src/class_linker.h - LeafOS-Project/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_SRC_CLASS_LINKER_H_
 #define ART_SRC_CLASS_LINKER_H_

 #include <map>
 #include <string>
 #include <utility>
 #include <vector>

 #include "dex_cache.h"
 #include "dex_file.h"
 #include "gtest/gtest.h"
 #include "heap.h"
 #include "macros.h"
 #include "mutex.h"
 #include "oat_file.h"
 #include "object.h"
 #include "stack_indirect_reference_table.h"

 namespace art {

 class ClassLoader;
 class ImageSpace;
 class InternTable;
 class ObjectLock;

 typedef bool (ClassVisitor)(Class* c, void* arg);

 class ClassLinker {
  public:
   // Creates the class linker by boot strapping from dex files.
   static ClassLinker* CreateFromCompiler(const std::vector<const DexFile*>& boot_class_path,
                                          InternTable* intern_table);

   // Creates the class linker from an image.
   static ClassLinker* CreateFromImage(InternTable* intern_table);

   ~ClassLinker();

   // Finds a class by its descriptor, loading it if necessary.
   // If class_loader is null, searches boot_class_path_.
   Class* FindClass(const char* descriptor, const ClassLoader* class_loader);

   Class* FindSystemClass(const char* descriptor);

   // Define a new a class based on a ClassDef from a DexFile
   Class* DefineClass(const StringPiece& descriptor, const ClassLoader* class_loader,
                      const DexFile& dex_file, const DexFile::ClassDef& dex_class_def);

   // Finds a class by its descriptor, returning NULL if it isn't wasn't loaded
   // by the given 'class_loader'.
   Class* LookupClass(const char* descriptor, const ClassLoader* class_loader);

   // Finds all the classes with the given descriptor, regardless of ClassLoader.
   void LookupClasses(const char* descriptor, std::vector<Class*>& classes);

   Class* FindPrimitiveClass(char type);

   // General class unloading is not supported, this is used to prune
   // unwanted classes during image writing.
   bool RemoveClass(const char* descriptor, const ClassLoader* class_loader);

   void DumpAllClasses(int flags) const;

   void DumpForSigQuit(std::ostream& os) const;

   size_t NumLoadedClasses() const;

   // Resolve a String with the given index from the DexFile, storing the
   // result in the DexCache. The referrer is used to identify the
   // target DexCache and ClassLoader to use for resolution.
   String* ResolveString(uint32_t string_idx, const Method* referrer) {
     String* resolved_string = referrer->GetDexCacheStrings()->Get(string_idx);
     if (UNLIKELY(resolved_string == NULL)) {
       Class* declaring_class = referrer->GetDeclaringClass();
       DexCache* dex_cache = declaring_class->GetDexCache();
       const DexFile& dex_file = FindDexFile(dex_cache);
       resolved_string = ResolveString(dex_file, string_idx, dex_cache);
     }
     return resolved_string;
   }

   // Resolve a String with the given index from the DexFile, storing the
   // result in the DexCache.
   String* ResolveString(const DexFile& dex_file, uint32_t string_idx, DexCache* dex_cache);

   // Resolve a Type with the given index from the DexFile, storing the
   // result in the DexCache. The referrer is used to identity the
   // target DexCache and ClassLoader to use for resolution.
   Class* ResolveType(const DexFile& dex_file,
                      uint16_t type_idx,
                      const Class* referrer) {
     return ResolveType(dex_file,
                        type_idx,
                        referrer->GetDexCache(),
                        referrer->GetClassLoader());
   }

   // Resolve a Type with the given index from the DexFile, storing the
   // result in the DexCache. The referrer is used to identify the
   // target DexCache and ClassLoader to use for resolution.
   Class* ResolveType(uint16_t type_idx, const Method* referrer) {
     Class* resolved_type = referrer->GetDexCacheResolvedTypes()->Get(type_idx);
     if (UNLIKELY(resolved_type == NULL)) {
       Class* declaring_class = referrer->GetDeclaringClass();
       DexCache* dex_cache = declaring_class->GetDexCache();
       const ClassLoader* class_loader = declaring_class->GetClassLoader();
       const DexFile& dex_file = FindDexFile(dex_cache);
       resolved_type = ResolveType(dex_file, type_idx, dex_cache, class_loader);
     }
     return resolved_type;
   }

   Class* ResolveType(uint16_t type_idx, const Field* referrer) {
     Class* declaring_class = referrer->GetDeclaringClass();
     DexCache* dex_cache = declaring_class->GetDexCache();
     Class* resolved_type = dex_cache->GetResolvedType(type_idx);
     if (UNLIKELY(resolved_type == NULL)) {
       const ClassLoader* class_loader = declaring_class->GetClassLoader();
       const DexFile& dex_file = FindDexFile(dex_cache);
       resolved_type = ResolveType(dex_file, type_idx, dex_cache, class_loader);
     }
     return resolved_type;
   }

   // Resolve a type with the given ID from the DexFile, storing the
   // result in DexCache. The ClassLoader is used to search for the
   // type, since it may be referenced from but not contained within
   // the given DexFile.
   Class* ResolveType(const DexFile& dex_file,
                      uint16_t type_idx,
                      DexCache* dex_cache,
                      const ClassLoader* class_loader);

   // Resolve a method with a given ID from the DexFile, storing the
   // result in DexCache. The ClassLinker and ClassLoader are used as
   // in ResolveType. What is unique is the method type argument which
   // is used to determine if this method is a direct, static, or
   // virtual method.
   Method* ResolveMethod(const DexFile& dex_file,
                         uint32_t method_idx,
                         DexCache* dex_cache,
                         const ClassLoader* class_loader,
                         bool is_direct);

   Method* ResolveMethod(uint32_t method_idx, const Method* referrer, bool is_direct) {
     Method* resolved_method = referrer->GetDexCacheResolvedMethods()->Get(method_idx);
     if (UNLIKELY(resolved_method == NULL || resolved_method->IsRuntimeMethod())) {
       Class* declaring_class = referrer->GetDeclaringClass();
       DexCache* dex_cache = declaring_class->GetDexCache();
       const ClassLoader* class_loader = declaring_class->GetClassLoader();
       const DexFile& dex_file = FindDexFile(dex_cache);
       resolved_method = ResolveMethod(dex_file, method_idx, dex_cache, class_loader, is_direct);
     }
     return resolved_method;
   }

   Field* ResolveField(uint32_t field_idx, const Method* referrer, bool is_static) {
     Field* resolved_field =
         referrer->GetDeclaringClass()->GetDexCache()->GetResolvedField(field_idx);
     if (UNLIKELY(resolved_field == NULL)) {
       Class* declaring_class = referrer->GetDeclaringClass();
       DexCache* dex_cache = declaring_class->GetDexCache();
       const ClassLoader* class_loader = declaring_class->GetClassLoader();
       const DexFile& dex_file = FindDexFile(dex_cache);
       resolved_field = ResolveField(dex_file, field_idx, dex_cache, class_loader, is_static);
     }
     return resolved_field;
   }

   // Resolve a field with a given ID from the DexFile, storing the
   // result in DexCache. The ClassLinker and ClassLoader are used as
   // in ResolveType. What is unique is the is_static argument which is
   // used to determine if we are resolving a static or non-static
   // field.
   Field* ResolveField(const DexFile& dex_file,
                       uint32_t field_idx,
                       DexCache* dex_cache,
                       const ClassLoader* class_loader,
                       bool is_static);

   Field* ResolveFieldJLS(uint32_t field_idx, const Method* referrer) {
     Field* resolved_field =
         referrer->GetDeclaringClass()->GetDexCache()->GetResolvedField(field_idx);
     if (UNLIKELY(resolved_field == NULL)) {
       Class* declaring_class = referrer->GetDeclaringClass();
       DexCache* dex_cache = declaring_class->GetDexCache();
       const ClassLoader* class_loader = declaring_class->GetClassLoader();
       const DexFile& dex_file = FindDexFile(dex_cache);
       resolved_field = ResolveFieldJLS(dex_file, field_idx, dex_cache, class_loader);
     }
     return resolved_field;
   }

   // Resolve a field with a given ID from the DexFile, storing the
   // result in DexCache. The ClassLinker and ClassLoader are used as
   // in ResolveType. No is_static argument is provided so that Java
   // field resolution semantics are followed.
   Field* ResolveFieldJLS(const DexFile& dex_file,
                          uint32_t field_idx,
                          DexCache* dex_cache,
                          const ClassLoader* class_loader);

   // Get shorty from method index without resolution. Used to do handlerization.
   const char* MethodShorty(uint32_t method_idx, Method* referrer, uint32_t* length);

   // Returns true on success, false if there's an exception pending.
   // can_run_clinit=false allows the compiler to attempt to init a class,
   // given the restriction that no <clinit> execution is possible.
   bool EnsureInitialized(Class* c, bool can_run_clinit, bool can_init_fields);

   // Initializes classes that have instances in the image but that have
   // <clinit> methods so they could not be initialized by the compiler.
   void RunRootClinits();

   void RegisterDexFile(const DexFile& dex_file);
   void RegisterDexFile(const DexFile& dex_file, SirtRef<DexCache>& dex_cache);

   void RegisterOatFile(const OatFile& oat_file);

   const std::vector<const DexFile*>& GetBootClassPath() {
     return boot_class_path_;
   }

   void VisitClasses(ClassVisitor* visitor, void* arg) const;

   void VisitRoots(Heap::RootVisitor* visitor, void* arg) const;

   const DexFile& FindDexFile(const DexCache* dex_cache) const;
   DexCache* FindDexCache(const DexFile& dex_file) const;
   bool IsDexFileRegistered(const DexFile& dex_file) const;
   void FixupDexCaches(Method* resolution_method) const;

   // Generate an oat file from a dex file
   bool GenerateOatFile(const std::string& dex_filename,
                        int oat_fd,
                        const std::string& oat_cache_filename);

   const OatFile* FindOatFileFromOatLocation(const std::string& location);

   // Finds the oat file for a dex location, generating the oat file if
   // it is missing or out of date. Returns the DexFile from within the
   // created oat file.
   const DexFile* FindOrCreateOatFileForDexLocation(const std::string& dex_location,
                                                    const std::string& oat_location);
   // Find a DexFile within an OatFile given a DexFile location. Note
   // that this returns null if the location checksum of the DexFile
   // does not match the OatFile.
   const DexFile* FindDexFileInOatFileFromDexLocation(const std::string& location);


   // TODO: replace this with multiple methods that allocate the correct managed type.
   template <class T>
   ObjectArray<T>* AllocObjectArray(size_t length) {
     return ObjectArray<T>::Alloc(GetClassRoot(kObjectArrayClass), length);
   }

   ObjectArray<Class>* AllocClassArray(size_t length) {
     return ObjectArray<Class>::Alloc(GetClassRoot(kClassArrayClass), length);
   }

   ObjectArray<StackTraceElement>* AllocStackTraceElementArray(size_t length);

   void VerifyClass(Class* klass);
   bool VerifyClassUsingOatFile(const DexFile& dex_file, Class* klass,
                                Class::Status& oat_file_class_status);
   void ResolveClassExceptionHandlerTypes(const DexFile& dex_file, Class* klass);
   void ResolveMethodExceptionHandlerTypes(const DexFile& dex_file, Method* klass);

   Class* CreateProxyClass(String* name, ObjectArray<Class>* interfaces, ClassLoader* loader,
                           ObjectArray<Method>* methods, ObjectArray<ObjectArray<Class> >* throws);
   std::string GetDescriptorForProxy(const Class* proxy_class);
   Method* FindMethodForProxy(const Class* proxy_class, const Method* proxy_method);

   // Get the oat code for a method when its class isn't yet initialized
   const void* GetOatCodeFor(const Method* method);

   void LinkOatCodeFor(Method* method);

   // Relocate the OatFiles (ELF images)
   void RelocateExecutable();

   pid_t GetClassesLockOwner(); // For SignalCatcher.
   pid_t GetDexLockOwner(); // For SignalCatcher.

  private:
   explicit ClassLinker(InternTable*);

   const OatFile::OatMethod GetOatMethodFor(const Method* method);

   // Initialize class linker by bootstraping from dex files
   void InitFromCompiler(const std::vector<const DexFile*>& boot_class_path);

   // Initialize class linker from one or more images.
   void InitFromImage();
   OatFile* OpenOat(const ImageSpace* space);
   static void InitFromImageCallback(Object* obj, void* arg);
   struct InitFromImageCallbackState;

   void FinishInit();

   // For early bootstrapping by Init
   Class* AllocClass(Class* java_lang_Class, size_t class_size);

   // Alloc* convenience functions to avoid needing to pass in Class*
   // values that are known to the ClassLinker such as
   // kObjectArrayClass and kJavaLangString etc.
   Class* AllocClass(size_t class_size);
   DexCache* AllocDexCache(const DexFile& dex_file);
   Field* AllocField();

   Method* AllocMethod();

   InterfaceEntry* AllocInterfaceEntry(Class* interface);

   Class* CreatePrimitiveClass(const char* descriptor, Primitive::Type type) {
     return InitializePrimitiveClass(AllocClass(sizeof(Class)), descriptor, type);
   }
   Class* InitializePrimitiveClass(Class* primitive_class,
                                   const char* descriptor,
                                   Primitive::Type type);


   Class* CreateArrayClass(const std::string& descriptor, const ClassLoader* class_loader);

   void AppendToBootClassPath(const DexFile& dex_file);
   void AppendToBootClassPath(const DexFile& dex_file, SirtRef<DexCache>& dex_cache);

   void ConstructFieldMap(const DexFile& dex_file, const DexFile::ClassDef& dex_class_def,
                          Class* c, std::map<uint32_t, Field*>& field_map);

   size_t SizeOfClass(const DexFile& dex_file,
                      const DexFile::ClassDef& dex_class_def);

   void LoadClass(const DexFile& dex_file,
                  const DexFile::ClassDef& dex_class_def,
                  SirtRef<Class>& klass,
                  const ClassLoader* class_loader);

   void LoadField(const DexFile& dex_file, const ClassDataItemIterator& it, SirtRef<Class>& klass,
                  SirtRef<Field>& dst);

   void LoadMethod(const DexFile& dex_file, const ClassDataItemIterator& dex_method,
                   SirtRef<Class>& klass, SirtRef<Method>& dst);

   void FixupStaticTrampolines(Class* klass);

   // Finds the associated oat class for a dex_file and descriptor
   const OatFile::OatClass* GetOatClass(const DexFile& dex_file, const char* descriptor);

   // Attempts to insert a class into a class table.  Returns NULL if
   // the class was inserted, otherwise returns an existing class with
   // the same descriptor and ClassLoader.
   Class* InsertClass(const StringPiece& descriptor, Class* klass, bool image_class);

   void RegisterDexFileLocked(const DexFile& dex_file, SirtRef<DexCache>& dex_cache);
   bool IsDexFileRegisteredLocked(const DexFile& dex_file) const;
   void RegisterOatFileLocked(const OatFile& oat_file);

   bool InitializeClass(Class* klass, bool can_run_clinit, bool can_init_statics);
   bool WaitForInitializeClass(Class* klass, Thread* self, ObjectLock& lock);
   bool ValidateSuperClassDescriptors(const Class* klass);
   bool InitializeSuperClass(Class* klass, bool can_run_clinit, bool can_init_fields);
   // Initialize static fields, returns true if fields were initialized.
   bool InitializeStaticFields(Class* klass);

   bool IsSameDescriptorInDifferentClassContexts(const char* descriptor,
                                                 const Class* klass1,
                                                 const Class* klass2);

   bool IsSameMethodSignatureInDifferentClassContexts(const Method* descriptor,
                                                      const Class* klass1,
                                                      const Class* klass2);

   bool LinkClass(SirtRef<Class>& klass, ObjectArray<Class>* interfaces);

   bool LinkSuperClass(SirtRef<Class>& klass);

   bool LoadSuperAndInterfaces(SirtRef<Class>& klass, const DexFile& dex_file);

   bool LinkMethods(SirtRef<Class>& klass, ObjectArray<Class>* interfaces);

   bool LinkVirtualMethods(SirtRef<Class>& klass);

   bool LinkInterfaceMethods(SirtRef<Class>& klass, ObjectArray<Class>* interfaces);

   bool LinkStaticFields(SirtRef<Class>& klass);
   bool LinkInstanceFields(SirtRef<Class>& klass);
   bool LinkFields(SirtRef<Class>& klass, bool is_static);


   void CreateReferenceInstanceOffsets(SirtRef<Class>& klass);
   void CreateReferenceStaticOffsets(SirtRef<Class>& klass);
   void CreateReferenceOffsets(SirtRef<Class>& klass, bool is_static,
                               uint32_t reference_offsets);

   // For use by ImageWriter to find DexCaches for its roots
   const std::vector<DexCache*>& GetDexCaches() {
     return dex_caches_;
   }

   const OatFile* FindOpenedOatFileForDexFile(const DexFile& dex_file);
   const OatFile* FindOpenedOatFileFromDexLocation(const std::string& dex_location);
   const OatFile* FindOpenedOatFileFromOatLocation(const std::string& oat_location);

   Method* CreateProxyConstructor(SirtRef<Class>& klass, Class* proxy_class);
   Method* CreateProxyMethod(SirtRef<Class>& klass, SirtRef<Method>& prototype);

   std::vector<const DexFile*> boot_class_path_;

   std::vector<const DexFile*> dex_files_;
   std::vector<DexCache*> dex_caches_;
   std::vector<const OatFile*> oat_files_;
   // lock to protect concurrent access to dex_files_, dex_caches_, and oat_files_
   mutable Mutex dex_lock_;


   // multimap from a string hash code of a class descriptor to
   // Class* instances. Results should be compared for a matching
   // Class::descriptor_ and Class::class_loader_.
   // Protected by classes_lock_
   typedef std::multimap<size_t, Class*> Table;
   Class* LookupClass(const char* descriptor, const ClassLoader* class_loader,
                      size_t hash, const Table& classes);
   Table image_classes_;
   Table classes_;
   mutable Mutex classes_lock_;

   // indexes into class_roots_.
   // needs to be kept in sync with class_roots_descriptors_.
   enum ClassRoot {
     kJavaLangClass,
     kJavaLangObject,
     kClassArrayClass,
     kObjectArrayClass,
     kJavaLangString,
     kJavaLangRefReference,
     kJavaLangReflectConstructor,
     kJavaLangReflectField,
     kJavaLangReflectMethod,
     kJavaLangReflectProxy,
     kJavaLangClassLoader,
     kDalvikSystemBaseDexClassLoader,
     kDalvikSystemPathClassLoader,
     kJavaLangThrowable,
     kJavaLangClassNotFoundException,
     kJavaLangStackTraceElement,
     kPrimitiveBoolean,
     kPrimitiveByte,
     kPrimitiveChar,
     kPrimitiveDouble,
     kPrimitiveFloat,
     kPrimitiveInt,
     kPrimitiveLong,
     kPrimitiveShort,
     kPrimitiveVoid,
     kBooleanArrayClass,
     kByteArrayClass,
     kCharArrayClass,
     kDoubleArrayClass,
     kFloatArrayClass,
     kIntArrayClass,
     kLongArrayClass,
     kShortArrayClass,
     kJavaLangStackTraceElementArrayClass,
     kClassRootsMax,
   };
   ObjectArray<Class>* class_roots_;

   Class* GetClassRoot(ClassRoot class_root) {
     DCHECK(class_roots_ != NULL);
     Class* klass = class_roots_->Get(class_root);
     DCHECK(klass != NULL);
     return klass;
   }

   void SetClassRoot(ClassRoot class_root, Class* klass);

   ObjectArray<Class>* GetClassRoots() {
     DCHECK(class_roots_ != NULL);
     return class_roots_;
   }

   static const char* class_roots_descriptors_[];

   const char* GetClassRootDescriptor(ClassRoot class_root) {
     const char* descriptor = class_roots_descriptors_[class_root];
     CHECK(descriptor != NULL);
     return descriptor;
   }

   ObjectArray<InterfaceEntry>* array_iftable_;

   bool init_done_;

   InternTable* intern_table_;

   friend class CommonTest;
   friend class ImageWriter;  // for GetClassRoots
   friend class ObjectTest;
   FRIEND_TEST(ClassLinkerTest, ClassRootDescriptors);
   FRIEND_TEST(DexCacheTest, Open);
   FRIEND_TEST(ExceptionTest, FindExceptionHandler);
   FRIEND_TEST(ObjectTest, AllocObjectArray);
   DISALLOW_COPY_AND_ASSIGN(ClassLinker);
 };

 }  // namespace art

 #endif  // ART_SRC_CLASS_LINKER_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_SRC_CLASS_LINKER_H_
	#define ART_SRC_CLASS_LINKER_H_

	#include <map>
	#include <string>
	#include <utility>
	#include <vector>

	#include "dex_cache.h"
	#include "dex_file.h"
	#include "gtest/gtest.h"
	#include "heap.h"
	#include "macros.h"
	#include "mutex.h"
	#include "oat_file.h"
	#include "object.h"
	#include "stack_indirect_reference_table.h"

	namespace art {

	class ClassLoader;
	class ImageSpace;
	class InternTable;
	class ObjectLock;

	typedef bool (ClassVisitor)(Class* c, void* arg);

	class ClassLinker {
	public:
	// Creates the class linker by boot strapping from dex files.
	static ClassLinker* CreateFromCompiler(const std::vector<const DexFile*>& boot_class_path,
	InternTable* intern_table);

	// Creates the class linker from an image.
	static ClassLinker* CreateFromImage(InternTable* intern_table);

	~ClassLinker();

	// Finds a class by its descriptor, loading it if necessary.
	// If class_loader is null, searches boot_class_path_.
	Class* FindClass(const char* descriptor, const ClassLoader* class_loader);

	Class* FindSystemClass(const char* descriptor);

	// Define a new a class based on a ClassDef from a DexFile
	Class* DefineClass(const StringPiece& descriptor, const ClassLoader* class_loader,
	const DexFile& dex_file, const DexFile::ClassDef& dex_class_def);

	// Finds a class by its descriptor, returning NULL if it isn't wasn't loaded
	// by the given 'class_loader'.
	Class* LookupClass(const char* descriptor, const ClassLoader* class_loader);

	// Finds all the classes with the given descriptor, regardless of ClassLoader.
	void LookupClasses(const char* descriptor, std::vector<Class*>& classes);

	Class* FindPrimitiveClass(char type);

	// General class unloading is not supported, this is used to prune
	// unwanted classes during image writing.
	bool RemoveClass(const char* descriptor, const ClassLoader* class_loader);

	void DumpAllClasses(int flags) const;

	void DumpForSigQuit(std::ostream& os) const;

	size_t NumLoadedClasses() const;

	// Resolve a String with the given index from the DexFile, storing the
	// result in the DexCache. The referrer is used to identify the
	// target DexCache and ClassLoader to use for resolution.
	String* ResolveString(uint32_t string_idx, const Method* referrer) {
	String* resolved_string = referrer->GetDexCacheStrings()->Get(string_idx);
	if (UNLIKELY(resolved_string == NULL)) {
	Class* declaring_class = referrer->GetDeclaringClass();
	DexCache* dex_cache = declaring_class->GetDexCache();
	const DexFile& dex_file = FindDexFile(dex_cache);
	resolved_string = ResolveString(dex_file, string_idx, dex_cache);
	}
	return resolved_string;
	}

	// Resolve a String with the given index from the DexFile, storing the
	// result in the DexCache.
	String* ResolveString(const DexFile& dex_file, uint32_t string_idx, DexCache* dex_cache);

	// Resolve a Type with the given index from the DexFile, storing the
	// result in the DexCache. The referrer is used to identity the
	// target DexCache and ClassLoader to use for resolution.
	Class* ResolveType(const DexFile& dex_file,
	uint16_t type_idx,
	const Class* referrer) {
	return ResolveType(dex_file,
	type_idx,
	referrer->GetDexCache(),
	referrer->GetClassLoader());
	}

	// Resolve a Type with the given index from the DexFile, storing the
	// result in the DexCache. The referrer is used to identify the
	// target DexCache and ClassLoader to use for resolution.
	Class* ResolveType(uint16_t type_idx, const Method* referrer) {
	Class* resolved_type = referrer->GetDexCacheResolvedTypes()->Get(type_idx);
	if (UNLIKELY(resolved_type == NULL)) {
	Class* declaring_class = referrer->GetDeclaringClass();
	DexCache* dex_cache = declaring_class->GetDexCache();
	const ClassLoader* class_loader = declaring_class->GetClassLoader();
	const DexFile& dex_file = FindDexFile(dex_cache);
	resolved_type = ResolveType(dex_file, type_idx, dex_cache, class_loader);
	}
	return resolved_type;
	}

	Class* ResolveType(uint16_t type_idx, const Field* referrer) {
	Class* declaring_class = referrer->GetDeclaringClass();
	DexCache* dex_cache = declaring_class->GetDexCache();
	Class* resolved_type = dex_cache->GetResolvedType(type_idx);
	if (UNLIKELY(resolved_type == NULL)) {
	const ClassLoader* class_loader = declaring_class->GetClassLoader();
	const DexFile& dex_file = FindDexFile(dex_cache);
	resolved_type = ResolveType(dex_file, type_idx, dex_cache, class_loader);
	}
	return resolved_type;
	}

	// Resolve a type with the given ID from the DexFile, storing the
	// result in DexCache. The ClassLoader is used to search for the
	// type, since it may be referenced from but not contained within
	// the given DexFile.
	Class* ResolveType(const DexFile& dex_file,
	uint16_t type_idx,
	DexCache* dex_cache,
	const ClassLoader* class_loader);

	// Resolve a method with a given ID from the DexFile, storing the
	// result in DexCache. The ClassLinker and ClassLoader are used as
	// in ResolveType. What is unique is the method type argument which
	// is used to determine if this method is a direct, static, or
	// virtual method.
	Method* ResolveMethod(const DexFile& dex_file,
	uint32_t method_idx,
	DexCache* dex_cache,
	const ClassLoader* class_loader,
	bool is_direct);

	Method* ResolveMethod(uint32_t method_idx, const Method* referrer, bool is_direct) {
	Method* resolved_method = referrer->GetDexCacheResolvedMethods()->Get(method_idx);
	if (UNLIKELY(resolved_method == NULL \|\| resolved_method->IsRuntimeMethod())) {
	Class* declaring_class = referrer->GetDeclaringClass();
	DexCache* dex_cache = declaring_class->GetDexCache();
	const ClassLoader* class_loader = declaring_class->GetClassLoader();
	const DexFile& dex_file = FindDexFile(dex_cache);
	resolved_method = ResolveMethod(dex_file, method_idx, dex_cache, class_loader, is_direct);
	}
	return resolved_method;
	}

	Field* ResolveField(uint32_t field_idx, const Method* referrer, bool is_static) {
	Field* resolved_field =
	referrer->GetDeclaringClass()->GetDexCache()->GetResolvedField(field_idx);
	if (UNLIKELY(resolved_field == NULL)) {
	Class* declaring_class = referrer->GetDeclaringClass();
	DexCache* dex_cache = declaring_class->GetDexCache();
	const ClassLoader* class_loader = declaring_class->GetClassLoader();
	const DexFile& dex_file = FindDexFile(dex_cache);
	resolved_field = ResolveField(dex_file, field_idx, dex_cache, class_loader, is_static);
	}
	return resolved_field;
	}

	// Resolve a field with a given ID from the DexFile, storing the
	// result in DexCache. The ClassLinker and ClassLoader are used as
	// in ResolveType. What is unique is the is_static argument which is
	// used to determine if we are resolving a static or non-static
	// field.
	Field* ResolveField(const DexFile& dex_file,
	uint32_t field_idx,
	DexCache* dex_cache,
	const ClassLoader* class_loader,
	bool is_static);

	Field* ResolveFieldJLS(uint32_t field_idx, const Method* referrer) {
	Field* resolved_field =
	referrer->GetDeclaringClass()->GetDexCache()->GetResolvedField(field_idx);
	if (UNLIKELY(resolved_field == NULL)) {
	Class* declaring_class = referrer->GetDeclaringClass();
	DexCache* dex_cache = declaring_class->GetDexCache();
	const ClassLoader* class_loader = declaring_class->GetClassLoader();
	const DexFile& dex_file = FindDexFile(dex_cache);
	resolved_field = ResolveFieldJLS(dex_file, field_idx, dex_cache, class_loader);
	}
	return resolved_field;
	}

	// Resolve a field with a given ID from the DexFile, storing the
	// result in DexCache. The ClassLinker and ClassLoader are used as
	// in ResolveType. No is_static argument is provided so that Java
	// field resolution semantics are followed.
	Field* ResolveFieldJLS(const DexFile& dex_file,
	uint32_t field_idx,
	DexCache* dex_cache,
	const ClassLoader* class_loader);

	// Get shorty from method index without resolution. Used to do handlerization.
	const char* MethodShorty(uint32_t method_idx, Method* referrer, uint32_t* length);

	// Returns true on success, false if there's an exception pending.
	// can_run_clinit=false allows the compiler to attempt to init a class,
	// given the restriction that no <clinit> execution is possible.
	bool EnsureInitialized(Class* c, bool can_run_clinit, bool can_init_fields);

	// Initializes classes that have instances in the image but that have
	// <clinit> methods so they could not be initialized by the compiler.
	void RunRootClinits();

	void RegisterDexFile(const DexFile& dex_file);
	void RegisterDexFile(const DexFile& dex_file, SirtRef<DexCache>& dex_cache);

	void RegisterOatFile(const OatFile& oat_file);

	const std::vector<const DexFile*>& GetBootClassPath() {
	return boot_class_path_;
	}

	void VisitClasses(ClassVisitor* visitor, void* arg) const;

	void VisitRoots(Heap::RootVisitor* visitor, void* arg) const;

	const DexFile& FindDexFile(const DexCache* dex_cache) const;
	DexCache* FindDexCache(const DexFile& dex_file) const;
	bool IsDexFileRegistered(const DexFile& dex_file) const;
	void FixupDexCaches(Method* resolution_method) const;

	// Generate an oat file from a dex file
	bool GenerateOatFile(const std::string& dex_filename,
	int oat_fd,
	const std::string& oat_cache_filename);

	const OatFile* FindOatFileFromOatLocation(const std::string& location);

	// Finds the oat file for a dex location, generating the oat file if
	// it is missing or out of date. Returns the DexFile from within the
	// created oat file.
	const DexFile* FindOrCreateOatFileForDexLocation(const std::string& dex_location,
	const std::string& oat_location);
	// Find a DexFile within an OatFile given a DexFile location. Note
	// that this returns null if the location checksum of the DexFile
	// does not match the OatFile.
	const DexFile* FindDexFileInOatFileFromDexLocation(const std::string& location);


	// TODO: replace this with multiple methods that allocate the correct managed type.
	template <class T>
	ObjectArray<T>* AllocObjectArray(size_t length) {
	return ObjectArray<T>::Alloc(GetClassRoot(kObjectArrayClass), length);
	}

	ObjectArray<Class>* AllocClassArray(size_t length) {
	return ObjectArray<Class>::Alloc(GetClassRoot(kClassArrayClass), length);
	}

	ObjectArray<StackTraceElement>* AllocStackTraceElementArray(size_t length);

	void VerifyClass(Class* klass);
	bool VerifyClassUsingOatFile(const DexFile& dex_file, Class* klass,
	Class::Status& oat_file_class_status);
	void ResolveClassExceptionHandlerTypes(const DexFile& dex_file, Class* klass);
	void ResolveMethodExceptionHandlerTypes(const DexFile& dex_file, Method* klass);

	Class* CreateProxyClass(String* name, ObjectArray<Class>* interfaces, ClassLoader* loader,
	ObjectArray<Method>* methods, ObjectArray<ObjectArray<Class> >* throws);
	std::string GetDescriptorForProxy(const Class* proxy_class);
	Method* FindMethodForProxy(const Class* proxy_class, const Method* proxy_method);

	// Get the oat code for a method when its class isn't yet initialized
	const void* GetOatCodeFor(const Method* method);

	void LinkOatCodeFor(Method* method);

	// Relocate the OatFiles (ELF images)
	void RelocateExecutable();

	pid_t GetClassesLockOwner(); // For SignalCatcher.
	pid_t GetDexLockOwner(); // For SignalCatcher.

	private:
	explicit ClassLinker(InternTable*);

	const OatFile::OatMethod GetOatMethodFor(const Method* method);

	// Initialize class linker by bootstraping from dex files
	void InitFromCompiler(const std::vector<const DexFile*>& boot_class_path);

	// Initialize class linker from one or more images.
	void InitFromImage();
	OatFile* OpenOat(const ImageSpace* space);
	static void InitFromImageCallback(Object* obj, void* arg);
	struct InitFromImageCallbackState;

	void FinishInit();

	// For early bootstrapping by Init
	Class* AllocClass(Class* java_lang_Class, size_t class_size);

	// Alloc* convenience functions to avoid needing to pass in Class*
	// values that are known to the ClassLinker such as
	// kObjectArrayClass and kJavaLangString etc.
	Class* AllocClass(size_t class_size);
	DexCache* AllocDexCache(const DexFile& dex_file);
	Field* AllocField();

	Method* AllocMethod();

	InterfaceEntry* AllocInterfaceEntry(Class* interface);

	Class* CreatePrimitiveClass(const char* descriptor, Primitive::Type type) {
	return InitializePrimitiveClass(AllocClass(sizeof(Class)), descriptor, type);
	}
	Class* InitializePrimitiveClass(Class* primitive_class,
	const char* descriptor,
	Primitive::Type type);


	Class* CreateArrayClass(const std::string& descriptor, const ClassLoader* class_loader);

	void AppendToBootClassPath(const DexFile& dex_file);
	void AppendToBootClassPath(const DexFile& dex_file, SirtRef<DexCache>& dex_cache);

	void ConstructFieldMap(const DexFile& dex_file, const DexFile::ClassDef& dex_class_def,
	Class* c, std::map<uint32_t, Field*>& field_map);

	size_t SizeOfClass(const DexFile& dex_file,
	const DexFile::ClassDef& dex_class_def);

	void LoadClass(const DexFile& dex_file,
	const DexFile::ClassDef& dex_class_def,
	SirtRef<Class>& klass,
	const ClassLoader* class_loader);

	void LoadField(const DexFile& dex_file, const ClassDataItemIterator& it, SirtRef<Class>& klass,
	SirtRef<Field>& dst);

	void LoadMethod(const DexFile& dex_file, const ClassDataItemIterator& dex_method,
	SirtRef<Class>& klass, SirtRef<Method>& dst);

	void FixupStaticTrampolines(Class* klass);

	// Finds the associated oat class for a dex_file and descriptor
	const OatFile::OatClass* GetOatClass(const DexFile& dex_file, const char* descriptor);

	// Attempts to insert a class into a class table. Returns NULL if
	// the class was inserted, otherwise returns an existing class with
	// the same descriptor and ClassLoader.
	Class* InsertClass(const StringPiece& descriptor, Class* klass, bool image_class);

	void RegisterDexFileLocked(const DexFile& dex_file, SirtRef<DexCache>& dex_cache);
	bool IsDexFileRegisteredLocked(const DexFile& dex_file) const;
	void RegisterOatFileLocked(const OatFile& oat_file);

	bool InitializeClass(Class* klass, bool can_run_clinit, bool can_init_statics);
	bool WaitForInitializeClass(Class* klass, Thread* self, ObjectLock& lock);
	bool ValidateSuperClassDescriptors(const Class* klass);
	bool InitializeSuperClass(Class* klass, bool can_run_clinit, bool can_init_fields);
	// Initialize static fields, returns true if fields were initialized.
	bool InitializeStaticFields(Class* klass);

	bool IsSameDescriptorInDifferentClassContexts(const char* descriptor,
	const Class* klass1,
	const Class* klass2);

	bool IsSameMethodSignatureInDifferentClassContexts(const Method* descriptor,
	const Class* klass1,
	const Class* klass2);

	bool LinkClass(SirtRef<Class>& klass, ObjectArray<Class>* interfaces);

	bool LinkSuperClass(SirtRef<Class>& klass);

	bool LoadSuperAndInterfaces(SirtRef<Class>& klass, const DexFile& dex_file);

	bool LinkMethods(SirtRef<Class>& klass, ObjectArray<Class>* interfaces);

	bool LinkVirtualMethods(SirtRef<Class>& klass);

	bool LinkInterfaceMethods(SirtRef<Class>& klass, ObjectArray<Class>* interfaces);

	bool LinkStaticFields(SirtRef<Class>& klass);
	bool LinkInstanceFields(SirtRef<Class>& klass);
	bool LinkFields(SirtRef<Class>& klass, bool is_static);


	void CreateReferenceInstanceOffsets(SirtRef<Class>& klass);
	void CreateReferenceStaticOffsets(SirtRef<Class>& klass);
	void CreateReferenceOffsets(SirtRef<Class>& klass, bool is_static,
	uint32_t reference_offsets);

	// For use by ImageWriter to find DexCaches for its roots
	const std::vector<DexCache*>& GetDexCaches() {
	return dex_caches_;
	}

	const OatFile* FindOpenedOatFileForDexFile(const DexFile& dex_file);
	const OatFile* FindOpenedOatFileFromDexLocation(const std::string& dex_location);
	const OatFile* FindOpenedOatFileFromOatLocation(const std::string& oat_location);

	Method* CreateProxyConstructor(SirtRef<Class>& klass, Class* proxy_class);
	Method* CreateProxyMethod(SirtRef<Class>& klass, SirtRef<Method>& prototype);

	std::vector<const DexFile*> boot_class_path_;

	std::vector<const DexFile*> dex_files_;
	std::vector<DexCache*> dex_caches_;
	std::vector<const OatFile*> oat_files_;
	// lock to protect concurrent access to dex_files_, dex_caches_, and oat_files_
	mutable Mutex dex_lock_;


	// multimap from a string hash code of a class descriptor to
	// Class* instances. Results should be compared for a matching
	// Class::descriptor_ and Class::class_loader_.
	// Protected by classes_lock_
	typedef std::multimap<size_t, Class*> Table;
	Class* LookupClass(const char* descriptor, const ClassLoader* class_loader,
	size_t hash, const Table& classes);
	Table image_classes_;
	Table classes_;
	mutable Mutex classes_lock_;

	// indexes into class_roots_.
	// needs to be kept in sync with class_roots_descriptors_.
	enum ClassRoot {
	kJavaLangClass,
	kJavaLangObject,
	kClassArrayClass,
	kObjectArrayClass,
	kJavaLangString,
	kJavaLangRefReference,
	kJavaLangReflectConstructor,
	kJavaLangReflectField,
	kJavaLangReflectMethod,
	kJavaLangReflectProxy,
	kJavaLangClassLoader,
	kDalvikSystemBaseDexClassLoader,
	kDalvikSystemPathClassLoader,
	kJavaLangThrowable,
	kJavaLangClassNotFoundException,
	kJavaLangStackTraceElement,
	kPrimitiveBoolean,
	kPrimitiveByte,
	kPrimitiveChar,
	kPrimitiveDouble,
	kPrimitiveFloat,
	kPrimitiveInt,
	kPrimitiveLong,
	kPrimitiveShort,
	kPrimitiveVoid,
	kBooleanArrayClass,
	kByteArrayClass,
	kCharArrayClass,
	kDoubleArrayClass,
	kFloatArrayClass,
	kIntArrayClass,
	kLongArrayClass,
	kShortArrayClass,
	kJavaLangStackTraceElementArrayClass,
	kClassRootsMax,
	};
	ObjectArray<Class>* class_roots_;

	Class* GetClassRoot(ClassRoot class_root) {
	DCHECK(class_roots_ != NULL);
	Class* klass = class_roots_->Get(class_root);
	DCHECK(klass != NULL);
	return klass;
	}

	void SetClassRoot(ClassRoot class_root, Class* klass);

	ObjectArray<Class>* GetClassRoots() {
	DCHECK(class_roots_ != NULL);
	return class_roots_;
	}

	static const char* class_roots_descriptors_[];

	const char* GetClassRootDescriptor(ClassRoot class_root) {
	const char* descriptor = class_roots_descriptors_[class_root];
	CHECK(descriptor != NULL);
	return descriptor;
	}

	ObjectArray<InterfaceEntry>* array_iftable_;

	bool init_done_;

	InternTable* intern_table_;

	friend class CommonTest;
	friend class ImageWriter; // for GetClassRoots
	friend class ObjectTest;
	FRIEND_TEST(ClassLinkerTest, ClassRootDescriptors);
	FRIEND_TEST(DexCacheTest, Open);
	FRIEND_TEST(ExceptionTest, FindExceptionHandler);
	FRIEND_TEST(ObjectTest, AllocObjectArray);
	DISALLOW_COPY_AND_ASSIGN(ClassLinker);
	};

	} // namespace art

	#endif // ART_SRC_CLASS_LINKER_H_