[rab/gsab] Re-enable serializing flags with ValueSerializer

Also:
- Refactor the ValueSerializer tests using raw data, so that we test all
valid versions for each test (not only one hard-coded one)
- Mark some tests as backwards compatibility tests, to make it less
likely that somebody updates them not realizing they are backwards
compatibility tests.

Bug: v8:11111, v8:12532
Change-Id: I670849de07742c8d442249ef4f013781e4ee9255
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3386802Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Commit-Queue: Marja Hölttä <marja@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78681}

include/v8-value-serializer-version.h

@@ -17,7 +17,7 @@
 
 namespace v8 {
 
-constexpr uint32_t CurrentValueSerializerFormatVersion() { return 13; }
+constexpr uint32_t CurrentValueSerializerFormatVersion() { return 14; }
 
 }  // namespace v8
 

src/objects/value-serializer.cc

@@ -49,6 +49,7 @@ namespace internal {
 // Version 12: regexp and string objects share normal string encoding
 // Version 13: host objects have an explicit tag (rather than handling all
 //             unknown tags)
+// Version 14: flags for JSArrayBufferViews
 //
 // WARNING: Increasing this value is a change which cannot safely be rolled
 // back without breaking compatibility with data stored on disk. It is
@@ -57,7 +58,7 @@ namespace internal {
 //
 // Recent changes are routinely reverted in preparation for branch, and this
 // has been the cause of at least one bug in the past.
-static const uint32_t kLatestVersion = 13;
+static const uint32_t kLatestVersion = 14;
 static_assert(kLatestVersion == v8::CurrentValueSerializerFormatVersion(),
               "Exported format version must match latest version.");
 
@@ -938,11 +939,7 @@ Maybe<bool> ValueSerializer::WriteJSArrayBufferView(JSArrayBufferView view) {
   WriteVarint(static_cast<uint8_t>(tag));
   WriteVarint(static_cast<uint32_t>(view.byte_offset()));
   WriteVarint(static_cast<uint32_t>(view.byte_length()));
-  // TODO(crbug.com/v8/12532): Re-enable the flags serialization logic below.
-  // Bump the serialization format version number when doing so, and preserve
-  // logic and tests for reading from the old format.
-  //
-  // WriteVarint(static_cast<uint32_t>(view.bit_field()));
+  WriteVarint(static_cast<uint32_t>(view.bit_field()));
   return ThrowIfOutOfMemory();
 }
 
@@ -1868,8 +1865,6 @@ MaybeHandle<JSArrayBufferView> ValueDeserializer::ReadJSArrayBufferView(
   uint32_t byte_offset = 0;
   uint32_t byte_length = 0;
   uint32_t flags = 0;
-  // TODO(crbug.com/v8/12532): Read `flags` from the serialized value, when we
-  // restore the logic for serializing them.
   if (!ReadVarint<uint8_t>().To(&tag) ||
       !ReadVarint<uint32_t>().To(&byte_offset) ||
       !ReadVarint<uint32_t>().To(&byte_length) ||
@@ -1877,6 +1872,9 @@ MaybeHandle<JSArrayBufferView> ValueDeserializer::ReadJSArrayBufferView(
       byte_length > buffer_byte_length - byte_offset) {
     return MaybeHandle<JSArrayBufferView>();
   }
+  if (version_ >= 14 && !ReadVarint<uint32_t>().To(&flags)) {
+    return MaybeHandle<JSArrayBufferView>();
+  }
   uint32_t id = next_id_++;
   ExternalArrayType external_array_type = kExternalInt8Array;
   unsigned element_size = 0;

test/unittests/BUILD.gn

@@ -523,6 +523,7 @@ v8_source_set("unittests_sources") {
     "../..:v8_libbase",
     "../..:v8_libplatform",
     "../..:v8_shared_internal_headers",
+    "../..:v8_version",
     "../../third_party/inspector_protocol:crdtp_test",
     "//build/win:default_exe_manifest",
     "//testing/gmock",