Files
sdk/runtime/vm/mirrors_api_impl.cc
T
Aske Simon Christensen cec963f028 The current growth strategy for growable arrays allocates a backing array of size 2 at (empty) creation and doubles the size whenever the capacity is insufficient while adding elements.
I collected statistics for the sizes and capacities of growable arrays which are promoted to old-space or survive an old-space gc when running dart2js and Fasta. For these applications, the vast majority of arrays stay empty. More than half of the total object size of promoted backing arrays is backing for empty growable arrays.

Furthermore, since the overhead for an array is 3 words (header, type parameters and length), and object sizes are rounded up to an even number of words, we waste one word for all even-sized arrays.

This CL changes the growth strategy so that empty growable arrays are created with a shared, zero-sized array as backing, avoiding the allocation of a backing array if no elements are added. When the array needs to grow, it starts out at 3 and grows to double size plus one each time: 7, 15, 31, ...

A few places in the VM code need to handle these shared, zero-sized arrays specially. In particular, the Array::MakeArray function needs to allocate a new, empty array if its result is to be returned to Dart code.

Benchmarks suggest that the change improves memory usage by a few percent overall and does not significantly affect run time.

BUG=
R=erikcorry@google.com

Review-Url: https://codereview.chromium.org/2949803002 .
2017-06-22 10:51:54 +02:00

359 lines
11 KiB
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// Copyright (c) 2013, 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 "include/dart_mirrors_api.h"
#include "platform/assert.h"
#include "vm/class_finalizer.h"
#include "vm/dart.h"
#include "vm/dart_api_impl.h"
#include "vm/dart_api_state.h"
#include "vm/dart_entry.h"
#include "vm/exceptions.h"
#include "vm/growable_array.h"
#include "vm/object.h"
#include "vm/resolver.h"
#include "vm/stack_frame.h"
#include "vm/symbols.h"
namespace dart {
// Facilitate quick access to the current zone once we have the current thread.
#define Z (T->zone())
// --- Classes and Interfaces Reflection ---
DART_EXPORT Dart_Handle Dart_TypeName(Dart_Handle object) {
DARTSCOPE(Thread::Current());
const Object& obj = Object::Handle(Z, Api::UnwrapHandle(object));
if (obj.IsType()) {
const Class& cls = Class::Handle(Type::Cast(obj).type_class());
return Api::NewHandle(T, cls.UserVisibleName());
} else {
RETURN_TYPE_ERROR(Z, object, Class / Type);
}
}
DART_EXPORT Dart_Handle Dart_QualifiedTypeName(Dart_Handle object) {
DARTSCOPE(Thread::Current());
const Object& obj = Object::Handle(Z, Api::UnwrapHandle(object));
if (obj.IsType() || obj.IsClass()) {
const Class& cls = (obj.IsType())
? Class::Handle(Z, Type::Cast(obj).type_class())
: Class::Cast(obj);
const char* str = cls.ToCString();
if (str == NULL) {
RETURN_NULL_ERROR(str);
}
CHECK_CALLBACK_STATE(T);
return Api::NewHandle(T, String::New(str));
} else {
RETURN_TYPE_ERROR(Z, object, Class / Type);
}
}
// --- Function and Variable Reflection ---
// Outside of the vm, we expose setter names with a trailing '='.
static bool HasExternalSetterSuffix(const String& name) {
return name.CharAt(name.Length() - 1) == '=';
}
static RawString* RemoveExternalSetterSuffix(const String& name) {
ASSERT(HasExternalSetterSuffix(name));
return String::SubString(name, 0, name.Length() - 1);
}
DART_EXPORT Dart_Handle Dart_GetFunctionNames(Dart_Handle target) {
DARTSCOPE(Thread::Current());
const Object& obj = Object::Handle(Z, Api::UnwrapHandle(target));
if (obj.IsError()) {
return target;
}
const GrowableObjectArray& names =
GrowableObjectArray::Handle(Z, GrowableObjectArray::New());
Function& func = Function::Handle(Z);
String& name = String::Handle(Z);
if (obj.IsType()) {
const Class& cls = Class::Handle(Z, Type::Cast(obj).type_class());
const Error& error = Error::Handle(Z, cls.EnsureIsFinalized(T));
if (!error.IsNull()) {
return Api::NewHandle(T, error.raw());
}
const Array& func_array = Array::Handle(Z, cls.functions());
// Some special types like 'dynamic' have a null functions list.
if (!func_array.IsNull()) {
for (intptr_t i = 0; i < func_array.Length(); ++i) {
func ^= func_array.At(i);
// Skip implicit getters and setters.
if (func.kind() == RawFunction::kImplicitGetter ||
func.kind() == RawFunction::kImplicitSetter ||
func.kind() == RawFunction::kImplicitStaticFinalGetter ||
func.kind() == RawFunction::kMethodExtractor ||
func.kind() == RawFunction::kNoSuchMethodDispatcher) {
continue;
}
name = func.UserVisibleName();
names.Add(name);
}
}
} else if (obj.IsLibrary()) {
const Library& lib = Library::Cast(obj);
DictionaryIterator it(lib);
Object& obj = Object::Handle();
while (it.HasNext()) {
obj = it.GetNext();
if (obj.IsFunction()) {
func ^= obj.raw();
name = func.UserVisibleName();
names.Add(name);
}
}
} else {
return Api::NewError(
"%s expects argument 'target' to be a class or library.", CURRENT_FUNC);
}
return Api::NewHandle(T, Array::MakeFixedLength(names));
}
DART_EXPORT Dart_Handle Dart_LookupFunction(Dart_Handle target,
Dart_Handle function_name) {
DARTSCOPE(Thread::Current());
const Object& obj = Object::Handle(Z, Api::UnwrapHandle(target));
if (obj.IsError()) {
return target;
}
const String& func_name = Api::UnwrapStringHandle(Z, function_name);
if (func_name.IsNull()) {
RETURN_TYPE_ERROR(Z, function_name, String);
}
Function& func = Function::Handle(Z);
String& tmp_name = String::Handle(Z);
if (obj.IsType()) {
const Class& cls = Class::Handle(Z, Type::Cast(obj).type_class());
// Case 1. Lookup the unmodified function name.
func = cls.LookupFunctionAllowPrivate(func_name);
// Case 2. Lookup the function without the external setter suffix
// '='. Make sure to do this check after the regular lookup, so
// that we don't interfere with operator lookups (like ==).
if (func.IsNull() && HasExternalSetterSuffix(func_name)) {
tmp_name = RemoveExternalSetterSuffix(func_name);
tmp_name = Field::SetterName(tmp_name);
func = cls.LookupFunctionAllowPrivate(tmp_name);
}
// Case 3. Lookup the function with the getter prefix prepended.
if (func.IsNull()) {
tmp_name = Field::GetterName(func_name);
func = cls.LookupFunctionAllowPrivate(tmp_name);
}
// Case 4. Lookup the function with a . appended to find the
// unnamed constructor.
if (func.IsNull()) {
tmp_name = String::Concat(func_name, Symbols::Dot());
func = cls.LookupFunctionAllowPrivate(tmp_name);
}
} else if (obj.IsLibrary()) {
const Library& lib = Library::Cast(obj);
// Case 1. Lookup the unmodified function name.
func = lib.LookupFunctionAllowPrivate(func_name);
// Case 2. Lookup the function without the external setter suffix
// '='. Make sure to do this check after the regular lookup, so
// that we don't interfere with operator lookups (like ==).
if (func.IsNull() && HasExternalSetterSuffix(func_name)) {
tmp_name = RemoveExternalSetterSuffix(func_name);
tmp_name = Field::SetterName(tmp_name);
func = lib.LookupFunctionAllowPrivate(tmp_name);
}
// Case 3. Lookup the function with the getter prefix prepended.
if (func.IsNull()) {
tmp_name = Field::GetterName(func_name);
func = lib.LookupFunctionAllowPrivate(tmp_name);
}
} else {
return Api::NewError(
"%s expects argument 'target' to be a class or library.", CURRENT_FUNC);
}
#if defined(DEBUG)
if (!func.IsNull()) {
// We only provide access to a subset of function kinds.
RawFunction::Kind func_kind = func.kind();
ASSERT(func_kind == RawFunction::kRegularFunction ||
func_kind == RawFunction::kGetterFunction ||
func_kind == RawFunction::kSetterFunction ||
func_kind == RawFunction::kConstructor);
}
#endif
return Api::NewHandle(T, func.raw());
}
DART_EXPORT Dart_Handle Dart_FunctionName(Dart_Handle function) {
DARTSCOPE(Thread::Current());
const Function& func = Api::UnwrapFunctionHandle(Z, function);
if (func.IsNull()) {
RETURN_TYPE_ERROR(Z, function, Function);
}
return Api::NewHandle(T, func.UserVisibleName());
}
DART_EXPORT Dart_Handle Dart_FunctionOwner(Dart_Handle function) {
DARTSCOPE(Thread::Current());
const Function& func = Api::UnwrapFunctionHandle(Z, function);
if (func.IsNull()) {
RETURN_TYPE_ERROR(Z, function, Function);
}
if (func.IsNonImplicitClosureFunction()) {
RawFunction* parent_function = func.parent_function();
return Api::NewHandle(T, parent_function);
}
const Class& owner = Class::Handle(Z, func.Owner());
ASSERT(!owner.IsNull());
if (owner.IsTopLevel()) {
// Top-level functions are implemented as members of a hidden class. We hide
// that class here and instead answer the library.
#if defined(DEBUG)
const Library& lib = Library::Handle(Z, owner.library());
if (lib.IsNull()) {
ASSERT(owner.IsDynamicClass() || owner.IsVoidClass());
}
#endif
return Api::NewHandle(T, owner.library());
} else {
return Api::NewHandle(T, owner.RareType());
}
}
DART_EXPORT Dart_Handle Dart_FunctionIsStatic(Dart_Handle function,
bool* is_static) {
DARTSCOPE(Thread::Current());
if (is_static == NULL) {
RETURN_NULL_ERROR(is_static);
}
const Function& func = Api::UnwrapFunctionHandle(Z, function);
if (func.IsNull()) {
RETURN_TYPE_ERROR(Z, function, Function);
}
*is_static = func.is_static();
return Api::Success();
}
DART_EXPORT Dart_Handle Dart_FunctionIsConstructor(Dart_Handle function,
bool* is_constructor) {
DARTSCOPE(Thread::Current());
if (is_constructor == NULL) {
RETURN_NULL_ERROR(is_constructor);
}
const Function& func = Api::UnwrapFunctionHandle(Z, function);
if (func.IsNull()) {
RETURN_TYPE_ERROR(Z, function, Function);
}
*is_constructor = func.kind() == RawFunction::kConstructor;
return Api::Success();
}
DART_EXPORT Dart_Handle Dart_FunctionIsGetter(Dart_Handle function,
bool* is_getter) {
DARTSCOPE(Thread::Current());
if (is_getter == NULL) {
RETURN_NULL_ERROR(is_getter);
}
const Function& func = Api::UnwrapFunctionHandle(Z, function);
if (func.IsNull()) {
RETURN_TYPE_ERROR(Z, function, Function);
}
*is_getter = func.IsGetterFunction();
return Api::Success();
}
DART_EXPORT Dart_Handle Dart_FunctionIsSetter(Dart_Handle function,
bool* is_setter) {
DARTSCOPE(Thread::Current());
if (is_setter == NULL) {
RETURN_NULL_ERROR(is_setter);
}
const Function& func = Api::UnwrapFunctionHandle(Z, function);
if (func.IsNull()) {
RETURN_TYPE_ERROR(Z, function, Function);
}
*is_setter = (func.kind() == RawFunction::kSetterFunction);
return Api::Success();
}
// --- Libraries Reflection ---
DART_EXPORT Dart_Handle Dart_LibraryName(Dart_Handle library) {
DARTSCOPE(Thread::Current());
const Library& lib = Api::UnwrapLibraryHandle(Z, library);
if (lib.IsNull()) {
RETURN_TYPE_ERROR(Z, library, Library);
}
const String& name = String::Handle(Z, lib.name());
ASSERT(!name.IsNull());
return Api::NewHandle(T, name.raw());
}
DART_EXPORT Dart_Handle Dart_LibraryGetClassNames(Dart_Handle library) {
DARTSCOPE(Thread::Current());
const Library& lib = Api::UnwrapLibraryHandle(Z, library);
if (lib.IsNull()) {
RETURN_TYPE_ERROR(Z, library, Library);
}
const GrowableObjectArray& names =
GrowableObjectArray::Handle(Z, GrowableObjectArray::New());
ClassDictionaryIterator it(lib);
Class& cls = Class::Handle(Z);
String& name = String::Handle(Z);
while (it.HasNext()) {
cls = it.GetNextClass();
name = cls.UserVisibleName();
names.Add(name);
}
return Api::NewHandle(T, Array::MakeFixedLength(names));
}
// --- Closures Reflection ---
DART_EXPORT Dart_Handle Dart_ClosureFunction(Dart_Handle closure) {
DARTSCOPE(Thread::Current());
const Instance& closure_obj = Api::UnwrapInstanceHandle(Z, closure);
if (closure_obj.IsNull() || !closure_obj.IsClosure()) {
RETURN_TYPE_ERROR(Z, closure, Instance);
}
ASSERT(ClassFinalizer::AllClassesFinalized());
RawFunction* rf = Closure::Cast(closure_obj).function();
return Api::NewHandle(T, rf);
}
} // namespace dart