From cd26f5e1cc5c82ec5453a5770bf2f7c95b6e4d5f Mon Sep 17 00:00:00 2001
From: Ryan Macnak <rmacnak@google.com>
Date: Tue, 21 Apr 2026 10:13:04 -0700
Subject: [PATCH] [vm] Add missing serialization clusters for VM isolate
 objects.

TEST=ci
Change-Id: I738cf1a189accd2e449728bb599b6b92b5797924
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/496800
Reviewed-by: Alexander Aprelev <aam@google.com>
Commit-Queue: Ryan Macnak <rmacnak@google.com>
---
 .../lib/runtime/vm_offsets.g.dart             |  13 +
 runtime/vm/app_snapshot.cc                    | 235 ++++++++++++++++++
 runtime/vm/compiler/runtime_api.cc            |   4 -
 runtime/vm/compiler/runtime_api.h             |   2 +
 .../vm/compiler/runtime_offsets_extracted.h   | 120 +++++++++
 runtime/vm/compiler/runtime_offsets_list.h    |   2 +
 runtime/vm/object.cc                          |   1 +
 runtime/vm/object.h                           |  16 +-
 runtime/vm/raw_object.h                       |   6 +
 9 files changed, 390 insertions(+), 9 deletions(-)

diff --git a/pkg/native_compiler/lib/runtime/vm_offsets.g.dart b/pkg/native_compiler/lib/runtime/vm_offsets.g.dart
index fa6d1f2608e..6f1bc2cdab5 100644
--- a/pkg/native_compiler/lib/runtime/vm_offsets.g.dart
+++ b/pkg/native_compiler/lib/runtime/vm_offsets.g.dart
@@ -505,6 +505,11 @@ base class VMOffsets {
   int get ContextScope_elementSize => throw 'Unknown';
   int ContextScope_elementOffset(int index) =>
       ContextScope_elementsStartOffset + index * ContextScope_elementSize;
+  int get LocalVarDescriptors_elementsStartOffset => throw 'Unknown';
+  int get LocalVarDescriptors_elementSize => throw 'Unknown';
+  int LocalVarDescriptors_elementOffset(int index) =>
+      LocalVarDescriptors_elementsStartOffset +
+      index * LocalVarDescriptors_elementSize;
   int get ExceptionHandlers_elementsStartOffset => throw 'Unknown';
   int get ExceptionHandlers_elementSize => throw 'Unknown';
   int ExceptionHandlers_elementOffset(int index) =>
@@ -573,6 +578,10 @@ final class Arm64VMOffsets extends VMOffsets {
   @override
   int get ContextScope_elementSize => 0x50;
   @override
+  int get LocalVarDescriptors_elementsStartOffset => 0x10;
+  @override
+  int get LocalVarDescriptors_elementSize => 0x1c;
+  @override
   int get ExceptionHandlers_elementsStartOffset => 0x18;
   @override
   int get ExceptionHandlers_elementSize => 0xc;
@@ -1536,6 +1545,10 @@ final class Arm64ProductVMOffsets extends VMOffsets {
   @override
   int get ContextScope_elementSize => 0x50;
   @override
+  int get LocalVarDescriptors_elementsStartOffset => 0x10;
+  @override
+  int get LocalVarDescriptors_elementSize => 0x1c;
+  @override
   int get ExceptionHandlers_elementsStartOffset => 0x18;
   @override
   int get ExceptionHandlers_elementSize => 0xc;
diff --git a/runtime/vm/app_snapshot.cc b/runtime/vm/app_snapshot.cc
index 0c438edddab..4a017bd7c37 100644
--- a/runtime/vm/app_snapshot.cc
+++ b/runtime/vm/app_snapshot.cc
@@ -3756,6 +3756,103 @@ class RODataDeserializationCluster
 };
 #endif  // !DART_COMPRESSED_POINTERS
 
+#if !defined(DART_PRECOMPILED_RUNTIME)
+class LocalVarDescriptorsSerializationCluster : public SerializationCluster {
+ public:
+  LocalVarDescriptorsSerializationCluster()
+      : SerializationCluster("LocalVarDescriptors", kLocalVarDescriptorsCid) {}
+  ~LocalVarDescriptorsSerializationCluster() {}
+
+  void Trace(Serializer* s, ObjectPtr object) {
+    LocalVarDescriptorsPtr handlers = LocalVarDescriptors::RawCast(object);
+    objects_.Add(handlers);
+
+    const intptr_t length = handlers->untag()->num_entries_;
+    for (intptr_t i = 0; i < length; i++) {
+      s->Push(handlers->untag()->name(i));
+    }
+  }
+
+  void WriteAlloc(Serializer* s) {
+    const intptr_t count = objects_.length();
+    s->WriteUnsigned(count);
+    for (intptr_t i = 0; i < count; i++) {
+      LocalVarDescriptorsPtr handlers = objects_[i];
+      s->AssignRef(handlers);
+      AutoTraceObject(handlers);
+      const intptr_t length = handlers->untag()->num_entries_;
+      s->WriteUnsigned(length);
+      target_memory_size_ +=
+          compiler::target::LocalVarDescriptors::InstanceSize(length);
+    }
+  }
+
+  void WriteFill(Serializer* s) {
+    const intptr_t count = objects_.length();
+    for (intptr_t i = 0; i < count; i++) {
+      LocalVarDescriptorsPtr handlers = objects_[i];
+      AutoTraceObject(handlers);
+      const intptr_t length = handlers->untag()->num_entries_;
+      s->WriteUnsigned(length);
+      WriteFromTo(handlers, length);
+      for (intptr_t j = 0; j < length; j++) {
+        UntaggedLocalVarDescriptors::VarInfo& info =
+            handlers->untag()->data()[j];
+        s->Write<int32_t>(info.index_kind);
+        s->WriteTokenPosition(info.declaration_pos);
+        s->WriteTokenPosition(info.begin_pos);
+        s->WriteTokenPosition(info.end_pos);
+        s->Write<int64_t>(info.scope_id);
+      }
+    }
+  }
+
+ private:
+  GrowableArray<LocalVarDescriptorsPtr> objects_;
+};
+#endif  // !DART_PRECOMPILED_RUNTIME
+
+class LocalVarDescriptorsDeserializationCluster
+    : public DeserializationCluster {
+ public:
+  LocalVarDescriptorsDeserializationCluster()
+      : DeserializationCluster("LocalVarDescriptors") {}
+  ~LocalVarDescriptorsDeserializationCluster() {}
+
+  void ReadAlloc(Deserializer* d) override {
+    start_index_ = d->next_index();
+    const intptr_t count = d->ReadUnsigned();
+    for (intptr_t i = 0; i < count; i++) {
+      const intptr_t length = d->ReadUnsigned();
+      d->AssignRef(d->Allocate(LocalVarDescriptors::InstanceSize(length)));
+    }
+    stop_index_ = d->next_index();
+  }
+
+  void ReadFill(Deserializer* d_) override {
+    Deserializer::Local d(d_);
+
+    ASSERT(!is_canonical());  // Never canonical.
+    for (intptr_t id = start_index_, n = stop_index_; id < n; id++) {
+      LocalVarDescriptorsPtr handlers =
+          static_cast<LocalVarDescriptorsPtr>(d.Ref(id));
+      const intptr_t length = d.ReadUnsigned();
+      Deserializer::InitializeHeader(handlers, kLocalVarDescriptorsCid,
+                                     LocalVarDescriptors::InstanceSize(length));
+      d.ReadFromTo(handlers, length);
+      for (intptr_t j = 0; j < length; j++) {
+        UntaggedLocalVarDescriptors::VarInfo& info =
+            handlers->untag()->data()[j];
+        info.index_kind = d.Read<int32_t>();
+        info.declaration_pos = d.ReadTokenPosition();
+        info.begin_pos = d.ReadTokenPosition();
+        info.end_pos = d.ReadTokenPosition();
+        info.scope_id = d.Read<int64_t>();
+      }
+    }
+  }
+};
+
 #if !defined(DART_PRECOMPILED_RUNTIME)
 class ExceptionHandlersSerializationCluster : public SerializationCluster {
  public:
@@ -4341,6 +4438,66 @@ class LoadingUnitDeserializationCluster : public DeserializationCluster {
   }
 };
 
+#if !defined(DART_PRECOMPILED_RUNTIME)
+class ApiErrorSerializationCluster : public SerializationCluster {
+ public:
+  ApiErrorSerializationCluster()
+      : SerializationCluster("ApiError",
+                             kApiErrorCid,
+                             compiler::target::ApiError::InstanceSize()) {}
+  ~ApiErrorSerializationCluster() {}
+
+  void Trace(Serializer* s, ObjectPtr object) {
+    ApiErrorPtr error = ApiError::RawCast(object);
+    objects_.Add(error);
+    PushFromTo(error);
+  }
+
+  void WriteAlloc(Serializer* s) {
+    const intptr_t count = objects_.length();
+    s->WriteUnsigned(count);
+    for (intptr_t i = 0; i < count; i++) {
+      ApiErrorPtr error = objects_[i];
+      s->AssignRef(error);
+    }
+  }
+
+  void WriteFill(Serializer* s) {
+    const intptr_t count = objects_.length();
+    for (intptr_t i = 0; i < count; i++) {
+      ApiErrorPtr error = objects_[i];
+      AutoTraceObject(error);
+      WriteFromTo(error);
+    }
+  }
+
+ private:
+  GrowableArray<ApiErrorPtr> objects_;
+};
+#endif  // !DART_PRECOMPILED_RUNTIME
+
+class ApiErrorDeserializationCluster : public DeserializationCluster {
+ public:
+  ApiErrorDeserializationCluster() : DeserializationCluster("ApiError") {}
+  ~ApiErrorDeserializationCluster() {}
+
+  void ReadAlloc(Deserializer* d) override {
+    ReadAllocFixedSize(d, ApiError::InstanceSize());
+  }
+
+  void ReadFill(Deserializer* d_) override {
+    Deserializer::Local d(d_);
+
+    ASSERT(!is_canonical());  // Never canonical.
+    for (intptr_t id = start_index_, n = stop_index_; id < n; id++) {
+      ApiErrorPtr error = static_cast<ApiErrorPtr>(d.Ref(id));
+      Deserializer::InitializeHeader(error, kApiErrorCid,
+                                     ApiError::InstanceSize());
+      d.ReadFromTo(error);
+    }
+  }
+};
+
 #if !defined(DART_PRECOMPILED_RUNTIME)
 class LanguageErrorSerializationCluster : public SerializationCluster {
  public:
@@ -4471,6 +4628,68 @@ class UnhandledExceptionDeserializationCluster : public DeserializationCluster {
   }
 };
 
+#if !defined(DART_PRECOMPILED_RUNTIME)
+class UnwindErrorSerializationCluster : public SerializationCluster {
+ public:
+  UnwindErrorSerializationCluster()
+      : SerializationCluster("UnwindError",
+                             kUnwindErrorCid,
+                             compiler::target::UnwindError::InstanceSize()) {}
+  ~UnwindErrorSerializationCluster() {}
+
+  void Trace(Serializer* s, ObjectPtr object) {
+    UnwindErrorPtr error = UnwindError::RawCast(object);
+    objects_.Add(error);
+    PushFromTo(error);
+  }
+
+  void WriteAlloc(Serializer* s) {
+    const intptr_t count = objects_.length();
+    s->WriteUnsigned(count);
+    for (intptr_t i = 0; i < count; i++) {
+      UnwindErrorPtr error = objects_[i];
+      s->AssignRef(error);
+    }
+  }
+
+  void WriteFill(Serializer* s) {
+    const intptr_t count = objects_.length();
+    for (intptr_t i = 0; i < count; i++) {
+      UnwindErrorPtr error = objects_[i];
+      AutoTraceObject(error);
+      WriteFromTo(error);
+      s->Write<bool>(error->untag()->is_user_initiated_);
+    }
+  }
+
+ private:
+  GrowableArray<UnwindErrorPtr> objects_;
+};
+#endif  // !DART_PRECOMPILED_RUNTIME
+
+class UnwindErrorDeserializationCluster : public DeserializationCluster {
+ public:
+  UnwindErrorDeserializationCluster() : DeserializationCluster("UnwindError") {}
+  ~UnwindErrorDeserializationCluster() {}
+
+  void ReadAlloc(Deserializer* d) override {
+    ReadAllocFixedSize(d, UnwindError::InstanceSize());
+  }
+
+  void ReadFill(Deserializer* d_) override {
+    Deserializer::Local d(d_);
+
+    ASSERT(!is_canonical());  // Never canonical.
+    for (intptr_t id = start_index_, n = stop_index_; id < n; id++) {
+      UnwindErrorPtr error = static_cast<UnwindErrorPtr>(d.Ref(id));
+      Deserializer::InitializeHeader(error, kUnwindErrorCid,
+                                     UnwindError::InstanceSize());
+      d.ReadFromTo(error);
+      error->untag()->is_user_initiated_ = d.Read<bool>();
+    }
+  }
+};
+
 #if !defined(DART_PRECOMPILED_RUNTIME)
 class InstanceSerializationCluster : public SerializationCluster {
  public:
@@ -8058,10 +8277,14 @@ SerializationCluster* Serializer::NewClusterForClass(intptr_t cid,
       return new (Z) SubtypeTestCacheSerializationCluster();
     case kLoadingUnitCid:
       return new (Z) LoadingUnitSerializationCluster();
+    case kApiErrorCid:
+      return new (Z) ApiErrorSerializationCluster();
     case kLanguageErrorCid:
       return new (Z) LanguageErrorSerializationCluster();
     case kUnhandledExceptionCid:
       return new (Z) UnhandledExceptionSerializationCluster();
+    case kUnwindErrorCid:
+      return new (Z) UnwindErrorSerializationCluster();
     case kLibraryPrefixCid:
       return new (Z) LibraryPrefixSerializationCluster();
     case kTypeCid:
@@ -9270,6 +9493,10 @@ DeserializationCluster* Deserializer::ReadCluster() {
       ASSERT(!is_canonical);
       ASSERT(!is_deeply_immutable);
       return new (Z) CompressedStackMapsDeserializationCluster();
+    case kLocalVarDescriptorsCid:
+      ASSERT(!is_canonical);
+      ASSERT(!is_deeply_immutable);
+      return new (Z) LocalVarDescriptorsDeserializationCluster();
     case kExceptionHandlersCid:
       ASSERT(!is_canonical);
       ASSERT(!is_deeply_immutable);
@@ -9302,6 +9529,10 @@ DeserializationCluster* Deserializer::ReadCluster() {
       ASSERT(!is_canonical);
       ASSERT(!is_deeply_immutable);
       return new (Z) LoadingUnitDeserializationCluster();
+    case kApiErrorCid:
+      ASSERT(!is_canonical);
+      ASSERT(!is_deeply_immutable);
+      return new (Z) ApiErrorDeserializationCluster();
     case kLanguageErrorCid:
       ASSERT(!is_canonical);
       ASSERT(!is_deeply_immutable);
@@ -9310,6 +9541,10 @@ DeserializationCluster* Deserializer::ReadCluster() {
       ASSERT(!is_canonical);
       ASSERT(!is_deeply_immutable);
       return new (Z) UnhandledExceptionDeserializationCluster();
+    case kUnwindErrorCid:
+      ASSERT(!is_canonical);
+      ASSERT(!is_deeply_immutable);
+      return new (Z) UnwindErrorDeserializationCluster();
     case kLibraryPrefixCid:
       ASSERT(!is_canonical);
       ASSERT(!is_deeply_immutable);
diff --git a/runtime/vm/compiler/runtime_api.cc b/runtime/vm/compiler/runtime_api.cc
index c2f9fb6b297..7f3fe599b89 100644
--- a/runtime/vm/compiler/runtime_api.cc
+++ b/runtime/vm/compiler/runtime_api.cc
@@ -1038,10 +1038,6 @@ word String::InstanceSize(word payload_size) {
   return RoundedAllocationSize(String::InstanceSize() + payload_size);
 }
 
-word LocalVarDescriptors::InstanceSize() {
-  return 0;
-}
-
 word Integer::NextFieldOffset() {
   return TranslateOffsetInWords(dart::Integer::NextFieldOffset());
 }
diff --git a/runtime/vm/compiler/runtime_api.h b/runtime/vm/compiler/runtime_api.h
index 641b9355359..89068624eed 100644
--- a/runtime/vm/compiler/runtime_api.h
+++ b/runtime/vm/compiler/runtime_api.h
@@ -916,6 +916,8 @@ class CompressedStackMaps : public AllStatic {
 
 class LocalVarDescriptors : public AllStatic {
  public:
+  static word element_offset(intptr_t index);
+  static word InstanceSize(intptr_t length);
   static word InstanceSize();
   FINAL_CLASS();
 };
diff --git a/runtime/vm/compiler/runtime_offsets_extracted.h b/runtime/vm/compiler/runtime_offsets_extracted.h
index fc9509e6ab0..f9f098d0059 100644
--- a/runtime/vm/compiler/runtime_offsets_extracted.h
+++ b/runtime/vm/compiler/runtime_offsets_extracted.h
@@ -41,6 +41,10 @@ static constexpr dart::compiler::target::word Context_element_size = 0x4;
 static constexpr dart::compiler::target::word
     ContextScope_elements_start_offset = 0xc;
 static constexpr dart::compiler::target::word ContextScope_element_size = 0x28;
+static constexpr dart::compiler::target::word
+    LocalVarDescriptors_elements_start_offset = 0x8;
+static constexpr dart::compiler::target::word LocalVarDescriptors_element_size =
+    0x18;
 static constexpr dart::compiler::target::word
     ExceptionHandlers_elements_start_offset = 0xc;
 static constexpr dart::compiler::target::word ExceptionHandlers_element_size =
@@ -805,6 +809,10 @@ static constexpr dart::compiler::target::word Context_element_size = 0x8;
 static constexpr dart::compiler::target::word
     ContextScope_elements_start_offset = 0x10;
 static constexpr dart::compiler::target::word ContextScope_element_size = 0x50;
+static constexpr dart::compiler::target::word
+    LocalVarDescriptors_elements_start_offset = 0x10;
+static constexpr dart::compiler::target::word LocalVarDescriptors_element_size =
+    0x1c;
 static constexpr dart::compiler::target::word
     ExceptionHandlers_elements_start_offset = 0x18;
 static constexpr dart::compiler::target::word ExceptionHandlers_element_size =
@@ -1580,6 +1588,10 @@ static constexpr dart::compiler::target::word Context_element_size = 0x4;
 static constexpr dart::compiler::target::word
     ContextScope_elements_start_offset = 0xc;
 static constexpr dart::compiler::target::word ContextScope_element_size = 0x28;
+static constexpr dart::compiler::target::word
+    LocalVarDescriptors_elements_start_offset = 0x8;
+static constexpr dart::compiler::target::word LocalVarDescriptors_element_size =
+    0x18;
 static constexpr dart::compiler::target::word
     ExceptionHandlers_elements_start_offset = 0xc;
 static constexpr dart::compiler::target::word ExceptionHandlers_element_size =
@@ -2343,6 +2355,10 @@ static constexpr dart::compiler::target::word Context_element_size = 0x8;
 static constexpr dart::compiler::target::word
     ContextScope_elements_start_offset = 0x10;
 static constexpr dart::compiler::target::word ContextScope_element_size = 0x50;
+static constexpr dart::compiler::target::word
+    LocalVarDescriptors_elements_start_offset = 0x10;
+static constexpr dart::compiler::target::word LocalVarDescriptors_element_size =
+    0x1c;
 static constexpr dart::compiler::target::word
     ExceptionHandlers_elements_start_offset = 0x18;
 static constexpr dart::compiler::target::word ExceptionHandlers_element_size =
@@ -3121,6 +3137,10 @@ static constexpr dart::compiler::target::word Context_element_size = 0x4;
 static constexpr dart::compiler::target::word
     ContextScope_elements_start_offset = 0x10;
 static constexpr dart::compiler::target::word ContextScope_element_size = 0x28;
+static constexpr dart::compiler::target::word
+    LocalVarDescriptors_elements_start_offset = 0x10;
+static constexpr dart::compiler::target::word LocalVarDescriptors_element_size =
+    0x18;
 static constexpr dart::compiler::target::word
     ExceptionHandlers_elements_start_offset = 0x10;
 static constexpr dart::compiler::target::word ExceptionHandlers_element_size =
@@ -3893,6 +3913,10 @@ static constexpr dart::compiler::target::word Context_element_size = 0x4;
 static constexpr dart::compiler::target::word
     ContextScope_elements_start_offset = 0x10;
 static constexpr dart::compiler::target::word ContextScope_element_size = 0x28;
+static constexpr dart::compiler::target::word
+    LocalVarDescriptors_elements_start_offset = 0x10;
+static constexpr dart::compiler::target::word LocalVarDescriptors_element_size =
+    0x18;
 static constexpr dart::compiler::target::word
     ExceptionHandlers_elements_start_offset = 0x10;
 static constexpr dart::compiler::target::word ExceptionHandlers_element_size =
@@ -4666,6 +4690,10 @@ static constexpr dart::compiler::target::word Context_element_size = 0x4;
 static constexpr dart::compiler::target::word
     ContextScope_elements_start_offset = 0xc;
 static constexpr dart::compiler::target::word ContextScope_element_size = 0x28;
+static constexpr dart::compiler::target::word
+    LocalVarDescriptors_elements_start_offset = 0x8;
+static constexpr dart::compiler::target::word LocalVarDescriptors_element_size =
+    0x18;
 static constexpr dart::compiler::target::word
     ExceptionHandlers_elements_start_offset = 0xc;
 static constexpr dart::compiler::target::word ExceptionHandlers_element_size =
@@ -5431,6 +5459,10 @@ static constexpr dart::compiler::target::word Context_element_size = 0x8;
 static constexpr dart::compiler::target::word
     ContextScope_elements_start_offset = 0x10;
 static constexpr dart::compiler::target::word ContextScope_element_size = 0x50;
+static constexpr dart::compiler::target::word
+    LocalVarDescriptors_elements_start_offset = 0x10;
+static constexpr dart::compiler::target::word LocalVarDescriptors_element_size =
+    0x1c;
 static constexpr dart::compiler::target::word
     ExceptionHandlers_elements_start_offset = 0x18;
 static constexpr dart::compiler::target::word ExceptionHandlers_element_size =
@@ -6204,6 +6236,10 @@ static constexpr dart::compiler::target::word Context_element_size = 0x4;
 static constexpr dart::compiler::target::word
     ContextScope_elements_start_offset = 0xc;
 static constexpr dart::compiler::target::word ContextScope_element_size = 0x28;
+static constexpr dart::compiler::target::word
+    LocalVarDescriptors_elements_start_offset = 0x8;
+static constexpr dart::compiler::target::word LocalVarDescriptors_element_size =
+    0x18;
 static constexpr dart::compiler::target::word
     ExceptionHandlers_elements_start_offset = 0xc;
 static constexpr dart::compiler::target::word ExceptionHandlers_element_size =
@@ -6960,6 +6996,10 @@ static constexpr dart::compiler::target::word Context_element_size = 0x8;
 static constexpr dart::compiler::target::word
     ContextScope_elements_start_offset = 0x10;
 static constexpr dart::compiler::target::word ContextScope_element_size = 0x50;
+static constexpr dart::compiler::target::word
+    LocalVarDescriptors_elements_start_offset = 0x10;
+static constexpr dart::compiler::target::word LocalVarDescriptors_element_size =
+    0x1c;
 static constexpr dart::compiler::target::word
     ExceptionHandlers_elements_start_offset = 0x18;
 static constexpr dart::compiler::target::word ExceptionHandlers_element_size =
@@ -7727,6 +7767,10 @@ static constexpr dart::compiler::target::word Context_element_size = 0x4;
 static constexpr dart::compiler::target::word
     ContextScope_elements_start_offset = 0xc;
 static constexpr dart::compiler::target::word ContextScope_element_size = 0x28;
+static constexpr dart::compiler::target::word
+    LocalVarDescriptors_elements_start_offset = 0x8;
+static constexpr dart::compiler::target::word LocalVarDescriptors_element_size =
+    0x18;
 static constexpr dart::compiler::target::word
     ExceptionHandlers_elements_start_offset = 0xc;
 static constexpr dart::compiler::target::word ExceptionHandlers_element_size =
@@ -8482,6 +8526,10 @@ static constexpr dart::compiler::target::word Context_element_size = 0x8;
 static constexpr dart::compiler::target::word
     ContextScope_elements_start_offset = 0x10;
 static constexpr dart::compiler::target::word ContextScope_element_size = 0x50;
+static constexpr dart::compiler::target::word
+    LocalVarDescriptors_elements_start_offset = 0x10;
+static constexpr dart::compiler::target::word LocalVarDescriptors_element_size =
+    0x1c;
 static constexpr dart::compiler::target::word
     ExceptionHandlers_elements_start_offset = 0x18;
 static constexpr dart::compiler::target::word ExceptionHandlers_element_size =
@@ -9252,6 +9300,10 @@ static constexpr dart::compiler::target::word Context_element_size = 0x4;
 static constexpr dart::compiler::target::word
     ContextScope_elements_start_offset = 0x10;
 static constexpr dart::compiler::target::word ContextScope_element_size = 0x28;
+static constexpr dart::compiler::target::word
+    LocalVarDescriptors_elements_start_offset = 0x10;
+static constexpr dart::compiler::target::word LocalVarDescriptors_element_size =
+    0x18;
 static constexpr dart::compiler::target::word
     ExceptionHandlers_elements_start_offset = 0x10;
 static constexpr dart::compiler::target::word ExceptionHandlers_element_size =
@@ -10016,6 +10068,10 @@ static constexpr dart::compiler::target::word Context_element_size = 0x4;
 static constexpr dart::compiler::target::word
     ContextScope_elements_start_offset = 0x10;
 static constexpr dart::compiler::target::word ContextScope_element_size = 0x28;
+static constexpr dart::compiler::target::word
+    LocalVarDescriptors_elements_start_offset = 0x10;
+static constexpr dart::compiler::target::word LocalVarDescriptors_element_size =
+    0x18;
 static constexpr dart::compiler::target::word
     ExceptionHandlers_elements_start_offset = 0x10;
 static constexpr dart::compiler::target::word ExceptionHandlers_element_size =
@@ -10781,6 +10837,10 @@ static constexpr dart::compiler::target::word Context_element_size = 0x4;
 static constexpr dart::compiler::target::word
     ContextScope_elements_start_offset = 0xc;
 static constexpr dart::compiler::target::word ContextScope_element_size = 0x28;
+static constexpr dart::compiler::target::word
+    LocalVarDescriptors_elements_start_offset = 0x8;
+static constexpr dart::compiler::target::word LocalVarDescriptors_element_size =
+    0x18;
 static constexpr dart::compiler::target::word
     ExceptionHandlers_elements_start_offset = 0xc;
 static constexpr dart::compiler::target::word ExceptionHandlers_element_size =
@@ -11538,6 +11598,10 @@ static constexpr dart::compiler::target::word Context_element_size = 0x8;
 static constexpr dart::compiler::target::word
     ContextScope_elements_start_offset = 0x10;
 static constexpr dart::compiler::target::word ContextScope_element_size = 0x50;
+static constexpr dart::compiler::target::word
+    LocalVarDescriptors_elements_start_offset = 0x10;
+static constexpr dart::compiler::target::word LocalVarDescriptors_element_size =
+    0x1c;
 static constexpr dart::compiler::target::word
     ExceptionHandlers_elements_start_offset = 0x18;
 static constexpr dart::compiler::target::word ExceptionHandlers_element_size =
@@ -12306,6 +12370,10 @@ static constexpr dart::compiler::target::word
     AOT_ContextScope_elements_start_offset = 0xc;
 static constexpr dart::compiler::target::word AOT_ContextScope_element_size =
     0x28;
+static constexpr dart::compiler::target::word
+    AOT_LocalVarDescriptors_elements_start_offset = 0x8;
+static constexpr dart::compiler::target::word
+    AOT_LocalVarDescriptors_element_size = 0x18;
 static constexpr dart::compiler::target::word
     AOT_ExceptionHandlers_elements_start_offset = 0xc;
 static constexpr dart::compiler::target::word
@@ -13155,6 +13223,10 @@ static constexpr dart::compiler::target::word
     AOT_ContextScope_elements_start_offset = 0x10;
 static constexpr dart::compiler::target::word AOT_ContextScope_element_size =
     0x50;
+static constexpr dart::compiler::target::word
+    AOT_LocalVarDescriptors_elements_start_offset = 0x10;
+static constexpr dart::compiler::target::word
+    AOT_LocalVarDescriptors_element_size = 0x1c;
 static constexpr dart::compiler::target::word
     AOT_ExceptionHandlers_elements_start_offset = 0x18;
 static constexpr dart::compiler::target::word
@@ -14015,6 +14087,10 @@ static constexpr dart::compiler::target::word
     AOT_ContextScope_elements_start_offset = 0x10;
 static constexpr dart::compiler::target::word AOT_ContextScope_element_size =
     0x50;
+static constexpr dart::compiler::target::word
+    AOT_LocalVarDescriptors_elements_start_offset = 0x10;
+static constexpr dart::compiler::target::word
+    AOT_LocalVarDescriptors_element_size = 0x1c;
 static constexpr dart::compiler::target::word
     AOT_ExceptionHandlers_elements_start_offset = 0x18;
 static constexpr dart::compiler::target::word
@@ -14871,6 +14947,10 @@ static constexpr dart::compiler::target::word
     AOT_ContextScope_elements_start_offset = 0x10;
 static constexpr dart::compiler::target::word AOT_ContextScope_element_size =
     0x28;
+static constexpr dart::compiler::target::word
+    AOT_LocalVarDescriptors_elements_start_offset = 0x10;
+static constexpr dart::compiler::target::word
+    AOT_LocalVarDescriptors_element_size = 0x18;
 static constexpr dart::compiler::target::word
     AOT_ExceptionHandlers_elements_start_offset = 0x10;
 static constexpr dart::compiler::target::word
@@ -15727,6 +15807,10 @@ static constexpr dart::compiler::target::word
     AOT_ContextScope_elements_start_offset = 0x10;
 static constexpr dart::compiler::target::word AOT_ContextScope_element_size =
     0x28;
+static constexpr dart::compiler::target::word
+    AOT_LocalVarDescriptors_elements_start_offset = 0x10;
+static constexpr dart::compiler::target::word
+    AOT_LocalVarDescriptors_element_size = 0x18;
 static constexpr dart::compiler::target::word
     AOT_ExceptionHandlers_elements_start_offset = 0x10;
 static constexpr dart::compiler::target::word
@@ -16585,6 +16669,10 @@ static constexpr dart::compiler::target::word
     AOT_ContextScope_elements_start_offset = 0xc;
 static constexpr dart::compiler::target::word AOT_ContextScope_element_size =
     0x28;
+static constexpr dart::compiler::target::word
+    AOT_LocalVarDescriptors_elements_start_offset = 0x8;
+static constexpr dart::compiler::target::word
+    AOT_LocalVarDescriptors_element_size = 0x18;
 static constexpr dart::compiler::target::word
     AOT_ExceptionHandlers_elements_start_offset = 0xc;
 static constexpr dart::compiler::target::word
@@ -17435,6 +17523,10 @@ static constexpr dart::compiler::target::word
     AOT_ContextScope_elements_start_offset = 0x10;
 static constexpr dart::compiler::target::word AOT_ContextScope_element_size =
     0x50;
+static constexpr dart::compiler::target::word
+    AOT_LocalVarDescriptors_elements_start_offset = 0x10;
+static constexpr dart::compiler::target::word
+    AOT_LocalVarDescriptors_element_size = 0x1c;
 static constexpr dart::compiler::target::word
     AOT_ExceptionHandlers_elements_start_offset = 0x18;
 static constexpr dart::compiler::target::word
@@ -18287,6 +18379,10 @@ static constexpr dart::compiler::target::word
     AOT_ContextScope_elements_start_offset = 0xc;
 static constexpr dart::compiler::target::word AOT_ContextScope_element_size =
     0x28;
+static constexpr dart::compiler::target::word
+    AOT_LocalVarDescriptors_elements_start_offset = 0x8;
+static constexpr dart::compiler::target::word
+    AOT_LocalVarDescriptors_element_size = 0x18;
 static constexpr dart::compiler::target::word
     AOT_ExceptionHandlers_elements_start_offset = 0xc;
 static constexpr dart::compiler::target::word
@@ -19127,6 +19223,10 @@ static constexpr dart::compiler::target::word
     AOT_ContextScope_elements_start_offset = 0x10;
 static constexpr dart::compiler::target::word AOT_ContextScope_element_size =
     0x50;
+static constexpr dart::compiler::target::word
+    AOT_LocalVarDescriptors_elements_start_offset = 0x10;
+static constexpr dart::compiler::target::word
+    AOT_LocalVarDescriptors_element_size = 0x1c;
 static constexpr dart::compiler::target::word
     AOT_ExceptionHandlers_elements_start_offset = 0x18;
 static constexpr dart::compiler::target::word
@@ -19978,6 +20078,10 @@ static constexpr dart::compiler::target::word
     AOT_ContextScope_elements_start_offset = 0x10;
 static constexpr dart::compiler::target::word AOT_ContextScope_element_size =
     0x50;
+static constexpr dart::compiler::target::word
+    AOT_LocalVarDescriptors_elements_start_offset = 0x10;
+static constexpr dart::compiler::target::word
+    AOT_LocalVarDescriptors_element_size = 0x1c;
 static constexpr dart::compiler::target::word
     AOT_ExceptionHandlers_elements_start_offset = 0x18;
 static constexpr dart::compiler::target::word
@@ -20825,6 +20929,10 @@ static constexpr dart::compiler::target::word
     AOT_ContextScope_elements_start_offset = 0x10;
 static constexpr dart::compiler::target::word AOT_ContextScope_element_size =
     0x28;
+static constexpr dart::compiler::target::word
+    AOT_LocalVarDescriptors_elements_start_offset = 0x10;
+static constexpr dart::compiler::target::word
+    AOT_LocalVarDescriptors_element_size = 0x18;
 static constexpr dart::compiler::target::word
     AOT_ExceptionHandlers_elements_start_offset = 0x10;
 static constexpr dart::compiler::target::word
@@ -21672,6 +21780,10 @@ static constexpr dart::compiler::target::word
     AOT_ContextScope_elements_start_offset = 0x10;
 static constexpr dart::compiler::target::word AOT_ContextScope_element_size =
     0x28;
+static constexpr dart::compiler::target::word
+    AOT_LocalVarDescriptors_elements_start_offset = 0x10;
+static constexpr dart::compiler::target::word
+    AOT_LocalVarDescriptors_element_size = 0x18;
 static constexpr dart::compiler::target::word
     AOT_ExceptionHandlers_elements_start_offset = 0x10;
 static constexpr dart::compiler::target::word
@@ -22521,6 +22633,10 @@ static constexpr dart::compiler::target::word
     AOT_ContextScope_elements_start_offset = 0xc;
 static constexpr dart::compiler::target::word AOT_ContextScope_element_size =
     0x28;
+static constexpr dart::compiler::target::word
+    AOT_LocalVarDescriptors_elements_start_offset = 0x8;
+static constexpr dart::compiler::target::word
+    AOT_LocalVarDescriptors_element_size = 0x18;
 static constexpr dart::compiler::target::word
     AOT_ExceptionHandlers_elements_start_offset = 0xc;
 static constexpr dart::compiler::target::word
@@ -23362,6 +23478,10 @@ static constexpr dart::compiler::target::word
     AOT_ContextScope_elements_start_offset = 0x10;
 static constexpr dart::compiler::target::word AOT_ContextScope_element_size =
     0x50;
+static constexpr dart::compiler::target::word
+    AOT_LocalVarDescriptors_elements_start_offset = 0x10;
+static constexpr dart::compiler::target::word
+    AOT_LocalVarDescriptors_element_size = 0x1c;
 static constexpr dart::compiler::target::word
     AOT_ExceptionHandlers_elements_start_offset = 0x18;
 static constexpr dart::compiler::target::word
diff --git a/runtime/vm/compiler/runtime_offsets_list.h b/runtime/vm/compiler/runtime_offsets_list.h
index e3000a5e25d..af2c8f4740d 100644
--- a/runtime/vm/compiler/runtime_offsets_list.h
+++ b/runtime/vm/compiler/runtime_offsets_list.h
@@ -64,6 +64,7 @@
   ARRAY(Code, element_offset)                                                  \
   ARRAY(Context, variable_offset)                                              \
   ARRAY(ContextScope, element_offset)                                          \
+  ARRAY(LocalVarDescriptors, element_offset)                                   \
   ARRAY(ExceptionHandlers, element_offset)                                     \
   ARRAY(ObjectPool, element_offset)                                            \
   ARRAY(OneByteString, element_offset)                                         \
@@ -76,6 +77,7 @@
   ARRAY_SIZEOF(Code, InstanceSize, element_offset)                             \
   ARRAY_SIZEOF(Context, InstanceSize, variable_offset)                         \
   ARRAY_SIZEOF(ContextScope, InstanceSize, element_offset)                     \
+  ARRAY_SIZEOF(LocalVarDescriptors, InstanceSize, element_offset)              \
   ARRAY_SIZEOF(ExceptionHandlers, InstanceSize, element_offset)                \
   ARRAY_SIZEOF(ObjectPool, InstanceSize, element_offset)                       \
   ARRAY_SIZEOF(OneByteString, InstanceSize, element_offset)                    \
diff --git a/runtime/vm/object.cc b/runtime/vm/object.cc
index 0af3fd5d1ab..6851623badd 100644
--- a/runtime/vm/object.cc
+++ b/runtime/vm/object.cc
@@ -1111,6 +1111,7 @@ void Object::Init(IsolateGroup* isolate_group) {
         static_cast<TypeArgumentsPtr>(address + kHeapObjectTag));
     Roots::empty_type_arguments().untag()->set_length(Smi::New(0));
     Roots::empty_type_arguments().untag()->set_hash(Smi::New(0));
+    Roots::empty_type_arguments().untag()->set_nullability(Smi::New(0));
     Roots::empty_type_arguments().ComputeHash();
     Roots::empty_type_arguments().SetCanonical();
   }
diff --git a/runtime/vm/object.h b/runtime/vm/object.h
index 46de032f0cf..bc11f517cec 100644
--- a/runtime/vm/object.h
+++ b/runtime/vm/object.h
@@ -6203,10 +6203,18 @@ class LocalVarDescriptors : public Object {
                UntaggedLocalVarDescriptors::VarInfo* info) const;
 
   static constexpr intptr_t kBytesPerElement =
-      sizeof(UntaggedLocalVarDescriptors::VarInfo);
+      sizeof(UntaggedLocalVarDescriptors::VarInfo) +
+      sizeof(CompressedStringPtr);
   static constexpr intptr_t kMaxElements =
       UntaggedLocalVarDescriptors::VarInfo::kMaxIndex;
 
+  struct ArrayTraits {
+    static intptr_t elements_start_offset() {
+      return sizeof(UntaggedLocalVarDescriptors);
+    }
+    static constexpr intptr_t kElementSize = kBytesPerElement;
+  };
+
   static intptr_t InstanceSize() {
     ASSERT(sizeof(UntaggedLocalVarDescriptors) ==
            OFFSET_OF_RETURNED_VALUE(UntaggedLocalVarDescriptors, names));
@@ -6214,10 +6222,8 @@ class LocalVarDescriptors : public Object {
   }
   static intptr_t InstanceSize(intptr_t len) {
     ASSERT(0 <= len && len <= kMaxElements);
-    return RoundedAllocationSize(
-        sizeof(UntaggedLocalVarDescriptors) +
-        (len * kWordSize)  // RawStrings for names.
-        + (len * sizeof(UntaggedLocalVarDescriptors::VarInfo)));
+    return RoundedAllocationSize(sizeof(UntaggedLocalVarDescriptors) +
+                                 len * kBytesPerElement);
   }
 
   static LocalVarDescriptorsPtr New(intptr_t num_variables);
diff --git a/runtime/vm/raw_object.h b/runtime/vm/raw_object.h
index 43c1b43e9d3..6c2f226dca0 100644
--- a/runtime/vm/raw_object.h
+++ b/runtime/vm/raw_object.h
@@ -2556,6 +2556,10 @@ class UntaggedLocalVarDescriptors : public UntaggedObject {
     return reinterpret_cast<VarInfo*>(nameAddrAt(num_entries_));
   }
 
+  CompressedObjectPtr* to_snapshot(Snapshot::Kind kind, intptr_t num_entries) {
+    return to(num_entries);
+  }
+
   friend class Object;
 };
 
@@ -2831,6 +2835,7 @@ class UntaggedApiError : public UntaggedError {
   COMPRESSED_POINTER_FIELD(StringPtr, message)
   VISIT_FROM(message)
   VISIT_TO(message)
+  CompressedObjectPtr* to_snapshot(Snapshot::Kind kind) { return to(); }
 };
 
 class UntaggedLanguageError : public UntaggedError {
@@ -2867,6 +2872,7 @@ class UntaggedUnwindError : public UntaggedError {
   VISIT_FROM(message)
   VISIT_TO(message)
   bool is_user_initiated_;
+  CompressedObjectPtr* to_snapshot(Snapshot::Kind kind) { return to(); }
 };
 
 class UntaggedInstance : public UntaggedObject {