[Ignition/turbo] Add a NewWithSpread bytecode.

src/runtime/runtime-classes.cc

Index: src/runtime/runtime-classes.cc
diff --git a/src/runtime/runtime-classes.cc b/src/runtime/runtime-classes.cc
index aafd7779870f74cbd9bc2e5380b79f4842e8638b..5789a848c4f9c9c14c4d7162582de6d032aff686 100644
--- a/src/runtime/runtime-classes.cc
+++ b/src/runtime/runtime-classes.cc
@@ -388,5 +388,57 @@ RUNTIME_FUNCTION(Runtime_GetSuperConstructor) {
   return active_function->map()->prototype();
 }
 
+RUNTIME_FUNCTION(Runtime_ConstructWithSpread) {
+  HandleScope scope(isolate);
+  DCHECK_LE(3, args.length());
+  CONVERT_ARG_HANDLE_CHECKED(JSReceiver, constructor, 0);
+  CONVERT_ARG_HANDLE_CHECKED(Object, new_target, 1);
+
+  int constructor_argc = args.length() - 2;
+  CONVERT_ARG_HANDLE_CHECKED(Object, spread, args.length() - 1);
+
+  // Iterate over the spread if we need to.
+  if (spread->MustIterate()) {
+    Handle<JSFunction> spread_iterable_function = isolate->spread_iterable();
+    ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
+        isolate, spread,
+        Execution::Call(isolate, spread_iterable_function,
+                        isolate->factory()->undefined_value(), 1, &spread));
+  }
+
+  Handle<JSArray> spread_array = Handle<JSArray>::cast(spread);
+  if (constructor_argc > 1) {
+    uint32_t spread_length;
+    CHECK(spread_array->length()->ToArrayIndex(&spread_length));
+
+    // Append each of the individual args to the result.
+    int result_length = constructor_argc - 1 + spread_length;
+    Handle<FixedArray> args_array =
+        isolate->factory()->NewFixedArray(result_length);
+    for (int i = 0; i < constructor_argc - 1; i++) {
+      args_array->set(i, *args.at<Object>(2 + i));
+    }
+
+    // Append element of the spread to the result.
+    for (uint32_t i = 0; i < spread_length; i++) {
+      LookupIterator it(isolate, spread, i);
+      Handle<Object> element = spread_array->GetDataProperty(&it);
+      args_array->set(constructor_argc - 1 + i, *element);
+    }
+
+    spread_array = isolate->factory()->NewJSArrayWithElements(
+        args_array, FAST_ELEMENTS, result_length);
+  }
+
+  // Call ReflectConstruct to do the actual super constructor call.

[Benedikt Meurer, 2016/12/05 11:42:10]

It'd be nice to use Execution::New directly here, instead of the indirection via
Reflect.construct.

[petermarshall, 2016/12/05 13:30:46]

That is nice, I think we avoid allocating that JS array that way

+  Handle<Object> construct_args[] = {constructor, spread_array, new_target};
+  Handle<Object> result;
+  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
+      isolate, result, Execution::Call(isolate, isolate->reflect_construct(),
+                                       isolate->factory()->undefined_value(), 3,
+                                       construct_args));
+  return *result;
+}
+
 }  // namespace internal
 }  // namespace v8