Use NativeContext's embedder field for MicrotaskQueue

A pointer to MicrotaskQueue is stored in a NativeContext field as a Smi,
that is discouraged. This CL replaces it to use the dedicated field.

Bug: v8:8124
Change-Id: I5a770624b3a9c922051e86243da2ae216aaacf3a
Reviewed-on: https://chromium-review.googlesource.com/c/1351855
Commit-Queue: Taiju Tsuiki <tzik@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57870}

src/bootstrapper.cc

@@ -5884,8 +5884,7 @@ Genesis::Genesis(
     }
   }
 
-  native_context()->set_microtask_queue_pointer(
-      reinterpret_cast<Object*>(isolate->default_microtask_queue()));
+  native_context()->set_microtask_queue(isolate->default_microtask_queue());
 
   // Install experimental natives. Do not include them into the
   // snapshot as we should be able to turn them off at runtime. Re-installing

src/builtins/builtins-microtask-queue-gen.cc

@@ -54,11 +54,10 @@ TNode<IntPtrT> MicrotaskQueueBuiltinsAssembler::GetDefaultMicrotaskQueue() {
 }
 
 TNode<IntPtrT> MicrotaskQueueBuiltinsAssembler::GetMicrotaskQueue(
-    TNode<Context> context) {
-  // TODO(ishell): move microtask queue pointer to embedder data array.
-  int offset = Context::SlotOffset(Context::MICROTASK_QUEUE_POINTER);
-  return UncheckedCast<IntPtrT>(
-      Load(MachineType::Pointer(), context, IntPtrConstant(offset)));
+    TNode<Context> native_context) {
+  CSA_ASSERT(this, IsNativeContext(native_context));
+  return LoadObjectField<IntPtrT>(native_context,
+                                  NativeContext::kMicrotaskQueueOffset);
 }
 
 TNode<IntPtrT> MicrotaskQueueBuiltinsAssembler::GetMicrotaskRingBuffer(

src/contexts.h

@@ -273,9 +273,6 @@ enum ContextLookupFlags {
   V(PROMISE_ALL_RESOLVE_ELEMENT_SHARED_FUN, SharedFunctionInfo,                \
     promise_all_resolve_element_shared_fun)                                    \
   V(PROMISE_PROTOTYPE_INDEX, JSObject, promise_prototype)                      \
-  /* TODO(ishell): [ptr-compr] this field contains a pointer to a C++ */       \
-  /* object */                                                                 \
-  V(MICROTASK_QUEUE_POINTER, Object, microtask_queue_pointer)                  \
   V(REGEXP_EXEC_FUNCTION_INDEX, JSFunction, regexp_exec_function)              \
   V(REGEXP_FUNCTION_INDEX, JSFunction, regexp_function)                        \
   V(REGEXP_LAST_MATCH_INFO_INDEX, RegExpMatchInfo, regexp_last_match_info)     \

src/snapshot/partial-serializer.cc

@@ -44,10 +44,8 @@ void PartialSerializer::Serialize(Context* o, bool include_global_proxy) {
   // Reset math random cache to get fresh random numbers.
   MathRandom::ResetContext(context_);
 
-  DCHECK_EQ(
-      0, reinterpret_cast<MicrotaskQueue*>(context_->microtask_queue_pointer())
-             ->size());
-  context_->set_microtask_queue_pointer(nullptr);
+  DCHECK_EQ(0, context_->native_context()->microtask_queue()->size());
+  context_->native_context()->set_microtask_queue(nullptr);
 
   VisitRootPointer(Root::kPartialSnapshotCache, nullptr, ObjectSlot(o));
   SerializeDeferredObjects();