Bug 1496378 part 1 - Make ArrayBufferViewObject a base class of TypedArrayObject and DataViewObject. r=jwalden

Differential Revision: https://phabricator.services.mozilla.com/D7721

--HG--
extra : moz-landing-system : lando

js/src/builtin/DataViewObject.cpp

@@ -71,9 +71,9 @@ DataViewObject::create(JSContext* cx, uint32_t byteOffset, uint32_t byteLength,
         obj->setIsSharedMemory();
     }
 
-    obj->setFixedSlot(TypedArrayObject::BYTEOFFSET_SLOT, Int32Value(byteOffset));
-    obj->setFixedSlot(TypedArrayObject::LENGTH_SLOT, Int32Value(byteLength));
-    obj->setFixedSlot(TypedArrayObject::BUFFER_SLOT, ObjectValue(*arrayBuffer));
+    obj->setFixedSlot(BYTEOFFSET_SLOT, Int32Value(byteOffset));
+    obj->setFixedSlot(LENGTH_SLOT, Int32Value(byteLength));
+    obj->setFixedSlot(BUFFER_SLOT, ObjectValue(*arrayBuffer));
 
     SharedMem<uint8_t*> ptr = arrayBuffer->dataPointerEither();
     // A pointer to raw shared memory is exposed through the private slot.  This
@@ -98,7 +98,7 @@ DataViewObject::create(JSContext* cx, uint32_t byteOffset, uint32_t byteLength,
     }
 
     // Verify that the private slot is at the expected place
-    MOZ_ASSERT(obj->numFixedSlots() == TypedArrayObject::DATA_SLOT);
+    MOZ_ASSERT(obj->numFixedSlots() == DATA_SLOT);
 
     if (arrayBuffer->is<ArrayBufferObject>()) {
         if (!arrayBuffer->as<ArrayBufferObject>().addView(cx, obj)) {
@@ -967,7 +967,7 @@ const ClassSpec DataViewObject::classSpec_ = {
 const Class DataViewObject::class_ = {
     "DataView",
     JSCLASS_HAS_PRIVATE |
-    JSCLASS_HAS_RESERVED_SLOTS(TypedArrayObject::RESERVED_SLOTS) |
+    JSCLASS_HAS_RESERVED_SLOTS(DataViewObject::RESERVED_SLOTS) |
     JSCLASS_HAS_CACHED_PROTO(JSProto_DataView),
     &DataViewObjectClassOps,
     &DataViewObject::classSpec_
@@ -1013,8 +1013,8 @@ const JSPropertySpec DataViewObject::properties[] = {
 void
 DataViewObject::notifyBufferDetached(void* newData)
 {
-    setFixedSlot(TypedArrayObject::LENGTH_SLOT, Int32Value(0));
-    setFixedSlot(TypedArrayObject::BYTEOFFSET_SLOT, Int32Value(0));
+    setFixedSlot(LENGTH_SLOT, Int32Value(0));
+    setFixedSlot(BYTEOFFSET_SLOT, Int32Value(0));
     setPrivate(newData);
 }
 

js/src/builtin/DataViewObject.h

@@ -14,7 +14,6 @@
 #include "vm/ArrayBufferObject.h"
 #include "vm/JSObject.h"
 #include "vm/SharedArrayObject.h"
-#include "vm/TypedArrayObject.h"
 
 namespace js {
 
@@ -23,7 +22,7 @@ namespace js {
 // should not be exposed without sharedness information accompanying
 // it.
 
-class DataViewObject : public NativeObject
+class DataViewObject : public ArrayBufferViewObject
 {
   private:
     static const ClassSpec classSpec_;
@@ -62,19 +61,19 @@ class DataViewObject : public NativeObject
     static const Class protoClass_;
 
     static Value byteOffsetValue(const DataViewObject* view) {
-        Value v = view->getFixedSlot(TypedArrayObject::BYTEOFFSET_SLOT);
+        Value v = view->getFixedSlot(BYTEOFFSET_SLOT);
         MOZ_ASSERT(v.toInt32() >= 0);
         return v;
     }
 
     static Value byteLengthValue(const DataViewObject* view) {
-        Value v = view->getFixedSlot(TypedArrayObject::LENGTH_SLOT);
+        Value v = view->getFixedSlot(LENGTH_SLOT);
         MOZ_ASSERT(v.toInt32() >= 0);
         return v;
     }
 
     static Value bufferValue(const DataViewObject* view) {
-        return view->getFixedSlot(TypedArrayObject::BUFFER_SLOT);
+        return view->getFixedSlot(BUFFER_SLOT);
     }
 
     uint32_t byteOffset() const {

js/src/vm/ArrayBufferObject.cpp

@@ -1761,34 +1761,14 @@ ArrayBufferViewObject::dataPointerUnshared(const JS::AutoRequireNoGC& nogc)
         MOZ_ASSERT(!as<TypedArrayObject>().isSharedMemory());
         return static_cast<uint8_t*>(as<TypedArrayObject>().viewDataUnshared());
     }
-    return as<TypedObject>().typedMem(nogc);
+    MOZ_CRASH("Unknown ArrayBufferViewObject");
 }
 
-#ifdef DEBUG
-bool
-ArrayBufferViewObject::isSharedMemory()
-{
-    if (is<TypedArrayObject>()) {
-        return as<TypedArrayObject>().isSharedMemory();
-    }
-    return false;
-}
-#endif
-
 void
 ArrayBufferViewObject::setDataPointerUnshared(uint8_t* data)
 {
-    if (is<DataViewObject>()) {
-        MOZ_ASSERT(!as<DataViewObject>().isSharedMemory());
-        as<DataViewObject>().setPrivate(data);
-    } else if (is<TypedArrayObject>()) {
-        MOZ_ASSERT(!as<TypedArrayObject>().isSharedMemory());
-        as<TypedArrayObject>().setPrivate(data);
-    } else if (is<OutlineTypedObject>()) {
-        as<OutlineTypedObject>().setData(data);
-    } else {
-        MOZ_CRASH();
-    }
+    MOZ_ASSERT(!isSharedMemory());
+    setPrivate(data);
 }
 
 /* static */ ArrayBufferObjectMaybeShared*

js/src/vm/ArrayBufferObject.h

@@ -52,19 +52,20 @@ int32_t LiveMappedBufferCount();
 // The inheritance hierarchy for the various classes relating to typed arrays
 // is as follows.
 //
-// - NativeObject
-//   - ArrayBufferObjectMaybeShared
-//     - ArrayBufferObject
-//     - SharedArrayBufferObject
-//   - DataViewObject
-//   - TypedArrayObject (declared in vm/TypedArrayObject.h)
-//     - TypedArrayObjectTemplate
-//       - Int8ArrayObject
-//       - Uint8ArrayObject
-//       - ...
+//
 // - JSObject
-//   - ArrayBufferViewObject
 //   - TypedObject (declared in builtin/TypedObject.h)
+//   - NativeObject
+//     - ArrayBufferObjectMaybeShared
+//       - ArrayBufferObject
+//       - SharedArrayBufferObject
+//     - ArrayBufferViewObject
+//       - DataViewObject
+//       - TypedArrayObject (declared in vm/TypedArrayObject.h)
+//         - TypedArrayObjectTemplate
+//           - Int8ArrayObject
+//           - Uint8ArrayObject
+//           - ...
 //
 // Note that |TypedArrayObjectTemplate| is just an implementation
 // detail that makes implementing its various subclasses easier.
@@ -461,14 +462,40 @@ bool CreateWasmBuffer(JSContext* cx, const wasm::Limits& memory,
 class ArrayBufferViewObject : public NativeObject
 {
   public:
+    // Underlying (Shared)ArrayBufferObject.
+    static constexpr size_t BUFFER_SLOT = 0;
+    static_assert(BUFFER_SLOT == JS_TYPEDARRAYLAYOUT_BUFFER_SLOT,
+                  "self-hosted code with burned-in constants must get the "
+                  "right buffer slot");
+
+    // Slot containing length of the view in number of typed elements.
+    static constexpr size_t LENGTH_SLOT = 1;
+    static_assert(LENGTH_SLOT == JS_TYPEDARRAYLAYOUT_LENGTH_SLOT,
+                  "self-hosted code with burned-in constants must get the "
+                  "right length slot");
+
+    // Offset of view within underlying (Shared)ArrayBufferObject.
+    static constexpr size_t BYTEOFFSET_SLOT = 2;
+    static_assert(BYTEOFFSET_SLOT == JS_TYPEDARRAYLAYOUT_BYTEOFFSET_SLOT,
+                  "self-hosted code with burned-in constants must get the "
+                  "right byteOffset slot");
+
+    static constexpr size_t RESERVED_SLOTS = 3;
+
+#ifdef DEBUG
+    static const uint8_t ZeroLengthArrayData = 0x4A;
+#endif
+
+    // The raw pointer to the buffer memory, the "private" value.
+    //
+    // This offset is exposed for performance reasons - so that it
+    // need not be looked up on accesses.
+    static constexpr size_t DATA_SLOT = 3;
+
     static ArrayBufferObjectMaybeShared* bufferObject(JSContext* cx, Handle<ArrayBufferViewObject*> obj);
 
     void notifyBufferDetached(JSContext* cx, void* newData);
 
-#ifdef DEBUG
-    bool isSharedMemory();
-#endif
-
     // By construction we only need unshared variants here.  See
     // comments in ArrayBufferObject.cpp.
     uint8_t* dataPointerUnshared(const JS::AutoRequireNoGC&);

js/src/vm/TypedArrayObject.h

@@ -37,42 +37,12 @@ namespace js {
  * the subclasses.
  */
 
-class TypedArrayObject : public NativeObject
+class TypedArrayObject : public ArrayBufferViewObject
 {
   public:
-    // Underlying (Shared)ArrayBufferObject.
-    static const size_t BUFFER_SLOT = 0;
-    static_assert(BUFFER_SLOT == JS_TYPEDARRAYLAYOUT_BUFFER_SLOT,
-                  "self-hosted code with burned-in constants must get the "
-                  "right buffer slot");
-
-    // Slot containing length of the view in number of typed elements.
-    static const size_t LENGTH_SLOT = 1;
-    static_assert(LENGTH_SLOT == JS_TYPEDARRAYLAYOUT_LENGTH_SLOT,
-                  "self-hosted code with burned-in constants must get the "
-                  "right length slot");
-
-    // Offset of view within underlying (Shared)ArrayBufferObject.
-    static const size_t BYTEOFFSET_SLOT = 2;
-    static_assert(BYTEOFFSET_SLOT == JS_TYPEDARRAYLAYOUT_BYTEOFFSET_SLOT,
-                  "self-hosted code with burned-in constants must get the "
-                  "right byteOffset slot");
-
-    static const size_t RESERVED_SLOTS = 3;
-
-#ifdef DEBUG
-    static const uint8_t ZeroLengthArrayData = 0x4A;
-#endif
-
     static int lengthOffset();
     static int dataOffset();
 
-    // The raw pointer to the buffer memory, the "private" value.
-    //
-    // This offset is exposed for performance reasons - so that it
-    // need not be looked up on accesses.
-    static const size_t DATA_SLOT = 3;
-
     static_assert(js::detail::TypedArrayLengthSlot == LENGTH_SLOT,
                   "bad inlined constant in jsfriendapi.h");