Bug 989276 Part 2 -- Refactor the slots to group by subtype r=sfink

js/src/builtin/TypedObject.cpp

@@ -1478,11 +1478,11 @@ TypedObject::createUnattachedWithClass(JSContext *cx,
     if (!obj)
         return nullptr;
 
-    obj->setPrivate(nullptr);
-    obj->initReservedSlot(JS_TYPEDOBJ_SLOT_BYTEOFFSET, Int32Value(0));
-    obj->initReservedSlot(JS_TYPEDOBJ_SLOT_LENGTH, Int32Value(length));
-    obj->initReservedSlot(JS_TYPEDOBJ_SLOT_OWNER, NullValue());
-    obj->initReservedSlot(JS_TYPEDOBJ_SLOT_NEXT_VIEW, PrivateValue(nullptr));
+    obj->initPrivate(nullptr);
+    obj->initReservedSlot(JS_BUFVIEW_SLOT_BYTEOFFSET, Int32Value(0));
+    obj->initReservedSlot(JS_BUFVIEW_SLOT_LENGTH, Int32Value(length));
+    obj->initReservedSlot(JS_BUFVIEW_SLOT_OWNER, NullValue());
+    obj->initReservedSlot(JS_BUFVIEW_SLOT_NEXT_VIEW, PrivateValue(nullptr));
     obj->initReservedSlot(JS_TYPEDOBJ_SLOT_TYPE_DESCR, ObjectValue(*type));
 
     // Tag the type object for this instance with the type
@@ -1506,8 +1506,8 @@ TypedObject::attach(ArrayBufferObject &buffer, int32_t offset)
 
     buffer.addView(this);
     InitArrayBufferViewDataPointer(this, &buffer, offset);
-    setReservedSlot(JS_TYPEDOBJ_SLOT_BYTEOFFSET, Int32Value(offset));
-    setReservedSlot(JS_TYPEDOBJ_SLOT_OWNER, ObjectValue(buffer));
+    setReservedSlot(JS_BUFVIEW_SLOT_BYTEOFFSET, Int32Value(offset));
+    setReservedSlot(JS_BUFVIEW_SLOT_OWNER, ObjectValue(buffer));
 }
 
 void
@@ -2216,27 +2216,35 @@ TypedObject::obj_enumerate(JSContext *cx, HandleObject obj, JSIterateOp enum_op,
 /* static */ size_t
 TypedObject::offsetOfOwnerSlot()
 {
-    return JSObject::getFixedSlotOffset(JS_TYPEDOBJ_SLOT_OWNER);
+    return JSObject::getFixedSlotOffset(JS_BUFVIEW_SLOT_OWNER);
 }
 
 /* static */ size_t
 TypedObject::offsetOfDataSlot()
 {
-    // the offset of 7 is based on the alloc kind
+#   ifdef DEBUG
+    // Compute offset of private data based on TransparentTypedObject;
+    // both OpaqueTypedObject and TransparentTypedObject have the same
+    // number of slots, so no problem there.
+    gc::AllocKind allocKind = gc::GetGCObjectKind(&TransparentTypedObject::class_);
+    size_t nfixed = gc::GetGCKindSlots(allocKind);
+    JS_ASSERT(JS_TYPEDOBJ_SLOT_DATA == nfixed - 1);
+#   endif
+
     return JSObject::getPrivateDataOffset(JS_TYPEDOBJ_SLOT_DATA);
 }
 
 /* static */ size_t
 TypedObject::offsetOfByteOffsetSlot()
 {
-    return JSObject::getFixedSlotOffset(JS_TYPEDOBJ_SLOT_BYTEOFFSET);
+    return JSObject::getFixedSlotOffset(JS_BUFVIEW_SLOT_BYTEOFFSET);
 }
 
 void
 TypedObject::neuter(void *newData)
 {
-    setSlot(JS_TYPEDOBJ_SLOT_LENGTH, Int32Value(0));
-    setSlot(JS_TYPEDOBJ_SLOT_BYTEOFFSET, Int32Value(0));
+    setSlot(JS_BUFVIEW_SLOT_LENGTH, Int32Value(0));
+    setSlot(JS_BUFVIEW_SLOT_BYTEOFFSET, Int32Value(0));
     setPrivate(newData);
 }
 
@@ -2721,7 +2729,7 @@ js::SetTypedObjectOffset(ThreadSafeContext *, unsigned argc, Value *vp)
     JS_ASSERT(typedObj.typedMem() != nullptr); // must be attached already
 
     typedObj.setPrivate(typedObj.owner().dataPointer() + offset);
-    typedObj.setReservedSlot(JS_TYPEDOBJ_SLOT_BYTEOFFSET, Int32Value(offset));
+    typedObj.setReservedSlot(JS_BUFVIEW_SLOT_BYTEOFFSET, Int32Value(offset));
     args.rval().setUndefined();
     return true;
 }

js/src/builtin/TypedObject.h

@@ -648,11 +648,11 @@ class TypedObject : public ArrayBufferViewObject
     void neuter(void *newData);
 
     int32_t offset() const {
-        return getReservedSlot(JS_TYPEDOBJ_SLOT_BYTEOFFSET).toInt32();
+        return getReservedSlot(JS_BUFVIEW_SLOT_BYTEOFFSET).toInt32();
     }
 
     ArrayBufferObject &owner() const {
-        return getReservedSlot(JS_TYPEDOBJ_SLOT_OWNER).toObject().as<ArrayBufferObject>();
+        return getReservedSlot(JS_BUFVIEW_SLOT_OWNER).toObject().as<ArrayBufferObject>();
     }
 
     TypeDescr &typeDescr() const {
@@ -664,7 +664,7 @@ class TypedObject : public ArrayBufferViewObject
     }
 
     int32_t length() const {
-        return getReservedSlot(JS_TYPEDOBJ_SLOT_LENGTH).toInt32();
+        return getReservedSlot(JS_BUFVIEW_SLOT_LENGTH).toInt32();
     }
 
     int32_t size() const {

js/src/builtin/TypedObject.js

@@ -31,13 +31,13 @@
 // Typed object slots
 
 #define TYPEDOBJ_BYTEOFFSET(obj) \
-    TO_INT32(UnsafeGetReservedSlot(obj, JS_TYPEDOBJ_SLOT_BYTEOFFSET))
+    TO_INT32(UnsafeGetReservedSlot(obj, JS_BUFVIEW_SLOT_BYTEOFFSET))
 #define TYPEDOBJ_TYPE_DESCR(obj) \
     UnsafeGetReservedSlot(obj, JS_TYPEDOBJ_SLOT_TYPE_DESCR)
 #define TYPEDOBJ_OWNER(obj) \
-    UnsafeGetReservedSlot(obj, JS_TYPEDOBJ_SLOT_OWNER)
+    UnsafeGetReservedSlot(obj, JS_BUFVIEW_SLOT_OWNER)
 #define TYPEDOBJ_LENGTH(obj) \
-    TO_INT32(UnsafeGetReservedSlot(obj, JS_TYPEDOBJ_SLOT_LENGTH))
+    TO_INT32(UnsafeGetReservedSlot(obj, JS_BUFVIEW_SLOT_LENGTH))
 
 #define HAS_PROPERTY(obj, prop) \
     callFunction(std_Object_hasOwnProperty, obj, prop)

js/src/builtin/TypedObjectConstants.h

@@ -91,21 +91,37 @@
 ///////////////////////////////////////////////////////////////////////////
 // Slots for typed objects
 
-#define JS_TYPEDOBJ_SLOT_BYTEOFFSET       0
-#define JS_TYPEDOBJ_SLOT_LENGTH           1 // Length of array (see (*) below)
-#define JS_TYPEDOBJ_SLOT_OWNER            2
-#define JS_TYPEDOBJ_SLOT_NEXT_VIEW        3
 
-#define JS_DATAVIEW_SLOTS                 4 // Number of slots for data views
+// Common to data view, typed arrays, and typed objects:
+#define JS_BUFVIEW_SLOT_BYTEOFFSET       0
+#define JS_BUFVIEW_SLOT_LENGTH           1 // see (*) below
+#define JS_BUFVIEW_SLOT_OWNER            2
+#define JS_BUFVIEW_SLOT_NEXT_VIEW        3
 
-#define JS_TYPEDOBJ_SLOT_TYPE_DESCR       4 // For typed objects, type descr
+// Specific to data view:
+#define JS_DATAVIEW_SLOT_DATA            7 // see (**) below
+#define JS_DATAVIEW_SLOTS                4 // Number of slots for data views
 
-#define JS_TYPEDOBJ_SLOT_DATA             7 // private slot, based on alloc kind
-#define JS_TYPEDOBJ_SLOTS                 5 // Number of slots for typed objs
+// Specific to typed arrays:
+#define JS_TYPEDARR_SLOT_TYPE            4 // A ScalarTypeDescr::Type constant
+#define JS_TYPEDARR_SLOT_DATA            7 // see (**) below
+#define JS_TYPEDARR_SLOTS                5 // Number of slots for typed arrays
 
-// (*) The JS_TYPEDOBJ_SLOT_LENGTH slot stores the length for typed objects of
-// sized and unsized array type. The slot contains 0 for non-arrays.
-// The slot also contains 0 for *unattached* typed objects, no matter what
-// type they have.
+// Specific to typed objects:
+#define JS_TYPEDOBJ_SLOT_TYPE_DESCR      4 // A ScalarTypeDescr::Type constant
+#define JS_TYPEDOBJ_SLOT_DATA            7
+#define JS_TYPEDOBJ_SLOTS                5 // Number of slots for typed objs
+
+// (*) The interpretation of the JS_BUFVIEW_SLOT_LENGTH slot depends on
+// the kind of view:
+// - DataView: stores the length in bytes
+// - TypedArray: stores the array length
+// - TypedObject: for arrays, stores the array length, else 0
+
+// (**) This is the index of the slot that will be used for private data.
+// It is hardcoded here based on the GC Kind that will be assigned. It is
+// a function of the total number of slots, but it is non-trivial to encode
+// that function at compile-time, so we instead use a hardcoded constant
+// coupled with some handy assertions.
 
 #endif

js/src/jit/IonBuilder.cpp

@@ -6844,7 +6844,7 @@ IonBuilder::checkTypedObjectIndexInBounds(int32_t elemSize,
         // then we still need to check if the object was neutered.
         *canBeNeutered = true;
     } else {
-        MInstruction *lengthValue = MLoadFixedSlot::New(alloc(), obj, JS_TYPEDOBJ_SLOT_LENGTH);
+        MInstruction *lengthValue = MLoadFixedSlot::New(alloc(), obj, JS_BUFVIEW_SLOT_LENGTH);
         current->add(lengthValue);
 
         MInstruction *length32 = MTruncateToInt32::New(alloc(), lengthValue);

js/src/vm/ArrayBufferObject.h

@@ -237,16 +237,16 @@ class ArrayBufferViewObject : public JSObject
 {
   protected:
     /* Offset of view in underlying ArrayBufferObject */
-    static const size_t BYTEOFFSET_SLOT  = JS_TYPEDOBJ_SLOT_BYTEOFFSET;
+    static const size_t BYTEOFFSET_SLOT  = JS_BUFVIEW_SLOT_BYTEOFFSET;
 
     /* Byte length of view */
-    static const size_t LENGTH_SLOT      = JS_TYPEDOBJ_SLOT_LENGTH;
+    static const size_t LENGTH_SLOT      = JS_BUFVIEW_SLOT_LENGTH;
 
     /* Underlying ArrayBufferObject */
-    static const size_t BUFFER_SLOT      = JS_TYPEDOBJ_SLOT_OWNER;
+    static const size_t BUFFER_SLOT      = JS_BUFVIEW_SLOT_OWNER;
 
     /* ArrayBufferObjects point to a linked list of views, chained through this slot */
-    static const size_t NEXT_VIEW_SLOT   = JS_TYPEDOBJ_SLOT_NEXT_VIEW;
+    static const size_t NEXT_VIEW_SLOT   = JS_BUFVIEW_SLOT_NEXT_VIEW;
 
   public:
     static ArrayBufferObject *bufferObject(JSContext *cx, Handle<ArrayBufferViewObject *> obj);

js/src/vm/TypedArrayObject.h

@@ -31,10 +31,9 @@ class TypedArrayObject : public ArrayBufferViewObject
   protected:
     // Typed array properties stored in slots, beyond those shared by all
     // ArrayBufferViews.
-    static const size_t LENGTH_SLOT    = JS_TYPEDOBJ_SLOT_LENGTH;
-    static const size_t TYPE_SLOT      = JS_TYPEDOBJ_SLOT_TYPE_DESCR;
-    static const size_t RESERVED_SLOTS = JS_TYPEDOBJ_SLOTS;
-    static const size_t DATA_SLOT      = JS_TYPEDOBJ_SLOT_DATA;
+    static const size_t TYPE_SLOT      = JS_TYPEDARR_SLOT_TYPE;
+    static const size_t RESERVED_SLOTS = JS_TYPEDARR_SLOTS;
+    static const size_t DATA_SLOT      = JS_TYPEDARR_SLOT_DATA;
 
     static_assert(js::detail::TypedArrayLengthSlot == LENGTH_SLOT,
                   "bad inlined constant in jsfriendapi.h");
@@ -222,7 +221,7 @@ TypedArrayShift(ArrayBufferView::ViewType viewType)
 class DataViewObject : public ArrayBufferViewObject
 {
     static const size_t RESERVED_SLOTS = JS_DATAVIEW_SLOTS;
-    static const size_t DATA_SLOT      = JS_TYPEDOBJ_SLOT_DATA;
+    static const size_t DATA_SLOT      = JS_DATAVIEW_SLOT_DATA;
 
   private:
     static const Class protoClass;