset AccessModesBitMaskOffset() {
	return MemberOffset(OFFSETOF_MEMBER(VarHandle, access_modes_bit_mask_));
	}

	private:
	ObjPtr<Class> GetCoordinateType0() REQUIRES_SHARED(Locks::mutator_lock_);
	ObjPtr<Class> GetCoordinateType1() REQUIRES_SHARED(Locks::mutator_lock_);
	int32_t GetAccessModesBitMask() REQUIRES_SHARED(Locks::mutator_lock_);

	static ObjPtr<MethodType> GetMethodTypeForAccessMode(Thread* self,
	ObjPtr<VarHandle> var_handle,
	AccessMode access_mode)
	REQUIRES_SHARED(Locks::mutator_lock_);

	HeapReference<mirror::Class> coordinate_type0_;
	HeapReference<mirror::Class> coordinate_type1_;
	HeapReference<mirror::Class> var_type_;
	int32_t access_modes_bit_mask_;

	friend class VarHandleTest; // for testing purposes
	friend struct art::VarHandleOffsets; // for verifying offset information
	DISALLOW_IMPLICIT_CONSTRUCTORS(VarHandle);
	};

	// Represents a VarHandle to a static or instance field.
	// The corresponding managed class in libart java.lang.invoke.FieldVarHandle.
	class MANAGED FieldVarHandle : public VarHandle {
	public:
	bool Access(AccessMode access_mode,
	ShadowFrame* shadow_frame,
	const InstructionOperands* const operands,
	JValue* result)
	REQUIRES_SHARED(Locks::mutator_lock_);

	ArtField* GetField() REQUIRES_SHARED(Locks::mutator_lock_);

	// Used for updating var-handles to obsolete fields.
	void VisitTarget(ReflectiveValueVisitor* v) REQUIRES(Locks::mutator_lock_);

	static MemberOffset ArtFieldOffset() {
	return MemberOffset(OFFSETOF_MEMBER(FieldVarHandle, art_field_));
	}

	private:
	// ArtField instance corresponding to variable for accessors.
	int64_t art_field_;

	friend class VarHandleTest; // for var_handle_test.
	friend struct art::FieldVarHandleOffsets; // for verifying offset information
	DISALLOW_IMPLICIT_CONSTRUCTORS(FieldVarHandle);
	};

	// Represents a VarHandle providing accessors to an array.
	// The corresponding managed class in libart java.lang.invoke.ArrayElementVarHandle.
	class MANAGED ArrayElementVarHandle : public VarHandle {
	public:
	bool Access(AccessMode access_mode,
	ShadowFrame* shadow_frame,
	const InstructionOperands* const operands,
	JValue* result)
	REQUIRES_SHARED(Locks::mutator_lock_);

	private:
	friend class VarHandleTest;
	DISALLOW_IMPLICIT_CONSTRUCTORS(ArrayElementVarHandle);
	};

	// Represents a VarHandle providing accessors to a view of a ByteArray.
	// The corresponding managed class in libart java.lang.invoke.ByteArrayViewVarHandle.
	class MANAGED ByteArrayViewVarHandle : public VarHandle {
	public:
	bool Access(AccessMode access_mode,
	ShadowFrame* shadow_frame,
	const InstructionOperands* const operands,
	JValue* result)
	REQUIRES_SHARED(Locks::mutator_lock_);

	bool GetNativeByteOrder() REQUIRES_SHARED(Locks::mutator_lock_);

	private:
	static MemberOffset NativeByteOrderOffset() {
	return MemberOffset(OFFSETOF_MEMBER(ByteArrayViewVarHandle, native_byte_order_));
	}

	// Flag indicating that accessors should use native byte-ordering.
	uint8_t native_byte_order_;

	friend class VarHandleTest; // for var_handle_test.
	friend struct art::ByteArrayViewVarHandleOffsets; // for verifying offset information
	DISALLOW_IMPLICIT_CONSTRUCTORS(ByteArrayViewVarHandle);
	};

	// Represents a VarHandle providing accessors to a view of a ByteBuffer
	// The corresponding managed class in libart java.lang.invoke.ByteBufferViewVarHandle.
	class MANAGED ByteBufferViewVarHandle : public VarHandle {
	public:
	bool Access(AccessMode access_mode,
	ShadowFrame* shadow_frame,
	const InstructionOperands* const operands,
	JValue* result)
	REQUIRES_SHARED(Locks::mutator_lock_);

	bool GetNativeByteOrder() REQUIRES_SHARED(Locks::mutator_lock_);

	private:
	bool AccessHeapBuffer(AccessMode access_mode,
	ObjPtr<Object> byte_buffer,
	int buffer_offset,
	ObjPtr<ByteArray> heap_byte_array,
	ShadowFrameGetter* getter,
	JValue* result)
	REQUIRES_SHARED(Locks::mutator_lock_);

	bool AccessFixedMemory(AccessMode access_mode,
	ObjPtr<Object> byte_buffer,
	int buffer_offset,
	ShadowFrameGetter* getter,
	JValue* result)
	REQUIRES_SHARED(Locks::mutator_lock_);

	static MemberOffset NativeByteOrderOffset() {
	return MemberOffset(OFFSETOF_MEMBER(ByteBufferViewVarHandle, native_byte_order_));
	}

	// Flag indicating that accessors should use native byte-ordering.
	uint8_t native_byte_order_;

	friend class VarHandleTest; // for var_handle_test.
	friend struct art::ByteBufferViewVarHandleOffsets; // for verifying offset information
	DISALLOW_IMPLICIT_CONSTRUCTORS(ByteBufferViewVarHandle);
	};

	} // namespace mirror
	} // namespace art

	#endif // ART_RUNTIME_MIRROR_VAR_HANDLE_H_