runtime/verifier/verifier_deps.cc - LeafOS-Project/android_art - Gitiles

 /*
  * Copyright (C) 2016 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.
  */

 #include "verifier_deps.h"

 #include "compiler_callbacks.h"
 #include "leb128.h"
 #include "mirror/class-inl.h"
 #include "runtime.h"

 namespace art {
 namespace verifier {

 VerifierDeps::VerifierDeps(const std::vector<const DexFile*>& dex_files) {
   MutexLock mu(Thread::Current(), *Locks::verifier_deps_lock_);
   for (const DexFile* dex_file : dex_files) {
     DCHECK(GetDexFileDeps(*dex_file) == nullptr);
     std::unique_ptr<DexFileDeps> deps(new DexFileDeps());
     dex_deps_.emplace(dex_file, std::move(deps));
   }
 }

 VerifierDeps::DexFileDeps* VerifierDeps::GetDexFileDeps(const DexFile& dex_file) {
   auto it = dex_deps_.find(&dex_file);
   return (it == dex_deps_.end()) ? nullptr : it->second.get();
 }

 template <typename T>
 uint16_t VerifierDeps::GetAccessFlags(T* element) {
   static_assert(kAccJavaFlagsMask == 0xFFFF, "Unexpected value of a constant");
   if (element == nullptr) {
     return VerifierDeps::kUnresolvedMarker;
   } else {
     uint16_t access_flags = Low16Bits(element->GetAccessFlags());
     CHECK_NE(access_flags, VerifierDeps::kUnresolvedMarker);
     return access_flags;
   }
 }

 template <typename T>
 uint32_t VerifierDeps::GetDeclaringClassStringId(const DexFile& dex_file, T* element) {
   static_assert(kAccJavaFlagsMask == 0xFFFF, "Unexpected value of a constant");
   if (element == nullptr) {
     return VerifierDeps::kUnresolvedMarker;
   } else {
     std::string temp;
     uint32_t string_id = GetIdFromString(
         dex_file, element->GetDeclaringClass()->GetDescriptor(&temp));
     return string_id;
   }
 }

 uint32_t VerifierDeps::GetIdFromString(const DexFile& dex_file, const std::string& str) {
   const DexFile::StringId* string_id = dex_file.FindStringId(str.c_str());
   if (string_id != nullptr) {
     // String is in the DEX file. Return its ID.
     return dex_file.GetIndexForStringId(*string_id);
   }

   // String is not in the DEX file. Assign a new ID to it which is higher than
   // the number of strings in the DEX file.

   DexFileDeps* deps = GetDexFileDeps(dex_file);
   DCHECK(deps != nullptr);

   uint32_t num_ids_in_dex = dex_file.NumStringIds();
   uint32_t num_extra_ids = deps->strings_.size();

   for (size_t i = 0; i < num_extra_ids; ++i) {
     if (deps->strings_[i] == str) {
       return num_ids_in_dex + i;
     }
   }

   deps->strings_.push_back(str);

   uint32_t new_id = num_ids_in_dex + num_extra_ids;
   CHECK_GE(new_id, num_ids_in_dex);  // check for overflows
   DCHECK_EQ(str, GetStringFromId(dex_file, new_id));

   return new_id;
 }

 std::string VerifierDeps::GetStringFromId(const DexFile& dex_file, uint32_t string_id) {
   uint32_t num_ids_in_dex = dex_file.NumStringIds();
   if (string_id < num_ids_in_dex) {
     return std::string(dex_file.StringDataByIdx(string_id));
   } else {
     DexFileDeps* deps = GetDexFileDeps(dex_file);
     DCHECK(deps != nullptr);
     string_id -= num_ids_in_dex;
     CHECK_LT(string_id, deps->strings_.size());
     return deps->strings_[string_id];
   }
 }

 bool VerifierDeps::IsInClassPath(mirror::Class* klass) {
   DCHECK(klass != nullptr);

   mirror::DexCache* dex_cache = klass->GetDexCache();
   if (dex_cache == nullptr) {
     // This is a synthesized class, in this case always an array. They are not
     // defined in the compiled DEX files and therefore are part of the classpath.
     // We could avoid recording dependencies on arrays with component types in
     // the compiled DEX files but we choose to record them anyway so as to
     // record the access flags VM sets for array classes.
     DCHECK(klass->IsArrayClass()) << PrettyDescriptor(klass);
     return true;
   }

   const DexFile* dex_file = dex_cache->GetDexFile();
   DCHECK(dex_file != nullptr);

   // Test if the `dex_deps_` contains an entry for `dex_file`. If not, the dex
   // file was not registered as being compiled and we assume `klass` is in the
   // classpath.
   return (GetDexFileDeps(*dex_file) == nullptr);
 }

 void VerifierDeps::AddClassResolution(const DexFile& dex_file,
                                       uint16_t type_idx,
                                       mirror::Class* klass) {
   DexFileDeps* dex_deps = GetDexFileDeps(dex_file);
   if (dex_deps == nullptr) {
     // This invocation is from verification of a dex file which is not being compiled.
     return;
   }

   if (klass != nullptr && !IsInClassPath(klass)) {
     // Class resolved into one of the DEX files which are being compiled.
     // This is not a classpath dependency.
     return;
   }

   MutexLock mu(Thread::Current(), *Locks::verifier_deps_lock_);
   dex_deps->classes_.emplace(ClassResolution(type_idx, GetAccessFlags(klass)));
 }

 void VerifierDeps::AddFieldResolution(const DexFile& dex_file,
                                       uint32_t field_idx,
                                       ArtField* field) {
   DexFileDeps* dex_deps = GetDexFileDeps(dex_file);
   if (dex_deps == nullptr) {
     // This invocation is from verification of a dex file which is not being compiled.
     return;
   }

   if (field != nullptr && !IsInClassPath(field->GetDeclaringClass())) {
     // Field resolved into one of the DEX files which are being compiled.
     // This is not a classpath dependency.
     return;
   }

   MutexLock mu(Thread::Current(), *Locks::verifier_deps_lock_);
   dex_deps->fields_.emplace(FieldResolution(
       field_idx, GetAccessFlags(field), GetDeclaringClassStringId(dex_file, field)));
 }

 void VerifierDeps::AddMethodResolution(const DexFile& dex_file,
                                        uint32_t method_idx,
                                        MethodResolutionKind resolution_kind,
                                        ArtMethod* method) {
   DexFileDeps* dex_deps = GetDexFileDeps(dex_file);
   if (dex_deps == nullptr) {
     // This invocation is from verification of a dex file which is not being compiled.
     return;
   }

   if (method != nullptr && !IsInClassPath(method->GetDeclaringClass())) {
     // Method resolved into one of the DEX files which are being compiled.
     // This is not a classpath dependency.
     return;
   }

   MutexLock mu(Thread::Current(), *Locks::verifier_deps_lock_);
   MethodResolution method_tuple(method_idx,
                                 GetAccessFlags(method),
                                 GetDeclaringClassStringId(dex_file, method));
   if (resolution_kind == kDirectMethodResolution) {
     dex_deps->direct_methods_.emplace(method_tuple);
   } else if (resolution_kind == kVirtualMethodResolution) {
     dex_deps->virtual_methods_.emplace(method_tuple);
   } else {
     DCHECK_EQ(resolution_kind, kInterfaceMethodResolution);
     dex_deps->interface_methods_.emplace(method_tuple);
   }
 }

 void VerifierDeps::AddAssignability(const DexFile& dex_file,
                                     mirror::Class* destination,
                                     mirror::Class* source,
                                     bool is_strict,
                                     bool is_assignable) {
   // Test that the method is only called on reference types.
   // Note that concurrent verification of `destination` and `source` may have
   // set their status to erroneous. However, the tests performed below rely
   // merely on no issues with linking (valid access flags, superclass and
   // implemented interfaces). If the class at any point reached the IsResolved
   // status, the requirement holds. This is guaranteed by RegTypeCache::ResolveClass.
   DCHECK(destination != nullptr && !destination->IsPrimitive());
   DCHECK(source != nullptr && !source->IsPrimitive());

   if (destination == source ||
       destination->IsObjectClass() ||
       (!is_strict && destination->IsInterface())) {
     // Cases when `destination` is trivially assignable from `source`.
     DCHECK(is_assignable);
     return;
   }

   DCHECK_EQ(is_assignable, destination->IsAssignableFrom(source));

   if (destination->IsArrayClass() && source->IsArrayClass()) {
     // Both types are arrays. Break down to component types and add recursively.
     // This helps filter out destinations from compiled DEX files (see below)
     // and deduplicate entries with the same canonical component type.
     mirror::Class* destination_component = destination->GetComponentType();
     mirror::Class* source_component = source->GetComponentType();

     // Only perform the optimization if both types are resolved which guarantees
     // that they linked successfully, as required at the top of this method.
     if (destination_component->IsResolved() && source_component->IsResolved()) {
       AddAssignability(dex_file,
                        destination_component,
                        source_component,
                        /* is_strict */ true,
                        is_assignable);
       return;
     }
   }

   DexFileDeps* dex_deps = GetDexFileDeps(dex_file);
   if (dex_deps == nullptr) {
     // This invocation is from verification of a DEX file which is not being compiled.
     return;
   }

   if (!IsInClassPath(destination) && !IsInClassPath(source)) {
     // Both `destination` and `source` are defined in the compiled DEX files.
     // No need to record a dependency.
     return;
   }

   MutexLock mu(Thread::Current(), *Locks::verifier_deps_lock_);

   // Get string IDs for both descriptors and store in the appropriate set.

   std::string temp1, temp2;
   std::string destination_desc(destination->GetDescriptor(&temp1));
   std::string source_desc(source->GetDescriptor(&temp2));
   uint32_t destination_id = GetIdFromString(dex_file, destination_desc);
   uint32_t source_id = GetIdFromString(dex_file, source_desc);

   if (is_assignable) {
     dex_deps->assignable_types_.emplace(TypeAssignability(destination_id, source_id));
   } else {
     dex_deps->unassignable_types_.emplace(TypeAssignability(destination_id, source_id));
   }
 }

 static inline VerifierDeps* GetVerifierDepsSingleton() {
   CompilerCallbacks* callbacks = Runtime::Current()->GetCompilerCallbacks();
   if (callbacks == nullptr) {
     return nullptr;
   }
   return callbacks->GetVerifierDeps();
 }

 void VerifierDeps::MaybeRecordClassResolution(const DexFile& dex_file,
                                               uint16_t type_idx,
                                               mirror::Class* klass) {
   VerifierDeps* singleton = GetVerifierDepsSingleton();
   if (singleton != nullptr) {
     singleton->AddClassResolution(dex_file, type_idx, klass);
   }
 }

 void VerifierDeps::MaybeRecordFieldResolution(const DexFile& dex_file,
                                               uint32_t field_idx,
                                               ArtField* field) {
   VerifierDeps* singleton = GetVerifierDepsSingleton();
   if (singleton != nullptr) {
     singleton->AddFieldResolution(dex_file, field_idx, field);
   }
 }

 void VerifierDeps::MaybeRecordMethodResolution(const DexFile& dex_file,
                                                uint32_t method_idx,
                                                MethodResolutionKind resolution_kind,
                                                ArtMethod* method) {
   VerifierDeps* singleton = GetVerifierDepsSingleton();
   if (singleton != nullptr) {
     singleton->AddMethodResolution(dex_file, method_idx, resolution_kind, method);
   }
 }

 void VerifierDeps::MaybeRecordAssignability(const DexFile& dex_file,
                                             mirror::Class* destination,
                                             mirror::Class* source,
                                             bool is_strict,
                                             bool is_assignable) {
   VerifierDeps* singleton = GetVerifierDepsSingleton();
   if (singleton != nullptr) {
     singleton->AddAssignability(dex_file, destination, source, is_strict, is_assignable);
   }
 }

 static inline uint32_t DecodeUint32WithOverflowCheck(const uint8_t** in, const uint8_t* end) {
   CHECK_LT(*in, end);
   return DecodeUnsignedLeb128(in);
 }

 template<typename T1, typename T2>
 static inline void EncodeTuple(std::vector<uint8_t>* out, const std::tuple<T1, T2>& t) {
   EncodeUnsignedLeb128(out, std::get<0>(t));
   EncodeUnsignedLeb128(out, std::get<1>(t));
 }

 template<typename T1, typename T2>
 static inline void DecodeTuple(const uint8_t** in, const uint8_t* end, std::tuple<T1, T2>* t) {
   T1 v1 = static_cast<T1>(DecodeUint32WithOverflowCheck(in, end));
   T2 v2 = static_cast<T2>(DecodeUint32WithOverflowCheck(in, end));
   *t = std::make_tuple(v1, v2);
 }

 template<typename T1, typename T2, typename T3>
 static inline void EncodeTuple(std::vector<uint8_t>* out, const std::tuple<T1, T2, T3>& t) {
   EncodeUnsignedLeb128(out, std::get<0>(t));
   EncodeUnsignedLeb128(out, std::get<1>(t));
   EncodeUnsignedLeb128(out, std::get<2>(t));
 }

 template<typename T1, typename T2, typename T3>
 static inline void DecodeTuple(const uint8_t** in, const uint8_t* end, std::tuple<T1, T2, T3>* t) {
   T1 v1 = static_cast<T1>(DecodeUint32WithOverflowCheck(in, end));
   T2 v2 = static_cast<T2>(DecodeUint32WithOverflowCheck(in, end));
   T3 v3 = static_cast<T2>(DecodeUint32WithOverflowCheck(in, end));
   *t = std::make_tuple(v1, v2, v3);
 }

 template<typename T>
 static inline void EncodeSet(std::vector<uint8_t>* out, const std::set<T>& set) {
   EncodeUnsignedLeb128(out, set.size());
   for (const T& entry : set) {
     EncodeTuple(out, entry);
   }
 }

 template<typename T>
 static inline void DecodeSet(const uint8_t** in, const uint8_t* end, std::set<T>* set) {
   DCHECK(set->empty());
   size_t num_entries = DecodeUint32WithOverflowCheck(in, end);
   for (size_t i = 0; i < num_entries; ++i) {
     T tuple;
     DecodeTuple(in, end, &tuple);
     set->emplace(tuple);
   }
 }

 static inline void EncodeStringVector(std::vector<uint8_t>* out,
                                       const std::vector<std::string>& strings) {
   EncodeUnsignedLeb128(out, strings.size());
   for (const std::string& str : strings) {
     const uint8_t* data = reinterpret_cast<const uint8_t*>(str.c_str());
     size_t length = str.length() + 1;
     out->insert(out->end(), data, data + length);
     DCHECK_EQ(0u, out->back());
   }
 }

 static inline void DecodeStringVector(const uint8_t** in,
                                       const uint8_t* end,
                                       std::vector<std::string>* strings) {
   DCHECK(strings->empty());
   size_t num_strings = DecodeUint32WithOverflowCheck(in, end);
   strings->reserve(num_strings);
   for (size_t i = 0; i < num_strings; ++i) {
     CHECK_LT(*in, end);
     const char* string_start = reinterpret_cast<const char*>(*in);
     strings->emplace_back(std::string(string_start));
     *in += strings->back().length() + 1;
   }
 }

 void VerifierDeps::Encode(std::vector<uint8_t>* buffer) const {
   MutexLock mu(Thread::Current(), *Locks::verifier_deps_lock_);
   for (auto& entry : dex_deps_) {
     EncodeStringVector(buffer, entry.second->strings_);
     EncodeSet(buffer, entry.second->assignable_types_);
     EncodeSet(buffer, entry.second->unassignable_types_);
     EncodeSet(buffer, entry.second->classes_);
     EncodeSet(buffer, entry.second->fields_);
     EncodeSet(buffer, entry.second->direct_methods_);
     EncodeSet(buffer, entry.second->virtual_methods_);
     EncodeSet(buffer, entry.second->interface_methods_);
   }
 }

 VerifierDeps::VerifierDeps(const std::vector<const DexFile*>& dex_files, ArrayRef<uint8_t> data)
     : VerifierDeps(dex_files) {
   const uint8_t* data_start = data.data();
   const uint8_t* data_end = data_start + data.size();
   for (auto& entry : dex_deps_) {
     DecodeStringVector(&data_start, data_end, &entry.second->strings_);
     DecodeSet(&data_start, data_end, &entry.second->assignable_types_);
     DecodeSet(&data_start, data_end, &entry.second->unassignable_types_);
     DecodeSet(&data_start, data_end, &entry.second->classes_);
     DecodeSet(&data_start, data_end, &entry.second->fields_);
     DecodeSet(&data_start, data_end, &entry.second->direct_methods_);
     DecodeSet(&data_start, data_end, &entry.second->virtual_methods_);
     DecodeSet(&data_start, data_end, &entry.second->interface_methods_);
   }
   CHECK_LE(data_start, data_end);
 }

 bool VerifierDeps::Equals(const VerifierDeps& rhs) const {
   MutexLock mu(Thread::Current(), *Locks::verifier_deps_lock_);

   if (dex_deps_.size() != rhs.dex_deps_.size()) {
     return false;
   }

   auto lhs_it = dex_deps_.begin();
   auto rhs_it = rhs.dex_deps_.begin();

   for (; (lhs_it != dex_deps_.end()) && (rhs_it != rhs.dex_deps_.end()); lhs_it++, rhs_it++) {
     const DexFile* lhs_dex_file = lhs_it->first;
     const DexFile* rhs_dex_file = rhs_it->first;
     if (lhs_dex_file != rhs_dex_file) {
       return false;
     }

     DexFileDeps* lhs_deps = lhs_it->second.get();
     DexFileDeps* rhs_deps = rhs_it->second.get();
     if (!lhs_deps->Equals(*rhs_deps)) {
       return false;
     }
   }

   DCHECK((lhs_it == dex_deps_.end()) && (rhs_it == rhs.dex_deps_.end()));
   return true;
 }

 bool VerifierDeps::DexFileDeps::Equals(const VerifierDeps::DexFileDeps& rhs) const {
   return (strings_ == rhs.strings_) &&
          (assignable_types_ == rhs.assignable_types_) &&
          (unassignable_types_ == rhs.unassignable_types_) &&
          (classes_ == rhs.classes_) &&
          (fields_ == rhs.fields_) &&
          (direct_methods_ == rhs.direct_methods_) &&
          (virtual_methods_ == rhs.virtual_methods_) &&
          (interface_methods_ == rhs.interface_methods_);
 }

 }  // namespace verifier
 }  // namespace art
	/*
	* Copyright (C) 2016 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.
	*/

	#include "verifier_deps.h"

	#include "compiler_callbacks.h"
	#include "leb128.h"
	#include "mirror/class-inl.h"
	#include "runtime.h"

	namespace art {
	namespace verifier {

	VerifierDeps::VerifierDeps(const std::vector<const DexFile*>& dex_files) {
	MutexLock mu(Thread::Current(), *Locks::verifier_deps_lock_);
	for (const DexFile* dex_file : dex_files) {
	DCHECK(GetDexFileDeps(*dex_file) == nullptr);
	std::unique_ptr<DexFileDeps> deps(new DexFileDeps());
	dex_deps_.emplace(dex_file, std::move(deps));
	}
	}

	VerifierDeps::DexFileDeps* VerifierDeps::GetDexFileDeps(const DexFile& dex_file) {
	auto it = dex_deps_.find(&dex_file);
	return (it == dex_deps_.end()) ? nullptr : it->second.get();
	}

	template <typename T>
	uint16_t VerifierDeps::GetAccessFlags(T* element) {
	static_assert(kAccJavaFlagsMask == 0xFFFF, "Unexpected value of a constant");
	if (element == nullptr) {
	return VerifierDeps::kUnresolvedMarker;
	} else {
	uint16_t access_flags = Low16Bits(element->GetAccessFlags());
	CHECK_NE(access_flags, VerifierDeps::kUnresolvedMarker);
	return access_flags;
	}
	}

	template <typename T>
	uint32_t VerifierDeps::GetDeclaringClassStringId(const DexFile& dex_file, T* element) {
	static_assert(kAccJavaFlagsMask == 0xFFFF, "Unexpected value of a constant");
	if (element == nullptr) {
	return VerifierDeps::kUnresolvedMarker;
	} else {
	std::string temp;
	uint32_t string_id = GetIdFromString(
	dex_file, element->GetDeclaringClass()->GetDescriptor(&temp));
	return string_id;
	}
	}

	uint32_t VerifierDeps::GetIdFromString(const DexFile& dex_file, const std::string& str) {
	const DexFile::StringId* string_id = dex_file.FindStringId(str.c_str());
	if (string_id != nullptr) {
	// String is in the DEX file. Return its ID.
	return dex_file.GetIndexForStringId(*string_id);
	}

	// String is not in the DEX file. Assign a new ID to it which is higher than
	// the number of strings in the DEX file.

	DexFileDeps* deps = GetDexFileDeps(dex_file);
	DCHECK(deps != nullptr);

	uint32_t num_ids_in_dex = dex_file.NumStringIds();
	uint32_t num_extra_ids = deps->strings_.size();

	for (size_t i = 0; i < num_extra_ids; ++i) {
	if (deps->strings_[i] == str) {
	return num_ids_in_dex + i;
	}
	}

	deps->strings_.push_back(str);

	uint32_t new_id = num_ids_in_dex + num_extra_ids;
	CHECK_GE(new_id, num_ids_in_dex); // check for overflows
	DCHECK_EQ(str, GetStringFromId(dex_file, new_id));

	return new_id;
	}

	std::string VerifierDeps::GetStringFromId(const DexFile& dex_file, uint32_t string_id) {
	uint32_t num_ids_in_dex = dex_file.NumStringIds();
	if (string_id < num_ids_in_dex) {
	return std::string(dex_file.StringDataByIdx(string_id));
	} else {
	DexFileDeps* deps = GetDexFileDeps(dex_file);
	DCHECK(deps != nullptr);
	string_id -= num_ids_in_dex;
	CHECK_LT(string_id, deps->strings_.size());
	return deps->strings_[string_id];
	}
	}

	bool VerifierDeps::IsInClassPath(mirror::Class* klass) {
	DCHECK(klass != nullptr);

	mirror::DexCache* dex_cache = klass->GetDexCache();
	if (dex_cache == nullptr) {
	// This is a synthesized class, in this case always an array. They are not
	// defined in the compiled DEX files and therefore are part of the classpath.
	// We could avoid recording dependencies on arrays with component types in
	// the compiled DEX files but we choose to record them anyway so as to
	// record the access flags VM sets for array classes.
	DCHECK(klass->IsArrayClass()) << PrettyDescriptor(klass);
	return true;
	}

	const DexFile* dex_file = dex_cache->GetDexFile();
	DCHECK(dex_file != nullptr);

	// Test if the `dex_deps_` contains an entry for `dex_file`. If not, the dex
	// file was not registered as being compiled and we assume `klass` is in the
	// classpath.
	return (GetDexFileDeps(*dex_file) == nullptr);
	}

	void VerifierDeps::AddClassResolution(const DexFile& dex_file,
	uint16_t type_idx,
	mirror::Class* klass) {
	DexFileDeps* dex_deps = GetDexFileDeps(dex_file);
	if (dex_deps == nullptr) {
	// This invocation is from verification of a dex file which is not being compiled.
	return;
	}

	if (klass != nullptr && !IsInClassPath(klass)) {
	// Class resolved into one of the DEX files which are being compiled.
	// This is not a classpath dependency.
	return;
	}

	MutexLock mu(Thread::Current(), *Locks::verifier_deps_lock_);
	dex_deps->classes_.emplace(ClassResolution(type_idx, GetAccessFlags(klass)));
	}

	void VerifierDeps::AddFieldResolution(const DexFile& dex_file,
	uint32_t field_idx,
	ArtField* field) {
	DexFileDeps* dex_deps = GetDexFileDeps(dex_file);
	if (dex_deps == nullptr) {
	// This invocation is from verification of a dex file which is not being compiled.
	return;
	}

	if (field != nullptr && !IsInClassPath(field->GetDeclaringClass())) {
	// Field resolved into one of the DEX files which are being compiled.
	// This is not a classpath dependency.
	return;
	}

	MutexLock mu(Thread::Current(), *Locks::verifier_deps_lock_);
	dex_deps->fields_.emplace(FieldResolution(
	field_idx, GetAccessFlags(field), GetDeclaringClassStringId(dex_file, field)));
	}

	void VerifierDeps::AddMethodResolution(const DexFile& dex_file,
	uint32_t method_idx,
	MethodResolutionKind resolution_kind,
	ArtMethod* method) {
	DexFileDeps* dex_deps = GetDexFileDeps(dex_file);
	if (dex_deps == nullptr) {
	// This invocation is from verification of a dex file which is not being compiled.
	return;
	}

	if (method != nullptr && !IsInClassPath(method->GetDeclaringClass())) {
	// Method resolved into one of the DEX files which are being compiled.
	// This is not a classpath dependency.
	return;
	}

	MutexLock mu(Thread::Current(), *Locks::verifier_deps_lock_);
	MethodResolution method_tuple(method_idx,
	GetAccessFlags(method),
	GetDeclaringClassStringId(dex_file, method));
	if (resolution_kind == kDirectMethodResolution) {
	dex_deps->direct_methods_.emplace(method_tuple);
	} else if (resolution_kind == kVirtualMethodResolution) {
	dex_deps->virtual_methods_.emplace(method_tuple);
	} else {
	DCHECK_EQ(resolution_kind, kInterfaceMethodResolution);
	dex_deps->interface_methods_.emplace(method_tuple);
	}
	}

	void VerifierDeps::AddAssignability(const DexFile& dex_file,
	mirror::Class* destination,
	mirror::Class* source,
	bool is_strict,
	bool is_assignable) {
	// Test that the method is only called on reference types.
	// Note that concurrent verification of `destination` and `source` may have
	// set their status to erroneous. However, the tests performed below rely
	// merely on no issues with linking (valid access flags, superclass and
	// implemented interfaces). If the class at any point reached the IsResolved
	// status, the requirement holds. This is guaranteed by RegTypeCache::ResolveClass.
	DCHECK(destination != nullptr && !destination->IsPrimitive());
	DCHECK(source != nullptr && !source->IsPrimitive());

	if (destination == source \|\|
	destination->IsObjectClass() \|\|
	(!is_strict && destination->IsInterface())) {
	// Cases when `destination` is trivially assignable from `source`.
	DCHECK(is_assignable);
	return;
	}

	DCHECK_EQ(is_assignable, destination->IsAssignableFrom(source));

	if (destination->IsArrayClass() && source->IsArrayClass()) {
	// Both types are arrays. Break down to component types and add recursively.
	// This helps filter out destinations from compiled DEX files (see below)
	// and deduplicate entries with the same canonical component type.
	mirror::Class* destination_component = destination->GetComponentType();
	mirror::Class* source_component = source->GetComponentType();

	// Only perform the optimization if both types are resolved which guarantees
	// that they linked successfully, as required at the top of this method.
	if (destination_component->IsResolved() && source_component->IsResolved()) {
	AddAssignability(dex_file,
	destination_component,
	source_component,
	/* is_strict */ true,
	is_assignable);
	return;
	}
	}

	DexFileDeps* dex_deps = GetDexFileDeps(dex_file);
	if (dex_deps == nullptr) {
	// This invocation is from verification of a DEX file which is not being compiled.
	return;
	}

	if (!IsInClassPath(destination) && !IsInClassPath(source)) {
	// Both `destination` and `source` are defined in the compiled DEX files.
	// No need to record a dependency.
	return;
	}

	MutexLock mu(Thread::Current(), *Locks::verifier_deps_lock_);

	// Get string IDs for both descriptors and store in the appropriate set.

	std::string temp1, temp2;
	std::string destination_desc(destination->GetDescriptor(&temp1));
	std::string source_desc(source->GetDescriptor(&temp2));
	uint32_t destination_id = GetIdFromString(dex_file, destination_desc);
	uint32_t source_id = GetIdFromString(dex_file, source_desc);

	if (is_assignable) {
	dex_deps->assignable_types_.emplace(TypeAssignability(destination_id, source_id));
	} else {
	dex_deps->unassignable_types_.emplace(TypeAssignability(destination_id, source_id));
	}
	}

	static inline VerifierDeps* GetVerifierDepsSingleton() {
	CompilerCallbacks* callbacks = Runtime::Current()->GetCompilerCallbacks();
	if (callbacks == nullptr) {
	return nullptr;
	}
	return callbacks->GetVerifierDeps();
	}

	void VerifierDeps::MaybeRecordClassResolution(const DexFile& dex_file,
	uint16_t type_idx,
	mirror::Class* klass) {
	VerifierDeps* singleton = GetVerifierDepsSingleton();
	if (singleton != nullptr) {
	singleton->AddClassResolution(dex_file, type_idx, klass);
	}
	}

	void VerifierDeps::MaybeRecordFieldResolution(const DexFile& dex_file,
	uint32_t field_idx,
	ArtField* field) {
	VerifierDeps* singleton = GetVerifierDepsSingleton();
	if (singleton != nullptr) {
	singleton->AddFieldResolution(dex_file, field_idx, field);
	}
	}

	void VerifierDeps::MaybeRecordMethodResolution(const DexFile& dex_file,
	uint32_t method_idx,
	MethodResolutionKind resolution_kind,
	ArtMethod* method) {
	VerifierDeps* singleton = GetVerifierDepsSingleton();
	if (singleton != nullptr) {
	singleton->AddMethodResolution(dex_file, method_idx, resolution_kind, method);
	}
	}

	void VerifierDeps::MaybeRecordAssignability(const DexFile& dex_file,
	mirror::Class* destination,
	mirror::Class* source,
	bool is_strict,
	bool is_assignable) {
	VerifierDeps* singleton = GetVerifierDepsSingleton();
	if (singleton != nullptr) {
	singleton->AddAssignability(dex_file, destination, source, is_strict, is_assignable);
	}
	}

	static inline uint32_t DecodeUint32WithOverflowCheck(const uint8_t** in, const uint8_t* end) {
	CHECK_LT(*in, end);
	return DecodeUnsignedLeb128(in);
	}

	template<typename T1, typename T2>
	static inline void EncodeTuple(std::vector<uint8_t>* out, const std::tuple<T1, T2>& t) {
	EncodeUnsignedLeb128(out, std::get<0>(t));
	EncodeUnsignedLeb128(out, std::get<1>(t));
	}

	template<typename T1, typename T2>
	static inline void DecodeTuple(const uint8_t** in, const uint8_t* end, std::tuple<T1, T2>* t) {
	T1 v1 = static_cast<T1>(DecodeUint32WithOverflowCheck(in, end));
	T2 v2 = static_cast<T2>(DecodeUint32WithOverflowCheck(in, end));
	*t = std::make_tuple(v1, v2);
	}

	template<typename T1, typename T2, typename T3>
	static inline void EncodeTuple(std::vector<uint8_t>* out, const std::tuple<T1, T2, T3>& t) {
	EncodeUnsignedLeb128(out, std::get<0>(t));
	EncodeUnsignedLeb128(out, std::get<1>(t));
	EncodeUnsignedLeb128(out, std::get<2>(t));
	}

	template<typename T1, typename T2, typename T3>
	static inline void DecodeTuple(const uint8_t** in, const uint8_t* end, std::tuple<T1, T2, T3>* t) {
	T1 v1 = static_cast<T1>(DecodeUint32WithOverflowCheck(in, end));
	T2 v2 = static_cast<T2>(DecodeUint32WithOverflowCheck(in, end));
	T3 v3 = static_cast<T2>(DecodeUint32WithOverflowCheck(in, end));
	*t = std::make_tuple(v1, v2, v3);
	}

	template<typename T>
	static inline void EncodeSet(std::vector<uint8_t>* out, const std::set<T>& set) {
	EncodeUnsignedLeb128(out, set.size());
	for (const T& entry : set) {
	EncodeTuple(out, entry);
	}
	}

	template<typename T>
	static inline void DecodeSet(const uint8_t** in, const uint8_t* end, std::set<T>* set) {
	DCHECK(set->empty());
	size_t num_entries = DecodeUint32WithOverflowCheck(in, end);
	for (size_t i = 0; i < num_entries; ++i) {
	T tuple;
	DecodeTuple(in, end, &tuple);
	set->emplace(tuple);
	}
	}

	static inline void EncodeStringVector(std::vector<uint8_t>* out,
	const std::vector<std::string>& strings) {
	EncodeUnsignedLeb128(out, strings.size());
	for (const std::string& str : strings) {
	const uint8_t* data = reinterpret_cast<const uint8_t*>(str.c_str());
	size_t length = str.length() + 1;
	out->insert(out->end(), data, data + length);
	DCHECK_EQ(0u, out->back());
	}
	}

	static inline void DecodeStringVector(const uint8_t** in,
	const uint8_t* end,
	std::vector<std::string>* strings) {
	DCHECK(strings->empty());
	size_t num_strings = DecodeUint32WithOverflowCheck(in, end);
	strings->reserve(num_strings);
	for (size_t i = 0; i < num_strings; ++i) {
	CHECK_LT(*in, end);
	const char* string_start = reinterpret_cast<const char>(in);
	strings->emplace_back(std::string(string_start));
	*in += strings->back().length() + 1;
	}
	}

	void VerifierDeps::Encode(std::vector<uint8_t>* buffer) const {
	MutexLock mu(Thread::Current(), *Locks::verifier_deps_lock_);
	for (auto& entry : dex_deps_) {
	EncodeStringVector(buffer, entry.second->strings_);
	EncodeSet(buffer, entry.second->assignable_types_);
	EncodeSet(buffer, entry.second->unassignable_types_);
	EncodeSet(buffer, entry.second->classes_);
	EncodeSet(buffer, entry.second->fields_);
	EncodeSet(buffer, entry.second->direct_methods_);
	EncodeSet(buffer, entry.second->virtual_methods_);
	EncodeSet(buffer, entry.second->interface_methods_);
	}
	}

	VerifierDeps::VerifierDeps(const std::vector<const DexFile*>& dex_files, ArrayRef<uint8_t> data)
	: VerifierDeps(dex_files) {
	const uint8_t* data_start = data.data();
	const uint8_t* data_end = data_start + data.size();
	for (auto& entry : dex_deps_) {
	DecodeStringVector(&data_start, data_end, &entry.second->strings_);
	DecodeSet(&data_start, data_end, &entry.second->assignable_types_);
	DecodeSet(&data_start, data_end, &entry.second->unassignable_types_);
	DecodeSet(&data_start, data_end, &entry.second->classes_);
	DecodeSet(&data_start, data_end, &entry.second->fields_);
	DecodeSet(&data_start, data_end, &entry.second->direct_methods_);
	DecodeSet(&data_start, data_end, &entry.second->virtual_methods_);
	DecodeSet(&data_start, data_end, &entry.second->interface_methods_);
	}
	CHECK_LE(data_start, data_end);
	}

	bool VerifierDeps::Equals(const VerifierDeps& rhs) const {
	MutexLock mu(Thread::Current(), *Locks::verifier_deps_lock_);

	if (dex_deps_.size() != rhs.dex_deps_.size()) {
	return false;
	}

	auto lhs_it = dex_deps_.begin();
	auto rhs_it = rhs.dex_deps_.begin();

	for (; (lhs_it != dex_deps_.end()) && (rhs_it != rhs.dex_deps_.end()); lhs_it++, rhs_it++) {
	const DexFile* lhs_dex_file = lhs_it->first;
	const DexFile* rhs_dex_file = rhs_it->first;
	if (lhs_dex_file != rhs_dex_file) {
	return false;
	}

	DexFileDeps* lhs_deps = lhs_it->second.get();
	DexFileDeps* rhs_deps = rhs_it->second.get();
	if (!lhs_deps->Equals(*rhs_deps)) {
	return false;
	}
	}

	DCHECK((lhs_it == dex_deps_.end()) && (rhs_it == rhs.dex_deps_.end()));
	return true;
	}

	bool VerifierDeps::DexFileDeps::Equals(const VerifierDeps::DexFileDeps& rhs) const {
	return (strings_ == rhs.strings_) &&
	(assignable_types_ == rhs.assignable_types_) &&
	(unassignable_types_ == rhs.unassignable_types_) &&
	(classes_ == rhs.classes_) &&
	(fields_ == rhs.fields_) &&
	(direct_methods_ == rhs.direct_methods_) &&
	(virtual_methods_ == rhs.virtual_methods_) &&
	(interface_methods_ == rhs.interface_methods_);
	}

	} // namespace verifier
	} // namespace art