[wasm] Create a proper map for functions created from WASM.

R=verwaest@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1778863002

Cr-Commit-Position: refs/heads/master@{#34617}

src/objects.cc

@@ -13638,14 +13638,11 @@ int SharedFunctionInfo::SourceSize() {
   return end_position() - start_position();
 }
 
-
-namespace {
-
-void CalculateInstanceSizeHelper(InstanceType instance_type,
-                                 int requested_internal_fields,
-                                 int requested_in_object_properties,
-                                 int* instance_size,
-                                 int* in_object_properties) {
+void JSFunction::CalculateInstanceSizeHelper(InstanceType instance_type,
+                                             int requested_internal_fields,
+                                             int requested_in_object_properties,
+                                             int* instance_size,
+                                             int* in_object_properties) {
   int header_size = JSObject::GetHeaderSize(instance_type);
   DCHECK_LE(requested_internal_fields,
             (JSObject::kMaxInstanceSize - header_size) >> kPointerSizeLog2);
@@ -13658,8 +13655,6 @@ void CalculateInstanceSizeHelper(InstanceType instance_type,
                           requested_internal_fields;
 }
 
-}  // namespace
-
 
 void JSFunction::CalculateInstanceSize(InstanceType instance_type,
                                        int requested_internal_fields,

src/objects.h

@@ -7562,7 +7562,11 @@ class JSFunction: public JSObject {
                                             int requested_internal_fields,
                                             int* instance_size,
                                             int* in_object_properties);
-
+  static void CalculateInstanceSizeHelper(InstanceType instance_type,
+                                          int requested_internal_fields,
+                                          int requested_in_object_properties,
+                                          int* instance_size,
+                                          int* in_object_properties);
   // Visiting policy flags define whether the code entry or next function
   // should be visited or not.
   enum BodyVisitingPolicy {

src/wasm/wasm-js.cc

@@ -307,10 +307,26 @@ void WasmJs::Install(Isolate* isolate, Handle<JSGlobalObject> global) {
 
 void WasmJs::InstallWasmFunctionMap(Isolate* isolate, Handle<Context> context) {
   if (!context->get(Context::WASM_FUNCTION_MAP_INDEX)->IsMap()) {
-    Handle<Map> wasm_function_map = isolate->factory()->NewMap(
-        JS_FUNCTION_TYPE, JSFunction::kSize + kPointerSize);
-    wasm_function_map->set_is_callable();
-    context->set_wasm_function_map(*wasm_function_map);
+    // TODO(titzer): Move this to bootstrapper.cc??
+    // TODO(titzer): Also make one for strict mode functions?
+    Handle<Map> prev_map = Handle<Map>(context->sloppy_function_map(), isolate);
+
+    InstanceType instance_type = prev_map->instance_type();
+    int internal_fields = JSObject::GetInternalFieldCount(*prev_map);
+    CHECK_EQ(0, internal_fields);
+    int pre_allocated =
+        prev_map->GetInObjectProperties() - prev_map->unused_property_fields();
+    int instance_size;
+    int in_object_properties;
+    JSFunction::CalculateInstanceSizeHelper(instance_type, internal_fields + 1,
+                                            0, &instance_size,
+                                            &in_object_properties);
+
+    int unused_property_fields = in_object_properties - pre_allocated;
+    Handle<Map> map = Map::CopyInitialMap(
+        prev_map, instance_size, in_object_properties, unused_property_fields);
+
+    context->set_wasm_function_map(*map);
   }
 }
 

test/mjsunit/wasm/function-prototype.js

+// Copyright 2016 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --expose-wasm
+
+load("test/mjsunit/wasm/wasm-constants.js");
+load("test/mjsunit/wasm/wasm-module-builder.js");
+
+(function TestFunctionPrototype() {
+  var builder = new WasmModuleBuilder();
+
+  builder.addFunction("nine", [kAstI32])
+    .addBody([kExprI8Const, 9])
+    .exportFunc();
+
+  var func = builder.instantiate().exports.nine;
+
+  // Check type and existence of prototype
+  assertEquals("function", typeof func.apply);
+  assertTrue(func.prototype != undefined);
+  assertEquals("nine", func.name);
+  assertEquals(undefined, func.displayName);
+
+  // Check that .apply() works.
+  assertEquals(9, func.apply([]));
+  assertEquals(9, func.apply([1]));
+  assertEquals(9, func.apply([2, 3]));
+  assertEquals(9, func.apply([6, 7, 9, 9]));
+
+  // TODO(titzer): assertEquals(1, func.length);
+
+  // Check we don't crash when converting to a string.
+  print(func.toString());
+})();