[vm,dynamic_modules] Fix object allocation/initialization in interpreter in compressed pointers mode

Fix initialization of a newly allocated Closure object when compressed
pointers are used.

Also, fix how instance size is calculated when allocating an object with
instance type arguments.

Fixes b/383719624.
TEST=tools/test.py -n vm-aot-dyn-linux-debug-x64c language corelib

Change-Id: I4bf848ac9b9c9c76d069d1861683cb6dc626ceb9
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/400400
Commit-Queue: Slava Egorov <[email protected]>
Auto-Submit: Alexander Markov <[email protected]>
Reviewed-by: Slava Egorov <[email protected]>

Author: alexmarkov

runtime/vm/interpreter.cc

@@ -1525,11 +1525,10 @@ bool Interpreter::AllocateClosure(Thread* thread,
   if (TryAllocate(thread, kClosureCid, instance_size,
                   reinterpret_cast<ObjectPtr*>(&result))) {
     uword start = UntaggedObject::ToAddr(result);
-    ObjectPtr null_value = Object::null();
-    for (intptr_t offset = sizeof(UntaggedInstance); offset < instance_size;
-         offset += kWordSize) {
-      *reinterpret_cast<ObjectPtr*>(start + offset) = null_value;
-    }
+    Object::InitializeObject(start, kClosureCid, instance_size,
+                             Closure::ContainsCompressedPointers(),
+                             Object::from_offset<Closure>(),
+                             Object::to_offset<Closure>());
     SP[0] = result;
     return true;
   } else {
@@ -2472,8 +2471,8 @@ ObjectPtr Interpreter::Run(Thread* thread,
     TypeArgumentsPtr type_args = TypeArguments::RawCast(SP[-1]);
     if (LIKELY(InterpreterHelpers::IsAllocateFinalized(cls))) {
       const intptr_t class_id = cls->untag()->id_;
-      const intptr_t instance_size = cls->untag()->host_instance_size_in_words_
-                                     << kWordSizeLog2;
+      const intptr_t instance_size =
+          cls->untag()->host_instance_size_in_words_ * kCompressedWordSize;
       ObjectPtr result;
       if (TryAllocate(thread, class_id, instance_size, &result)) {
         uword start = UntaggedObject::ToAddr(result);