gecko/js/public/TypeDecls.h
Jason Orendorff 42a78a347e Bug 645416, part 3 - Symbol layout and GC support for allocating them. r=terrence.
Layout: js/src/vm/Symbol.h defines the new class JS::Symbol. JS::Symbol is the
same size as JSString on all platforms, because the allocator does not support
smaller allocations.

Allocation: Since the purpose of symbols is to serve as property keys, they are
always allocated in the atoms compartment.

We take a lock when allocating. This could probably be replaced with a
main-thread-only assertion. However, if atom allocation is not already a
bottleneck, symbol allocation probably never will be.

Symbols are given their own finalize-class in the GC. This means we allocate a
page per zone for symbols, even though they are only ever allocated in the
atoms zone. Terrence thought this could be easily fixed later. It should be; we
never touch the page, but a 32-bit virtual address space does not just have
infinite pages to spare.

A jsapi-test exercises the new symbol allocation code. A few oddities in
jsapi-tests are fixed in passing.

Discussion after review led to some new assertions about minimum object size in
AllocateObject and AllocateNonObject.

--HG--
extra : rebase_source : 45abb651d3b1b493d77a5dd0eb554f96b058c63a
2014-06-23 10:55:51 -05:00

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2.6 KiB
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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* vim: set ts=8 sts=4 et sw=4 tw=99:
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
// This file contains public type declarations that are used *frequently*. If
// it doesn't occur at least 10 times in Gecko, it probably shouldn't be in
// here.
//
// It includes only:
// - forward declarations of structs and classes;
// - typedefs;
// - enums (maybe).
// It does *not* contain any struct or class definitions.
#ifndef js_TypeDecls_h
#define js_TypeDecls_h
#include <stddef.h>
#include <stdint.h>
#include "js-config.h"
struct JSContext;
class JSFunction;
class JSObject;
class JSScript;
class JSString;
class JSAddonId;
struct jsid;
typedef char16_t jschar;
namespace JS {
typedef unsigned char Latin1Char;
class Symbol;
class Value;
template <typename T> class Handle;
template <typename T> class MutableHandle;
template <typename T> class Rooted;
template <typename T> class PersistentRooted;
typedef Handle<JSFunction*> HandleFunction;
typedef Handle<jsid> HandleId;
typedef Handle<JSObject*> HandleObject;
typedef Handle<JSScript*> HandleScript;
typedef Handle<JSString*> HandleString;
typedef Handle<JS::Symbol*> HandleSymbol;
typedef Handle<Value> HandleValue;
typedef MutableHandle<JSFunction*> MutableHandleFunction;
typedef MutableHandle<jsid> MutableHandleId;
typedef MutableHandle<JSObject*> MutableHandleObject;
typedef MutableHandle<JSScript*> MutableHandleScript;
typedef MutableHandle<JSString*> MutableHandleString;
typedef MutableHandle<JS::Symbol*> MutableHandleSymbol;
typedef MutableHandle<Value> MutableHandleValue;
typedef Rooted<JSObject*> RootedObject;
typedef Rooted<JSFunction*> RootedFunction;
typedef Rooted<JSScript*> RootedScript;
typedef Rooted<JSString*> RootedString;
typedef Rooted<JS::Symbol*> RootedSymbol;
typedef Rooted<jsid> RootedId;
typedef Rooted<JS::Value> RootedValue;
typedef PersistentRooted<JSFunction*> PersistentRootedFunction;
typedef PersistentRooted<jsid> PersistentRootedId;
typedef PersistentRooted<JSObject*> PersistentRootedObject;
typedef PersistentRooted<JSScript*> PersistentRootedScript;
typedef PersistentRooted<JSString*> PersistentRootedString;
typedef PersistentRooted<JS::Symbol*> PersistentRootedSymbol;
typedef PersistentRooted<Value> PersistentRootedValue;
} // namespace JS
#endif /* js_TypeDecls_h */