Load app images

Support in-place patching of the app image based on boot image
location and app oat location. Only loads for art run test so far
since we do not automatically generate app images for app installs.

N5 maps launch time (~200 runs):
Before: 930ms
After: 878.18ms
After + image class table: 864.57ms

TODO:
Oatdump support.
Store class loaders as class roots in image.

Bug: 22858531

Change-Id: I9cbc645645e62ea2ed1ad8e139e91af7d88514c1

1 files changed, 608 insertions, 149 deletions

diff --git a/runtime/class_linker.cc b/runtime/class_linker.cc
index ed833c4335..be9310abd8 100644
--- a/runtime/class_linker.cc
+++ b/runtime/class_linker.cc
@@ -336,6 +336,10 @@ bool ClassLinker::InitWithoutImage(std::vector<std::unique_ptr<const DexFile>> b
 
   // Use the pointer size from the runtime since we are probably creating the image.
   image_pointer_size_ = InstructionSetPointerSize(runtime->GetInstructionSet());
+  if (!ValidPointerSize(image_pointer_size_)) {
+    *error_msg = StringPrintf("Invalid image pointer size: %zu", image_pointer_size_);
+    return false;
+  }
 
   // java_lang_Class comes first, it's needed for AllocClass
   // The GC can't handle an object with a null class since we can't get the size of this object.
@@ -489,7 +493,7 @@ bool ClassLinker::InitWithoutImage(std::vector<std::unique_ptr<const DexFile>> b
       return false;
     }
     AppendToBootClassPath(self, *dex_file);
-    opened_dex_files_.push_back(std::move(dex_file));
+    boot_dex_files_.push_back(std::move(dex_file));
   }
 
   // now we can use FindSystemClass
@@ -878,6 +882,7 @@ struct TrampolineCheckData {
   ArtMethod* m;
   bool error;
 };
+
 static void CheckTrampolines(mirror::Object* obj, void* arg) NO_THREAD_SAFETY_ANALYSIS {
   if (obj->IsClass()) {
     mirror::Class* klass = obj->AsClass();
@@ -896,8 +901,8 @@ static void CheckTrampolines(mirror::Object* obj, void* arg) NO_THREAD_SAFETY_AN
   }
 }
 
-bool ClassLinker::InitFromImage(std::string* error_msg) {
-  VLOG(startup) << "ClassLinker::InitFromImage entering";
+bool ClassLinker::InitFromBootImage(std::string* error_msg) {
+  VLOG(startup) << __FUNCTION__ << " entering";
   CHECK(!init_done_);
 
   Runtime* const runtime = Runtime::Current();
@@ -906,6 +911,21 @@ bool ClassLinker::InitFromImage(std::string* error_msg) {
   std::vector<gc::space::ImageSpace*> spaces = heap->GetBootImageSpaces();
   CHECK(!spaces.empty());
   image_pointer_size_ = spaces[0]->GetImageHeader().GetPointerSize();
+  if (!ValidPointerSize(image_pointer_size_)) {
+    *error_msg = StringPrintf("Invalid image pointer size: %zu", image_pointer_size_);
+    return false;
+  }
+  if (!runtime->IsAotCompiler()) {
+    // Only the Aot compiler supports having an image with a different pointer size than the
+    // runtime. This happens on the host for compiling 32 bit tests since we use a 64 bit libart
+    // compiler. We may also use 32 bit dex2oat on a system with 64 bit apps.
+    if (image_pointer_size_ != sizeof(void*)) {
+      *error_msg = StringPrintf("Runtime must use current image pointer size: %zu vs %zu",
+                                image_pointer_size_,
+                                sizeof(void*));
+      return false;
+    }
+  }
   dex_cache_boot_image_class_lookup_required_ = true;
   std::vector<const OatFile*> oat_files =
       runtime->GetOatFileManager().RegisterImageOatFiles(spaces);
@@ -957,19 +977,10 @@ bool ClassLinker::InitFromImage(std::string* error_msg) {
     }
   }
 
-  StackHandleScopeCollection handles(self);
-  std::vector<Handle<mirror::ObjectArray<mirror::DexCache>>> dex_caches_vector;
-  for (gc::space::ImageSpace* space : spaces) {
-    Handle<mirror::ObjectArray<mirror::DexCache>> dex_caches(handles.NewHandle(
-        space->GetImageHeader().GetImageRoot(ImageHeader::kDexCaches)->
-        AsObjectArray<mirror::DexCache>()));
-    dex_caches_vector.push_back(dex_caches);
-  }
-
-  Handle<mirror::ObjectArray<mirror::Class>> class_roots(handles.NewHandle(
-      spaces[0]->GetImageHeader().GetImageRoot(ImageHeader::kClassRoots)->
-      AsObjectArray<mirror::Class>()));
-  class_roots_ = GcRoot<mirror::ObjectArray<mirror::Class>>(class_roots.Get());
+  class_roots_ = GcRoot<mirror::ObjectArray<mirror::Class>>(
+      down_cast<mirror::ObjectArray<mirror::Class>*>(
+          spaces[0]->GetImageHeader().GetImageRoot(ImageHeader::kClassRoots)));
+  mirror::Class::SetClassClass(class_roots_.Read()->Get(kJavaLangClass));
 
   // Special case of setting up the String class early so that we can test arbitrary objects
   // as being Strings or not
@@ -982,162 +993,595 @@ bool ClassLinker::InitFromImage(std::string* error_msg) {
   runtime->SetSentinel(heap->AllocNonMovableObject<true>(
       self, java_lang_Object, java_lang_Object->GetObjectSize(), VoidFunctor()));
 
-  uint32_t dex_file_count = 0;
-  for (const OatFile* oat_file : oat_files) {
-    dex_file_count += oat_file->GetOatHeader().GetDexFileCount();
+  // reinit array_iftable_ from any array class instance, they should be ==
+  array_iftable_ = GcRoot<mirror::IfTable>(GetClassRoot(kObjectArrayClass)->GetIfTable());
+  DCHECK_EQ(array_iftable_.Read(), GetClassRoot(kBooleanArrayClass)->GetIfTable());
+  // String class root was set above
+  mirror::Field::SetClass(GetClassRoot(kJavaLangReflectField));
+  mirror::Field::SetArrayClass(GetClassRoot(kJavaLangReflectFieldArrayClass));
+  mirror::Constructor::SetClass(GetClassRoot(kJavaLangReflectConstructor));
+  mirror::Constructor::SetArrayClass(GetClassRoot(kJavaLangReflectConstructorArrayClass));
+  mirror::Method::SetClass(GetClassRoot(kJavaLangReflectMethod));
+  mirror::Method::SetArrayClass(GetClassRoot(kJavaLangReflectMethodArrayClass));
+  mirror::Reference::SetClass(GetClassRoot(kJavaLangRefReference));
+  mirror::BooleanArray::SetArrayClass(GetClassRoot(kBooleanArrayClass));
+  mirror::ByteArray::SetArrayClass(GetClassRoot(kByteArrayClass));
+  mirror::CharArray::SetArrayClass(GetClassRoot(kCharArrayClass));
+  mirror::DoubleArray::SetArrayClass(GetClassRoot(kDoubleArrayClass));
+  mirror::FloatArray::SetArrayClass(GetClassRoot(kFloatArrayClass));
+  mirror::IntArray::SetArrayClass(GetClassRoot(kIntArrayClass));
+  mirror::LongArray::SetArrayClass(GetClassRoot(kLongArrayClass));
+  mirror::ShortArray::SetArrayClass(GetClassRoot(kShortArrayClass));
+  mirror::Throwable::SetClass(GetClassRoot(kJavaLangThrowable));
+  mirror::StackTraceElement::SetClass(GetClassRoot(kJavaLangStackTraceElement));
+
+  for (gc::space::ImageSpace* image_space : spaces) {
+    // Boot class loader, use a null handle.
+    std::vector<std::unique_ptr<const DexFile>> dex_files;
+    if (!AddImageSpace(image_space,
+                       ScopedNullHandle<mirror::ClassLoader>(),
+                       /*dex_elements*/nullptr,
+                       /*dex_location*/nullptr,
+                       /*out*/&dex_files,
+                       error_msg)) {
+      return false;
+    }
+    // Append opened dex files at the end.
+    boot_dex_files_.insert(boot_dex_files_.end(),
+                           std::make_move_iterator(dex_files.begin()),
+                           std::make_move_iterator(dex_files.end()));
   }
-  uint32_t dex_caches_count = 0;
-  for (auto dex_caches : dex_caches_vector) {
-    dex_caches_count += dex_caches->GetLength();
+  FinishInit(self);
+
+  VLOG(startup) << __FUNCTION__ << " exiting";
+  return true;
+}
+
+static bool IsBootClassLoader(ScopedObjectAccessAlreadyRunnable& soa,
+                              mirror::ClassLoader* class_loader)
+    SHARED_REQUIRES(Locks::mutator_lock_) {
+  return class_loader == nullptr ||
+      class_loader->GetClass() ==
+          soa.Decode<mirror::Class*>(WellKnownClasses::java_lang_BootClassLoader);
+}
+
+static mirror::String* GetDexPathListElementName(ScopedObjectAccessUnchecked& soa,
+                                                 mirror::Object* element)
+    SHARED_REQUIRES(Locks::mutator_lock_) {
+  ArtField* const dex_file_field =
+      soa.DecodeField(WellKnownClasses::dalvik_system_DexPathList__Element_dexFile);
+  ArtField* const dex_file_name_field =
+      soa.DecodeField(WellKnownClasses::dalvik_system_DexFile_fileName);
+  DCHECK(dex_file_field != nullptr);
+  DCHECK(dex_file_name_field != nullptr);
+  DCHECK(element != nullptr);
+  CHECK_EQ(dex_file_field->GetDeclaringClass(), element->GetClass()) << PrettyTypeOf(element);
+  mirror::Object* dex_file = dex_file_field->GetObject(element);
+  if (dex_file == nullptr) {
+    return nullptr;
   }
-  if (dex_file_count != dex_caches_count) {
-    *error_msg = "Dex cache count and dex file count mismatch while trying to initialize from "
-                 "image";
-    return false;
+  mirror::Object* const name_object = dex_file_name_field->GetObject(dex_file);
+  if (name_object != nullptr) {
+    return name_object->AsString();
   }
-  for (auto dex_caches : dex_caches_vector) {
-    for (int32_t i = 0; i < dex_caches->GetLength(); i++) {
-      StackHandleScope<1> hs2(self);
-      Handle<mirror::DexCache> dex_cache(hs2.NewHandle(dex_caches->Get(i)));
-      const std::string& dex_file_location(dex_cache->GetLocation()->ToModifiedUtf8());
-      const OatFile::OatDexFile* oat_dex_file = nullptr;
-      for (const OatFile* oat_file : oat_files) {
-        const OatFile::OatDexFile* oat_dex =
-            oat_file->GetOatDexFile(dex_file_location.c_str(), nullptr, false);
-        if (oat_dex != nullptr) {
-          DCHECK(oat_dex_file == nullptr);
-          oat_dex_file = oat_dex;
+  return nullptr;
+}
+
+static bool FlattenPathClassLoader(mirror::ClassLoader* class_loader,
+                                   std::list<mirror::String*>* out_dex_file_names,
+                                   std::string* error_msg)
+    SHARED_REQUIRES(Locks::mutator_lock_) {
+  DCHECK(out_dex_file_names != nullptr);
+  DCHECK(error_msg != nullptr);
+  ScopedObjectAccessUnchecked soa(Thread::Current());
+  ArtField* const dex_path_list_field =
+      soa.DecodeField(WellKnownClasses::dalvik_system_PathClassLoader_pathList);
+  ArtField* const dex_elements_field =
+      soa.DecodeField(WellKnownClasses::dalvik_system_DexPathList_dexElements);
+  CHECK(dex_path_list_field != nullptr);
+  CHECK(dex_elements_field != nullptr);
+  while (!IsBootClassLoader(soa, class_loader)) {
+    if (class_loader->GetClass() !=
+        soa.Decode<mirror::Class*>(WellKnownClasses::dalvik_system_PathClassLoader)) {
+      *error_msg = StringPrintf("Unknown class loader type %s", PrettyTypeOf(class_loader).c_str());
+      // Unsupported class loader.
+      return false;
+    }
+    mirror::Object* dex_path_list = dex_path_list_field->GetObject(class_loader);
+    if (dex_path_list != nullptr) {
+      // DexPathList has an array dexElements of Elements[] which each contain a dex file.
+      mirror::Object* dex_elements_obj = dex_elements_field->GetObject(dex_path_list);
+      // Loop through each dalvik.system.DexPathList$Element's dalvik.system.DexFile and look
+      // at the mCookie which is a DexFile vector.
+      if (dex_elements_obj != nullptr) {
+        mirror::ObjectArray<mirror::Object>* dex_elements =
+            dex_elements_obj->AsObjectArray<mirror::Object>();
+        // Reverse order since we insert the parent at the front.
+        for (int32_t i = dex_elements->GetLength() - 1; i >= 0; --i) {
+          mirror::Object* const element = dex_elements->GetWithoutChecks(i);
+          if (element == nullptr) {
+            *error_msg = StringPrintf("Null dex element at index %d", i);
+            return false;
+          }
+          mirror::String* const name = GetDexPathListElementName(soa, element);
+          if (name == nullptr) {
+            *error_msg = StringPrintf("Null name for dex element at index %d", i);
+            return false;
+          }
+          out_dex_file_names->push_front(name);
         }
       }
+    }
+    class_loader = class_loader->GetParent();
+  }
+  return true;
+}
 
-      if (oat_dex_file == nullptr) {
-        *error_msg = StringPrintf("Failed finding oat dex file for %s",
-                                  dex_file_location.c_str());
-        return false;
+class FixupArtMethodArrayVisitor : public ArtMethodVisitor {
+ public:
+  explicit FixupArtMethodArrayVisitor(const ImageHeader& header) : header_(header) {}
+
+  virtual void Visit(ArtMethod* method) SHARED_REQUIRES(Locks::mutator_lock_) {
+    GcRoot<mirror::Class>* resolved_types = method->GetDexCacheResolvedTypes(sizeof(void*));
+    const bool is_miranda = method->IsMiranda();
+    if (resolved_types != nullptr) {
+      bool in_image_space = false;
+      if (kIsDebugBuild || is_miranda) {
+        in_image_space = header_.GetImageSection(ImageHeader::kSectionDexCacheArrays).Contains(
+            reinterpret_cast<const uint8_t*>(resolved_types) - header_.GetImageBegin());
       }
-      std::string inner_error_msg;
-      std::unique_ptr<const DexFile> dex_file = oat_dex_file->OpenDexFile(&inner_error_msg);
-      if (dex_file == nullptr) {
-        *error_msg = StringPrintf("Failed to open dex file %s error '%s'",
-                                  dex_file_location.c_str(),
-                                  inner_error_msg.c_str());
-        return false;
+      // Must be in image space for non-miranda method.
+      DCHECK(is_miranda || in_image_space)
+          << resolved_types << " is not in image starting at "
+          << reinterpret_cast<void*>(header_.GetImageBegin());
+      if (!is_miranda || in_image_space) {
+        // Go through the array so that we don't need to do a slow map lookup.
+        method->SetDexCacheResolvedTypes(*reinterpret_cast<GcRoot<mirror::Class>**>(resolved_types),
+                                         sizeof(void*));
       }
-
-      if (kSanityCheckObjects) {
-        SanityCheckArtMethodPointerArray(dex_cache->GetResolvedMethods(),
-                                         dex_cache->NumResolvedMethods(),
-                                         image_pointer_size_,
-                                         spaces);
+    }
+    ArtMethod** resolved_methods = method->GetDexCacheResolvedMethods(sizeof(void*));
+    if (resolved_methods != nullptr) {
+      bool in_image_space = false;
+      if (kIsDebugBuild || is_miranda) {
+        in_image_space = header_.GetImageSection(ImageHeader::kSectionDexCacheArrays).Contains(
+              reinterpret_cast<const uint8_t*>(resolved_methods) - header_.GetImageBegin());
+      }
+      // Must be in image space for non-miranda method.
+      DCHECK(is_miranda || in_image_space)
+          << resolved_methods << " is not in image starting at "
+          << reinterpret_cast<void*>(header_.GetImageBegin());
+      if (!is_miranda || in_image_space) {
+        // Go through the array so that we don't need to do a slow map lookup.
+        method->SetDexCacheResolvedMethods(*reinterpret_cast<ArtMethod***>(resolved_methods),
+                                           sizeof(void*));
       }
+    }
+  }
 
-      if (dex_file->GetLocationChecksum() != oat_dex_file->GetDexFileLocationChecksum()) {
-        *error_msg = StringPrintf("Checksums do not match for %s: %x vs %x",
-                                  dex_file_location.c_str(),
-                                  dex_file->GetLocationChecksum(),
-                                  oat_dex_file->GetDexFileLocationChecksum());
-        return false;
+ private:
+  const ImageHeader& header_;
+};
+
+class VerifyClassInTableArtMethodVisitor : public ArtMethodVisitor {
+ public:
+  explicit VerifyClassInTableArtMethodVisitor(ClassTable* table) : table_(table) {}
+
+  virtual void Visit(ArtMethod* method)
+      SHARED_REQUIRES(Locks::mutator_lock_, Locks::classlinker_classes_lock_) {
+    mirror::Class* klass = method->GetDeclaringClass();
+    if (klass != nullptr && !Runtime::Current()->GetHeap()->ObjectIsInBootImageSpace(klass)) {
+      CHECK_EQ(table_->LookupByDescriptor(klass), klass) << PrettyClass(klass);
+    }
+  }
+
+ private:
+  ClassTable* const table_;
+};
+
+void ClassLinker::UpdateAppImageClassLoadersAndDexCaches(
+    gc::space::ImageSpace* space,
+    Handle<mirror::ClassLoader> class_loader,
+    Handle<mirror::ObjectArray<mirror::DexCache>> dex_caches,
+    bool added_class_table) {
+  Thread* const self = Thread::Current();
+  gc::Heap* const heap = Runtime::Current()->GetHeap();
+  const ImageHeader& header = space->GetImageHeader();
+  // Add image classes into the class table for the class loader, and fixup the dex caches and
+  // class loader fields.
+  WriterMutexLock mu(self, *Locks::classlinker_classes_lock_);
+  ClassTable* table = InsertClassTableForClassLoader(class_loader.Get());
+  // TODO: Store class table in the image to avoid manually adding the classes.
+  for (int32_t i = 0, num_dex_caches = dex_caches->GetLength(); i < num_dex_caches; i++) {
+    mirror::DexCache* const dex_cache = dex_caches->Get(i);
+    const DexFile* const dex_file = dex_cache->GetDexFile();
+    // If the oat file expects the dex cache arrays to be in the BSS, then allocate there and
+    // copy over the arrays.
+    DCHECK(dex_file != nullptr);
+    const size_t num_strings = dex_file->NumStringIds();
+    const size_t num_types = dex_file->NumTypeIds();
+    const size_t num_methods = dex_file->NumMethodIds();
+    const size_t num_fields = dex_file->NumFieldIds();
+    CHECK_EQ(num_strings, dex_cache->NumStrings());
+    CHECK_EQ(num_types, dex_cache->NumResolvedTypes());
+    CHECK_EQ(num_methods, dex_cache->NumResolvedMethods());
+    CHECK_EQ(num_fields, dex_cache->NumResolvedFields());
+    if (dex_file->GetOatDexFile() != nullptr &&
+        dex_file->GetOatDexFile()->GetDexCacheArrays() != nullptr) {
+      DexCacheArraysLayout layout(image_pointer_size_, dex_file);
+      uint8_t* const raw_arrays = dex_file->GetOatDexFile()->GetDexCacheArrays();
+      // The space is not yet visible to the GC, we can avoid the read barriers and use
+      // std::copy_n.
+      if (num_strings != 0u) {
+        GcRoot<mirror::String>* const strings =
+            reinterpret_cast<GcRoot<mirror::String>*>(raw_arrays + layout.StringsOffset());
+        for (size_t j = 0; kIsDebugBuild && j < num_strings; ++j) {
+          DCHECK(strings[j].IsNull());
+        }
+        std::copy_n(dex_cache->GetStrings(), num_strings, strings);
+        dex_cache->SetStrings(strings);
       }
 
-      AppendToBootClassPath(*dex_file.get(), dex_cache);
-      opened_dex_files_.push_back(std::move(dex_file));
+      if (num_types != 0u) {
+        GcRoot<mirror::Class>* const image_resolved_types = dex_cache->GetResolvedTypes();
+        GcRoot<mirror::Class>* const types =
+            reinterpret_cast<GcRoot<mirror::Class>*>(raw_arrays + layout.TypesOffset());
+        for (size_t j = 0; kIsDebugBuild && j < num_types; ++j) {
+          DCHECK(types[j].IsNull());
+        }
+        std::copy_n(image_resolved_types, num_types, types);
+        // Store a pointer to the new location for fast ArtMethod patching without requiring map.
+        // This leaves random garbage at the start of the dex cache array, but nobody should ever
+        // read from it again.
+        *reinterpret_cast<GcRoot<mirror::Class>**>(image_resolved_types) = types;
+        dex_cache->SetResolvedTypes(types);
+      }
+      if (num_methods != 0u) {
+        ArtMethod** const methods = reinterpret_cast<ArtMethod**>(
+            raw_arrays + layout.MethodsOffset());
+        ArtMethod** const image_resolved_methods = dex_cache->GetResolvedMethods();
+        for (size_t j = 0; kIsDebugBuild && j < num_methods; ++j) {
+          DCHECK(methods[j] == nullptr);
+        }
+        std::copy_n(image_resolved_methods, num_methods, methods);
+        // Store a pointer to the new location for fast ArtMethod patching without requiring map.
+        *reinterpret_cast<ArtMethod***>(image_resolved_methods) = methods;
+        dex_cache->SetResolvedMethods(methods);
+      }
+      if (num_fields != 0u) {
+        ArtField** const fields = reinterpret_cast<ArtField**>(raw_arrays + layout.FieldsOffset());
+        for (size_t j = 0; kIsDebugBuild && j < num_fields; ++j) {
+          DCHECK(fields[j] == nullptr);
+        }
+        std::copy_n(dex_cache->GetResolvedFields(), num_fields, fields);
+        dex_cache->SetResolvedFields(fields);
+      }
     }
+    {
+      WriterMutexLock mu2(self, dex_lock_);
+      // Make sure to do this after we update the arrays since we store the resolved types array
+      // in DexCacheData in RegisterDexFileLocked. We need the array pointer to be the one in the
+      // BSS.
+      mirror::DexCache* existing_dex_cache = FindDexCacheLocked(self,
+                                                                *dex_file,
+                                                                /*allow_failure*/true);
+      CHECK(existing_dex_cache == nullptr);
+      StackHandleScope<1> hs3(self);
+      RegisterDexFileLocked(*dex_file, hs3.NewHandle(dex_cache));
+    }
+    GcRoot<mirror::Class>* const types = dex_cache->GetResolvedTypes();
+    if (!added_class_table) {
+      for (int32_t j = 0; j < static_cast<int32_t>(num_types); j++) {
+        // The image space is not yet added to the heap, avoid read barriers.
+        mirror::Class* klass = types[j].Read<kWithoutReadBarrier>();
+        if (klass != nullptr) {
+          DCHECK_NE(klass->GetStatus(), mirror::Class::kStatusError);
+          // Update the class loader from the one in the image class loader to the one that loaded
+          // the app image.
+          klass->SetClassLoader(class_loader.Get());
+          // If there are multiple dex caches, there may be the same class multiple times
+          // in different dex caches. Check for this since inserting will add duplicates
+          // otherwise.
+          if (num_dex_caches > 1) {
+            mirror::Class* existing = table->LookupByDescriptor(klass);
+            if (existing != nullptr) {
+              DCHECK_EQ(existing, klass) << PrettyClass(klass);
+            } else {
+              table->Insert(klass);
+            }
+          } else {
+            table->Insert(klass);
+          }
+          // Double checked VLOG to avoid overhead.
+          if (VLOG_IS_ON(image)) {
+            VLOG(image) << PrettyClass(klass) << " " << klass->GetStatus();
+            if (!klass->IsArrayClass()) {
+              VLOG(image) << "From " << klass->GetDexCache()->GetDexFile()->GetBaseLocation();
+            }
+            VLOG(image) << "Direct methods";
+            for (ArtMethod& m : klass->GetDirectMethods(sizeof(void*))) {
+              VLOG(image) << PrettyMethod(&m);
+            }
+            VLOG(image) << "Virtual methods";
+            for (ArtMethod& m : klass->GetVirtualMethods(sizeof(void*))) {
+              VLOG(image) << PrettyMethod(&m);
+            }
+          }
+        }
+      }
+    }
+    if (kIsDebugBuild) {
+      for (int32_t j = 0; j < static_cast<int32_t>(num_types); j++) {
+        // The image space is not yet added to the heap, avoid read barriers.
+        mirror::Class* klass = types[j].Read<kWithoutReadBarrier>();
+        if (klass != nullptr) {
+          DCHECK_NE(klass->GetStatus(), mirror::Class::kStatusError);
+          if (kIsDebugBuild) {
+            DCHECK_EQ(table->LookupByDescriptor(klass), klass);
+            mirror::Class* super_class = klass->GetSuperClass();
+            if (super_class != nullptr && !heap->ObjectIsInBootImageSpace(super_class)) {
+              CHECK_EQ(table->LookupByDescriptor(super_class), super_class);
+            }
+          }
+          DCHECK_EQ(klass->GetClassLoader(), class_loader.Get());
+          if (kIsDebugBuild) {
+            for (ArtMethod& m : klass->GetDirectMethods(sizeof(void*))) {
+                const void* code = m.GetEntryPointFromQuickCompiledCode();
+                const void* oat_code = m.IsInvokable() ? GetQuickOatCodeFor(&m) : code;
+                if (!IsQuickResolutionStub(code) &&
+                    !IsQuickGenericJniStub(code) &&
+                    !IsQuickToInterpreterBridge(code) &&
+                    !m.IsNative()) {
+                  DCHECK_EQ(code, oat_code) << PrettyMethod(&m);
+                }
+              }
+              VLOG(image) << "Virtual methods";
+              for (ArtMethod& m : klass->GetVirtualMethods(sizeof(void*))) {
+                const void* code = m.GetEntryPointFromQuickCompiledCode();
+                const void* oat_code = m.IsInvokable() ? GetQuickOatCodeFor(&m) : code;
+                if (!IsQuickResolutionStub(code) &&
+                    !IsQuickGenericJniStub(code) &&
+                    !IsQuickToInterpreterBridge(code) &&
+                    !m.IsNative()) {
+                  DCHECK_EQ(code, oat_code) << PrettyMethod(&m);
+                }
+              }
+          }
+        }
+      }
+    }
+  }
+  {
+    FixupArtMethodArrayVisitor visitor(header);
+    header.GetImageSection(ImageHeader::kSectionArtMethods).VisitPackedArtMethods(
+        &visitor, space->Begin(), sizeof(void*));
+    Runtime::Current()->GetHeap()->WriteBarrierEveryFieldOf(class_loader.Get());
   }
+  if (kIsDebugBuild) {
+    ClassTable* const class_table = class_loader.Get()->GetClassTable();
+    VerifyClassInTableArtMethodVisitor visitor2(class_table);
+    header.GetImageSection(ImageHeader::kSectionArtMethods).VisitPackedArtMethods(
+        &visitor2, space->Begin(), sizeof(void*));
+  }
+}
 
-  if (!ValidPointerSize(image_pointer_size_)) {
-    *error_msg = StringPrintf("Invalid image pointer size: %zu", image_pointer_size_);
+bool ClassLinker::AddImageSpace(
+    gc::space::ImageSpace* space,
+    Handle<mirror::ClassLoader> class_loader,
+    jobjectArray dex_elements,
+    const char* dex_location,
+    std::vector<std::unique_ptr<const DexFile>>* out_dex_files,
+    std::string* error_msg) {
+  DCHECK(out_dex_files != nullptr);
+  DCHECK(error_msg != nullptr);
+  const uint64_t start_time = NanoTime();
+  const bool app_image = class_loader.Get() != nullptr;
+  const ImageHeader& header = space->GetImageHeader();
+  mirror::Object* dex_caches_object = header.GetImageRoot(ImageHeader::kDexCaches);
+  DCHECK(dex_caches_object != nullptr);
+  Runtime* const runtime = Runtime::Current();
+  gc::Heap* const heap = runtime->GetHeap();
+  Thread* const self = Thread::Current();
+  StackHandleScope<2> hs(self);
+  Handle<mirror::ObjectArray<mirror::DexCache>> dex_caches(
+      hs.NewHandle(dex_caches_object->AsObjectArray<mirror::DexCache>()));
+  Handle<mirror::ObjectArray<mirror::Class>> class_roots(hs.NewHandle(
+      header.GetImageRoot(ImageHeader::kClassRoots)->AsObjectArray<mirror::Class>()));
+  const OatFile* oat_file = space->GetOatFile();
+  std::unordered_set<mirror::ClassLoader*> image_class_loaders;
+  // Check that the image is what we are expecting.
+  if (image_pointer_size_ != space->GetImageHeader().GetPointerSize()) {
+    *error_msg = StringPrintf("Application image pointer size does not match runtime: %zu vs %zu",
+                              static_cast<size_t>(space->GetImageHeader().GetPointerSize()),
+                              image_pointer_size_);
+    return false;
+  }
+  DCHECK(class_roots.Get() != nullptr);
+  if (class_roots->GetLength() != static_cast<int32_t>(kClassRootsMax)) {
+    *error_msg = StringPrintf("Expected %d class roots but got %d",
+                              class_roots->GetLength(),
+                              static_cast<int32_t>(kClassRootsMax));
+    return false;
+  }
+  // Check against existing class roots to make sure they match the ones in the boot image.
+  for (size_t i = 0; i < kClassRootsMax; i++) {
+    if (class_roots->Get(i) != GetClassRoot(static_cast<ClassRoot>(i))) {
+      *error_msg = "App image class roots must have pointer equality with runtime ones.";
+      return false;
+    }
+  }
+  if (oat_file->GetOatHeader().GetDexFileCount() !=
+      static_cast<uint32_t>(dex_caches->GetLength())) {
+    *error_msg = "Dex cache count and dex file count mismatch while trying to initialize from "
+                 "image";
     return false;
   }
 
-  // Set classes on AbstractMethod early so that IsMethod tests can be performed during the live
-  // bitmap walk.
-  if (!runtime->IsAotCompiler()) {
-    // Only the Aot compiler supports having an image with a different pointer size than the
-    // runtime. This happens on the host for compile 32 bit tests since we use a 64 bit libart
-    // compiler. We may also use 32 bit dex2oat on a system with 64 bit apps.
-    if (image_pointer_size_ != sizeof(void*)) {
-      *error_msg = StringPrintf("Runtime must use current image pointer size: %zu vs %zu",
-                                image_pointer_size_ ,
-                                sizeof(void*));
+  StackHandleScope<1> hs2(self);
+  MutableHandle<mirror::DexCache> h_dex_cache(hs2.NewHandle<mirror::DexCache>(nullptr));
+  for (int32_t i = 0; i < dex_caches->GetLength(); i++) {
+    h_dex_cache.Assign(dex_caches->Get(i));
+    std::string dex_file_location(h_dex_cache->GetLocation()->ToModifiedUtf8());
+    // TODO: Only store qualified paths.
+    // If non qualified, qualify it.
+    if (dex_file_location.find('/') == std::string::npos) {
+      std::string dex_location_path = dex_location;
+      const size_t pos = dex_location_path.find_last_of('/');
+      CHECK_NE(pos, std::string::npos);
+      dex_location_path = dex_location_path.substr(0, pos + 1);  // Keep trailing '/'
+      dex_file_location = dex_location_path + dex_file_location;
+    }
+    const OatFile::OatDexFile* oat_dex_file = oat_file->GetOatDexFile(dex_file_location.c_str(),
+                                                                      nullptr);
+    if (oat_dex_file == nullptr) {
+      *error_msg = StringPrintf("Failed finding oat dex file for %s %s",
+                                oat_file->GetLocation().c_str(),
+                                dex_file_location.c_str());
+      return false;
+    }
+    std::string inner_error_msg;
+    std::unique_ptr<const DexFile> dex_file = oat_dex_file->OpenDexFile(&inner_error_msg);
+    if (dex_file == nullptr) {
+      *error_msg = StringPrintf("Failed to open dex file %s from within oat file %s error '%s'",
+                                dex_file_location.c_str(),
+                                oat_file->GetLocation().c_str(),
+                                inner_error_msg.c_str());
+      return false;
+    }
+
+    if (dex_file->GetLocationChecksum() != oat_dex_file->GetDexFileLocationChecksum()) {
+      *error_msg = StringPrintf("Checksums do not match for %s: %x vs %x",
+                                dex_file_location.c_str(),
+                                dex_file->GetLocationChecksum(),
+                                oat_dex_file->GetDexFileLocationChecksum());
       return false;
     }
+
+    if (app_image) {
+      // The current dex file field is bogus, overwrite it so that we can get the dex file in the
+      // loop below.
+      h_dex_cache->SetDexFile(dex_file.get());
+      // Check that each class loader resolved the same way.
+      // TODO: Store image class loaders as image roots.
+      GcRoot<mirror::Class>* const types = h_dex_cache->GetResolvedTypes();
+      for (int32_t j = 0, num_types = h_dex_cache->NumResolvedTypes(); j < num_types; j++) {
+        mirror::Class* klass = types[j].Read();
+        if (klass != nullptr) {
+          DCHECK_NE(klass->GetStatus(), mirror::Class::kStatusError);
+          mirror::ClassLoader* image_class_loader = klass->GetClassLoader();
+          image_class_loaders.insert(image_class_loader);
+        }
+      }
+    } else {
+      if (kSanityCheckObjects) {
+        SanityCheckArtMethodPointerArray(h_dex_cache->GetResolvedMethods(),
+                                         h_dex_cache->NumResolvedMethods(),
+                                         image_pointer_size_,
+                                         heap->GetBootImageSpaces());
+      }
+      // Register dex files, keep track of existing ones that are conflicts.
+      AppendToBootClassPath(*dex_file.get(), h_dex_cache);
+    }
+    out_dex_files->push_back(std::move(dex_file));
+  }
+
+  if (app_image) {
+    ScopedObjectAccessUnchecked soa(Thread::Current());
+    // Check that the class loader resolves the same way as the ones in the image.
+    // Image class loader [A][B][C][image dex files]
+    // Class loader = [???][dex_elements][image dex files]
+    // Need to ensure that [???][dex_elements] == [A][B][C].
+    // For each class loader, PathClassLoader, the laoder checks the parent first. Also the logic
+    // for PathClassLoader does this by looping through the array of dex files. To ensure they
+    // resolve the same way, simply flatten the hierarchy in the way the resolution order would be,
+    // and check that the dex file names are the same.
+    for (mirror::ClassLoader* image_class_loader : image_class_loaders) {
+      std::list<mirror::String*> image_dex_file_names;
+      std::string temp_error_msg;
+      if (!FlattenPathClassLoader(image_class_loader, &image_dex_file_names, &temp_error_msg)) {
+        *error_msg = StringPrintf("Failed to flatten image class loader hierarchy '%s'",
+                                  temp_error_msg.c_str());
+        return false;
+      }
+      std::list<mirror::String*> loader_dex_file_names;
+      if (!FlattenPathClassLoader(class_loader.Get(), &loader_dex_file_names, &temp_error_msg)) {
+        *error_msg = StringPrintf("Failed to flatten class loader hierarchy '%s'",
+                                  temp_error_msg.c_str());
+        return false;
+      }
+      // Add the temporary dex path list elements at the end.
+      auto* elements = soa.Decode<mirror::ObjectArray<mirror::Object>*>(dex_elements);
+      for (size_t i = 0, num_elems = elements->GetLength(); i < num_elems; ++i) {
+        mirror::Object* element = elements->GetWithoutChecks(i);
+        if (element != nullptr) {
+          // If we are somewhere in the middle of the array, there may be nulls at the end.
+          loader_dex_file_names.push_back(GetDexPathListElementName(soa, element));
+        }
+      }
+      // Ignore the number of image dex files since we are adding those to the class loader anyways.
+      CHECK_GE(static_cast<size_t>(image_dex_file_names.size()),
+               static_cast<size_t>(dex_caches->GetLength()));
+      size_t image_count = image_dex_file_names.size() - dex_caches->GetLength();
+      // Check that the dex file names match.
+      bool equal = image_count == loader_dex_file_names.size();
+      if (equal) {
+        auto it1 = image_dex_file_names.begin();
+        auto it2 = loader_dex_file_names.begin();
+        for (size_t i = 0; equal && i < image_count; ++i, ++it1, ++it2) {
+          equal = equal && (*it1)->Equals(*it2);
+        }
+      }
+      if (!equal) {
+        *error_msg = "Rejecting application image due to class loader mismatch";
+        return false;
+      }
+    }
   }
 
   if (kSanityCheckObjects) {
-    for (auto dex_caches : dex_caches_vector) {
-      for (int32_t i = 0; i < dex_caches->GetLength(); i++) {
-        auto* dex_cache = dex_caches->Get(i);
-        for (size_t j = 0; j < dex_cache->NumResolvedFields(); ++j) {
-          auto* field = dex_cache->GetResolvedField(j, image_pointer_size_);
-          if (field != nullptr) {
-            CHECK(field->GetDeclaringClass()->GetClass() != nullptr);
-          }
+    for (int32_t i = 0; i < dex_caches->GetLength(); i++) {
+      auto* dex_cache = dex_caches->Get(i);
+      for (size_t j = 0; j < dex_cache->NumResolvedFields(); ++j) {
+        auto* field = dex_cache->GetResolvedField(j, image_pointer_size_);
+        if (field != nullptr) {
+          CHECK(field->GetDeclaringClass()->GetClass() != nullptr);
         }
       }
     }
-    heap->VisitObjects(SanityCheckObjectsCallback, nullptr);
+    if (!app_image) {
+      heap->VisitObjects(SanityCheckObjectsCallback, nullptr);
+    }
   }
 
   // Set entry point to interpreter if in InterpretOnly mode.
   if (!runtime->IsAotCompiler() && runtime->GetInstrumentation()->InterpretOnly()) {
-    for (gc::space::ImageSpace* space : spaces) {
-      const ImageHeader& header = space->GetImageHeader();
-      const ImageSection& methods = header.GetMethodsSection();
-      SetInterpreterEntrypointArtMethodVisitor visitor(image_pointer_size_);
-      methods.VisitPackedArtMethods(&visitor, space->Begin(), image_pointer_size_);
-    }
-  }
-
-  // reinit class_roots_
-  mirror::Class::SetClassClass(class_roots->Get(kJavaLangClass));
-  class_roots_ = GcRoot<mirror::ObjectArray<mirror::Class>>(class_roots.Get());
-
-  // reinit array_iftable_ from any array class instance, they should be ==
-  array_iftable_ = GcRoot<mirror::IfTable>(GetClassRoot(kObjectArrayClass)->GetIfTable());
-  DCHECK_EQ(array_iftable_.Read(), GetClassRoot(kBooleanArrayClass)->GetIfTable());
-  // String class root was set above
-  mirror::Field::SetClass(GetClassRoot(kJavaLangReflectField));
-  mirror::Field::SetArrayClass(GetClassRoot(kJavaLangReflectFieldArrayClass));
-  mirror::Constructor::SetClass(GetClassRoot(kJavaLangReflectConstructor));
-  mirror::Constructor::SetArrayClass(GetClassRoot(kJavaLangReflectConstructorArrayClass));
-  mirror::Method::SetClass(GetClassRoot(kJavaLangReflectMethod));
-  mirror::Method::SetArrayClass(GetClassRoot(kJavaLangReflectMethodArrayClass));
-  mirror::Reference::SetClass(GetClassRoot(kJavaLangRefReference));
-  mirror::BooleanArray::SetArrayClass(GetClassRoot(kBooleanArrayClass));
-  mirror::ByteArray::SetArrayClass(GetClassRoot(kByteArrayClass));
-  mirror::CharArray::SetArrayClass(GetClassRoot(kCharArrayClass));
-  mirror::DoubleArray::SetArrayClass(GetClassRoot(kDoubleArrayClass));
-  mirror::FloatArray::SetArrayClass(GetClassRoot(kFloatArrayClass));
-  mirror::IntArray::SetArrayClass(GetClassRoot(kIntArrayClass));
-  mirror::LongArray::SetArrayClass(GetClassRoot(kLongArrayClass));
-  mirror::ShortArray::SetArrayClass(GetClassRoot(kShortArrayClass));
-  mirror::Throwable::SetClass(GetClassRoot(kJavaLangThrowable));
-  mirror::StackTraceElement::SetClass(GetClassRoot(kJavaLangStackTraceElement));
-
-  size_t class_tables_added = 0;
-  for (gc::space::ImageSpace* space : spaces) {
-    const ImageHeader& header = space->GetImageHeader();
-    const ImageSection& section = header.GetImageSection(ImageHeader::kSectionClassTable);
-    if (section.Size() > 0u) {
-      WriterMutexLock mu(self, *Locks::classlinker_classes_lock_);
-      ClassTable* const class_table = InsertClassTableForClassLoader(nullptr);
-      class_table->ReadFromMemory(space->Begin() + section.Offset());
-      ++class_tables_added;
+    const ImageSection& methods = header.GetMethodsSection();
+    SetInterpreterEntrypointArtMethodVisitor visitor(image_pointer_size_);
+    methods.VisitPackedArtMethods(&visitor, space->Begin(), image_pointer_size_);
+  }
+
+  const ImageSection& class_table_section = header.GetImageSection(ImageHeader::kSectionClassTable);
+  bool added_class_table = false;
+  if (app_image) {
+    GetOrCreateAllocatorForClassLoader(class_loader.Get());  // Make sure we have a linear alloc.
+  }
+  if (class_table_section.Size() > 0u) {
+    const uint64_t start_time2 = NanoTime();
+    WriterMutexLock mu(self, *Locks::classlinker_classes_lock_);
+    ClassTable* const class_table = InsertClassTableForClassLoader(class_loader.Get());
+    class_table->ReadFromMemory(space->Begin() + class_table_section.Offset());
+    if (app_image) {
+      class_table->SetClassLoader(class_loader.Get());
+    } else {
+      dex_cache_boot_image_class_lookup_required_ = false;
     }
+    VLOG(image) << "Adding class table classes took " << PrettyDuration(NanoTime() - start_time2);
+    added_class_table = true;
   }
-  if (class_tables_added != 0) {
-    // Either all of the image spaces have an empty class section or none do. In the case where
-    // an image space has no classes, it will still have a non-empty class section that contains
-    // metadata.
-    CHECK_EQ(spaces.size(), class_tables_added)
-        << "Expected non-empty class section for each image space.";
-    dex_cache_boot_image_class_lookup_required_ = false;
+  if (app_image) {
+    UpdateAppImageClassLoadersAndDexCaches(space, class_loader, dex_caches, added_class_table);
   }
-
-  FinishInit(self);
-
-  VLOG(startup) << "ClassLinker::InitFromImage exiting";
-
+  VLOG(class_linker) << "Adding image space took " << PrettyDuration(NanoTime() - start_time);
   return true;
 }
 
@@ -1527,14 +1971,6 @@ ClassPathEntry FindInClassPath(const char* descriptor,
   return ClassPathEntry(nullptr, nullptr);
 }
 
-static bool IsBootClassLoader(ScopedObjectAccessAlreadyRunnable& soa,
-                              mirror::ClassLoader* class_loader)
-    SHARED_REQUIRES(Locks::mutator_lock_) {
-  return class_loader == nullptr ||
-      class_loader->GetClass() ==
-          soa.Decode<mirror::Class*>(WellKnownClasses::java_lang_BootClassLoader);
-}
-
 bool ClassLinker::FindClassInPathClassLoader(ScopedObjectAccessAlreadyRunnable& soa,
                                              Thread* self,
                                              const char* descriptor,
@@ -1820,6 +2256,7 @@ mirror::Class* ClassLinker::DefineClass(Thread* self,
   // inserted before we allocate / fill in these fields.
   LoadClass(self, dex_file, dex_class_def, klass);
   if (self->IsExceptionPending()) {
+    VLOG(class_linker) << self->GetException()->Dump();
     // An exception occured during load, set status to erroneous while holding klass' lock in case
     // notification is necessary.
     if (!klass->IsErroneous()) {
@@ -2487,7 +2924,20 @@ void ClassLinker::RegisterDexFileLocked(const DexFile& dex_file,
   Thread* const self = Thread::Current();
   dex_lock_.AssertExclusiveHeld(self);
   CHECK(dex_cache.Get() != nullptr) << dex_file.GetLocation();
-  CHECK(dex_cache->GetLocation()->Equals(dex_file.GetLocation()))
+  // For app images, the dex cache location may be a suffix of the dex file location since the
+  // dex file location is an absolute path.
+  const size_t dex_cache_length = dex_cache->GetLocation()->GetLength();
+  CHECK_GT(dex_cache_length, 0u) << dex_file.GetLocation();
+  std::string dex_file_location = dex_file.GetLocation();
+  CHECK_GE(dex_file_location.length(), dex_cache_length)
+      << dex_cache->GetLocation()->ToModifiedUtf8() << " " << dex_file.GetLocation();
+  // Take suffix.
+  const std::string dex_file_suffix = dex_file_location.substr(
+      dex_file_location.length() - dex_cache_length,
+      dex_cache_length);
+  // Example dex_cache location is SettingsProvider.apk and
+  // dex file location is /system/priv-app/SettingsProvider/SettingsProvider.apk
+  CHECK(dex_cache->GetLocation()->Equals(dex_file_suffix))
       << dex_cache->GetLocation()->ToModifiedUtf8() << " " << dex_file.GetLocation();
   // Clean up pass to remove null dex caches.
   // Null dex caches can occur due to class unloading and we are lazily removing null entries.
@@ -6931,10 +7381,13 @@ jobject ClassLinker::CreatePathClassLoader(Thread* self, std::vector<const DexFi
   ArtField* cookie_field = soa.DecodeField(WellKnownClasses::dalvik_system_DexFile_cookie);
   DCHECK_EQ(cookie_field->GetDeclaringClass(), element_file_field->GetType<false>());
 
+  ArtField* file_name_field = soa.DecodeField(WellKnownClasses::dalvik_system_DexFile_fileName);
+  DCHECK_EQ(file_name_field->GetDeclaringClass(), element_file_field->GetType<false>());
+
   // Fill the elements array.
   int32_t index = 0;
   for (const DexFile* dex_file : dex_files) {
-    StackHandleScope<3> hs2(self);
+    StackHandleScope<4> hs2(self);
 
     // CreatePathClassLoader is only used by gtests. Index 0 of h_long_array is supposed to be the
     // oat file but we can leave it null.
@@ -6949,6 +7402,11 @@ jobject ClassLinker::CreatePathClassLoader(Thread* self, std::vector<const DexFi
     DCHECK(h_dex_file.Get() != nullptr);
     cookie_field->SetObject<false>(h_dex_file.Get(), h_long_array.Get());
 
+    Handle<mirror::String> h_file_name = hs2.NewHandle(
+        mirror::String::AllocFromModifiedUtf8(self, dex_file->GetLocation().c_str()));
+    DCHECK(h_file_name.Get() != nullptr);
+    file_name_field->SetObject<false>(h_dex_file.Get(), h_file_name.Get());
+
     Handle<mirror::Object> h_element = hs2.NewHandle(h_dex_element_class->AllocObject(self));
     DCHECK(h_element.Get() != nullptr);
     element_file_field->SetObject<false>(h_element.Get(), h_dex_file.Get());
@@ -7048,6 +7506,7 @@ void ClassLinker::CleanupClassLoaders() {
     if (class_loader != nullptr) {
       ++it;
     } else {
+      VLOG(class_linker) << "Freeing class loader";
       DeleteClassLoader(self, data);
       it = class_loaders_.erase(it);
     }