Remove JS natives support, step 1

The natives blob is deprecated and will be removed in the next
release.

This commit does two things, 1. it disables the v8_extra_library_files
gn argument which will make building natives_blob.bin through gn
impossible; 2. it marks API functions associated with the natives blob
as V8_DEPRECATE_SOON.

Embedders should remove any uses of SetNativesDataBlob and replace all
calls to

 InitializeExternalStartupData(const char*, const char*)

with the new function

 InitializeExternalStartupDataFromFile(const char*)

Step 2 is to mark API functions as V8_DEPRECATED.
Step 3, in the next V8 release, is to remove these functions and all
other natives support in V8.

Bug: v8:7624
Change-Id: I745e96c60204a9b94d9240be65dd59bb9bdd0699
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1824944
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Auto-Submit: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64080}

BUILD.gn

@@ -156,9 +156,7 @@ declare_args() {
 
   # List of extra files to snapshot. They will be snapshotted in order so
   # if files export symbols used by later files, they should go first.
-  #
-  # This default is used by cctests. Projects using V8 will want to override.
-  v8_extra_library_files = [ "//test/cctest/test-extra.js" ]
+  v8_extra_library_files = []
 
   v8_enable_gdbjit =
       ((v8_current_cpu == "x86" || v8_current_cpu == "x64") &&
@@ -258,6 +256,10 @@ assert(
 assert(v8_use_snapshot || !v8_enable_shared_ro_heap,
        "Shared read-only heap requires snapshot")
 
+assert(v8_extra_library_files == [],
+       "v8_extra_library_files is no longer supported. Consider implementing " +
+           "custom API in C++ instead.")
+
 v8_random_seed = "314159265"
 v8_toolset_for_shell = "host"
 

include/v8.h

@@ -9004,7 +9004,9 @@ class V8_EXPORT V8 {
    *   handled entirely on the embedders' side.
    * - The call will abort if the data is invalid.
    */
-  static void SetNativesDataBlob(StartupData* startup_blob);
+  V8_DEPRECATE_SOON(
+      "The natives blob is deprecated (https://crbug.com/v8/7624).",
+      static void SetNativesDataBlob(StartupData* startup_blob));
   static void SetSnapshotDataBlob(StartupData* startup_blob);
 
   /** Set the callback to invoke in case of Dcheck failures. */
@@ -9100,8 +9102,12 @@ class V8_EXPORT V8 {
    *   not perform any file IO.
    */
   static void InitializeExternalStartupData(const char* directory_path);
-  static void InitializeExternalStartupData(const char* natives_blob,
-                                            const char* snapshot_blob);
+  V8_DEPRECATE_SOON(
+      "The natives blob is deprecated (https://crbug.com/v8/7624).",
+      static void InitializeExternalStartupData(const char* natives_blob,
+                                                const char* snapshot_blob));
+  static void InitializeExternalStartupDataFromFile(const char* snapshot_blob);
+
   /**
    * Sets the v8::Platform to use. This should be invoked before V8 is
    * initialized.

src/api/api.cc

@@ -5723,6 +5723,11 @@ void v8::V8::InitializeExternalStartupData(const char* natives_blob,
   i::InitializeExternalStartupData(natives_blob, snapshot_blob);
 }
 
+// static
+void v8::V8::InitializeExternalStartupDataFromFile(const char* snapshot_blob) {
+  i::InitializeExternalStartupDataFromFile(snapshot_blob);
+}
+
 const char* v8::V8::GetVersion() { return i::Version::GetVersion(); }
 
 template <typename ObjectType>

src/d8/d8.cc

@@ -3001,9 +3001,6 @@ bool Shell::SetOptions(int argc, char* argv[]) {
       options.icu_locale = argv[i] + 13;
       argv[i] = nullptr;
 #ifdef V8_USE_EXTERNAL_STARTUP_DATA
-    } else if (strncmp(argv[i], "--natives_blob=", 15) == 0) {
-      options.natives_blob = argv[i] + 15;
-      argv[i] = nullptr;
     } else if (strncmp(argv[i], "--snapshot_blob=", 16) == 0) {
       options.snapshot_blob = argv[i] + 16;
       argv[i] = nullptr;
@@ -3592,9 +3589,8 @@ int Shell::Main(int argc, char* argv[]) {
   }
   v8::V8::InitializePlatform(g_platform.get());
   v8::V8::Initialize();
-  if (options.natives_blob || options.snapshot_blob) {
-    v8::V8::InitializeExternalStartupData(options.natives_blob,
-                                          options.snapshot_blob);
+  if (options.snapshot_blob) {
+    v8::V8::InitializeExternalStartupDataFromFile(options.snapshot_blob);
   } else {
     v8::V8::InitializeExternalStartupData(argv[0]);
   }

src/d8/d8.h

@@ -285,7 +285,6 @@ class ShellOptions {
   SourceGroup* isolate_sources = nullptr;
   const char* icu_data_file = nullptr;
   const char* icu_locale = nullptr;
-  const char* natives_blob = nullptr;
   const char* snapshot_blob = nullptr;
   bool trace_enabled = false;
   const char* trace_path = nullptr;

src/init/startup-data-util.cc

@@ -38,6 +38,10 @@ void FreeStartupData() {
   DeleteStartupData(&g_snapshot);
 }
 
+// TODO(jgruber): Rename to FreeStartupData once natives support has been
+// removed (https://crbug.com/v8/7624).
+void FreeStartupDataSnapshotOnly() { DeleteStartupData(&g_snapshot); }
+
 void Load(const char* blob_file, v8::StartupData* startup_data,
           void (*setter_fn)(v8::StartupData*)) {
   ClearStartupData(startup_data);
@@ -67,7 +71,7 @@ void Load(const char* blob_file, v8::StartupData* startup_data,
 }
 
 void LoadFromFiles(const char* natives_blob, const char* snapshot_blob) {
-  Load(natives_blob, &g_natives, v8::V8::SetNativesDataBlob);
+  Load(natives_blob, &g_natives, i::V8::SetNativesBlob);
   Load(snapshot_blob, &g_snapshot, v8::V8::SetSnapshotDataBlob);
 
   atexit(&FreeStartupData);
@@ -101,5 +105,12 @@ void InitializeExternalStartupData(const char* natives_blob,
 #endif  // V8_USE_EXTERNAL_STARTUP_DATA
 }
 
+void InitializeExternalStartupDataFromFile(const char* snapshot_blob) {
+#ifdef V8_USE_EXTERNAL_STARTUP_DATA
+  Load(snapshot_blob, &g_snapshot, v8::V8::SetSnapshotDataBlob);
+  atexit(&FreeStartupDataSnapshotOnly);
+#endif  // V8_USE_EXTERNAL_STARTUP_DATA
+}
+
 }  // namespace internal
 }  // namespace v8

src/init/startup-data-util.h

@@ -21,6 +21,7 @@ void InitializeExternalStartupData(const char* directory_path);
 
 void InitializeExternalStartupData(const char* natives_blob,
                                    const char* snapshot_blob);
+void InitializeExternalStartupDataFromFile(const char* snapshot_blob);
 
 }  // namespace internal
 }  // namespace v8

test/cctest/test-debug.cc

@@ -4509,7 +4509,7 @@ UNINITIALIZED_TEST(LoadedAtStartupScripts) {
       }
     }
     CHECK_EQ(count_by_type[i::Script::TYPE_NATIVE], 0);
-    CHECK_EQ(count_by_type[i::Script::TYPE_EXTENSION], 2);
+    CHECK_EQ(count_by_type[i::Script::TYPE_EXTENSION], 1);
     CHECK_EQ(count_by_type[i::Script::TYPE_NORMAL], 1);
     CHECK_EQ(count_by_type[i::Script::TYPE_WASM], 0);
     CHECK_EQ(count_by_type[i::Script::TYPE_INSPECTOR], 0);

tools/js2c.py

@@ -265,7 +265,9 @@ def BuildMetadata(sources, source_bytes, native_type):
 
   metadata = {
     "builtin_count": len(sources.modules),
-    "sources_declaration": SOURCES_DECLARATION % ToCArray(source_bytes),
+    "sources_declaration":
+        SOURCES_DECLARATION % ToCArray(
+          source_bytes if len(source_bytes) != 0 else "\0"),
     "total_length": total_length,
     "get_index_cases": "".join(get_index_cases),
     "get_script_source_cases": "".join(get_script_source_cases),