runtime/mirror/dex_cache-inl.h - platform/art - Git at Google

 /*
  * Copyright (C) 2013 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #ifndef ART_RUNTIME_MIRROR_DEX_CACHE_INL_H_
 #define ART_RUNTIME_MIRROR_DEX_CACHE_INL_H_

 #include "dex_cache.h"

 #include <android-base/logging.h>

 #include "art_field.h"
 #include "art_method.h"
 #include "base/casts.h"
 #include "base/enums.h"
 #include "class_linker.h"
 #include "dex/dex_file.h"
 #include "gc_root-inl.h"
 #include "mirror/call_site.h"
 #include "mirror/class.h"
 #include "mirror/method_type.h"
 #include "obj_ptr.h"
 #include "object-inl.h"
 #include "runtime.h"
 #include "write_barrier-inl.h"

 #include <atomic>

 namespace art {
 namespace mirror {

 template <typename T>
 inline DexCachePair<T>::DexCachePair(ObjPtr<T> object, uint32_t index)
     : object(object), index(index) {}

 template <typename T>
 inline void DexCachePair<T>::Initialize(std::atomic<DexCachePair<T>>* dex_cache) {
   DexCachePair<T> first_elem;
   first_elem.object = GcRoot<T>(nullptr);
   first_elem.index = InvalidIndexForSlot(0);
   dex_cache[0].store(first_elem, std::memory_order_relaxed);
 }

 template <typename T>
 inline T* DexCachePair<T>::GetObjectForIndex(uint32_t idx) {
   if (idx != index) {
     return nullptr;
   }
   DCHECK(!object.IsNull());
   return object.Read();
 }

 template <typename T>
 inline void NativeDexCachePair<T>::Initialize(std::atomic<NativeDexCachePair<T>>* dex_cache,
                                               PointerSize pointer_size) {
   NativeDexCachePair<T> first_elem;
   first_elem.object = nullptr;
   first_elem.index = InvalidIndexForSlot(0);
   DexCache::SetNativePairPtrSize(dex_cache, 0, first_elem, pointer_size);
 }

 inline uint32_t DexCache::ClassSize(PointerSize pointer_size) {
   const uint32_t vtable_entries = Object::kVTableLength;
   return Class::ComputeClassSize(true, vtable_entries, 0, 0, 0, 0, 0, pointer_size);
 }

 inline uint32_t DexCache::StringSlotIndex(dex::StringIndex string_idx) {
   DCHECK_LT(string_idx.index_, GetDexFile()->NumStringIds());
   const uint32_t slot_idx = string_idx.index_ % kDexCacheStringCacheSize;
   DCHECK_LT(slot_idx, NumStrings());
   return slot_idx;
 }

 inline String* DexCache::GetResolvedString(dex::StringIndex string_idx) {
   const uint32_t num_preresolved_strings = NumPreResolvedStrings();
   if (num_preresolved_strings != 0u) {
     DCHECK_LT(string_idx.index_, num_preresolved_strings);
     DCHECK_EQ(num_preresolved_strings, GetDexFile()->NumStringIds());
     mirror::String* string = GetPreResolvedStrings()[string_idx.index_].Read();
     if (LIKELY(string != nullptr)) {
       return string;
     }
   }
   return GetStrings()[StringSlotIndex(string_idx)].load(
       std::memory_order_relaxed).GetObjectForIndex(string_idx.index_);
 }

 inline void DexCache::SetResolvedString(dex::StringIndex string_idx, ObjPtr<String> resolved) {
   DCHECK(resolved != nullptr);
   GetStrings()[StringSlotIndex(string_idx)].store(
       StringDexCachePair(resolved, string_idx.index_), std::memory_order_relaxed);
   Runtime* const runtime = Runtime::Current();
   if (UNLIKELY(runtime->IsActiveTransaction())) {
     DCHECK(runtime->IsAotCompiler());
     runtime->RecordResolveString(this, string_idx);
   }
   // TODO: Fine-grained marking, so that we don't need to go through all arrays in full.
   WriteBarrier::ForEveryFieldWrite(this);
 }

 inline void DexCache::SetPreResolvedString(dex::StringIndex string_idx,
                                            ObjPtr<String> resolved) {
   DCHECK(resolved != nullptr);
   DCHECK_LT(string_idx.index_, GetDexFile()->NumStringIds());
   GetPreResolvedStrings()[string_idx.index_] = GcRoot<mirror::String>(resolved);
   Runtime* const runtime = Runtime::Current();
   CHECK(runtime->IsAotCompiler());
   CHECK(!runtime->IsActiveTransaction());
   // TODO: Fine-grained marking, so that we don't need to go through all arrays in full.
   WriteBarrier::ForEveryFieldWrite(this);
 }

 inline void DexCache::ClearString(dex::StringIndex string_idx) {
   DCHECK(Runtime::Current()->IsAotCompiler());
   uint32_t slot_idx = StringSlotIndex(string_idx);
   StringDexCacheType* slot = &GetStrings()[slot_idx];
   // This is racy but should only be called from the transactional interpreter.
   if (slot->load(std::memory_order_relaxed).index == string_idx.index_) {
     StringDexCachePair cleared(nullptr, StringDexCachePair::InvalidIndexForSlot(slot_idx));
     slot->store(cleared, std::memory_order_relaxed);
   }
 }

 inline uint32_t DexCache::TypeSlotIndex(dex::TypeIndex type_idx) {
   DCHECK_LT(type_idx.index_, GetDexFile()->NumTypeIds());
   const uint32_t slot_idx = type_idx.index_ % kDexCacheTypeCacheSize;
   DCHECK_LT(slot_idx, NumResolvedTypes());
   return slot_idx;
 }

 inline Class* DexCache::GetResolvedType(dex::TypeIndex type_idx) {
   // It is theorized that a load acquire is not required since obtaining the resolved class will
   // always have an address dependency or a lock.
   return GetResolvedTypes()[TypeSlotIndex(type_idx)].load(
       std::memory_order_relaxed).GetObjectForIndex(type_idx.index_);
 }

 inline void DexCache::SetResolvedType(dex::TypeIndex type_idx, ObjPtr<Class> resolved) {
   DCHECK(resolved != nullptr);
   // TODO default transaction support.
   // Use a release store for SetResolvedType. This is done to prevent other threads from seeing a
   // class but not necessarily seeing the loaded members like the static fields array.
   // See b/32075261.
   GetResolvedTypes()[TypeSlotIndex(type_idx)].store(
       TypeDexCachePair(resolved, type_idx.index_), std::memory_order_release);
   // TODO: Fine-grained marking, so that we don't need to go through all arrays in full.
   WriteBarrier::ForEveryFieldWrite(this);
 }

 inline void DexCache::ClearResolvedType(dex::TypeIndex type_idx) {
   DCHECK(Runtime::Current()->IsAotCompiler());
   uint32_t slot_idx = TypeSlotIndex(type_idx);
   TypeDexCacheType* slot = &GetResolvedTypes()[slot_idx];
   // This is racy but should only be called from the single-threaded ImageWriter and tests.
   if (slot->load(std::memory_order_relaxed).index == type_idx.index_) {
     TypeDexCachePair cleared(nullptr, TypeDexCachePair::InvalidIndexForSlot(slot_idx));
     slot->store(cleared, std::memory_order_relaxed);
   }
 }

 inline uint32_t DexCache::MethodTypeSlotIndex(dex::ProtoIndex proto_idx) {
   DCHECK(Runtime::Current()->IsMethodHandlesEnabled());
   DCHECK_LT(proto_idx.index_, GetDexFile()->NumProtoIds());
   const uint32_t slot_idx = proto_idx.index_ % kDexCacheMethodTypeCacheSize;
   DCHECK_LT(slot_idx, NumResolvedMethodTypes());
   return slot_idx;
 }

 inline MethodType* DexCache::GetResolvedMethodType(dex::ProtoIndex proto_idx) {
   return GetResolvedMethodTypes()[MethodTypeSlotIndex(proto_idx)].load(
       std::memory_order_relaxed).GetObjectForIndex(proto_idx.index_);
 }

 inline void DexCache::SetResolvedMethodType(dex::ProtoIndex proto_idx, MethodType* resolved) {
   DCHECK(resolved != nullptr);
   GetResolvedMethodTypes()[MethodTypeSlotIndex(proto_idx)].store(
       MethodTypeDexCachePair(resolved, proto_idx.index_), std::memory_order_relaxed);
   // TODO: Fine-grained marking, so that we don't need to go through all arrays in full.
   WriteBarrier::ForEveryFieldWrite(this);
 }

 inline CallSite* DexCache::GetResolvedCallSite(uint32_t call_site_idx) {
   DCHECK(Runtime::Current()->IsMethodHandlesEnabled());
   DCHECK_LT(call_site_idx, GetDexFile()->NumCallSiteIds());
   GcRoot<mirror::CallSite>& target = GetResolvedCallSites()[call_site_idx];
   Atomic<GcRoot<mirror::CallSite>>& ref =
       reinterpret_cast<Atomic<GcRoot<mirror::CallSite>>&>(target);
   return ref.load(std::memory_order_seq_cst).Read();
 }

 inline ObjPtr<CallSite> DexCache::SetResolvedCallSite(uint32_t call_site_idx,
                                                       ObjPtr<CallSite> call_site) {
   DCHECK(Runtime::Current()->IsMethodHandlesEnabled());
   DCHECK_LT(call_site_idx, GetDexFile()->NumCallSiteIds());

   GcRoot<mirror::CallSite> null_call_site(nullptr);
   GcRoot<mirror::CallSite> candidate(call_site);
   GcRoot<mirror::CallSite>& target = GetResolvedCallSites()[call_site_idx];

   // The first assignment for a given call site wins.
   Atomic<GcRoot<mirror::CallSite>>& ref =
       reinterpret_cast<Atomic<GcRoot<mirror::CallSite>>&>(target);
   if (ref.CompareAndSetStrongSequentiallyConsistent(null_call_site, candidate)) {
     // TODO: Fine-grained marking, so that we don't need to go through all arrays in full.
     WriteBarrier::ForEveryFieldWrite(this);
     return call_site;
   } else {
     return target.Read();
   }
 }

 inline uint32_t DexCache::FieldSlotIndex(uint32_t field_idx) {
   DCHECK_LT(field_idx, GetDexFile()->NumFieldIds());
   const uint32_t slot_idx = field_idx % kDexCacheFieldCacheSize;
   DCHECK_LT(slot_idx, NumResolvedFields());
   return slot_idx;
 }

 inline ArtField* DexCache::GetResolvedField(uint32_t field_idx, PointerSize ptr_size) {
   DCHECK_EQ(Runtime::Current()->GetClassLinker()->GetImagePointerSize(), ptr_size);
   auto pair = GetNativePairPtrSize(GetResolvedFields(), FieldSlotIndex(field_idx), ptr_size);
   return pair.GetObjectForIndex(field_idx);
 }

 inline void DexCache::SetResolvedField(uint32_t field_idx, ArtField* field, PointerSize ptr_size) {
   DCHECK_EQ(Runtime::Current()->GetClassLinker()->GetImagePointerSize(), ptr_size);
   DCHECK(field != nullptr);
   FieldDexCachePair pair(field, field_idx);
   SetNativePairPtrSize(GetResolvedFields(), FieldSlotIndex(field_idx), pair, ptr_size);
 }

 inline void DexCache::ClearResolvedField(uint32_t field_idx, PointerSize ptr_size) {
   DCHECK_EQ(Runtime::Current()->GetClassLinker()->GetImagePointerSize(), ptr_size);
   uint32_t slot_idx = FieldSlotIndex(field_idx);
   auto* resolved_fields = GetResolvedFields();
   // This is racy but should only be called from the single-threaded ImageWriter.
   DCHECK(Runtime::Current()->IsAotCompiler());
   if (GetNativePairPtrSize(resolved_fields, slot_idx, ptr_size).index == field_idx) {
     FieldDexCachePair cleared(nullptr, FieldDexCachePair::InvalidIndexForSlot(slot_idx));
     SetNativePairPtrSize(resolved_fields, slot_idx, cleared, ptr_size);
   }
 }

 inline uint32_t DexCache::MethodSlotIndex(uint32_t method_idx) {
   DCHECK_LT(method_idx, GetDexFile()->NumMethodIds());
   const uint32_t slot_idx = method_idx % kDexCacheMethodCacheSize;
   DCHECK_LT(slot_idx, NumResolvedMethods());
   return slot_idx;
 }

 inline ArtMethod* DexCache::GetResolvedMethod(uint32_t method_idx, PointerSize ptr_size) {
   DCHECK_EQ(Runtime::Current()->GetClassLinker()->GetImagePointerSize(), ptr_size);
   auto pair = GetNativePairPtrSize(GetResolvedMethods(), MethodSlotIndex(method_idx), ptr_size);
   return pair.GetObjectForIndex(method_idx);
 }

 inline void DexCache::SetResolvedMethod(uint32_t method_idx,
                                         ArtMethod* method,
                                         PointerSize ptr_size) {
   DCHECK_EQ(Runtime::Current()->GetClassLinker()->GetImagePointerSize(), ptr_size);
   DCHECK(method != nullptr);
   MethodDexCachePair pair(method, method_idx);
   SetNativePairPtrSize(GetResolvedMethods(), MethodSlotIndex(method_idx), pair, ptr_size);
 }

 inline void DexCache::ClearResolvedMethod(uint32_t method_idx, PointerSize ptr_size) {
   DCHECK_EQ(Runtime::Current()->GetClassLinker()->GetImagePointerSize(), ptr_size);
   uint32_t slot_idx = MethodSlotIndex(method_idx);
   auto* resolved_methods = GetResolvedMethods();
   // This is racy but should only be called from the single-threaded ImageWriter.
   DCHECK(Runtime::Current()->IsAotCompiler());
   if (GetNativePairPtrSize(resolved_methods, slot_idx, ptr_size).index == method_idx) {
     MethodDexCachePair cleared(nullptr, MethodDexCachePair::InvalidIndexForSlot(slot_idx));
     SetNativePairPtrSize(resolved_methods, slot_idx, cleared, ptr_size);
   }
 }

 template <typename T>
 NativeDexCachePair<T> DexCache::GetNativePairPtrSize(std::atomic<NativeDexCachePair<T>>* pair_array,
                                                      size_t idx,
                                                      PointerSize ptr_size) {
   if (ptr_size == PointerSize::k64) {
     auto* array = reinterpret_cast<std::atomic<ConversionPair64>*>(pair_array);
     ConversionPair64 value = AtomicLoadRelaxed16B(&array[idx]);
     return NativeDexCachePair<T>(reinterpret_cast64<T*>(value.first),
                                  dchecked_integral_cast<size_t>(value.second));
   } else {
     auto* array = reinterpret_cast<std::atomic<ConversionPair32>*>(pair_array);
     ConversionPair32 value = array[idx].load(std::memory_order_relaxed);
     return NativeDexCachePair<T>(reinterpret_cast32<T*>(value.first), value.second);
   }
 }

 template <typename T>
 void DexCache::SetNativePairPtrSize(std::atomic<NativeDexCachePair<T>>* pair_array,
                                     size_t idx,
                                     NativeDexCachePair<T> pair,
                                     PointerSize ptr_size) {
   if (ptr_size == PointerSize::k64) {
     auto* array = reinterpret_cast<std::atomic<ConversionPair64>*>(pair_array);
     ConversionPair64 v(reinterpret_cast64<uint64_t>(pair.object), pair.index);
     AtomicStoreRelease16B(&array[idx], v);
   } else {
     auto* array = reinterpret_cast<std::atomic<ConversionPair32>*>(pair_array);
     ConversionPair32 v(reinterpret_cast32<uint32_t>(pair.object),
                        dchecked_integral_cast<uint32_t>(pair.index));
     array[idx].store(v, std::memory_order_release);
   }
 }

 template <typename T,
           ReadBarrierOption kReadBarrierOption,
           typename Visitor>
 inline void VisitDexCachePairs(std::atomic<DexCachePair<T>>* pairs,
                                size_t num_pairs,
                                const Visitor& visitor)
     REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(Locks::heap_bitmap_lock_) {
   for (size_t i = 0; i < num_pairs; ++i) {
     DexCachePair<T> source = pairs[i].load(std::memory_order_relaxed);
     // NOTE: We need the "template" keyword here to avoid a compilation
     // failure. GcRoot<T> is a template argument-dependent type and we need to
     // tell the compiler to treat "Read" as a template rather than a field or
     // function. Otherwise, on encountering the "<" token, the compiler would
     // treat "Read" as a field.
     T* const before = source.object.template Read<kReadBarrierOption>();
     visitor.VisitRootIfNonNull(source.object.AddressWithoutBarrier());
     if (source.object.template Read<kReadBarrierOption>() != before) {
       pairs[i].store(source, std::memory_order_relaxed);
     }
   }
 }

 template <bool kVisitNativeRoots,
           VerifyObjectFlags kVerifyFlags,
           ReadBarrierOption kReadBarrierOption,
           typename Visitor>
 inline void DexCache::VisitReferences(ObjPtr<Class> klass, const Visitor& visitor) {
   // Visit instance fields first.
   VisitInstanceFieldsReferences<kVerifyFlags, kReadBarrierOption>(klass, visitor);
   // Visit arrays after.
   if (kVisitNativeRoots) {
     VisitDexCachePairs<String, kReadBarrierOption, Visitor>(
         GetStrings<kVerifyFlags>(), NumStrings<kVerifyFlags>(), visitor);

     VisitDexCachePairs<Class, kReadBarrierOption, Visitor>(
         GetResolvedTypes<kVerifyFlags>(), NumResolvedTypes<kVerifyFlags>(), visitor);

     VisitDexCachePairs<MethodType, kReadBarrierOption, Visitor>(
         GetResolvedMethodTypes<kVerifyFlags>(), NumResolvedMethodTypes<kVerifyFlags>(), visitor);

     GcRoot<mirror::CallSite>* resolved_call_sites = GetResolvedCallSites<kVerifyFlags>();
     size_t num_call_sites = NumResolvedCallSites<kVerifyFlags>();
     for (size_t i = 0; i != num_call_sites; ++i) {
       visitor.VisitRootIfNonNull(resolved_call_sites[i].AddressWithoutBarrier());
     }

     GcRoot<mirror::String>* const preresolved_strings = GetPreResolvedStrings();
     const size_t num_preresolved_strings = NumPreResolvedStrings();
     for (size_t i = 0; i != num_preresolved_strings; ++i) {
       visitor.VisitRootIfNonNull(preresolved_strings[i].AddressWithoutBarrier());
     }
   }
 }

 template <ReadBarrierOption kReadBarrierOption, typename Visitor>
 inline void DexCache::FixupStrings(StringDexCacheType* dest, const Visitor& visitor) {
   StringDexCacheType* src = GetStrings();
   for (size_t i = 0, count = NumStrings(); i < count; ++i) {
     StringDexCachePair source = src[i].load(std::memory_order_relaxed);
     String* ptr = source.object.Read<kReadBarrierOption>();
     String* new_source = visitor(ptr);
     source.object = GcRoot<String>(new_source);
     dest[i].store(source, std::memory_order_relaxed);
   }
 }

 template <ReadBarrierOption kReadBarrierOption, typename Visitor>
 inline void DexCache::FixupResolvedTypes(TypeDexCacheType* dest, const Visitor& visitor) {
   TypeDexCacheType* src = GetResolvedTypes();
   for (size_t i = 0, count = NumResolvedTypes(); i < count; ++i) {
     TypeDexCachePair source = src[i].load(std::memory_order_relaxed);
     Class* ptr = source.object.Read<kReadBarrierOption>();
     Class* new_source = visitor(ptr);
     source.object = GcRoot<Class>(new_source);
     dest[i].store(source, std::memory_order_relaxed);
   }
 }

 template <ReadBarrierOption kReadBarrierOption, typename Visitor>
 inline void DexCache::FixupResolvedMethodTypes(MethodTypeDexCacheType* dest,
                                                const Visitor& visitor) {
   MethodTypeDexCacheType* src = GetResolvedMethodTypes();
   for (size_t i = 0, count = NumResolvedMethodTypes(); i < count; ++i) {
     MethodTypeDexCachePair source = src[i].load(std::memory_order_relaxed);
     MethodType* ptr = source.object.Read<kReadBarrierOption>();
     MethodType* new_source = visitor(ptr);
     source.object = GcRoot<MethodType>(new_source);
     dest[i].store(source, std::memory_order_relaxed);
   }
 }

 template <ReadBarrierOption kReadBarrierOption, typename Visitor>
 inline void DexCache::FixupResolvedCallSites(GcRoot<mirror::CallSite>* dest,
                                              const Visitor& visitor) {
   GcRoot<mirror::CallSite>* src = GetResolvedCallSites();
   for (size_t i = 0, count = NumResolvedCallSites(); i < count; ++i) {
     mirror::CallSite* source = src[i].Read<kReadBarrierOption>();
     mirror::CallSite* new_source = visitor(source);
     dest[i] = GcRoot<mirror::CallSite>(new_source);
   }
 }

 }  // namespace mirror
 }  // namespace art

 #endif  // ART_RUNTIME_MIRROR_DEX_CACHE_INL_H_
	/*
	* Copyright (C) 2013 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#ifndef ART_RUNTIME_MIRROR_DEX_CACHE_INL_H_
	#define ART_RUNTIME_MIRROR_DEX_CACHE_INL_H_

	#include "dex_cache.h"

	#include <android-base/logging.h>

	#include "art_field.h"
	#include "art_method.h"
	#include "base/casts.h"
	#include "base/enums.h"
	#include "class_linker.h"
	#include "dex/dex_file.h"
	#include "gc_root-inl.h"
	#include "mirror/call_site.h"
	#include "mirror/class.h"
	#include "mirror/method_type.h"
	#include "obj_ptr.h"
	#include "object-inl.h"
	#include "runtime.h"
	#include "write_barrier-inl.h"

	#include <atomic>

	namespace art {
	namespace mirror {

	template <typename T>
	inline DexCachePair<T>::DexCachePair(ObjPtr<T> object, uint32_t index)
	: object(object), index(index) {}

	template <typename T>
	inline void DexCachePair<T>::Initialize(std::atomic<DexCachePair<T>>* dex_cache) {
	DexCachePair<T> first_elem;
	first_elem.object = GcRoot<T>(nullptr);
	first_elem.index = InvalidIndexForSlot(0);
	dex_cache[0].store(first_elem, std::memory_order_relaxed);
	}

	template <typename T>
	inline T* DexCachePair<T>::GetObjectForIndex(uint32_t idx) {
	if (idx != index) {
	return nullptr;
	}
	DCHECK(!object.IsNull());
	return object.Read();
	}

	template <typename T>
	inline void NativeDexCachePair<T>::Initialize(std::atomic<NativeDexCachePair<T>>* dex_cache,
	PointerSize pointer_size) {
	NativeDexCachePair<T> first_elem;
	first_elem.object = nullptr;
	first_elem.index = InvalidIndexForSlot(0);
	DexCache::SetNativePairPtrSize(dex_cache, 0, first_elem, pointer_size);
	}

	inline uint32_t DexCache::ClassSize(PointerSize pointer_size) {
	const uint32_t vtable_entries = Object::kVTableLength;
	return Class::ComputeClassSize(true, vtable_entries, 0, 0, 0, 0, 0, pointer_size);
	}

	inline uint32_t DexCache::StringSlotIndex(dex::StringIndex string_idx) {
	DCHECK_LT(string_idx.index_, GetDexFile()->NumStringIds());
	const uint32_t slot_idx = string_idx.index_ % kDexCacheStringCacheSize;
	DCHECK_LT(slot_idx, NumStrings());
	return slot_idx;
	}

	inline String* DexCache::GetResolvedString(dex::StringIndex string_idx) {
	const uint32_t num_preresolved_strings = NumPreResolvedStrings();
	if (num_preresolved_strings != 0u) {
	DCHECK_LT(string_idx.index_, num_preresolved_strings);
	DCHECK_EQ(num_preresolved_strings, GetDexFile()->NumStringIds());
	mirror::String* string = GetPreResolvedStrings()[string_idx.index_].Read();
	if (LIKELY(string != nullptr)) {
	return string;
	}
	}
	return GetStrings()[StringSlotIndex(string_idx)].load(
	std::memory_order_relaxed).GetObjectForIndex(string_idx.index_);
	}

	inline void DexCache::SetResolvedString(dex::StringIndex string_idx, ObjPtr<String> resolved) {
	DCHECK(resolved != nullptr);
	GetStrings()[StringSlotIndex(string_idx)].store(
	StringDexCachePair(resolved, string_idx.index_), std::memory_order_relaxed);
	Runtime* const runtime = Runtime::Current();
	if (UNLIKELY(runtime->IsActiveTransaction())) {
	DCHECK(runtime->IsAotCompiler());
	runtime->RecordResolveString(this, string_idx);
	}
	// TODO: Fine-grained marking, so that we don't need to go through all arrays in full.
	WriteBarrier::ForEveryFieldWrite(this);
	}

	inline void DexCache::SetPreResolvedString(dex::StringIndex string_idx,
	ObjPtr<String> resolved) {
	DCHECK(resolved != nullptr);
	DCHECK_LT(string_idx.index_, GetDexFile()->NumStringIds());
	GetPreResolvedStrings()[string_idx.index_] = GcRoot<mirror::String>(resolved);
	Runtime* const runtime = Runtime::Current();
	CHECK(runtime->IsAotCompiler());
	CHECK(!runtime->IsActiveTransaction());
	// TODO: Fine-grained marking, so that we don't need to go through all arrays in full.
	WriteBarrier::ForEveryFieldWrite(this);
	}

	inline void DexCache::ClearString(dex::StringIndex string_idx) {
	DCHECK(Runtime::Current()->IsAotCompiler());
	uint32_t slot_idx = StringSlotIndex(string_idx);
	StringDexCacheType* slot = &GetStrings()[slot_idx];
	// This is racy but should only be called from the transactional interpreter.
	if (slot->load(std::memory_order_relaxed).index == string_idx.index_) {
	StringDexCachePair cleared(nullptr, StringDexCachePair::InvalidIndexForSlot(slot_idx));
	slot->store(cleared, std::memory_order_relaxed);
	}
	}

	inline uint32_t DexCache::TypeSlotIndex(dex::TypeIndex type_idx) {
	DCHECK_LT(type_idx.index_, GetDexFile()->NumTypeIds());
	const uint32_t slot_idx = type_idx.index_ % kDexCacheTypeCacheSize;
	DCHECK_LT(slot_idx, NumResolvedTypes());
	return slot_idx;
	}

	inline Class* DexCache::GetResolvedType(dex::TypeIndex type_idx) {
	// It is theorized that a load acquire is not required since obtaining the resolved class will
	// always have an address dependency or a lock.
	return GetResolvedTypes()[TypeSlotIndex(type_idx)].load(
	std::memory_order_relaxed).GetObjectForIndex(type_idx.index_);
	}

	inline void DexCache::SetResolvedType(dex::TypeIndex type_idx, ObjPtr<Class> resolved) {
	DCHECK(resolved != nullptr);
	// TODO default transaction support.
	// Use a release store for SetResolvedType. This is done to prevent other threads from seeing a
	// class but not necessarily seeing the loaded members like the static fields array.
	// See b/32075261.
	GetResolvedTypes()[TypeSlotIndex(type_idx)].store(
	TypeDexCachePair(resolved, type_idx.index_), std::memory_order_release);
	// TODO: Fine-grained marking, so that we don't need to go through all arrays in full.
	WriteBarrier::ForEveryFieldWrite(this);
	}

	inline void DexCache::ClearResolvedType(dex::TypeIndex type_idx) {
	DCHECK(Runtime::Current()->IsAotCompiler());
	uint32_t slot_idx = TypeSlotIndex(type_idx);
	TypeDexCacheType* slot = &GetResolvedTypes()[slot_idx];
	// This is racy but should only be called from the single-threaded ImageWriter and tests.
	if (slot->load(std::memory_order_relaxed).index == type_idx.index_) {
	TypeDexCachePair cleared(nullptr, TypeDexCachePair::InvalidIndexForSlot(slot_idx));
	slot->store(cleared, std::memory_order_relaxed);
	}
	}

	inline uint32_t DexCache::MethodTypeSlotIndex(dex::ProtoIndex proto_idx) {
	DCHECK(Runtime::Current()->IsMethodHandlesEnabled());
	DCHECK_LT(proto_idx.index_, GetDexFile()->NumProtoIds());
	const uint32_t slot_idx = proto_idx.index_ % kDexCacheMethodTypeCacheSize;
	DCHECK_LT(slot_idx, NumResolvedMethodTypes());
	return slot_idx;
	}

	inline MethodType* DexCache::GetResolvedMethodType(dex::ProtoIndex proto_idx) {
	return GetResolvedMethodTypes()[MethodTypeSlotIndex(proto_idx)].load(
	std::memory_order_relaxed).GetObjectForIndex(proto_idx.index_);
	}

	inline void DexCache::SetResolvedMethodType(dex::ProtoIndex proto_idx, MethodType* resolved) {
	DCHECK(resolved != nullptr);
	GetResolvedMethodTypes()[MethodTypeSlotIndex(proto_idx)].store(
	MethodTypeDexCachePair(resolved, proto_idx.index_), std::memory_order_relaxed);
	// TODO: Fine-grained marking, so that we don't need to go through all arrays in full.
	WriteBarrier::ForEveryFieldWrite(this);
	}

	inline CallSite* DexCache::GetResolvedCallSite(uint32_t call_site_idx) {
	DCHECK(Runtime::Current()->IsMethodHandlesEnabled());
	DCHECK_LT(call_site_idx, GetDexFile()->NumCallSiteIds());
	GcRoot<mirror::CallSite>& target = GetResolvedCallSites()[call_site_idx];
	Atomic<GcRoot<mirror::CallSite>>& ref =
	reinterpret_cast<Atomic<GcRoot<mirror::CallSite>>&>(target);
	return ref.load(std::memory_order_seq_cst).Read();
	}

	inline ObjPtr<CallSite> DexCache::SetResolvedCallSite(uint32_t call_site_idx,
	ObjPtr<CallSite> call_site) {
	DCHECK(Runtime::Current()->IsMethodHandlesEnabled());
	DCHECK_LT(call_site_idx, GetDexFile()->NumCallSiteIds());

	GcRoot<mirror::CallSite> null_call_site(nullptr);
	GcRoot<mirror::CallSite> candidate(call_site);
	GcRoot<mirror::CallSite>& target = GetResolvedCallSites()[call_site_idx];

	// The first assignment for a given call site wins.
	Atomic<GcRoot<mirror::CallSite>>& ref =
	reinterpret_cast<Atomic<GcRoot<mirror::CallSite>>&>(target);
	if (ref.CompareAndSetStrongSequentiallyConsistent(null_call_site, candidate)) {
	// TODO: Fine-grained marking, so that we don't need to go through all arrays in full.
	WriteBarrier::ForEveryFieldWrite(this);
	return call_site;
	} else {
	return target.Read();
	}
	}

	inline uint32_t DexCache::FieldSlotIndex(uint32_t field_idx) {
	DCHECK_LT(field_idx, GetDexFile()->NumFieldIds());
	const uint32_t slot_idx = field_idx % kDexCacheFieldCacheSize;
	DCHECK_LT(slot_idx, NumResolvedFields());
	return slot_idx;
	}

	inline ArtField* DexCache::GetResolvedField(uint32_t field_idx, PointerSize ptr_size) {
	DCHECK_EQ(Runtime::Current()->GetClassLinker()->GetImagePointerSize(), ptr_size);
	auto pair = GetNativePairPtrSize(GetResolvedFields(), FieldSlotIndex(field_idx), ptr_size);
	return pair.GetObjectForIndex(field_idx);
	}

	inline void DexCache::SetResolvedField(uint32_t field_idx, ArtField* field, PointerSize ptr_size) {
	DCHECK_EQ(Runtime::Current()->GetClassLinker()->GetImagePointerSize(), ptr_size);
	DCHECK(field != nullptr);
	FieldDexCachePair pair(field, field_idx);
	SetNativePairPtrSize(GetResolvedFields(), FieldSlotIndex(field_idx), pair, ptr_size);
	}

	inline void DexCache::ClearResolvedField(uint32_t field_idx, PointerSize ptr_size) {
	DCHECK_EQ(Runtime::Current()->GetClassLinker()->GetImagePointerSize(), ptr_size);
	uint32_t slot_idx = FieldSlotIndex(field_idx);
	auto* resolved_fields = GetResolvedFields();
	// This is racy but should only be called from the single-threaded ImageWriter.
	DCHECK(Runtime::Current()->IsAotCompiler());
	if (GetNativePairPtrSize(resolved_fields, slot_idx, ptr_size).index == field_idx) {
	FieldDexCachePair cleared(nullptr, FieldDexCachePair::InvalidIndexForSlot(slot_idx));
	SetNativePairPtrSize(resolved_fields, slot_idx, cleared, ptr_size);
	}
	}

	inline uint32_t DexCache::MethodSlotIndex(uint32_t method_idx) {
	DCHECK_LT(method_idx, GetDexFile()->NumMethodIds());
	const uint32_t slot_idx = method_idx % kDexCacheMethodCacheSize;
	DCHECK_LT(slot_idx, NumResolvedMethods());
	return slot_idx;
	}

	inline ArtMethod* DexCache::GetResolvedMethod(uint32_t method_idx, PointerSize ptr_size) {
	DCHECK_EQ(Runtime::Current()->GetClassLinker()->GetImagePointerSize(), ptr_size);
	auto pair = GetNativePairPtrSize(GetResolvedMethods(), MethodSlotIndex(method_idx), ptr_size);
	return pair.GetObjectForIndex(method_idx);
	}

	inline void DexCache::SetResolvedMethod(uint32_t method_idx,
	ArtMethod* method,
	PointerSize ptr_size) {
	DCHECK_EQ(Runtime::Current()->GetClassLinker()->GetImagePointerSize(), ptr_size);
	DCHECK(method != nullptr);
	MethodDexCachePair pair(method, method_idx);
	SetNativePairPtrSize(GetResolvedMethods(), MethodSlotIndex(method_idx), pair, ptr_size);
	}

	inline void DexCache::ClearResolvedMethod(uint32_t method_idx, PointerSize ptr_size) {
	DCHECK_EQ(Runtime::Current()->GetClassLinker()->GetImagePointerSize(), ptr_size);
	uint32_t slot_idx = MethodSlotIndex(method_idx);
	auto* resolved_methods = GetResolvedMethods();
	// This is racy but should only be called from the single-threaded ImageWriter.
	DCHECK(Runtime::Current()->IsAotCompiler());
	if (GetNativePairPtrSize(resolved_methods, slot_idx, ptr_size).index == method_idx) {
	MethodDexCachePair cleared(nullptr, MethodDexCachePair::InvalidIndexForSlot(slot_idx));
	SetNativePairPtrSize(resolved_methods, slot_idx, cleared, ptr_size);
	}
	}

	template <typename T>
	NativeDexCachePair<T> DexCache::GetNativePairPtrSize(std::atomic<NativeDexCachePair<T>>* pair_array,
	size_t idx,
	PointerSize ptr_size) {
	if (ptr_size == PointerSize::k64) {
	auto* array = reinterpret_cast<std::atomic<ConversionPair64>*>(pair_array);
	ConversionPair64 value = AtomicLoadRelaxed16B(&array[idx]);
	return NativeDexCachePair<T>(reinterpret_cast64<T*>(value.first),
	dchecked_integral_cast<size_t>(value.second));
	} else {
	auto* array = reinterpret_cast<std::atomic<ConversionPair32>*>(pair_array);
	ConversionPair32 value = array[idx].load(std::memory_order_relaxed);
	return NativeDexCachePair<T>(reinterpret_cast32<T*>(value.first), value.second);
	}
	}

	template <typename T>
	void DexCache::SetNativePairPtrSize(std::atomic<NativeDexCachePair<T>>* pair_array,
	size_t idx,
	NativeDexCachePair<T> pair,
	PointerSize ptr_size) {
	if (ptr_size == PointerSize::k64) {
	auto* array = reinterpret_cast<std::atomic<ConversionPair64>*>(pair_array);
	ConversionPair64 v(reinterpret_cast64<uint64_t>(pair.object), pair.index);
	AtomicStoreRelease16B(&array[idx], v);
	} else {
	auto* array = reinterpret_cast<std::atomic<ConversionPair32>*>(pair_array);
	ConversionPair32 v(reinterpret_cast32<uint32_t>(pair.object),
	dchecked_integral_cast<uint32_t>(pair.index));
	array[idx].store(v, std::memory_order_release);
	}
	}

	template <typename T,
	ReadBarrierOption kReadBarrierOption,
	typename Visitor>
	inline void VisitDexCachePairs(std::atomic<DexCachePair<T>>* pairs,
	size_t num_pairs,
	const Visitor& visitor)
	REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(Locks::heap_bitmap_lock_) {
	for (size_t i = 0; i < num_pairs; ++i) {
	DexCachePair<T> source = pairs[i].load(std::memory_order_relaxed);
	// NOTE: We need the "template" keyword here to avoid a compilation
	// failure. GcRoot<T> is a template argument-dependent type and we need to
	// tell the compiler to treat "Read" as a template rather than a field or
	// function. Otherwise, on encountering the "<" token, the compiler would
	// treat "Read" as a field.
	T* const before = source.object.template Read<kReadBarrierOption>();
	visitor.VisitRootIfNonNull(source.object.AddressWithoutBarrier());
	if (source.object.template Read<kReadBarrierOption>() != before) {
	pairs[i].store(source, std::memory_order_relaxed);
	}
	}
	}

	template <bool kVisitNativeRoots,
	VerifyObjectFlags kVerifyFlags,
	ReadBarrierOption kReadBarrierOption,
	typename Visitor>
	inline void DexCache::VisitReferences(ObjPtr<Class> klass, const Visitor& visitor) {
	// Visit instance fields first.
	VisitInstanceFieldsReferences<kVerifyFlags, kReadBarrierOption>(klass, visitor);
	// Visit arrays after.
	if (kVisitNativeRoots) {
	VisitDexCachePairs<String, kReadBarrierOption, Visitor>(
	GetStrings<kVerifyFlags>(), NumStrings<kVerifyFlags>(), visitor);

	VisitDexCachePairs<Class, kReadBarrierOption, Visitor>(
	GetResolvedTypes<kVerifyFlags>(), NumResolvedTypes<kVerifyFlags>(), visitor);

	VisitDexCachePairs<MethodType, kReadBarrierOption, Visitor>(
	GetResolvedMethodTypes<kVerifyFlags>(), NumResolvedMethodTypes<kVerifyFlags>(), visitor);

	GcRoot<mirror::CallSite>* resolved_call_sites = GetResolvedCallSites<kVerifyFlags>();
	size_t num_call_sites = NumResolvedCallSites<kVerifyFlags>();
	for (size_t i = 0; i != num_call_sites; ++i) {
	visitor.VisitRootIfNonNull(resolved_call_sites[i].AddressWithoutBarrier());
	}

	GcRoot<mirror::String>* const preresolved_strings = GetPreResolvedStrings();
	const size_t num_preresolved_strings = NumPreResolvedStrings();
	for (size_t i = 0; i != num_preresolved_strings; ++i) {
	visitor.VisitRootIfNonNull(preresolved_strings[i].AddressWithoutBarrier());
	}
	}
	}

	template <ReadBarrierOption kReadBarrierOption, typename Visitor>
	inline void DexCache::FixupStrings(StringDexCacheType* dest, const Visitor& visitor) {
	StringDexCacheType* src = GetStrings();
	for (size_t i = 0, count = NumStrings(); i < count; ++i) {
	StringDexCachePair source = src[i].load(std::memory_order_relaxed);
	String* ptr = source.object.Read<kReadBarrierOption>();
	String* new_source = visitor(ptr);
	source.object = GcRoot<String>(new_source);
	dest[i].store(source, std::memory_order_relaxed);
	}
	}

	template <ReadBarrierOption kReadBarrierOption, typename Visitor>
	inline void DexCache::FixupResolvedTypes(TypeDexCacheType* dest, const Visitor& visitor) {
	TypeDexCacheType* src = GetResolvedTypes();
	for (size_t i = 0, count = NumResolvedTypes(); i < count; ++i) {
	TypeDexCachePair source = src[i].load(std::memory_order_relaxed);
	Class* ptr = source.object.Read<kReadBarrierOption>();
	Class* new_source = visitor(ptr);
	source.object = GcRoot<Class>(new_source);
	dest[i].store(source, std::memory_order_relaxed);
	}
	}

	template <ReadBarrierOption kReadBarrierOption, typename Visitor>
	inline void DexCache::FixupResolvedMethodTypes(MethodTypeDexCacheType* dest,
	const Visitor& visitor) {
	MethodTypeDexCacheType* src = GetResolvedMethodTypes();
	for (size_t i = 0, count = NumResolvedMethodTypes(); i < count; ++i) {
	MethodTypeDexCachePair source = src[i].load(std::memory_order_relaxed);
	MethodType* ptr = source.object.Read<kReadBarrierOption>();
	MethodType* new_source = visitor(ptr);
	source.object = GcRoot<MethodType>(new_source);
	dest[i].store(source, std::memory_order_relaxed);
	}
	}

	template <ReadBarrierOption kReadBarrierOption, typename Visitor>
	inline void DexCache::FixupResolvedCallSites(GcRoot<mirror::CallSite>* dest,
	const Visitor& visitor) {
	GcRoot<mirror::CallSite>* src = GetResolvedCallSites();
	for (size_t i = 0, count = NumResolvedCallSites(); i < count; ++i) {
	mirror::CallSite* source = src[i].Read<kReadBarrierOption>();
	mirror::CallSite* new_source = visitor(source);
	dest[i] = GcRoot<mirror::CallSite>(new_source);
	}
	}

	} // namespace mirror
	} // namespace art

	#endif // ART_RUNTIME_MIRROR_DEX_CACHE_INL_H_