Support deferred library prefix syntax

runtime/vm/object.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/object.h"
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "vm/assembler.h"
 #include "vm/cpu.h"
@@ skipping 107 matching lines @@
 RawClass* Object::patch_class_class_ = reinterpret_cast<RawClass*>(RAW_NULL);
 RawClass* Object::function_class_ = reinterpret_cast<RawClass*>(RAW_NULL);
 RawClass* Object::closure_data_class_ = reinterpret_cast<RawClass*>(RAW_NULL);
 RawClass* Object::redirection_data_class_ =
     reinterpret_cast<RawClass*>(RAW_NULL);
 RawClass* Object::field_class_ = reinterpret_cast<RawClass*>(RAW_NULL);
 RawClass* Object::literal_token_class_ = reinterpret_cast<RawClass*>(RAW_NULL);
 RawClass* Object::token_stream_class_ = reinterpret_cast<RawClass*>(RAW_NULL);
 RawClass* Object::script_class_ = reinterpret_cast<RawClass*>(RAW_NULL);
 RawClass* Object::library_class_ = reinterpret_cast<RawClass*>(RAW_NULL);
-RawClass* Object::library_prefix_class_ = reinterpret_cast<RawClass*>(RAW_NULL);
 RawClass* Object::namespace_class_ = reinterpret_cast<RawClass*>(RAW_NULL);
 RawClass* Object::code_class_ = reinterpret_cast<RawClass*>(RAW_NULL);
 RawClass* Object::instructions_class_ = reinterpret_cast<RawClass*>(RAW_NULL);
 RawClass* Object::pc_descriptors_class_ = reinterpret_cast<RawClass*>(RAW_NULL);
 RawClass* Object::stackmap_class_ = reinterpret_cast<RawClass*>(RAW_NULL);
 RawClass* Object::var_descriptors_class_ =
     reinterpret_cast<RawClass*>(RAW_NULL);
 RawClass* Object::exception_handlers_class_ =
     reinterpret_cast<RawClass*>(RAW_NULL);
 RawClass* Object::deopt_info_class_ = reinterpret_cast<RawClass*>(RAW_NULL);
@@ skipping 423 matching lines @@
 
   cls = Class::New<TokenStream>();
   token_stream_class_ = cls.raw();
 
   cls = Class::New<Script>();
   script_class_ = cls.raw();
 
   cls = Class::New<Library>();
   library_class_ = cls.raw();
 
-  cls = Class::New<LibraryPrefix>();
-  library_prefix_class_ = cls.raw();
-
   cls = Class::New<Namespace>();
   namespace_class_ = cls.raw();
 
   cls = Class::New<Code>();
   code_class_ = cls.raw();
 
   cls = Class::New<Instructions>();
   instructions_class_ = cls.raw();
 
   cls = Class::New<PcDescriptors>();
@@ skipping 178 matching lines @@
   SET_CLASS_NAME(type_arguments, TypeArguments);
   SET_CLASS_NAME(patch_class, PatchClass);
   SET_CLASS_NAME(function, Function);
   SET_CLASS_NAME(closure_data, ClosureData);
   SET_CLASS_NAME(redirection_data, RedirectionData);
   SET_CLASS_NAME(field, Field);
   SET_CLASS_NAME(literal_token, LiteralToken);
   SET_CLASS_NAME(token_stream, TokenStream);
   SET_CLASS_NAME(script, Script);
   SET_CLASS_NAME(library, LibraryClass);
-  SET_CLASS_NAME(library_prefix, LibraryPrefix);
   SET_CLASS_NAME(namespace, Namespace);
   SET_CLASS_NAME(code, Code);
   SET_CLASS_NAME(instructions, Instructions);
   SET_CLASS_NAME(pc_descriptors, PcDescriptors);
   SET_CLASS_NAME(stackmap, Stackmap);
   SET_CLASS_NAME(var_descriptors, LocalVarDescriptors);
   SET_CLASS_NAME(exception_handlers, ExceptionHandlers);
   SET_CLASS_NAME(deopt_info, DeoptInfo);
   SET_CLASS_NAME(context, Context);
   SET_CLASS_NAME(context_scope, ContextScope);
@@ skipping 154 matching lines @@
 
   cls = Class::New<TypeParameter>();
   object_store->set_type_parameter_class(cls);
 
   cls = Class::New<BoundedType>();
   object_store->set_bounded_type_class(cls);
 
   cls = Class::New<MixinAppType>();
   object_store->set_mixin_app_type_class(cls);
 
+  cls = Class::New<LibraryPrefix>();
+  object_store->set_library_prefix_class(cls);
+
   // Pre-allocate the OneByteString class needed by the symbol table.
   cls = Class::NewStringClass(kOneByteStringCid);
   object_store->set_one_byte_string_class(cls);
 
   // Pre-allocate the TwoByteString class needed by the symbol table.
   cls = Class::NewStringClass(kTwoByteStringCid);
   object_store->set_two_byte_string_class(cls);
 
   // Setup the symbol table for the symbols created in the isolate.
   Symbols::SetupSymbolTable(isolate);
@@ skipping 98 matching lines @@
   pending_classes.Add(cls);
 
   cls = Class::New<Instance>(kNullCid);
   object_store->set_null_class(cls);
   cls.set_num_type_arguments(0);
   cls.set_num_own_type_arguments(0);
   cls.set_is_prefinalized();
   RegisterClass(cls, Symbols::Null(), core_lib);
   pending_classes.Add(cls);
 
+  cls = object_store->library_prefix_class();
+  ASSERT(!cls.IsNull());
+  RegisterPrivateClass(cls, Symbols::_LibraryPrefix(), core_lib);
+  pending_classes.Add(cls);
+
   cls = object_store->type_class();
   RegisterPrivateClass(cls, Symbols::Type(), core_lib);
   pending_classes.Add(cls);
 
   cls = object_store->type_ref_class();
   RegisterPrivateClass(cls, Symbols::TypeRef(), core_lib);
   pending_classes.Add(cls);
 
   cls = object_store->type_parameter_class();
   RegisterPrivateClass(cls, Symbols::TypeParameter(), core_lib);
@@ skipping 254 matching lines @@
   ObjectStore* object_store = isolate->object_store();
 
   Class& cls = Class::Handle();
 
   // Set up empty classes in the object store, these will get
   // initialized correctly when we read from the snapshot.
   // This is done to allow bootstrapping of reading classes from the snapshot.
   cls = Class::New<Instance>(kInstanceCid);
   object_store->set_object_class(cls);
 
+  cls = Class::New<LibraryPrefix>();
+  object_store->set_library_prefix_class(cls);
+
   cls = Class::New<Type>();
   object_store->set_type_class(cls);
 
   cls = Class::New<TypeRef>();
   object_store->set_type_ref_class(cls);
 
   cls = Class::New<TypeParameter>();
   object_store->set_type_parameter_class(cls);
 
   cls = Class::New<BoundedType>();
@@ skipping 1086 matching lines @@
       weak_property ^= code_objects.At(i);
       code ^= weak_property.key();
       if (code.IsNull()) {
         // Code was garbage collected already.
         continue;
       }
 
       function ^= code.function();
       // If function uses dependent code switch it to unoptimized.
       if (function.CurrentCode() == code.raw()) {
-        ASSERT(function.HasOptimizedCode());
         ReportSwitchingCode(code);
-        function.SwitchToUnoptimizedCode();
+        if (code.is_optimized()) {

[Ivan Posva, 2014/03/27 07:38:48]

What if we have optimized code that needs to be entirely cleared such as on load
of libraries?

[hausner, 2014/03/27 20:45:39]

I think we spoke about this before i implemented it. You pointed out that if the
optimized code is in the list, then the unoptimized code is in the list as well
and we'll get rid of it in a separate iteration. The optimized code is thrown
away when we switch to unoptimized code. So I think both versions of the code
are nuked.

[Ivan Posva, 2014/03/27 21:41:18]

I worry about the ordering of code removal a bit. What is the behaviour of
SwitchToUnoptimizedCode if we have already removed the unoptimized code?

+          function.SwitchToUnoptimizedCode();
+        } else {
+          function.ClearCode();
+        }
       }
     }
   }
 
  private:
   const Array& array_;
   DISALLOW_COPY_AND_ASSIGN(WeakCodeReferences);
 };
 
 
@@ skipping 6275 matching lines @@
   result.StorePointer(&result.raw_ptr()->metadata_,
                       GrowableObjectArray::New(4, Heap::kOld));
   result.raw_ptr()->anonymous_classes_ = Object::empty_array().raw();
   result.raw_ptr()->num_anonymous_ = 0;
   result.raw_ptr()->imports_ = Object::empty_array().raw();
   result.raw_ptr()->exports_ = Object::empty_array().raw();
   result.raw_ptr()->loaded_scripts_ = Array::null();
   result.set_native_entry_resolver(NULL);
   result.raw_ptr()->corelib_imported_ = true;
   result.set_debuggable(false);
+  result.raw_ptr()->deferred_load_ = false;
   result.raw_ptr()->load_state_ = RawLibrary::kAllocated;
   result.raw_ptr()->index_ = -1;
   const intptr_t kInitialNameCacheSize = 64;
   result.InitResolvedNamesCache(kInitialNameCacheSize);
   result.InitClassDictionary();
   result.InitImportList();
   result.AllocatePrivateKey();
   if (import_core_lib) {
     const Library& core_lib = Library::Handle(Library::CoreLibrary());
     ASSERT(!core_lib.IsNull());
@@ skipping 346 matching lines @@
       }
     }
   }
   return false;
 }
 
 
 void LibraryPrefix::AddImport(const Namespace& import) const {
   intptr_t num_current_imports = num_imports();
 
+  // Prefixes with deferred libraries can only contain one library.
+  ASSERT((num_current_imports == 0) || !is_deferred_load());
+
   // The library needs to be added to the list.
   Array& imports = Array::Handle(this->imports());
   const intptr_t length = (imports.IsNull()) ? 0 : imports.Length();
   // Grow the list if it is full.
   if (num_current_imports >= length) {
     const intptr_t new_length = length + kIncrementSize;
     imports = Array::Grow(imports, new_length, Heap::kOld);
     set_imports(imports);
   }
   imports.SetAt(num_current_imports, import);
   set_num_imports(num_current_imports + 1);
 }
 
 
 RawObject* LibraryPrefix::LookupObject(const String& name) const {
+  if (!is_loaded()) {
+    return Object::null();
+  }
   Array& imports = Array::Handle(this->imports());
   Object& obj = Object::Handle();
   Namespace& import = Namespace::Handle();
   Library& import_lib = Library::Handle();
   String& import_lib_url = String::Handle();
   String& first_import_lib_url = String::Handle();
   Object& found_obj = Object::Handle();
   for (intptr_t i = 0; i < num_imports(); i++) {
     import ^= imports.At(i);
     obj = import.Lookup(name);
@@ skipping 26 matching lines @@
 
 RawClass* LibraryPrefix::LookupClass(const String& class_name) const {
   const Object& obj = Object::Handle(LookupObject(class_name));
   if (obj.IsClass()) {
     return Class::Cast(obj).raw();
   }
   return Class::null();
 }
 
 
+void LibraryPrefix::set_is_loaded() const {
+  raw_ptr()->is_loaded_ = true;
+}
+
+
+void LibraryPrefix::LoadLibrary() const {
+  if (!is_deferred_load()) {
+    return;
+  }
+  if (is_loaded()) {

[Ivan Posva, 2014/03/27 07:38:48]

What is the value of loaded for an eagerly loaded prefix? If it is marked as
loaded as I would expect, then the above check for deferred_load is not needed.

[hausner, 2014/03/27 20:45:39]

That is true. I'll change this to an assert to ensure the invariant.

+    return;
+  }
+  NukeDependentCode();
+  set_is_loaded();
+}
+
+
+RawArray* LibraryPrefix::dependent_code() const {
+  return raw_ptr()->dependent_code_;
+}
+
+
+void LibraryPrefix::set_dependent_code(const Array& array) const {
+  StorePointer(&raw_ptr()->dependent_code_, array.raw());
+}
+
+
+class PrefixDependentArray : public WeakCodeReferences {
+ public:
+  explicit PrefixDependentArray(const LibraryPrefix& prefix)
+      : WeakCodeReferences(Array::Handle(prefix.dependent_code())),
+                           prefix_(prefix) {}
+
+  virtual void UpdateArrayTo(const Array& value) {
+    prefix_.set_dependent_code(value);
+  }
+
+  virtual void ReportDeoptimization(const Code& code) {
+    // This gets called when the code object is on the stack
+    // while nuking code that depends on a prefix. We don't expect
+    // this to happen, so make sure we die loudly if we find
+    // ourselves here.
+    UNIMPLEMENTED();
+  }
+
+  virtual void ReportSwitchingCode(const Code& code) {
+    if (FLAG_trace_deoptimization || FLAG_trace_deoptimization_verbose) {
+      OS::PrintErr("Prefix '%s': deleting code for function '%s'\n",
+        String::Handle(prefix_.name()).ToCString(),
+        Function::Handle(code.function()).ToCString());
+    }
+  }
+
+ private:
+  const LibraryPrefix& prefix_;
+  DISALLOW_COPY_AND_ASSIGN(PrefixDependentArray);
+};
+
+
+void LibraryPrefix::RegisterDependentCode(const Code& code) const {
+  ASSERT(is_deferred_load());
+  ASSERT(!is_loaded());
+  PrefixDependentArray a(*this);
+  a.Register(code);
+}
+
+
+void LibraryPrefix::NukeDependentCode() const {
+  PrefixDependentArray a(*this);
+  a.DisableCode();
+}
+
+
 RawLibraryPrefix* LibraryPrefix::New() {
-  ASSERT(Object::library_prefix_class() != Class::null());
+  ASSERT(Isolate::Current()->object_store()->library_prefix_class() !=
+      Class::null());
   RawObject* raw = Object::Allocate(LibraryPrefix::kClassId,
                                     LibraryPrefix::InstanceSize(),
                                     Heap::kOld);
   return reinterpret_cast<RawLibraryPrefix*>(raw);
 }
 
 
 RawLibraryPrefix* LibraryPrefix::New(const String& name,
-                                     const Namespace& import) {
+                                     const Namespace& import,
+                                     bool deferred_load) {
   const LibraryPrefix& result = LibraryPrefix::Handle(LibraryPrefix::New());
   result.set_name(name);
   result.set_num_imports(0);
+  result.raw_ptr()->is_deferred_load_ = deferred_load;
+  result.raw_ptr()->is_loaded_ = !deferred_load;
   result.set_imports(Array::Handle(Array::New(kInitialSize)));
   result.AddImport(import);
+  result.set_dependent_code(Object::null_array());
   return result.raw();
 }
 
 
 void LibraryPrefix::set_name(const String& value) const {
   ASSERT(value.IsSymbol());
   StorePointer(&raw_ptr()->name_, value.raw());
 }
 
 
@@ skipping 8764 matching lines @@
   return "_MirrorReference";
 }
 
 
 void MirrorReference::PrintToJSONStream(JSONStream* stream, bool ref) const {
   Instance::PrintToJSONStream(stream, ref);
 }
 
 
 }  // namespace dart