In background compilation make a copy of Field in order to freeze its state

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 2999 matching lines @@
 
 
 void Class::SetFields(const Array& value) const {
   ASSERT(!value.IsNull());
 #if defined(DEBUG)
   // Verify that all the fields in the array have this class as owner.
   Field& field = Field::Handle();
   intptr_t len = value.Length();
   for (intptr_t i = 0; i < len; i++) {
     field ^= value.At(i);
-    ASSERT(field.owner() == raw());
+    ASSERT(field.IsOriginal());
+    ASSERT(field.Owner() == raw());
   }
 #endif
   // The value of static fields is already initialized to null.
   StorePointer(&raw_ptr()->fields_, value.raw());
 }
 
 
 void Class::AddField(const Field& field) const {
   const Array& arr = Array::Handle(fields());
   const Array& new_arr = Array::Handle(Array::Grow(arr, arr.Length() + 1));
@@ skipping 3748 matching lines @@
     }
   }
   array.SetAt(0, edge_counters_array);
   set_ic_data_array(array);
 }
 
 
 void Function::RestoreICDataMap(
     ZoneGrowableArray<const ICData*>* deopt_id_to_ic_data,
     bool clone_ic_data) const {
+  if (FLAG_force_clone_compiler_objects) {
+    clone_ic_data = true;
+  }
   ASSERT(deopt_id_to_ic_data->is_empty());
   Zone* zone = Thread::Current()->zone();
   const Array& saved_ic_data = Array::Handle(zone, ic_data_array());
   if (saved_ic_data.IsNull()) {
     // Could happen with deferred loading.
     return;
   }
   const intptr_t saved_length = saved_ic_data.Length();
   ASSERT(saved_length > 0);
   if (saved_length > 1) {
@@ skipping 176 matching lines @@
                                     Heap::kOld);
   return reinterpret_cast<RawRedirectionData*>(raw);
 }
 
 
 const char* RedirectionData::ToCString() const {
   return "RedirectionData class";
 }
 
 
+Field* Field::CloneFromOriginal() const {
+  return &Field::ZoneHandle(this->Clone(*this));
+}
+
+
+RawField* Field::Original() const {
+  if (IsNull()) {
+    return Field::null();
+  }
+  Object& obj = Object::Handle(raw_ptr()->owner_);
+  if (obj.IsField()) {
+    return Field::RawCast(obj.raw());
+  } else {
+    return this->raw();
+  }
+}
+
+
+void Field::SetOriginal(const Field& value) const {
+  ASSERT(value.IsOriginal());
+  ASSERT(!value.IsNull());
+  StorePointer(&raw_ptr()->owner_, reinterpret_cast<RawObject*>(value.raw()));
+}
+
+
 RawString* Field::GetterName(const String& field_name) {
   return String::Concat(Symbols::GetterPrefix(), field_name);
 }
 
 
 RawString* Field::GetterSymbol(const String& field_name) {
   return Symbols::FromConcat(Symbols::GetterPrefix(), field_name);
 }
 
 
@@ skipping 34 matching lines @@
 }
 
 
 bool Field::IsSetterName(const String& function_name) {
   return function_name.StartsWith(Symbols::SetterPrefix());
 }
 
 
 void Field::set_name(const String& value) const {
   ASSERT(value.IsSymbol());
+  ASSERT(IsOriginal());
   StorePointer(&raw_ptr()->name_, value.raw());
 }
 
 
-RawClass* Field::owner() const {
-  const Object& obj = Object::Handle(raw_ptr()->owner_);
+RawObject* Field::RawOwner() const {
+  const Field& field = Field::Handle(Original());
+  ASSERT(field.IsOriginal());
+  ASSERT(!Object::Handle(field.raw_ptr()->owner_).IsField());
+  return field.raw_ptr()->owner_;

[siva, 2016/02/25 23:38:33]

Maybe
  if (IsOriginal()) {
    return raw_ptr()->owner_;
  } else {
    const Field& field.....
    ....
    ....
  }

Would save creation of a handle in the common case.

[srdjan, 2016/02/26 00:40:42]

Done.

+}
+
+
+RawClass* Field::Owner() const {
+  const Field& field = Field::Handle(Original());
+  ASSERT(field.IsOriginal());
+  const Object& obj = Object::Handle(field.raw_ptr()->owner_);
   if (obj.IsClass()) {
     return Class::Cast(obj).raw();
   }
   ASSERT(obj.IsPatchClass());
   return PatchClass::Cast(obj).patched_class();

[siva, 2016/02/25 23:38:33]

See comment below in Field::Origin

[srdjan, 2016/02/26 00:40:43]

Discussed offline, leaving it as it is so that the indirection implementation is
encapsulated in fewer functions.

 }
 
 
-RawClass* Field::origin() const {
-  const Object& obj = Object::Handle(raw_ptr()->owner_);
+RawClass* Field::Origin() const {
+  const Field& field = Field::Handle(Original());
+  ASSERT(field.IsOriginal());
+  const Object& obj = Object::Handle(field.raw_ptr()->owner_);
   if (obj.IsClass()) {
     return Class::Cast(obj).raw();
   }
   ASSERT(obj.IsPatchClass());
   return PatchClass::Cast(obj).origin_class();

[siva, 2016/02/25 23:38:33]

Wouldn't it be more efficient to write this as :
Object& obj = Object::Handle(field.raw_ptr()->owner_);
if (obj.IsField()) {
  obj ^= Field::Cast(obj).raw_ptr()->owner_;
}
if (obj.IsClass()) {
 ...
}
...
...

[srdjan, 2016/02/26 00:40:43]

Discussed offline, leaving it as it is so that the indirection implementation is
encapsulated in fewer functions.

 }
 
 
-RawScript* Field::script() const {
-  const Object& obj = Object::Handle(raw_ptr()->owner_);
+RawScript* Field::Script() const {
+  const Field& field = Field::Handle(Original());
+  ASSERT(field.IsOriginal());
+  const Object& obj = Object::Handle(field.raw_ptr()->owner_);
   if (obj.IsClass()) {
     return Class::Cast(obj).script();
   }
   ASSERT(obj.IsPatchClass());
   return PatchClass::Cast(obj).script();

[siva, 2016/02/25 23:38:33]

Ditto comment.

[srdjan, 2016/02/26 00:40:42]

Discussed offline, leaving it as it is so that the indirection implementation is
encapsulated in fewer functions.

 }
 
 
 // Called at finalization time
 void Field::SetFieldType(const AbstractType& value) const {
   ASSERT(Thread::Current()->IsMutatorThread());
+  ASSERT(IsOriginal());
   ASSERT(!value.IsNull());
   if (value.raw() != type()) {
     StorePointer(&raw_ptr()->type_, value.raw());
   }
 }
 
 
 RawField* Field::New() {
   ASSERT(Object::field_class() != Class::null());
   RawObject* raw = Object::Allocate(Field::kClassId,
@@ skipping 66 matching lines @@
   } else {
     result.set_guarded_list_length(Field::kNoFixedLength);
   }
   return result.raw();
 }
 
 
 RawField* Field::Clone(const Class& new_owner) const {
   Field& clone = Field::Handle();
   clone ^= Object::Clone(*this, Heap::kOld);
-  const Class& owner = Class::Handle(this->owner());
+  const Class& owner = Class::Handle(this->Owner());
   const PatchClass& clone_owner =
       PatchClass::Handle(PatchClass::New(new_owner, owner));
   clone.set_owner(clone_owner);
   if (!clone.is_static()) {
     clone.SetOffset(0);
   }
   if (new_owner.NumTypeParameters() > 0) {
     // Adjust the field type to refer to type parameters of the new owner.
     AbstractType& type = AbstractType::Handle(clone.type());
     type ^= type.CloneUninstantiated(new_owner);
     clone.SetFieldType(type);
   }
   return clone.raw();
 }
 
 
+RawField* Field::Clone(const Field& original) const {
+  if (original.IsNull()) {
+    return Field::null();
+  }
+  ASSERT(original.IsOriginal());
+  Field& clone = Field::Handle();
+  clone ^= Object::Clone(*this, Heap::kOld);
+  clone.SetOriginal(original);
+  return clone.raw();
+}
+
+
 RawString* Field::UserVisibleName() const {
   if (FLAG_show_internal_names) {
     return name();
   }
   return String::ScrubName(String::Handle(name()));
 }
 
 
 intptr_t Field::guarded_list_length() const {
   return Smi::Value(raw_ptr()->guarded_list_length_);
 }
 
 
 void Field::set_guarded_list_length(intptr_t list_length) const {
   ASSERT(Thread::Current()->IsMutatorThread());
+  ASSERT(IsOriginal());
   StoreSmi(&raw_ptr()->guarded_list_length_, Smi::New(list_length));
 }
 
 
 intptr_t Field::guarded_list_length_in_object_offset() const {
   return raw_ptr()->guarded_list_length_in_object_offset_ + kHeapObjectTag;
 }
 
 
 void Field::set_guarded_list_length_in_object_offset(
     intptr_t list_length_offset) const {
   ASSERT(Thread::Current()->IsMutatorThread());
+  ASSERT(IsOriginal());
   StoreNonPointer(&raw_ptr()->guarded_list_length_in_object_offset_,
                   static_cast<int8_t>(list_length_offset - kHeapObjectTag));
   ASSERT(guarded_list_length_in_object_offset() == list_length_offset);
 }
 
 
 const char* Field::ToCString() const {
   if (IsNull()) {
     return "Field::null";
   }
   const char* kF0 = is_static() ? " static" : "";
   const char* kF1 = is_final() ? " final" : "";
   const char* kF2 = is_const() ? " const" : "";
   const char* field_name = String::Handle(name()).ToCString();
-  const Class& cls = Class::Handle(owner());
+  const Class& cls = Class::Handle(Owner());
   const char* cls_name = String::Handle(cls.Name()).ToCString();
   return OS::SCreate(Thread::Current()->zone(),
       "Field <%s.%s>:%s%s%s", cls_name, field_name, kF0, kF1, kF2);
 }
 
 
 // Build a closure object that gets (or sets) the contents of a static
 // field f and cache the closure in a newly created static field
 // named #f (or #f= in case of a setter).
 RawInstance* Field::AccessorClosure(bool make_setter) const {
   ASSERT(is_static());
-  const Class& field_owner = Class::Handle(owner());
+  const Class& field_owner = Class::Handle(Owner());
 
   String& closure_name = String::Handle(this->name());
   closure_name = Symbols::FromConcat(Symbols::HashMark(), closure_name);
   if (make_setter) {
     closure_name = Symbols::FromConcat(Symbols::HashMark(), closure_name);
   }
 
   Field& closure_field = Field::Handle();
   closure_field = field_owner.LookupStaticField(closure_name);
   if (!closure_field.IsNull()) {
@@ skipping 49 matching lines @@
   return AccessorClosure(true);
 }
 
 
 RawArray* Field::dependent_code() const {
   return raw_ptr()->dependent_code_;
 }
 
 
 void Field::set_dependent_code(const Array& array) const {
+  ASSERT(IsOriginal());
   StorePointer(&raw_ptr()->dependent_code_, array.raw());
 }
 
 
 class FieldDependentArray : public WeakCodeReferences {
  public:
   explicit FieldDependentArray(const Field& field)
       : WeakCodeReferences(Array::Handle(field.dependent_code())),
                            field_(field) {}
 
@@ skipping 23 matching lines @@
     Isolate::Current()->IncrFieldInvalidationGen();
   }
 
  private:
   const Field& field_;
   DISALLOW_COPY_AND_ASSIGN(FieldDependentArray);
 };
 
 
 void Field::RegisterDependentCode(const Code& code) const {
+  ASSERT(IsOriginal());
   DEBUG_ASSERT(IsMutatorOrAtSafepoint());
   ASSERT(code.is_optimized());
   FieldDependentArray a(*this);
   a.Register(code);
 }
 
 
 void Field::DeoptimizeDependentCode() const {
+  ASSERT(IsOriginal());
   ASSERT(Thread::Current()->IsMutatorThread());
   FieldDependentArray a(*this);
   a.DisableCode();
 }
 
 
 bool Field::IsUninitialized() const {
   const Instance& value = Instance::Handle(raw_ptr()->value_.static_value_);
   ASSERT(value.raw() != Object::transition_sentinel().raw());
   return value.raw() == Object::sentinel().raw();
 }
 
 
 void Field::SetPrecompiledInitializer(const Function& initializer) const {
+  ASSERT(IsOriginal());
   StorePointer(&raw_ptr()->initializer_.precompiled_, initializer.raw());
 }
 
 
 bool Field::HasPrecompiledInitializer() const {
   return raw_ptr()->initializer_.precompiled_->IsHeapObject() &&
          raw_ptr()->initializer_.precompiled_->IsFunction();
 }
 
 
 void Field::SetSavedInitialStaticValue(const Instance& value) const {
+  ASSERT(IsOriginal());
   ASSERT(!HasPrecompiledInitializer());
   StorePointer(&raw_ptr()->initializer_.saved_value_, value.raw());
 }
 
 
 void Field::EvaluateInitializer() const {
+  ASSERT(IsOriginal());
   ASSERT(is_static());
   if (StaticValue() == Object::sentinel().raw()) {
     SetStaticValue(Object::transition_sentinel());
     const Object& value =
         Object::Handle(Compiler::EvaluateStaticInitializer(*this));
     if (value.IsError()) {
       SetStaticValue(Object::null_instance());
       Exceptions::PropagateError(Error::Cast(value));
       UNREACHABLE();
     }
@@ skipping 81 matching lines @@
     }
   }
 
   return Thread::Current()->zone()->PrintToString("<%s %s>",
     is_nullable() ? "nullable" : "not-nullable",
     class_name);
 }
 
 
 void Field::InitializeGuardedListLengthInObjectOffset() const {
+  ASSERT(IsOriginal());
   if (needs_length_check() &&
       (guarded_list_length() != Field::kUnknownFixedLength)) {
     const intptr_t offset = GetListLengthOffset(guarded_cid());
     set_guarded_list_length_in_object_offset(offset);
     ASSERT(offset != Field::kUnknownLengthOffset);
   } else {
     set_guarded_list_length_in_object_offset(Field::kUnknownLengthOffset);
   }
 }
 
 
 bool Field::UpdateGuardedCidAndLength(const Object& value) const {
+  ASSERT(IsOriginal());
   const intptr_t cid = value.GetClassId();
 
   if (guarded_cid() == kIllegalCid) {
     // Field is assigned first time.
     set_guarded_cid(cid);
     set_is_nullable(cid == kNullCid);
 
     // Start tracking length if needed.
     ASSERT((guarded_list_length() == Field::kUnknownFixedLength) ||
            (guarded_list_length() == Field::kNoFixedLength));
@@ skipping 47 matching lines @@
     set_guarded_list_length(Field::kNoFixedLength);
     set_guarded_list_length_in_object_offset(Field::kUnknownLengthOffset);
   }
 
   // Expected class id or nullability of the field changed.
   return true;
 }
 
 
 void Field::RecordStore(const Object& value) const {
+  ASSERT(IsOriginal());
   if (!FLAG_use_field_guards) {
     return;
   }
 
   if (FLAG_trace_field_guards) {
     THR_Print("Store %s %s <- %s\n",
               ToCString(),
               GuardedPropertiesAsCString(),
               value.ToCString());
   }
@@ skipping 1341 matching lines @@
 }
 
 
 static RawString* MakeClassMetaName(const Class& cls) {
   return Symbols::FromConcat(Symbols::At(), String::Handle(cls.Name()));
 }
 
 
 static RawString* MakeFieldMetaName(const Field& field) {
   const String& cname =
-      String::Handle(MakeClassMetaName(Class::Handle(field.origin())));
+      String::Handle(MakeClassMetaName(Class::Handle(field.Origin())));
   GrowableHandlePtrArray<const String> pieces(Thread::Current()->zone(), 3);
   pieces.Add(cname);
   pieces.Add(Symbols::At());
   pieces.Add(String::Handle(field.name()));
   return Symbols::FromConcatAll(pieces);
 }
 
 
 static RawString* MakeFunctionMetaName(const Function& func) {
   const String& cname =
@@ skipping 444 matching lines @@
     Class& cls = Class::Handle();
     Script& owner_script = Script::Handle();
     DictionaryIterator it(*this);
     while (it.HasNext()) {
       entry = it.GetNext();
       if (entry.IsClass()) {
         owner_script = Class::Cast(entry).script();
       } else if (entry.IsFunction()) {
         owner_script = Function::Cast(entry).script();
       } else if (entry.IsField()) {
-        owner_script = Field::Cast(entry).script();
+        owner_script = Field::Cast(entry).Script();
       } else {
         continue;
       }
       AddScriptIfUnique(scripts, owner_script);
     }
 
     // Add all scripts from patch classes.
     GrowableObjectArray& patches = GrowableObjectArray::Handle(patch_classes());
     for (intptr_t i = 0; i < patches.Length(); i++) {
       entry = patches.At(i);
@@ skipping 12021 matching lines @@
   return UserTag::null();
 }
 
 
 const char* UserTag::ToCString() const {
   const String& tag_label = String::Handle(label());
   return tag_label.ToCString();
 }
 
 }  // namespace dart