Add m-esr52 at 52.6.0

1 files changed, 212 insertions, 0 deletions

diff --git a/js/public/TraceKind.h b/js/public/TraceKind.h
new file mode 100644
index 000000000..2eda9cb2c
--- /dev/null
+++ b/js/public/TraceKind.h
@@ -0,0 +1,212 @@
+/* -*- 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/. */
+
+#ifndef js_TraceKind_h
+#define js_TraceKind_h
+
+#include "mozilla/UniquePtr.h"
+
+#include "js/TypeDecls.h"
+
+// Forward declarations of all the types a TraceKind can denote.
+namespace js {
+class BaseShape;
+class LazyScript;
+class ObjectGroup;
+class Shape;
+class Scope;
+namespace jit {
+class JitCode;
+} // namespace jit
+} // namespace js
+
+namespace JS {
+
+// When tracing a thing, the GC needs to know about the layout of the object it
+// is looking at. There are a fixed number of different layouts that the GC
+// knows about. The "trace kind" is a static map which tells which layout a GC
+// thing has.
+//
+// Although this map is public, the details are completely hidden. Not all of
+// the matching C++ types are exposed, and those that are, are opaque.
+//
+// See Value::gcKind() and JSTraceCallback in Tracer.h for more details.
+enum class TraceKind
+{
+    // These trace kinds have a publicly exposed, although opaque, C++ type.
+    // Note: The order here is determined by our Value packing. Other users
+    //       should sort alphabetically, for consistency.
+    Object = 0x00,
+    String = 0x01,
+    Symbol = 0x02,
+    Script = 0x03,
+
+    // Shape details are exposed through JS_TraceShapeCycleCollectorChildren.
+    Shape = 0x04,
+
+    // ObjectGroup details are exposed through JS_TraceObjectGroupCycleCollectorChildren.
+    ObjectGroup = 0x05,
+
+    // The kind associated with a nullptr.
+    Null = 0x06,
+
+    // The following kinds do not have an exposed C++ idiom.
+    BaseShape = 0x0F,
+    JitCode = 0x1F,
+    LazyScript = 0x2F,
+    Scope = 0x3F
+};
+const static uintptr_t OutOfLineTraceKindMask = 0x07;
+static_assert(uintptr_t(JS::TraceKind::BaseShape) & OutOfLineTraceKindMask, "mask bits are set");
+static_assert(uintptr_t(JS::TraceKind::JitCode) & OutOfLineTraceKindMask, "mask bits are set");
+static_assert(uintptr_t(JS::TraceKind::LazyScript) & OutOfLineTraceKindMask, "mask bits are set");
+static_assert(uintptr_t(JS::TraceKind::Scope) & OutOfLineTraceKindMask, "mask bits are set");
+
+// When this header is imported inside SpiderMonkey, the class definitions are
+// available and we can query those definitions to find the correct kind
+// directly from the class hierarchy.
+template <typename T>
+struct MapTypeToTraceKind {
+    static const JS::TraceKind kind = T::TraceKind;
+};
+
+// When this header is used outside SpiderMonkey, the class definitions are not
+// available, so the following table containing all public GC types is used.
+#define JS_FOR_EACH_TRACEKIND(D) \
+ /* PrettyName       TypeName           AddToCCKind */ \
+    D(BaseShape,     js::BaseShape,     true) \
+    D(JitCode,       js::jit::JitCode,  true) \
+    D(LazyScript,    js::LazyScript,    true) \
+    D(Scope,         js::Scope,         true) \
+    D(Object,        JSObject,          true) \
+    D(ObjectGroup,   js::ObjectGroup,   true) \
+    D(Script,        JSScript,          true) \
+    D(Shape,         js::Shape,         true) \
+    D(String,        JSString,          false) \
+    D(Symbol,        JS::Symbol,        false)
+
+// Map from all public types to their trace kind.
+#define JS_EXPAND_DEF(name, type, _) \
+    template <> struct MapTypeToTraceKind<type> { \
+        static const JS::TraceKind kind = JS::TraceKind::name; \
+    };
+JS_FOR_EACH_TRACEKIND(JS_EXPAND_DEF);
+#undef JS_EXPAND_DEF
+
+// RootKind is closely related to TraceKind. Whereas TraceKind's indices are
+// laid out for convenient embedding as a pointer tag, the indicies of RootKind
+// are designed for use as array keys via EnumeratedArray.
+enum class RootKind : int8_t
+{
+    // These map 1:1 with trace kinds.
+#define EXPAND_ROOT_KIND(name, _0, _1) \
+    name,
+JS_FOR_EACH_TRACEKIND(EXPAND_ROOT_KIND)
+#undef EXPAND_ROOT_KIND
+
+    // These tagged pointers are special-cased for performance.
+    Id,
+    Value,
+
+    // Everything else.
+    Traceable,
+
+    Limit
+};
+
+// Most RootKind correspond directly to a trace kind.
+template <TraceKind traceKind> struct MapTraceKindToRootKind {};
+#define JS_EXPAND_DEF(name, _0, _1) \
+    template <> struct MapTraceKindToRootKind<JS::TraceKind::name> { \
+        static const JS::RootKind kind = JS::RootKind::name; \
+    };
+JS_FOR_EACH_TRACEKIND(JS_EXPAND_DEF)
+#undef JS_EXPAND_DEF
+
+// Specify the RootKind for all types. Value and jsid map to special cases;
+// pointer types we can derive directly from the TraceKind; everything else
+// should go in the Traceable list and use GCPolicy<T>::trace for tracing.
+template <typename T>
+struct MapTypeToRootKind {
+    static const JS::RootKind kind = JS::RootKind::Traceable;
+};
+template <typename T>
+struct MapTypeToRootKind<T*> {
+    static const JS::RootKind kind =
+        JS::MapTraceKindToRootKind<JS::MapTypeToTraceKind<T>::kind>::kind;
+};
+template <typename T>
+struct MapTypeToRootKind<mozilla::UniquePtr<T>> {
+    static const JS::RootKind kind = JS::MapTypeToRootKind<T>::kind;
+};
+template <> struct MapTypeToRootKind<JS::Value> {
+    static const JS::RootKind kind = JS::RootKind::Value;
+};
+template <> struct MapTypeToRootKind<jsid> {
+    static const JS::RootKind kind = JS::RootKind::Id;
+};
+template <> struct MapTypeToRootKind<JSFunction*> : public MapTypeToRootKind<JSObject*> {};
+
+// Fortunately, few places in the system need to deal with fully abstract
+// cells. In those places that do, we generally want to move to a layout
+// templated function as soon as possible. This template wraps the upcast
+// for that dispatch.
+//
+// Given a call:
+//
+//    DispatchTraceKindTyped(f, thing, traceKind, ... args)
+//
+// Downcast the |void *thing| to the specific type designated by |traceKind|,
+// and pass it to the functor |f| along with |... args|, forwarded. Pass the
+// type designated by |traceKind| as the functor's template argument. The
+// |thing| parameter is optional; without it, we simply pass through |... args|.
+
+// GCC and Clang require an explicit template declaration in front of the
+// specialization of operator() because it is a dependent template. MSVC, on
+// the other hand, gets very confused if we have a |template| token there.
+// The clang-cl front end defines _MSC_VER, but still requires the explicit
+// template declaration, so we must test for __clang__ here as well.
+#if defined(_MSC_VER) && !defined(__clang__)
+# define JS_DEPENDENT_TEMPLATE_HINT
+#else
+# define JS_DEPENDENT_TEMPLATE_HINT template
+#endif
+template <typename F, typename... Args>
+auto
+DispatchTraceKindTyped(F f, JS::TraceKind traceKind, Args&&... args)
+  -> decltype(f. JS_DEPENDENT_TEMPLATE_HINT operator()<JSObject>(mozilla::Forward<Args>(args)...))
+{
+    switch (traceKind) {
+#define JS_EXPAND_DEF(name, type, _) \
+      case JS::TraceKind::name: \
+        return f. JS_DEPENDENT_TEMPLATE_HINT operator()<type>(mozilla::Forward<Args>(args)...);
+      JS_FOR_EACH_TRACEKIND(JS_EXPAND_DEF);
+#undef JS_EXPAND_DEF
+      default:
+          MOZ_CRASH("Invalid trace kind in DispatchTraceKindTyped.");
+    }
+}
+#undef JS_DEPENDENT_TEMPLATE_HINT
+
+template <typename F, typename... Args>
+auto
+DispatchTraceKindTyped(F f, void* thing, JS::TraceKind traceKind, Args&&... args)
+  -> decltype(f(static_cast<JSObject*>(nullptr), mozilla::Forward<Args>(args)...))
+{
+    switch (traceKind) {
+#define JS_EXPAND_DEF(name, type, _) \
+      case JS::TraceKind::name: \
+          return f(static_cast<type*>(thing), mozilla::Forward<Args>(args)...);
+      JS_FOR_EACH_TRACEKIND(JS_EXPAND_DEF);
+#undef JS_EXPAND_DEF
+      default:
+          MOZ_CRASH("Invalid trace kind in DispatchTraceKindTyped.");
+    }
+}
+
+} // namespace JS
+
+#endif // js_TraceKind_h