Bug 1233011 - SharedArrayBuffer subclassing + tests. r=efaust

--HG--
extra : rebase_source : d4764a8be911c263edad6ddfb56bd7b1f789fa14
extra : amend_source : 5c5efcdd1dcf013f299eb93e49b2f2d8c247424f

js/src/jit-test/tests/sharedbuf/subtypes.js

@@ -0,0 +1,53 @@
+// Test cases for subclasses of SharedArrayBuffer.
+
+if (!this.SharedArrayBuffer)
+    quit(0);
+
+load(libdir + "asserts.js");
+
+// Basic subclassing.
+
+class MySharedArrayBuffer1 extends SharedArrayBuffer {
+    constructor(n) { super(n) }
+}
+
+let mv1 = new MySharedArrayBuffer1(1024);
+assertEq(mv1 instanceof SharedArrayBuffer, true);
+assertEq(mv1 instanceof MySharedArrayBuffer1, true);
+assertEq(mv1.byteLength, 1024);
+
+// Can construct views on the subclasses and read/write elements.
+
+let mva1 = new Int8Array(mv1);
+assertEq(mva1.length, mv1.byteLength);
+assertEq(mva1.buffer, mv1);
+
+for ( let i=1 ; i < mva1.length ; i++ )
+    mva1[i] = i;
+
+for ( let i=1 ; i < mva1.length ; i++ )
+    assertEq(mva1[i], (i << 24) >> 24);
+
+// Passing modified arguments to superclass to get a different length.
+
+class MySharedArrayBuffer2 extends SharedArrayBuffer {
+    constructor(n) { super(n-1) }
+}
+
+let mv2 = new MySharedArrayBuffer2(10);
+assertEq(mv2 instanceof SharedArrayBuffer, true);
+assertEq(mv2 instanceof MySharedArrayBuffer2, true);
+assertEq(mv2.byteLength, 9);
+
+// Returning a different object altogether.
+
+class MySharedArrayBuffer3 extends SharedArrayBuffer {
+    constructor(n) {
+	return new Array(n);
+    }
+}
+
+let mv3 = new MySharedArrayBuffer3(10);
+assertEq(mv3 instanceof Array, true);
+assertEq(mv3 instanceof MySharedArrayBuffer3, false);
+assertEq(mv3.length, 10);

js/src/tests/ecma_6/Class/extendBuiltinConstructors.js

@@ -101,5 +101,8 @@ testBuiltin(Array, 3.0);
 testBuiltin(Array, "non-length one-arg");
 testBuiltin(Array, 5, 10, 15, "these are elements");
 
+if (this.SharedArrayBuffer)
+    testBuiltin(SharedArrayBuffer);
+
 if (typeof reportCompare === 'function')
     reportCompare(0,0,"OK");

js/src/vm/SharedArrayObject.cpp

@@ -239,7 +239,12 @@ SharedArrayBufferObject::class_constructor(JSContext* cx, unsigned argc, Value*
         return false;
     }
 
-    JSObject* bufobj = New(cx, length);
+    RootedObject proto(cx);
+    RootedObject newTarget(cx, &args.newTarget().toObject());
+    if (!GetPrototypeFromConstructor(cx, newTarget, &proto))
+        return false;
+
+    JSObject* bufobj = New(cx, length, proto);
     if (!bufobj)
         return false;
     args.rval().setObject(*bufobj);
@@ -247,20 +252,21 @@ SharedArrayBufferObject::class_constructor(JSContext* cx, unsigned argc, Value*
 }
 
 SharedArrayBufferObject*
-SharedArrayBufferObject::New(JSContext* cx, uint32_t length)
+SharedArrayBufferObject::New(JSContext* cx, uint32_t length, HandleObject proto)
 {
     SharedArrayRawBuffer* buffer = SharedArrayRawBuffer::New(cx, length);
     if (!buffer)
         return nullptr;
 
-    return New(cx, buffer);
+    return New(cx, buffer, proto);
 }
 
 SharedArrayBufferObject*
-SharedArrayBufferObject::New(JSContext* cx, SharedArrayRawBuffer* buffer)
+SharedArrayBufferObject::New(JSContext* cx, SharedArrayRawBuffer* buffer, HandleObject proto)
 {
     AutoSetNewObjectMetadata metadata(cx);
-    Rooted<SharedArrayBufferObject*> obj(cx, NewBuiltinClassInstance<SharedArrayBufferObject>(cx));
+    Rooted<SharedArrayBufferObject*> obj(cx,
+        NewObjectWithClassProto<SharedArrayBufferObject>(cx, proto));
     if (!obj)
         return nullptr;
 
@@ -423,7 +429,7 @@ JS_FRIEND_API(JSObject*)
 JS_NewSharedArrayBuffer(JSContext* cx, uint32_t nbytes)
 {
     MOZ_ASSERT(nbytes <= INT32_MAX);
-    return SharedArrayBufferObject::New(cx, nbytes);
+    return SharedArrayBufferObject::New(cx, nbytes, /* proto = */ nullptr);
 }
 
 JS_FRIEND_API(bool)

js/src/vm/SharedArrayObject.h

@@ -130,10 +130,14 @@ class SharedArrayBufferObject : public ArrayBufferObjectMaybeShared
     static bool class_constructor(JSContext* cx, unsigned argc, Value* vp);
 
     // Create a SharedArrayBufferObject with a new SharedArrayRawBuffer.
-    static SharedArrayBufferObject* New(JSContext* cx, uint32_t length);
+    static SharedArrayBufferObject* New(JSContext* cx,
+                                        uint32_t length,
+                                        HandleObject proto = nullptr);
 
     // Create a SharedArrayBufferObject using an existing SharedArrayRawBuffer.
-    static SharedArrayBufferObject* New(JSContext* cx, SharedArrayRawBuffer* buffer);
+    static SharedArrayBufferObject* New(JSContext* cx,
+                                        SharedArrayRawBuffer* buffer,
+                                        HandleObject proto = nullptr);
 
     static void Finalize(FreeOp* fop, JSObject* obj);