compiler/utils/jni_macro_assembler.h - SHIFTPHONES/android_art - Gitiles

 /*
  * Copyright (C) 2011 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_COMPILER_UTILS_JNI_MACRO_ASSEMBLER_H_
 #define ART_COMPILER_UTILS_JNI_MACRO_ASSEMBLER_H_

 #include <vector>

 #include <android-base/logging.h>

 #include "arch/instruction_set.h"
 #include "base/arena_allocator.h"
 #include "base/arena_object.h"
 #include "base/array_ref.h"
 #include "base/enums.h"
 #include "base/macros.h"
 #include "managed_register.h"
 #include "offsets.h"

 namespace art {

 class ArenaAllocator;
 class DebugFrameOpCodeWriterForAssembler;
 class InstructionSetFeatures;
 class MemoryRegion;
 class JNIMacroLabel;

 enum class JNIMacroUnaryCondition {
   kZero,
   kNotZero
 };

 class ArgumentLocation {
  public:
   ArgumentLocation(ManagedRegister reg, size_t size)
       : reg_(reg), frame_offset_(0u), size_(size) {
     DCHECK(reg.IsRegister());
   }

   ArgumentLocation(FrameOffset frame_offset, size_t size)
       : reg_(ManagedRegister::NoRegister()), frame_offset_(frame_offset), size_(size) {}

   bool IsRegister() const {
     return reg_.IsRegister();
   }

   ManagedRegister GetRegister() const {
     DCHECK(IsRegister());
     return reg_;
   }

   FrameOffset GetFrameOffset() const {
     DCHECK(!IsRegister());
     return frame_offset_;
   }

   size_t GetSize() const {
     return size_;
   }

  private:
   ManagedRegister reg_;
   FrameOffset frame_offset_;
   size_t size_;
 };

 template <PointerSize kPointerSize>
 class JNIMacroAssembler : public DeletableArenaObject<kArenaAllocAssembler> {
  public:
   static std::unique_ptr<JNIMacroAssembler<kPointerSize>> Create(
       ArenaAllocator* allocator,
       InstructionSet instruction_set,
       const InstructionSetFeatures* instruction_set_features = nullptr);

   // Finalize the code; emit slow paths, fixup branches, add literal pool, etc.
   virtual void FinalizeCode() = 0;

   // Size of generated code
   virtual size_t CodeSize() const = 0;

   // Copy instructions out of assembly buffer into the given region of memory
   virtual void FinalizeInstructions(const MemoryRegion& region) = 0;

   // Emit code that will create an activation on the stack
   virtual void BuildFrame(size_t frame_size,
                           ManagedRegister method_reg,
                           ArrayRef<const ManagedRegister> callee_save_regs) = 0;

   // Emit code that will remove an activation from the stack
   //
   // Argument `may_suspend` must be `true` if the compiled method may be
   // suspended during its execution (otherwise `false`, if it is impossible
   // to suspend during its execution).
   virtual void RemoveFrame(size_t frame_size,
                            ArrayRef<const ManagedRegister> callee_save_regs,
                            bool may_suspend) = 0;

   virtual void IncreaseFrameSize(size_t adjust) = 0;
   virtual void DecreaseFrameSize(size_t adjust) = 0;

   // Return the same core register but with correct size if the architecture-specific
   // ManagedRegister has different representation for different sizes.
   virtual ManagedRegister CoreRegisterWithSize(ManagedRegister src, size_t size) = 0;

   // Store routines
   virtual void Store(FrameOffset offs, ManagedRegister src, size_t size) = 0;
   virtual void Store(ManagedRegister base, MemberOffset offs, ManagedRegister src, size_t size) = 0;
   virtual void StoreRef(FrameOffset dest, ManagedRegister src) = 0;
   virtual void StoreRawPtr(FrameOffset dest, ManagedRegister src) = 0;

   virtual void StoreImmediateToFrame(FrameOffset dest, uint32_t imm) = 0;

   virtual void StoreStackOffsetToThread(ThreadOffset<kPointerSize> thr_offs,
                                         FrameOffset fr_offs) = 0;

   virtual void StoreStackPointerToThread(ThreadOffset<kPointerSize> thr_offs) = 0;

   virtual void StoreSpanning(FrameOffset dest,
                              ManagedRegister src,
                              FrameOffset in_off) = 0;

   // Load routines
   virtual void Load(ManagedRegister dest, FrameOffset src, size_t size) = 0;
   virtual void Load(ManagedRegister dest, ManagedRegister base, MemberOffset offs, size_t size) = 0;

   virtual void LoadFromThread(ManagedRegister dest,
                               ThreadOffset<kPointerSize> src,
                               size_t size) = 0;

   virtual void LoadRef(ManagedRegister dest, FrameOffset src) = 0;
   // If unpoison_reference is true and kPoisonReference is true, then we negate the read reference.
   virtual void LoadRef(ManagedRegister dest,
                        ManagedRegister base,
                        MemberOffset offs,
                        bool unpoison_reference) = 0;

   virtual void LoadRawPtr(ManagedRegister dest, ManagedRegister base, Offset offs) = 0;

   virtual void LoadRawPtrFromThread(ManagedRegister dest, ThreadOffset<kPointerSize> offs) = 0;

   // Copying routines

   // Move arguments from `srcs` locations to `dests` locations.
   //
   // References shall be spilled to `refs` frame offsets (kInvalidReferenceOffset indicates
   // a non-reference type) if they are in registers and corresponding `dests` shall be
   // filled with `jobject` replacements. If the first argument is a reference, it is
   // assumed to be `this` and cannot be null, all other reference arguments can be null.
   virtual void MoveArguments(ArrayRef<ArgumentLocation> dests,
                              ArrayRef<ArgumentLocation> srcs,
                              ArrayRef<FrameOffset> refs) = 0;

   virtual void Move(ManagedRegister dest, ManagedRegister src, size_t size) = 0;

   virtual void CopyRawPtrFromThread(FrameOffset fr_offs, ThreadOffset<kPointerSize> thr_offs) = 0;

   virtual void CopyRawPtrToThread(ThreadOffset<kPointerSize> thr_offs,
                                   FrameOffset fr_offs,
                                   ManagedRegister scratch) = 0;

   virtual void CopyRef(FrameOffset dest, FrameOffset src) = 0;
   virtual void CopyRef(FrameOffset dest,
                        ManagedRegister base,
                        MemberOffset offs,
                        bool unpoison_reference) = 0;

   virtual void Copy(FrameOffset dest, FrameOffset src, size_t size) = 0;

   virtual void Copy(FrameOffset dest,
                     ManagedRegister src_base,
                     Offset src_offset,
                     ManagedRegister scratch,
                     size_t size) = 0;

   virtual void Copy(ManagedRegister dest_base,
                     Offset dest_offset,
                     FrameOffset src,
                     ManagedRegister scratch,
                     size_t size) = 0;

   virtual void Copy(FrameOffset dest,
                     FrameOffset src_base,
                     Offset src_offset,
                     ManagedRegister scratch,
                     size_t size) = 0;

   virtual void Copy(ManagedRegister dest,
                     Offset dest_offset,
                     ManagedRegister src,
                     Offset src_offset,
                     ManagedRegister scratch,
                     size_t size) = 0;

   virtual void Copy(FrameOffset dest,
                     Offset dest_offset,
                     FrameOffset src,
                     Offset src_offset,
                     ManagedRegister scratch,
                     size_t size) = 0;

   virtual void MemoryBarrier(ManagedRegister scratch) = 0;

   // Sign extension
   virtual void SignExtend(ManagedRegister mreg, size_t size) = 0;

   // Zero extension
   virtual void ZeroExtend(ManagedRegister mreg, size_t size) = 0;

   // Exploit fast access in managed code to Thread::Current()
   virtual void GetCurrentThread(ManagedRegister dest) = 0;
   virtual void GetCurrentThread(FrameOffset dest_offset) = 0;

   // Set up `out_reg` to hold a `jobject` (`StackReference<Object>*` to a spilled value),
   // or to be null if the value is null and `null_allowed`. `in_reg` holds a possibly
   // stale reference that can be used to avoid loading the spilled value to
   // see if the value is null.
   virtual void CreateJObject(ManagedRegister out_reg,
                              FrameOffset spilled_reference_offset,
                              ManagedRegister in_reg,
                              bool null_allowed) = 0;

   // Set up `out_off` to hold a `jobject` (`StackReference<Object>*` to a spilled value),
   // or to be null if the value is null and `null_allowed`.
   virtual void CreateJObject(FrameOffset out_off,
                              FrameOffset spilled_reference_offset,
                              bool null_allowed) = 0;

   // Heap::VerifyObject on src. In some cases (such as a reference to this) we
   // know that src may not be null.
   virtual void VerifyObject(ManagedRegister src, bool could_be_null) = 0;
   virtual void VerifyObject(FrameOffset src, bool could_be_null) = 0;

   // Jump to address held at [base+offset] (used for tail calls).
   virtual void Jump(ManagedRegister base, Offset offset) = 0;

   // Call to address held at [base+offset]
   virtual void Call(ManagedRegister base, Offset offset) = 0;
   virtual void Call(FrameOffset base, Offset offset) = 0;
   virtual void CallFromThread(ThreadOffset<kPointerSize> offset) = 0;

   // Generate suspend check and branch to `label` if there is a pending suspend request.
   virtual void SuspendCheck(JNIMacroLabel* label) = 0;

   // Generate code to check if Thread::Current()->exception_ is non-null
   // and branch to the `label` if it is.
   virtual void ExceptionPoll(JNIMacroLabel* label) = 0;
   // Deliver pending exception.
   virtual void DeliverPendingException() = 0;

   // Create a new label that can be used with Jump/Bind calls.
   virtual std::unique_ptr<JNIMacroLabel> CreateLabel() = 0;
   // Emit an unconditional jump to the label.
   virtual void Jump(JNIMacroLabel* label) = 0;
   // Emit a conditional jump to the label by applying a unary condition test to the GC marking flag.
   virtual void TestGcMarking(JNIMacroLabel* label, JNIMacroUnaryCondition cond) = 0;
   // Emit a conditional jump to the label by applying a unary condition test to object's mark bit.
   virtual void TestMarkBit(ManagedRegister ref,
                            JNIMacroLabel* label,
                            JNIMacroUnaryCondition cond) = 0;
   // Code at this offset will serve as the target for the Jump call.
   virtual void Bind(JNIMacroLabel* label) = 0;

   virtual ~JNIMacroAssembler() {}

   /**
    * @brief Buffer of DWARF's Call Frame Information opcodes.
    * @details It is used by debuggers and other tools to unwind the call stack.
    */
   virtual DebugFrameOpCodeWriterForAssembler& cfi() = 0;

   void SetEmitRunTimeChecksInDebugMode(bool value) {
     emit_run_time_checks_in_debug_mode_ = value;
   }

   static constexpr FrameOffset kInvalidReferenceOffset = FrameOffset(0);

  protected:
   JNIMacroAssembler() {}

   // Should run-time checks be emitted in debug mode?
   bool emit_run_time_checks_in_debug_mode_ = false;
 };

 // A "Label" class used with the JNIMacroAssembler
 // allowing one to use branches (jumping from one place to another).
 //
 // This is just an interface, so every platform must provide
 // its own implementation of it.
 //
 // It is only safe to use a label created
 // via JNIMacroAssembler::CreateLabel with that same macro assembler.
 class JNIMacroLabel {
  public:
   virtual ~JNIMacroLabel() = 0;

   const InstructionSet isa_;
  protected:
   explicit JNIMacroLabel(InstructionSet isa) : isa_(isa) {}
 };

 inline JNIMacroLabel::~JNIMacroLabel() {
   // Compulsory definition for a pure virtual destructor
   // to avoid linking errors.
 }

 template <typename T, PointerSize kPointerSize>
 class JNIMacroAssemblerFwd : public JNIMacroAssembler<kPointerSize> {
  public:
   void FinalizeCode() override {
     asm_.FinalizeCode();
   }

   size_t CodeSize() const override {
     return asm_.CodeSize();
   }

   void FinalizeInstructions(const MemoryRegion& region) override {
     asm_.FinalizeInstructions(region);
   }

   DebugFrameOpCodeWriterForAssembler& cfi() override {
     return asm_.cfi();
   }

  protected:
   explicit JNIMacroAssemblerFwd(ArenaAllocator* allocator) : asm_(allocator) {}

   T asm_;
 };

 template <typename Self, typename PlatformLabel, InstructionSet kIsa>
 class JNIMacroLabelCommon : public JNIMacroLabel {
  public:
   static Self* Cast(JNIMacroLabel* label) {
     CHECK(label != nullptr);
     CHECK_EQ(kIsa, label->isa_);

     return reinterpret_cast<Self*>(label);
   }

  protected:
   PlatformLabel* AsPlatformLabel() {
     return &label_;
   }

   JNIMacroLabelCommon() : JNIMacroLabel(kIsa) {
   }

   ~JNIMacroLabelCommon() override {}

  private:
   PlatformLabel label_;
 };

 }  // namespace art

 #endif  // ART_COMPILER_UTILS_JNI_MACRO_ASSEMBLER_H_
	/*
	* Copyright (C) 2011 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_COMPILER_UTILS_JNI_MACRO_ASSEMBLER_H_
	#define ART_COMPILER_UTILS_JNI_MACRO_ASSEMBLER_H_

	#include <vector>

	#include <android-base/logging.h>

	#include "arch/instruction_set.h"
	#include "base/arena_allocator.h"
	#include "base/arena_object.h"
	#include "base/array_ref.h"
	#include "base/enums.h"
	#include "base/macros.h"
	#include "managed_register.h"
	#include "offsets.h"

	namespace art {

	class ArenaAllocator;
	class DebugFrameOpCodeWriterForAssembler;
	class InstructionSetFeatures;
	class MemoryRegion;
	class JNIMacroLabel;

	enum class JNIMacroUnaryCondition {
	kZero,
	kNotZero
	};

	class ArgumentLocation {
	public:
	ArgumentLocation(ManagedRegister reg, size_t size)
	: reg_(reg), frame_offset_(0u), size_(size) {
	DCHECK(reg.IsRegister());
	}

	ArgumentLocation(FrameOffset frame_offset, size_t size)
	: reg_(ManagedRegister::NoRegister()), frame_offset_(frame_offset), size_(size) {}

	bool IsRegister() const {
	return reg_.IsRegister();
	}

	ManagedRegister GetRegister() const {
	DCHECK(IsRegister());
	return reg_;
	}

	FrameOffset GetFrameOffset() const {
	DCHECK(!IsRegister());
	return frame_offset_;
	}

	size_t GetSize() const {
	return size_;
	}

	private:
	ManagedRegister reg_;
	FrameOffset frame_offset_;
	size_t size_;
	};

	template <PointerSize kPointerSize>
	class JNIMacroAssembler : public DeletableArenaObject<kArenaAllocAssembler> {
	public:
	static std::unique_ptr<JNIMacroAssembler<kPointerSize>> Create(
	ArenaAllocator* allocator,
	InstructionSet instruction_set,
	const InstructionSetFeatures* instruction_set_features = nullptr);

	// Finalize the code; emit slow paths, fixup branches, add literal pool, etc.
	virtual void FinalizeCode() = 0;

	// Size of generated code
	virtual size_t CodeSize() const = 0;

	// Copy instructions out of assembly buffer into the given region of memory
	virtual void FinalizeInstructions(const MemoryRegion& region) = 0;

	// Emit code that will create an activation on the stack
	virtual void BuildFrame(size_t frame_size,
	ManagedRegister method_reg,
	ArrayRef<const ManagedRegister> callee_save_regs) = 0;

	// Emit code that will remove an activation from the stack
	//
	// Argument `may_suspend` must be `true` if the compiled method may be
	// suspended during its execution (otherwise `false`, if it is impossible
	// to suspend during its execution).
	virtual void RemoveFrame(size_t frame_size,
	ArrayRef<const ManagedRegister> callee_save_regs,
	bool may_suspend) = 0;

	virtual void IncreaseFrameSize(size_t adjust) = 0;
	virtual void DecreaseFrameSize(size_t adjust) = 0;

	// Return the same core register but with correct size if the architecture-specific
	// ManagedRegister has different representation for different sizes.
	virtual ManagedRegister CoreRegisterWithSize(ManagedRegister src, size_t size) = 0;

	// Store routines
	virtual void Store(FrameOffset offs, ManagedRegister src, size_t size) = 0;
	virtual void Store(ManagedRegister base, MemberOffset offs, ManagedRegister src, size_t size) = 0;
	virtual void StoreRef(FrameOffset dest, ManagedRegister src) = 0;
	virtual void StoreRawPtr(FrameOffset dest, ManagedRegister src) = 0;

	virtual void StoreImmediateToFrame(FrameOffset dest, uint32_t imm) = 0;

	virtual void StoreStackOffsetToThread(ThreadOffset<kPointerSize> thr_offs,
	FrameOffset fr_offs) = 0;

	virtual void StoreStackPointerToThread(ThreadOffset<kPointerSize> thr_offs) = 0;

	virtual void StoreSpanning(FrameOffset dest,
	ManagedRegister src,
	FrameOffset in_off) = 0;

	// Load routines
	virtual void Load(ManagedRegister dest, FrameOffset src, size_t size) = 0;
	virtual void Load(ManagedRegister dest, ManagedRegister base, MemberOffset offs, size_t size) = 0;

	virtual void LoadFromThread(ManagedRegister dest,
	ThreadOffset<kPointerSize> src,
	size_t size) = 0;

	virtual void LoadRef(ManagedRegister dest, FrameOffset src) = 0;
	// If unpoison_reference is true and kPoisonReference is true, then we negate the read reference.
	virtual void LoadRef(ManagedRegister dest,
	ManagedRegister base,
	MemberOffset offs,
	bool unpoison_reference) = 0;

	virtual void LoadRawPtr(ManagedRegister dest, ManagedRegister base, Offset offs) = 0;

	virtual void LoadRawPtrFromThread(ManagedRegister dest, ThreadOffset<kPointerSize> offs) = 0;

	// Copying routines

	// Move arguments from `srcs` locations to `dests` locations.
	//
	// References shall be spilled to `refs` frame offsets (kInvalidReferenceOffset indicates
	// a non-reference type) if they are in registers and corresponding `dests` shall be
	// filled with `jobject` replacements. If the first argument is a reference, it is
	// assumed to be `this` and cannot be null, all other reference arguments can be null.
	virtual void MoveArguments(ArrayRef<ArgumentLocation> dests,
	ArrayRef<ArgumentLocation> srcs,
	ArrayRef<FrameOffset> refs) = 0;

	virtual void Move(ManagedRegister dest, ManagedRegister src, size_t size) = 0;

	virtual void CopyRawPtrFromThread(FrameOffset fr_offs, ThreadOffset<kPointerSize> thr_offs) = 0;

	virtual void CopyRawPtrToThread(ThreadOffset<kPointerSize> thr_offs,
	FrameOffset fr_offs,
	ManagedRegister scratch) = 0;

	virtual void CopyRef(FrameOffset dest, FrameOffset src) = 0;
	virtual void CopyRef(FrameOffset dest,
	ManagedRegister base,
	MemberOffset offs,
	bool unpoison_reference) = 0;

	virtual void Copy(FrameOffset dest, FrameOffset src, size_t size) = 0;

	virtual void Copy(FrameOffset dest,
	ManagedRegister src_base,
	Offset src_offset,
	ManagedRegister scratch,
	size_t size) = 0;

	virtual void Copy(ManagedRegister dest_base,
	Offset dest_offset,
	FrameOffset src,
	ManagedRegister scratch,
	size_t size) = 0;

	virtual void Copy(FrameOffset dest,
	FrameOffset src_base,
	Offset src_offset,
	ManagedRegister scratch,
	size_t size) = 0;

	virtual void Copy(ManagedRegister dest,
	Offset dest_offset,
	ManagedRegister src,
	Offset src_offset,
	ManagedRegister scratch,
	size_t size) = 0;

	virtual void Copy(FrameOffset dest,
	Offset dest_offset,
	FrameOffset src,
	Offset src_offset,
	ManagedRegister scratch,
	size_t size) = 0;

	virtual void MemoryBarrier(ManagedRegister scratch) = 0;

	// Sign extension
	virtual void SignExtend(ManagedRegister mreg, size_t size) = 0;

	// Zero extension
	virtual void ZeroExtend(ManagedRegister mreg, size_t size) = 0;

	// Exploit fast access in managed code to Thread::Current()
	virtual void GetCurrentThread(ManagedRegister dest) = 0;
	virtual void GetCurrentThread(FrameOffset dest_offset) = 0;

	// Set up `out_reg` to hold a `jobject` (`StackReference<Object>*` to a spilled value),
	// or to be null if the value is null and `null_allowed`. `in_reg` holds a possibly
	// stale reference that can be used to avoid loading the spilled value to
	// see if the value is null.
	virtual void CreateJObject(ManagedRegister out_reg,
	FrameOffset spilled_reference_offset,
	ManagedRegister in_reg,
	bool null_allowed) = 0;

	// Set up `out_off` to hold a `jobject` (`StackReference<Object>*` to a spilled value),
	// or to be null if the value is null and `null_allowed`.
	virtual void CreateJObject(FrameOffset out_off,
	FrameOffset spilled_reference_offset,
	bool null_allowed) = 0;

	// Heap::VerifyObject on src. In some cases (such as a reference to this) we
	// know that src may not be null.
	virtual void VerifyObject(ManagedRegister src, bool could_be_null) = 0;
	virtual void VerifyObject(FrameOffset src, bool could_be_null) = 0;

	// Jump to address held at [base+offset] (used for tail calls).
	virtual void Jump(ManagedRegister base, Offset offset) = 0;

	// Call to address held at [base+offset]
	virtual void Call(ManagedRegister base, Offset offset) = 0;
	virtual void Call(FrameOffset base, Offset offset) = 0;
	virtual void CallFromThread(ThreadOffset<kPointerSize> offset) = 0;

	// Generate suspend check and branch to `label` if there is a pending suspend request.
	virtual void SuspendCheck(JNIMacroLabel* label) = 0;

	// Generate code to check if Thread::Current()->exception_ is non-null
	// and branch to the `label` if it is.
	virtual void ExceptionPoll(JNIMacroLabel* label) = 0;
	// Deliver pending exception.
	virtual void DeliverPendingException() = 0;

	// Create a new label that can be used with Jump/Bind calls.
	virtual std::unique_ptr<JNIMacroLabel> CreateLabel() = 0;
	// Emit an unconditional jump to the label.
	virtual void Jump(JNIMacroLabel* label) = 0;
	// Emit a conditional jump to the label by applying a unary condition test to the GC marking flag.
	virtual void TestGcMarking(JNIMacroLabel* label, JNIMacroUnaryCondition cond) = 0;
	// Emit a conditional jump to the label by applying a unary condition test to object's mark bit.
	virtual void TestMarkBit(ManagedRegister ref,
	JNIMacroLabel* label,
	JNIMacroUnaryCondition cond) = 0;
	// Code at this offset will serve as the target for the Jump call.
	virtual void Bind(JNIMacroLabel* label) = 0;

	virtual ~JNIMacroAssembler() {}

	/**
	* @brief Buffer of DWARF's Call Frame Information opcodes.
	* @details It is used by debuggers and other tools to unwind the call stack.
	*/
	virtual DebugFrameOpCodeWriterForAssembler& cfi() = 0;

	void SetEmitRunTimeChecksInDebugMode(bool value) {
	emit_run_time_checks_in_debug_mode_ = value;
	}

	static constexpr FrameOffset kInvalidReferenceOffset = FrameOffset(0);

	protected:
	JNIMacroAssembler() {}

	// Should run-time checks be emitted in debug mode?
	bool emit_run_time_checks_in_debug_mode_ = false;
	};

	// A "Label" class used with the JNIMacroAssembler
	// allowing one to use branches (jumping from one place to another).
	//
	// This is just an interface, so every platform must provide
	// its own implementation of it.
	//
	// It is only safe to use a label created
	// via JNIMacroAssembler::CreateLabel with that same macro assembler.
	class JNIMacroLabel {
	public:
	virtual ~JNIMacroLabel() = 0;

	const InstructionSet isa_;
	protected:
	explicit JNIMacroLabel(InstructionSet isa) : isa_(isa) {}
	};

	inline JNIMacroLabel::~JNIMacroLabel() {
	// Compulsory definition for a pure virtual destructor
	// to avoid linking errors.
	}

	template <typename T, PointerSize kPointerSize>
	class JNIMacroAssemblerFwd : public JNIMacroAssembler<kPointerSize> {
	public:
	void FinalizeCode() override {
	asm_.FinalizeCode();
	}

	size_t CodeSize() const override {
	return asm_.CodeSize();
	}

	void FinalizeInstructions(const MemoryRegion& region) override {
	asm_.FinalizeInstructions(region);
	}

	DebugFrameOpCodeWriterForAssembler& cfi() override {
	return asm_.cfi();
	}

	protected:
	explicit JNIMacroAssemblerFwd(ArenaAllocator* allocator) : asm_(allocator) {}

	T asm_;
	};

	template <typename Self, typename PlatformLabel, InstructionSet kIsa>
	class JNIMacroLabelCommon : public JNIMacroLabel {
	public:
	static Self* Cast(JNIMacroLabel* label) {
	CHECK(label != nullptr);
	CHECK_EQ(kIsa, label->isa_);

	return reinterpret_cast<Self*>(label);
	}

	protected:
	PlatformLabel* AsPlatformLabel() {
	return &label_;
	}

	JNIMacroLabelCommon() : JNIMacroLabel(kIsa) {
	}

	~JNIMacroLabelCommon() override {}

	private:
	PlatformLabel label_;
	};

	} // namespace art

	#endif // ART_COMPILER_UTILS_JNI_MACRO_ASSEMBLER_H_