Bug 985143 - Comment updates to new ArrayBuffer storage scheme

--HG--
extra : rebase_source : 22cee061dc536d327ae10171578bf60b5ccc1469

js/src/jscompartment.h

@@ -113,7 +113,6 @@ struct TypeInferenceSizes;
 
 namespace js {
 class AutoDebugModeInvalidation;
-class ArrayBufferObject;
 class DebugScopes;
 class WeakMapBase;
 }

js/src/jsgc.cpp

@@ -3358,9 +3358,10 @@ js::gc::MarkingValidator::nonIncrementalMark()
     }
 
     /*
-     * Save the lists of live weakmaps and array buffers for the compartments we
-     * are collecting.
+     * Temporarily clear the lists of live weakmaps and array buffers for the
+     * compartments we are collecting.
      */
+
     WeakMapVector weakmaps;
     ArrayBufferVector arrayBuffers;
     for (GCCompartmentsIter c(runtime); !c.done(); c.next()) {
@@ -3377,10 +3378,6 @@ js::gc::MarkingValidator::nonIncrementalMark()
      */
     initialized = true;
 
-    /*
-     * Reset the lists of live weakmaps and array buffers for the compartments we
-     * are collecting.
-     */
     for (GCCompartmentsIter c(runtime); !c.done(); c.next()) {
         WeakMapBase::resetCompartmentWeakMapList(c);
         ArrayBufferObject::resetArrayBufferList(c);
@@ -3437,7 +3434,6 @@ js::gc::MarkingValidator::nonIncrementalMark()
         Swap(*entry, *bitmap);
     }
 
-    /* Restore the weak map and array buffer lists. */
     for (GCCompartmentsIter c(runtime); !c.done(); c.next()) {
         WeakMapBase::resetCompartmentWeakMapList(c);
         ArrayBufferObject::resetArrayBufferList(c);

js/src/jsobj.h

@@ -165,7 +165,6 @@ extern const Class IntlClass;
 extern const Class JSONClass;
 extern const Class MathClass;
 
-class ArrayBufferObject;
 class GlobalObject;
 class MapObject;
 class NewObjectCache;

js/src/vm/ArrayBufferObject.cpp

@@ -545,6 +545,7 @@ ArrayBufferObject::releaseData(FreeOp *fop)
 void
 ArrayBufferObject::setDataPointer(void *data, OwnsState ownsData)
 {
+    MOZ_ASSERT_IF(!is<SharedArrayBufferObject>(), data != nullptr);
     setSlot(DATA_SLOT, PrivateValue(data));
     setOwnsData(ownsData);
 }

js/src/vm/ObjectImpl.cpp

@@ -159,9 +159,7 @@ bool
 ObjectImpl::canHaveNonEmptyElements()
 {
     JSObject *obj = static_cast<JSObject *>(this);
-    if (isNative())
-        return !obj->is<TypedArrayObject>();
-    return obj->is<ArrayBufferObject>() || obj->is<SharedArrayBufferObject>();
+    return isNative() && !obj->is<TypedArrayObject>();
 }
 
 #endif // DEBUG

js/src/vm/ObjectImpl.h

@@ -193,16 +193,9 @@ class ObjectElements
      * is <= the length. Memory for elements above the initialized length is
      * uninitialized, but values between the initialized length and the proper
      * length are conceptually holes.
-     *
-     * ArrayBufferObject uses this field to store byteLength.
      */
     uint32_t initializedLength;
 
-    /*
-     * Beware, one or both of the following fields is clobbered by
-     * ArrayBufferObject. See GetViewList.
-     */
-
     /* Number of allocated slots. */
     uint32_t capacity;
 
@@ -287,13 +280,15 @@ IsObjectValueInCompartment(js::Value v, JSCompartment *comp);
  * The |shape_| member stores the shape of the object, which includes the
  * object's class and the layout of all its properties.
  *
- * The type member stores the type of the object, which contains its prototype
- * object and the possible types of its properties.
+ * The |type_| member stores the type of the object, which contains its
+ * prototype object and the possible types of its properties.
  *
  * The rest of the object stores its named properties and indexed elements.
- * These are stored separately from one another. Objects are followed by an
+ * These are stored separately from one another. Objects are followed by a
  * variable-sized array of values for inline storage, which may be used by
- * either properties of native objects (fixed slots) or by elements.
+ * either properties of native objects (fixed slots), by elements (fixed
+ * elements), or by other data for certain kinds of objects, such as
+ * ArrayBufferObjects.
  *
  * Two native objects with the same shape are guaranteed to have the same
  * number of fixed slots.
@@ -315,12 +310,7 @@ IsObjectValueInCompartment(js::Value v, JSCompartment *comp);
  *   slots may be either names or indexes; no indexed property will be in both
  *   the slots and elements.
  *
- * - For non-native objects other than typed arrays, properties and elements
- *   are both empty.
- *
- * - For typed array buffers, elements are used and properties are not used.
- *   The data indexed by the elements do not represent Values, but primitive
- *   unboxed integers or floating point values.
+ * - For non-native objects, slots and elements are both empty.
  *
  * The members of this class are currently protected; in the long run this will
  * will change so that some members are private, and only certain methods that