[wasm-gc] Minimal JS interop: the basics

This CL introduces a new LookupIterator state WASM_OBJECT, and updates
all switches that need to handle it.

Bug: v8:7748
Change-Id: Ie3359aed2d37f5a6854e5577fa3799f0464391e4
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3865559
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/main@{#83234}

src/builtins/builtins-object.cc

@@ -4,10 +4,9 @@
 
 #include "src/builtins/builtins-utils-inl.h"
 #include "src/builtins/builtins.h"
-#include "src/codegen/code-factory.h"
 #include "src/common/message-template.h"
+#include "src/execution/isolate.h"
 #include "src/heap/heap-inl.h"  // For ToBoolean. TODO(jkummerow): Drop.
-#include "src/logging/counters.h"
 #include "src/objects/keys.h"
 #include "src/objects/lookup.h"
 #include "src/objects/objects-inl.h"
@@ -150,6 +149,10 @@ Object ObjectLookupAccessor(Isolate* isolate, Handle<Object> object,
         return ObjectLookupAccessor(isolate, prototype, key, component);
       }
 
+      case LookupIterator::WASM_OBJECT:
+        THROW_NEW_ERROR_RETURN_FAILURE(
+            isolate, NewTypeError(MessageTemplate::kWasmObjectsAreOpaque));
+
       case LookupIterator::INTEGER_INDEXED_EXOTIC:
       case LookupIterator::DATA:
         return ReadOnlyRoots(isolate).undefined_value();

src/common/message-template.h

@@ -658,6 +658,7 @@ namespace internal {
   T(WasmTrapStringIsolatedSurrogate,                                           \
     "Failed to encode string as UTF-8: contains unpaired surrogate")           \
   T(WasmExceptionError, "wasm exception")                                      \
+  T(WasmObjectsAreOpaque, "WebAssembly objects are opaque")                    \
   /* Asm.js validation related */                                              \
   T(AsmJsInvalid, "Invalid asm.js: %")                                         \
   T(AsmJsCompiled, "Converted asm.js to WebAssembly: %")                       \

src/ic/ic.cc

@@ -5,9 +5,7 @@
 #include "src/ic/ic.h"
 
 #include "src/api/api-arguments-inl.h"
-#include "src/api/api.h"
 #include "src/ast/ast.h"
-#include "src/base/bits.h"
 #include "src/base/logging.h"
 #include "src/builtins/accessors.h"
 #include "src/common/assert-scope.h"
@@ -16,6 +14,7 @@
 #include "src/execution/execution.h"
 #include "src/execution/frames-inl.h"
 #include "src/execution/isolate-inl.h"
+#include "src/execution/isolate.h"
 #include "src/execution/protectors-inl.h"
 #include "src/execution/tiering-manager.h"
 #include "src/handles/handles-inl.h"
@@ -27,19 +26,13 @@
 #include "src/ic/stub-cache.h"
 #include "src/numbers/conversions.h"
 #include "src/objects/api-callbacks.h"
-#include "src/objects/data-handler-inl.h"
 #include "src/objects/field-type.h"
-#include "src/objects/hash-table-inl.h"
-#include "src/objects/heap-number-inl.h"
 #include "src/objects/instance-type.h"
 #include "src/objects/js-array-buffer-inl.h"
 #include "src/objects/js-array-inl.h"
 #include "src/objects/megadom-handler.h"
-#include "src/objects/module-inl.h"
 #include "src/objects/property-descriptor.h"
 #include "src/objects/prototype.h"
-#include "src/objects/struct-inl.h"
-#include "src/runtime/runtime-utils.h"
 #include "src/runtime/runtime.h"
 #include "src/tracing/trace-event.h"
 #include "src/tracing/tracing-category-observer.h"
@@ -211,6 +204,7 @@ static void LookupForRead(LookupIterator* it, bool is_has_property) {
       case LookupIterator::TRANSITION:
         UNREACHABLE();
       case LookupIterator::JSPROXY:
+      case LookupIterator::WASM_OBJECT:
         return;
       case LookupIterator::INTERCEPTOR: {
         // If there is a getter, return; otherwise loop to perform the lookup.
@@ -870,68 +864,6 @@ void IC::UpdateMegamorphicCache(Handle<Map> map, Handle<Name> name,
   }
 }
 
-namespace {
-
-#if V8_ENABLE_WEBASSEMBLY
-
-inline WasmValueType GetWasmValueType(wasm::ValueType type) {
-#define TYPE_CASE(Name) \
-  case wasm::k##Name:   \
-    return WasmValueType::k##Name;
-
-  switch (type.kind()) {
-    TYPE_CASE(I8)
-    TYPE_CASE(I16)
-    TYPE_CASE(I32)
-    TYPE_CASE(I64)
-    TYPE_CASE(F32)
-    TYPE_CASE(F64)
-    TYPE_CASE(S128)
-    TYPE_CASE(Ref)
-    TYPE_CASE(RefNull)
-
-    case wasm::kRtt:
-      // Rtt values are not supposed to be made available to JavaScript side.
-      UNREACHABLE();
-
-    case wasm::kVoid:
-    case wasm::kBottom:
-      UNREACHABLE();
-  }
-#undef TYPE_CASE
-}
-
-Handle<Smi> MakeLoadWasmStructFieldHandler(Isolate* isolate,
-                                           Handle<JSReceiver> holder,
-                                           LookupIterator* lookup) {
-  DCHECK(holder->IsWasmObject(isolate));
-  WasmValueType type;
-  int field_offset;
-  if (holder->IsWasmArray(isolate)) {
-    // The only named property that WasmArray has is length.
-    DCHECK_EQ(0, lookup->property_details().field_index());
-    DCHECK_EQ(*isolate->factory()->length_string(), *lookup->name());
-    type = WasmValueType::kU32;
-    field_offset = WasmArray::kLengthOffset;
-  } else {
-    wasm::StructType* struct_type = Handle<WasmStruct>::cast(holder)->type();
-    int field_index = lookup->property_details().field_index();
-    type = GetWasmValueType(struct_type->field(field_index));
-    field_offset =
-        WasmStruct::kHeaderSize + struct_type->field_offset(field_index);
-
-    const size_t kMaxWasmFieldOffset =
-        WasmStruct::kHeaderSize + wasm::StructType::kMaxFieldOffset;
-    static_assert(kMaxWasmFieldOffset <= LoadHandler::WasmFieldOffsetBits::kMax,
-                  "Bigger numbers of struct fields require different approach");
-  }
-  return LoadHandler::LoadWasmStructField(isolate, type, field_offset);
-}
-
-#endif  // V8_ENABLE_WEBASSEMBLY
-
-}  // namespace
-
 MaybeObjectHandle LoadIC::ComputeHandler(LookupIterator* lookup) {
   Handle<Object> receiver = lookup->GetReceiver();
   ReadOnlyRoots roots(isolate());
@@ -1155,30 +1087,14 @@ MaybeObjectHandle LoadIC::ComputeHandler(LookupIterator* lookup) {
           return MaybeObjectHandle(smi_handler);
         TRACE_HANDLER_STATS(isolate(), LoadIC_LoadNormalFromPrototypeDH);
       } else if (lookup->IsElement(*holder)) {
-#if V8_ENABLE_WEBASSEMBLY
-        if (holder_is_lookup_start_object && holder->IsWasmStruct()) {
-          // TODO(ishell): Consider supporting indexed access to WasmStruct
-          // fields.
-          TRACE_HANDLER_STATS(isolate(), LoadIC_LoadNonexistentDH);
-          return MaybeObjectHandle(LoadHandler::LoadNonExistent(isolate()));
-        }
-#endif  // V8_ENABLE_WEBASSEMBLY
         TRACE_HANDLER_STATS(isolate(), LoadIC_SlowStub);
         return MaybeObjectHandle(LoadHandler::LoadSlow(isolate()));
       } else {
         DCHECK_EQ(PropertyLocation::kField,
                   lookup->property_details().location());
-#if V8_ENABLE_WEBASSEMBLY
-        if (V8_UNLIKELY(holder->IsWasmObject(isolate()))) {
-          smi_handler =
-              MakeLoadWasmStructFieldHandler(isolate(), holder, lookup);
-        } else  // NOLINT(readability/braces)
-#endif          // V8_ENABLE_WEBASSEMBLY
-        {
-          DCHECK(holder->IsJSObject(isolate()));
-          FieldIndex field = lookup->GetFieldIndex();
-          smi_handler = LoadHandler::LoadField(isolate(), field);
-        }
+        DCHECK(holder->IsJSObject(isolate()));
+        FieldIndex field = lookup->GetFieldIndex();
+        smi_handler = LoadHandler::LoadField(isolate(), field);
         TRACE_HANDLER_STATS(isolate(), LoadIC_LoadFieldDH);
         if (holder_is_lookup_start_object)
           return MaybeObjectHandle(smi_handler);
@@ -1227,6 +1143,9 @@ MaybeObjectHandle LoadIC::ComputeHandler(LookupIterator* lookup) {
       return MaybeObjectHandle(LoadHandler::LoadFromPrototype(
           isolate(), map, holder_proxy, smi_handler));
     }
+
+    case LookupIterator::WASM_OBJECT:
+      return MaybeObjectHandle(LoadHandler::LoadSlow(isolate()));
     case LookupIterator::ACCESS_CHECK:
     case LookupIterator::NOT_FOUND:
     case LookupIterator::TRANSITION:
@@ -1618,6 +1537,7 @@ bool StoreIC::LookupForWrite(LookupIterator* it, Handle<Object> value,
       switch (it->state()) {
         case LookupIterator::NOT_FOUND:
         case LookupIterator::TRANSITION:
+        case LookupIterator::WASM_OBJECT:
           UNREACHABLE();
         case LookupIterator::JSPROXY:
           return true;
@@ -1773,11 +1693,15 @@ Maybe<bool> DefineOwnDataProperty(LookupIterator* it,
       return JSProxy::DefineOwnProperty(it->isolate(), it->GetHolder<JSProxy>(),
                                         it->GetName(), &new_desc, should_throw);
     }
+    case LookupIterator::WASM_OBJECT:
+      RETURN_FAILURE(it->isolate(), kThrowOnError,
+                     NewTypeError(MessageTemplate::kWasmObjectsAreOpaque));
     // When lazy feedback is disabled, the original state could be different
     // while the object is already prepared for TRANSITION.
     case LookupIterator::TRANSITION: {
       switch (original_state) {
         case LookupIterator::JSPROXY:
+        case LookupIterator::WASM_OBJECT:
         case LookupIterator::TRANSITION:
         case LookupIterator::DATA:
         case LookupIterator::INTERCEPTOR:
@@ -2200,6 +2124,7 @@ MaybeObjectHandle StoreIC::ComputeHandler(LookupIterator* lookup) {
     case LookupIterator::INTEGER_INDEXED_EXOTIC:
     case LookupIterator::ACCESS_CHECK:
     case LookupIterator::NOT_FOUND:
+    case LookupIterator::WASM_OBJECT:
       UNREACHABLE();
   }
   return MaybeObjectHandle();
@@ -2550,6 +2475,12 @@ MaybeHandle<Object> KeyedStoreIC::Store(Handle<Object> object,
       set_slow_stub_reason("map in array prototype");
       use_ic = false;
     }
+#if V8_ENABLE_WEBASSEMBLY
+    if (heap_object->map().IsWasmObjectMap()) {
+      set_slow_stub_reason("wasm object");
+      use_ic = false;
+    }
+#endif
   }
 
   Handle<Map> old_receiver_map;

src/objects/js-objects.cc

@@ -97,6 +97,8 @@ Maybe<bool> JSReceiver::HasProperty(LookupIterator* it) {
       case LookupIterator::JSPROXY:
         return JSProxy::HasProperty(it->isolate(), it->GetHolder<JSProxy>(),
                                     it->GetName());
+      case LookupIterator::WASM_OBJECT:
+        return Just(false);
       case LookupIterator::INTERCEPTOR: {
         Maybe<PropertyAttributes> result =
             JSObject::GetPropertyAttributesWithInterceptor(it);
@@ -150,6 +152,7 @@ Handle<Object> JSReceiver::GetDataProperty(LookupIterator* it,
       case LookupIterator::INTERCEPTOR:
       case LookupIterator::NOT_FOUND:
       case LookupIterator::TRANSITION:
+      case LookupIterator::WASM_OBJECT:
         UNREACHABLE();
       case LookupIterator::ACCESS_CHECK:
         // Support calling this method without an active context, but refuse
@@ -223,6 +226,9 @@ Maybe<bool> JSReceiver::CheckPrivateNameStore(LookupIterator* it,
                          NewTypeError(message, name_string, it->GetReceiver()));
         }
         return Just(true);
+      case LookupIterator::WASM_OBJECT:
+        RETURN_FAILURE(isolate, kThrowOnError,
+                       NewTypeError(MessageTemplate::kWasmObjectsAreOpaque));
     }
   }
   DCHECK(!it->IsFound());
@@ -734,6 +740,8 @@ Maybe<PropertyAttributes> JSReceiver::GetPropertyAttributes(
         UNREACHABLE();
       case LookupIterator::JSPROXY:
         return JSProxy::GetPropertyAttributes(it);
+      case LookupIterator::WASM_OBJECT:
+        return Just(ABSENT);
       case LookupIterator::INTERCEPTOR: {
         Maybe<PropertyAttributes> result =
             JSObject::GetPropertyAttributesWithInterceptor(it);
@@ -948,7 +956,6 @@ Maybe<bool> JSReceiver::DeleteProperty(LookupIterator* it,
     }
     return Just(true);
   }
-  Handle<JSObject> receiver = Handle<JSObject>::cast(it->GetReceiver());
 
   for (; it->IsFound(); it->Next()) {
     switch (it->state()) {
@@ -956,6 +963,9 @@ Maybe<bool> JSReceiver::DeleteProperty(LookupIterator* it,
       case LookupIterator::NOT_FOUND:
       case LookupIterator::TRANSITION:
         UNREACHABLE();
+      case LookupIterator::WASM_OBJECT:
+        RETURN_FAILURE(isolate, kThrowOnError,
+                       NewTypeError(MessageTemplate::kWasmObjectsAreOpaque));
       case LookupIterator::ACCESS_CHECK:
         if (it->HasAccess()) break;
         isolate->ReportFailedAccessCheck(it->GetHolder<JSObject>());
@@ -986,7 +996,7 @@ Maybe<bool> JSReceiver::DeleteProperty(LookupIterator* it,
           if (is_strict(language_mode)) {
             isolate->Throw(*isolate->factory()->NewTypeError(
                 MessageTemplate::kStrictDeleteProperty, it->GetName(),
-                receiver));
+                it->GetReceiver()));
             return Nothing<bool>();
           }
           return Just(false);
@@ -1158,6 +1168,12 @@ Maybe<bool> JSReceiver::DefineOwnProperty(Isolate* isolate,
         isolate, Handle<JSModuleNamespace>::cast(object), key, desc,
         should_throw);
   }
+#if V8_ENABLE_WEBASSEMBLY
+  if (object->IsWasmObject()) {
+    RETURN_FAILURE(isolate, kThrowOnError,
+                   NewTypeError(MessageTemplate::kWasmObjectsAreOpaque));
+  }
+#endif
 
   // OrdinaryDefineOwnProperty, by virtue of calling
   // DefineOwnPropertyIgnoreAttributes, can handle arguments
@@ -1745,6 +1761,9 @@ Maybe<bool> JSReceiver::AddPrivateField(LookupIterator* it,
       return JSProxy::SetPrivateSymbol(isolate, Handle<JSProxy>::cast(receiver),
                                        symbol, &new_desc, should_throw);
     }
+    case LookupIterator::WASM_OBJECT:
+      RETURN_FAILURE(isolate, kThrowOnError,
+                     NewTypeError(MessageTemplate::kWasmObjectsAreOpaque));
     case LookupIterator::DATA:
     case LookupIterator::INTERCEPTOR:
     case LookupIterator::ACCESSOR:
@@ -2033,6 +2052,12 @@ Maybe<bool> JSReceiver::PreventExtensions(Handle<JSReceiver> object,
     return JSProxy::PreventExtensions(Handle<JSProxy>::cast(object),
                                       should_throw);
   }
+#if V8_ENABLE_WEBASSEMBLY
+  if (object->IsWasmObject()) {
+    RETURN_FAILURE(object->GetIsolate(), kThrowOnError,
+                   NewTypeError(MessageTemplate::kWasmObjectsAreOpaque));
+  }
+#endif
   DCHECK(object->IsJSObject());
   return JSObject::PreventExtensions(Handle<JSObject>::cast(object),
                                      should_throw);
@@ -2042,6 +2067,11 @@ Maybe<bool> JSReceiver::IsExtensible(Handle<JSReceiver> object) {
   if (object->IsJSProxy()) {
     return JSProxy::IsExtensible(Handle<JSProxy>::cast(object));
   }
+#if V8_ENABLE_WEBASSEMBLY
+  if (object->IsWasmObject()) {
+    return Just(false);
+  }
+#endif
   return Just(JSObject::IsExtensible(Handle<JSObject>::cast(object)));
 }
 
@@ -3561,6 +3591,7 @@ Maybe<bool> JSObject::DefineOwnPropertyIgnoreAttributes(
   for (; it->IsFound(); it->Next()) {
     switch (it->state()) {
       case LookupIterator::JSPROXY:
+      case LookupIterator::WASM_OBJECT:
       case LookupIterator::TRANSITION:
       case LookupIterator::NOT_FOUND:
         UNREACHABLE();

src/objects/keys.cc

@@ -253,6 +253,16 @@ Maybe<bool> KeyAccumulator::CollectKeys(Handle<JSReceiver> receiver,
     Maybe<bool> result = Just(false);  // Dummy initialization.
     if (current->IsJSProxy()) {
       result = CollectOwnJSProxyKeys(receiver, Handle<JSProxy>::cast(current));
+#if V8_ENABLE_WEBASSEMBLY
+    } else if (current->IsWasmObject()) {
+      if (mode_ == KeyCollectionMode::kIncludePrototypes) {
+        RETURN_FAILURE(isolate_, kThrowOnError,
+                       NewTypeError(MessageTemplate::kWasmObjectsAreOpaque));
+      } else {
+        DCHECK_EQ(KeyCollectionMode::kOwnOnly, mode_);
+        DCHECK_EQ(result, Just(false));  // Stop iterating.
+      }
+#endif
     } else {
       DCHECK(current->IsJSObject());
       result = CollectOwnKeys(receiver, Handle<JSObject>::cast(current));

src/objects/lookup.cc

@@ -22,10 +22,6 @@
 #include "src/objects/property-details.h"
 #include "src/objects/struct-inl.h"
 
-#if V8_ENABLE_WEBASSEMBLY
-#include "src/wasm/wasm-objects-inl.h"
-#endif  // V8_ENABLE_WEBASSEMBLY
-
 namespace v8 {
 namespace internal {
 
@@ -874,18 +870,10 @@ bool LookupIterator::HolderIsReceiverOrHiddenPrototype() const {
 Handle<Object> LookupIterator::FetchValue(
     AllocationPolicy allocation_policy) const {
   Object result;
-  if (IsElement(*holder_)) {
 #if V8_ENABLE_WEBASSEMBLY
-    if (V8_UNLIKELY(holder_->IsWasmObject(isolate_))) {
-      if (holder_->IsWasmStruct()) {
-        // WasmStructs don't have elements.
-        return isolate_->factory()->undefined_value();
-      }
-      Handle<WasmArray> holder = GetHolder<WasmArray>();
-      return WasmArray::GetElement(isolate_, holder, number_.as_uint32());
-    }
-#endif  // V8_ENABLE_WEBASSEMBLY
-    DCHECK(holder_->IsJSObject(isolate_));
+  DCHECK(!holder_->IsWasmObject());
+#endif
+  if (IsElement(*holder_)) {
     Handle<JSObject> holder = GetHolder<JSObject>();
     ElementsAccessor* accessor = holder->GetElementsAccessor(isolate_);
     return accessor->Get(isolate_, holder, number_);
@@ -903,27 +891,6 @@ Handle<Object> LookupIterator::FetchValue(
     }
   } else if (property_details_.location() == PropertyLocation::kField) {
     DCHECK_EQ(PropertyKind::kData, property_details_.kind());
-#if V8_ENABLE_WEBASSEMBLY
-    if (V8_UNLIKELY(holder_->IsWasmObject(isolate_))) {
-      if (allocation_policy == AllocationPolicy::kAllocationDisallowed) {
-        // TODO(ishell): consider taking field type into account and relaxing
-        // this a bit.
-        return isolate_->factory()->undefined_value();
-      }
-      if (holder_->IsWasmArray(isolate_)) {
-        // WasmArrays don't have other named properties besides "length".
-        DCHECK_EQ(*name_, ReadOnlyRoots(isolate_).length_string());
-        Handle<WasmArray> holder = GetHolder<WasmArray>();
-        uint32_t length = holder->length();
-        return isolate_->factory()->NewNumberFromUint(length);
-      }
-      Handle<WasmStruct> holder = GetHolder<WasmStruct>();
-      return WasmStruct::GetField(isolate_, holder,
-                                  property_details_.field_index());
-    }
-#endif  // V8_ENABLE_WEBASSEMBLY
-
-    DCHECK(holder_->IsJSObject(isolate_));
     Handle<JSObject> holder = GetHolder<JSObject>();
     FieldIndex field_index =
         FieldIndex::ForDescriptor(holder->map(isolate_), descriptor_number());
@@ -1179,42 +1146,6 @@ Handle<Object> LookupIterator::SwapDataValue(Handle<Object> value,
   return accessor->SwapAtomic(isolate_, holder, number_, *value, kSeqCstAccess);
 }
 
-#if V8_ENABLE_WEBASSEMBLY
-
-wasm::ValueType LookupIterator::wasm_value_type() const {
-  DCHECK(has_property_);
-  DCHECK(holder_->IsWasmObject(isolate_));
-  if (holder_->IsWasmStruct(isolate_)) {
-    wasm::StructType* wasm_struct_type = WasmStruct::cast(*holder_).type();
-    return wasm_struct_type->field(property_details_.field_index());
-
-  } else {
-    DCHECK(holder_->IsWasmArray(isolate_));
-    wasm::ArrayType* wasm_array_type = WasmArray::cast(*holder_).type();
-    return wasm_array_type->element_type();
-  }
-}
-
-void LookupIterator::WriteDataValueToWasmObject(Handle<Object> value) {
-  DCHECK_EQ(DATA, state_);
-  DCHECK(holder_->IsWasmObject(isolate_));
-  Handle<JSReceiver> holder = GetHolder<JSReceiver>();
-
-  if (IsElement(*holder)) {
-    // TODO(ishell): consider supporting indexed access to WasmStruct fields.
-    // TODO(v8:11804): implement stores to WasmArrays.
-    UNIMPLEMENTED();
-  } else {
-    // WasmArrays don't have writable properties.
-    DCHECK(holder->IsWasmStruct());
-    Handle<WasmStruct> wasm_holder = GetHolder<WasmStruct>();
-    WasmStruct::SetField(isolate_, wasm_holder, property_details_.field_index(),
-                         value);
-  }
-}
-
-#endif  // V8_ENABLE_WEBASSEMBLY
-
 template <bool is_element>
 bool LookupIterator::SkipInterceptor(JSObject holder) {
   InterceptorInfo info = GetInterceptor<is_element>(holder);
@@ -1284,9 +1215,7 @@ LookupIterator::State LookupIterator::LookupInSpecialHolder(
         if (is_element || !name_->IsPrivate(isolate_)) return JSPROXY;
       }
 #if V8_ENABLE_WEBASSEMBLY
-      if (map.IsWasmObjectMap()) {
-        return LookupInRegularHolder<is_element>(map, holder);
-      }
+      if (map.IsWasmObjectMap()) return WASM_OBJECT;
 #endif  // V8_ENABLE_WEBASSEMBLY
       if (map.is_access_check_needed()) {
         if (is_element || !name_->IsPrivate(isolate_) ||
@@ -1325,6 +1254,7 @@ LookupIterator::State LookupIterator::LookupInSpecialHolder(
       return NOT_FOUND;
     case INTEGER_INDEXED_EXOTIC:
     case JSPROXY:
+    case WASM_OBJECT:
     case TRANSITION:
       UNREACHABLE();
   }
@@ -1338,43 +1268,24 @@ LookupIterator::State LookupIterator::LookupInRegularHolder(
   if (interceptor_state_ == InterceptorState::kProcessNonMasking) {
     return NOT_FOUND;
   }
-
-  if (is_element && IsElement(holder)) {
 #if V8_ENABLE_WEBASSEMBLY
-    if (V8_UNLIKELY(holder.IsWasmObject(isolate_))) {
-      // TODO(ishell): consider supporting indexed access to WasmStruct fields.
-      if (holder.IsWasmArray(isolate_)) {
-        WasmArray wasm_array = WasmArray::cast(holder);
-        number_ = index_ < wasm_array.length() ? InternalIndex(index_)
-                                               : InternalIndex::NotFound();
-        wasm::ArrayType* wasm_array_type = wasm_array.type();
-        property_details_ =
-            PropertyDetails(PropertyKind::kData,
-                            wasm_array_type->mutability() ? SEALED : FROZEN,
-                            PropertyCellType::kNoCell);
-
-      } else {
-        DCHECK(holder.IsWasmStruct(isolate_));
-        DCHECK(number_.is_not_found());
-      }
-    } else  // NOLINT(readability/braces)
-#endif      // V8_ENABLE_WEBASSEMBLY
-    {
-      JSObject js_object = JSObject::cast(holder);
-      ElementsAccessor* accessor = js_object.GetElementsAccessor(isolate_);
-      FixedArrayBase backing_store = js_object.elements(isolate_);
-      number_ = accessor->GetEntryForIndex(isolate_, js_object, backing_store,
-                                           index_);
-      if (number_.is_not_found()) {
-        return holder.IsJSTypedArray(isolate_) ? INTEGER_INDEXED_EXOTIC
-                                               : NOT_FOUND;
-      }
-      property_details_ = accessor->GetDetails(js_object, number_);
-      if (map.has_frozen_elements()) {
-        property_details_ = property_details_.CopyAddAttributes(FROZEN);
-      } else if (map.has_sealed_elements()) {
-        property_details_ = property_details_.CopyAddAttributes(SEALED);
-      }
+  DCHECK(!holder.IsWasmObject(isolate_));
+#endif
+  if (is_element && IsElement(holder)) {
+    JSObject js_object = JSObject::cast(holder);
+    ElementsAccessor* accessor = js_object.GetElementsAccessor(isolate_);
+    FixedArrayBase backing_store = js_object.elements(isolate_);
+    number_ =
+        accessor->GetEntryForIndex(isolate_, js_object, backing_store, index_);
+    if (number_.is_not_found()) {
+      return holder.IsJSTypedArray(isolate_) ? INTEGER_INDEXED_EXOTIC
+                                             : NOT_FOUND;
+    }
+    property_details_ = accessor->GetDetails(js_object, number_);
+    if (map.has_frozen_elements()) {
+      property_details_ = property_details_.CopyAddAttributes(FROZEN);
+    } else if (map.has_sealed_elements()) {
+      property_details_ = property_details_.CopyAddAttributes(SEALED);
     }
   } else if (!map.is_dictionary_map()) {
     DescriptorArray descriptors = map.instance_descriptors(isolate_);

src/objects/lookup.h

@@ -60,6 +60,7 @@ class V8_EXPORT_PRIVATE LookupIterator final {
     INTEGER_INDEXED_EXOTIC,
     INTERCEPTOR,
     JSPROXY,
+    WASM_OBJECT,
     NOT_FOUND,
     ACCESSOR,
     DATA,
@@ -197,13 +198,6 @@ class V8_EXPORT_PRIVATE LookupIterator final {
   static inline void UpdateProtector(Isolate* isolate, Handle<Object> receiver,
                                      Handle<Name> name);
 
-#if V8_ENABLE_WEBASSEMBLY
-  // Fetches type of WasmStruct's field or WasmArray's elements, it
-  // is used for preparing the value for storing into WasmObjects.
-  wasm::ValueType wasm_value_type() const;
-  void WriteDataValueToWasmObject(Handle<Object> value);
-#endif  // V8_ENABLE_WEBASSEMBLY
-
   // Lookup a 'cached' private property for an accessor.
   // If not found returns false and leaves the LookupIterator unmodified.
   bool TryLookupCachedProperty(Handle<AccessorPair> accessor);

src/objects/objects.cc

@@ -1167,6 +1167,10 @@ MaybeHandle<Object> Object::GetProperty(LookupIterator* it,
         if (!was_found && !is_global_reference) it->NotFound();
         return result;
       }
+      case LookupIterator::WASM_OBJECT:
+        THROW_NEW_ERROR(it->isolate(),
+                        NewTypeError(MessageTemplate::kWasmObjectsAreOpaque),
+                        Object);
       case LookupIterator::INTERCEPTOR: {
         bool done;
         Handle<Object> result;
@@ -2505,6 +2509,10 @@ Maybe<bool> Object::SetPropertyInternal(LookupIterator* it,
                                     value, receiver, should_throw);
       }
 
+      case LookupIterator::WASM_OBJECT:
+        RETURN_FAILURE(it->isolate(), kThrowOnError,
+                       NewTypeError(MessageTemplate::kWasmObjectsAreOpaque));
+
       case LookupIterator::INTERCEPTOR: {
         if (it->HolderIsReceiverOrHiddenPrototype()) {
           Maybe<bool> result =
@@ -2722,6 +2730,7 @@ Maybe<bool> Object::SetSuperProperty(LookupIterator* it, Handle<Object> value,
 
       case LookupIterator::NOT_FOUND:
       case LookupIterator::TRANSITION:
+      case LookupIterator::WASM_OBJECT:
         UNREACHABLE();
     }
   }
@@ -2812,37 +2821,23 @@ Maybe<bool> Object::SetDataProperty(LookupIterator* it, Handle<Object> value) {
   }
 
 #if V8_ENABLE_WEBASSEMBLY
-  if (receiver->IsWasmObject(isolate)) {
-    // Prepares given value for being stored into a field of given Wasm type
-    // or throw if the value can't be stored into the field.
-    ASSIGN_RETURN_ON_EXCEPTION_VALUE(
-        isolate, to_assign,
-        WasmObject::ToWasmValue(isolate, it->wasm_value_type(), to_assign),
-        Nothing<bool>());
-
-    // Store prepared value.
-    it->WriteDataValueToWasmObject(to_assign);
-
-  } else  // NOLINT(readability/braces)
-#endif    // V8_ENABLE_WEBASSEMBLY
-          // clang-format off
+  DCHECK(!receiver->IsWasmObject(isolate));
+#endif  // V8_ENABLE_WEBASSEMBLY
   if (V8_UNLIKELY(receiver->IsJSSharedStruct(isolate) ||
                   receiver->IsJSSharedArray(isolate))) {
-      // clang-format on
-
-      // Shared structs can only point to primitives or shared values.
-      ASSIGN_RETURN_ON_EXCEPTION_VALUE(
-          isolate, to_assign, Object::Share(isolate, to_assign, kThrowOnError),
-          Nothing<bool>());
-      it->WriteDataValue(to_assign, false);
-    } else {
-      // Possibly migrate to the most up-to-date map that will be able to store
-      // |value| under it->name().
-      it->PrepareForDataProperty(to_assign);
+    // Shared structs can only point to primitives or shared values.
+    ASSIGN_RETURN_ON_EXCEPTION_VALUE(
+        isolate, to_assign, Object::Share(isolate, to_assign, kThrowOnError),
+        Nothing<bool>());
+    it->WriteDataValue(to_assign, false);
+  } else {
+    // Possibly migrate to the most up-to-date map that will be able to store
+    // |value| under it->name().
+    it->PrepareForDataProperty(to_assign);
 
-      // Write the property value.
-      it->WriteDataValue(to_assign, false);
-    }
+    // Write the property value.
+    it->WriteDataValue(to_assign, false);
+  }
 
 #if VERIFY_HEAP
   if (v8_flags.verify_heap) {

src/runtime/runtime-forin.cc

@@ -77,6 +77,10 @@ MaybeHandle<Object> HasEnumerableProperty(Isolate* isolate,
           return it.GetName();
         }
       }
+      case LookupIterator::WASM_OBJECT:
+        THROW_NEW_ERROR(isolate,
+                        NewTypeError(MessageTemplate::kWasmObjectsAreOpaque),
+                        Object);
       case LookupIterator::INTERCEPTOR: {
         result = JSObject::GetPropertyAttributesWithInterceptor(&it);
         if (result.IsNothing()) return MaybeHandle<Object>();

src/wasm/module-instantiate.cc

@@ -987,6 +987,7 @@ MaybeHandle<Object> InstanceBuilder::LookupImportAsm(
     case LookupIterator::INTEGER_INDEXED_EXOTIC:
     case LookupIterator::INTERCEPTOR:
     case LookupIterator::JSPROXY:
+    case LookupIterator::WASM_OBJECT:
     case LookupIterator::ACCESSOR:
     case LookupIterator::TRANSITION:
       return ReportLinkError("not a data property", index, import_name);

test/mjsunit/wasm/gc-js-interop.js

+// Copyright 2022 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: --experimental-wasm-gc --wasm-gc-js-interop --allow-natives-syntax
+
+d8.file.execute("test/mjsunit/wasm/wasm-module-builder.js");
+
+function MakeInstance() {
+  let builder = new WasmModuleBuilder();
+  let struct_type = builder.addStruct([makeField(kWasmI32, true)]);
+  let array_type = builder.addArray(kWasmI32, true);
+  builder.addFunction('MakeStruct', makeSig([], [kWasmExternRef]))
+      .exportFunc()
+      .addBody([
+        kExprI32Const, 42,                       // --
+        kGCPrefix, kExprStructNew, struct_type,  // --
+        kGCPrefix, kExprExternExternalize        // --
+      ]);
+  builder.addFunction('MakeArray', makeSig([], [kWasmExternRef]))
+      .exportFunc()
+      .addBody([
+        kExprI32Const, 2,                             // length
+        kGCPrefix, kExprArrayNewDefault, array_type,  // --
+        kGCPrefix, kExprExternExternalize             // --
+      ]);
+
+  return builder.instantiate();
+}
+
+let instance = MakeInstance();
+let struct = instance.exports.MakeStruct();
+let array = instance.exports.MakeArray();
+
+function testThrowsRepeated(fn) {
+  %PrepareFunctionForOptimization(fn);
+  for (let i = 0; i < 5; i++) assertThrows(fn, TypeError);
+  %OptimizeFunctionOnNextCall(fn);
+  assertThrows(fn, TypeError);
+}
+
+// TODO: test repeated execution of functions using ICs, including optimized.
+for (let wasm_obj of [struct, array]) {
+  testThrowsRepeated(() => wasm_obj.foo);
+  testThrowsRepeated(() => { wasm_obj.foo = 42; });
+  testThrowsRepeated(() => wasm_obj[0]);
+  testThrowsRepeated(() => { wasm_obj[0] = undefined; });
+  assertThrows(() => wasm_obj.__proto__, TypeError);
+  assertThrows(() => Object.prototype.__proto__.call(wasm_obj), TypeError);
+  assertThrows(() => wasm_obj.__proto__ = null, TypeError);
+  assertThrows(() => JSON.stringify(wasm_obj), TypeError);
+  assertThrows(() => { for (let p in wasm_obj) { } }, TypeError);
+  assertThrows(() => { for (let p of wasm_obj) { } }, TypeError);
+  assertThrows(() => wasm_obj.toString(), TypeError);
+  assertThrows(() => wasm_obj.valueOf(), TypeError);
+  assertThrows(() => "" + wasm_obj, TypeError);
+  assertThrows(() => 0 + wasm_obj, TypeError);
+  assertThrows(() => { delete wasm_obj.foo; }, TypeError);
+  assertThrows(() => Object.freeze(wasm_obj), TypeError);
+  assertThrows(() => Object.seal(wasm_obj), TypeError);
+  assertThrows(
+      () => Object.prototype.__lookupGetter__.call(wasm_obj, 'foo'), TypeError);
+  assertThrows(
+      () => Object.prototype.__lookupSetter__.call(wasm_obj, 'foo'), TypeError);
+  assertThrows(
+      () => Object.prototype.__defineGetter__.call(wasm_obj, 'foo', () => 42),
+      TypeError);
+  assertThrows(
+      () => Object.prototype.__defineSetter__.call(wasm_obj, 'foo', () => {}),
+      TypeError);
+  assertThrows(
+      () => Object.defineProperty(wasm_obj, 'foo', {value: 42}), TypeError);
+
+  assertEquals([], Object.getOwnPropertyNames(wasm_obj));
+  assertEquals([], Object.getOwnPropertySymbols(wasm_obj));
+  assertEquals({}, Object.getOwnPropertyDescriptors(wasm_obj));
+  assertEquals([], Object.keys(wasm_obj));
+  assertEquals([], Object.entries(wasm_obj));
+  assertEquals(undefined, Object.getOwnPropertyDescriptor(wasm_obj, "foo"));
+  assertEquals(false, "foo" in wasm_obj);
+  assertEquals(false, Object.prototype.hasOwnProperty.call(wasm_obj, "foo"));
+  assertEquals(true, Object.isSealed(wasm_obj));
+  assertEquals(true, Object.isFrozen(wasm_obj));
+  assertEquals(false, Object.isExtensible(wasm_obj));
+  assertEquals("object", typeof wasm_obj);
+  assertEquals("[object Object]", Object.prototype.toString.call(wasm_obj));
+
+  {
+    let js_obj = {};
+    js_obj.foo = wasm_obj;
+    assertEquals(wasm_obj, js_obj.foo);
+    js_obj[0] = wasm_obj;
+    assertEquals(wasm_obj, js_obj[0]);
+  }
+
+  assertEquals(42, wasm_obj ? 42 : 0);
+
+  assertFalse(Array.isArray(wasm_obj));
+}

test/mjsunit/wasm/wasm-array-js-interop.js

-// Copyright 2021 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: --allow-natives-syntax --experimental-wasm-gc --wasm-gc-js-interop
-// Flags: --expose-gc
-
-d8.file.execute("test/mjsunit/wasm/wasm-module-builder.js");
-
-const kIterationsCountForICProgression = 20;
-
-function createArray_i() {
-  let builder = new WasmModuleBuilder();
-
-  const type_index = builder.addArray(kWasmI32, true);
-
-  let sig_a_i = makeSig_r_x(kWasmDataRef, kWasmI32);
-  let sig_i_ai = makeSig([kWasmDataRef, kWasmI32], [kWasmI32]);
-  let sig_v_aii = makeSig([kWasmDataRef, kWasmI32, kWasmI32], []);
-
-  builder.addFunction("new_array", sig_a_i)
-    .addBody([
-      kExprLocalGet, 0,                      // --
-      kExprI32Const, 10,                     // --
-      kGCPrefix, kExprArrayNew, type_index]) // --
-    .exportAs("new_array");
-
-  builder.addFunction("array_get", sig_i_ai)
-    .addBody([
-      kExprLocalGet, 0,                      // --
-      kGCPrefix, kExprRefCast, type_index,   // --
-      kExprLocalGet, 1,                      // --
-      kGCPrefix, kExprArrayGet, type_index]) // --
-    .exportAs("array_get");
-
-  builder.addFunction("array_set", sig_v_aii)
-    .addBody([
-      kExprLocalGet, 0,                      // --
-      kGCPrefix, kExprRefCast, type_index,   // --
-      kExprLocalGet, 1,                      // --
-      kExprLocalGet, 2,                      // --
-      kGCPrefix, kExprArraySet, type_index]) // --
-    .exportAs("array_set");
-
-  let instance = builder.instantiate();
-  let new_array = instance.exports.new_array;
-  let array_get = instance.exports.array_get;
-  let array_set = instance.exports.array_set;
-
-  let value = 42;
-  let o = new_array(value);
-  %DebugPrint(o);
-  assertEquals(10, o.length);
-  for (let i = 0; i < o.length; i++) {
-    let res;
-    res = array_get(o, i);
-    assertEquals(value, res);
-
-    array_set(o, i, i);
-    res = array_get(o, i);
-    assertEquals(i, res);
-  }
-  return o;
-}
-
-(function TestSimpleArrayInterop() {
-  function f(o) {
-    assertEquals(10, o.length);
-    for (let i = 0; i < o.length; i++) {
-      let len = o.length;
-      assertEquals(10, len);
-      let v = o[i];
-      assertEquals(i, v);
-    }
-  }
-
-  let o = createArray_i();
-  %DebugPrint(o);
-
-  f(o);
-  gc();
-})();