Revert "[VM/CLI] Remove dartdev.dill"

This reverts commit c09f790d37.

Reason for revert: CI failures

Original change's description:
> [VM/CLI] Remove dartdev.dill
>
> Incompatible VM flags will no longer break the CLI when running from an
> AppJIT snapshot, so the fallback logic is no longer required. This CL
> thus removes dartdev.dill and the fallback logic.
>
> Relevant past CLs: https://dart-review.googlesource.com/c/sdk/+/157601
> and https://dart-review.googlesource.com/c/sdk/+/178300
>
> Fixes https://github.com/dart-lang/sdk/issues/50504
>
> TEST=I tried running `out/ReleaseX64/dart --observe --sound-null-safety test.dart`
> and `out/ReleaseX64/dart --observe --no-sound-null-safety test.dart` and
> both worked.
>
> Change-Id: I5cdcfbccf71ec557964014fdb80733b4a7c76b4d
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/274520
> Reviewed-by: Ben Konyi <bkonyi@google.com>
> Commit-Queue: Derek Xu <derekx@google.com>

TBR=bkonyi@google.com,derekx@google.com,dart-scoped@luci-project-accounts.iam.gserviceaccount.com

Change-Id: I5117f990dfabf93f5a9bae56098831280845e84e
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/275181
Reviewed-by: Ben Konyi <bkonyi@google.com>
Commit-Queue: Derek Xu <derekx@google.com>

pkg/dartdev/test/load_from_dill_test.dart

@@ -0,0 +1,29 @@
+// Copyright (c) 2021, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:io';
+
+import 'package:test/test.dart';
+
+import 'utils.dart';
+
+void main() {
+  late TestProject p;
+
+  tearDown(() async => await p.dispose());
+
+  test("Fallback to dartdev.dill from dartdev.dart.snapshot for 'Hello World'",
+      () async {
+    p = project(mainSrc: "void main() { print('Hello World'); }");
+    // The DartDev snapshot includes the --use_field_guards flag. If
+    // --no-use-field-guards is passed, the VM will fail to load the
+    // snapshot and should fall back to using the DartDev dill file.
+    ProcessResult result =
+        await p.run(['--no-use-field-guards', 'run', p.relativeFilePath]);
+
+    expect(result.stdout, contains('Hello World'));
+    expect(result.stderr, isEmpty);
+    expect(result.exitCode, 0);
+  });
+}

runtime/bin/dartdev_isolate.cc

@@ -59,14 +59,14 @@ bool DartDevIsolate::ShouldParseCommand(const char* script_uri) {
           (strncmp(script_uri, "google3://", 10) != 0));
 }
 
-Utils::CStringUniquePtr DartDevIsolate::TryResolveDartDevSnapshotPath() {
-  const char* snapshot_filename = "dartdev.dart.snapshot";
+Utils::CStringUniquePtr DartDevIsolate::TryResolveArtifactPath(
+    const char* filename) {
   // |dir_prefix| includes the last path separator.
   auto dir_prefix = EXEUtils::GetDirectoryPrefixFromExeName();
 
   // First assume we're in dart-sdk/bin.
   char* snapshot_path =
-      Utils::SCreate("%ssnapshots/%s", dir_prefix.get(), snapshot_filename);
+      Utils::SCreate("%ssnapshots/%s", dir_prefix.get(), filename);
   if (File::Exists(nullptr, snapshot_path)) {
     return Utils::CreateCStringUniquePtr(snapshot_path);
   }
@@ -74,7 +74,7 @@ Utils::CStringUniquePtr DartDevIsolate::TryResolveDartDevSnapshotPath() {
 
   // If we're not in dart-sdk/bin, we might be in one of the $SDK/out/*
   // directories. Try to use a snapshot from a previously built SDK.
-  snapshot_path = Utils::SCreate("%s%s", dir_prefix.get(), snapshot_filename);
+  snapshot_path = Utils::SCreate("%s%s", dir_prefix.get(), filename);
   if (File::Exists(nullptr, snapshot_path)) {
     return Utils::CreateCStringUniquePtr(snapshot_path);
   }
@@ -82,6 +82,14 @@ Utils::CStringUniquePtr DartDevIsolate::TryResolveDartDevSnapshotPath() {
   return Utils::CreateCStringUniquePtr(nullptr);
 }
 
+Utils::CStringUniquePtr DartDevIsolate::TryResolveDartDevSnapshotPath() {
+  return TryResolveArtifactPath("dartdev.dart.snapshot");
+}
+
+Utils::CStringUniquePtr DartDevIsolate::TryResolveDartDevKernelPath() {
+  return TryResolveArtifactPath("dartdev.dill");
+}
+
 void DartDevIsolate::DartDevRunner::Run(
     Dart_IsolateGroupCreateCallback create_isolate,
     char** packages_file,

runtime/bin/dartdev_isolate.h

@@ -46,6 +46,9 @@ class DartDevIsolate {
 
   static bool should_run_dart_dev() { return should_run_dart_dev_; }
 
+  // Attempts to find the path of the DartDev kernel file.
+  static Utils::CStringUniquePtr TryResolveDartDevKernelPath();
+
   // Attempts to find the path of the DartDev snapshot.
   static Utils::CStringUniquePtr TryResolveDartDevSnapshotPath();
 
@@ -96,6 +99,8 @@ class DartDevIsolate {
   };
 
  private:
+  static Utils::CStringUniquePtr TryResolveArtifactPath(const char* filename);
+
   static DartDevRunner runner_;
   static bool should_run_dart_dev_;
   static bool print_usage_error_;

runtime/bin/main.cc

@@ -581,35 +581,75 @@ static Dart_Isolate CreateAndSetupDartDevIsolate(const char* script_uri,
                                                  char** error,
                                                  int* exit_code) {
   int64_t start = Dart_TimelineGetMicros();
+
   auto dartdev_path = DartDevIsolate::TryResolveDartDevSnapshotPath();
-  if (dartdev_path.get() == nullptr) {
-    Syslog::PrintErr(
-        "Failed to start the Dart CLI isolate. Could not resolve DartDev "
-        "snapshot.\n");
-    return nullptr;
-  }
+
+  Dart_Isolate isolate = nullptr;
+  const uint8_t* isolate_snapshot_data = core_isolate_snapshot_data;
+  const uint8_t* isolate_snapshot_instructions =
+      core_isolate_snapshot_instructions;
+  IsolateGroupData* isolate_group_data = nullptr;
+  IsolateData* isolate_data = nullptr;
 
   if (error != nullptr) {
     *error = nullptr;
   }
-  Dart_Isolate isolate = nullptr;
   AppSnapshot* app_snapshot = nullptr;
-  const bool isolate_run_app_snapshot = true;
+  bool isolate_run_app_snapshot = true;
   if (dartdev_path.get() != nullptr &&
       (app_snapshot = Snapshot::TryReadAppSnapshot(
            dartdev_path.get(), /*force_load_elf_from_memory=*/false,
            /*decode_uri=*/false)) != nullptr) {
-    const uint8_t* isolate_snapshot_data = nullptr;
-    const uint8_t* isolate_snapshot_instructions = nullptr;
+    const uint8_t* isolate_snapshot_data = NULL;
+    const uint8_t* isolate_snapshot_instructions = NULL;
     const uint8_t* ignore_vm_snapshot_data;
     const uint8_t* ignore_vm_snapshot_instructions;
     app_snapshot->SetBuffers(
         &ignore_vm_snapshot_data, &ignore_vm_snapshot_instructions,
         &isolate_snapshot_data, &isolate_snapshot_instructions);
-    IsolateGroupData* isolate_group_data =
+    isolate_group_data =
         new IsolateGroupData(DART_DEV_ISOLATE_NAME, packages_config,
                              app_snapshot, isolate_run_app_snapshot);
-    IsolateData* isolate_data = new IsolateData(isolate_group_data);
+    isolate_data = new IsolateData(isolate_group_data);
+    isolate = Dart_CreateIsolateGroup(
+        DART_DEV_ISOLATE_NAME, DART_DEV_ISOLATE_NAME, isolate_snapshot_data,
+        isolate_snapshot_instructions, flags, isolate_group_data, isolate_data,
+        error);
+  }
+
+  if (isolate == nullptr) {
+    isolate_run_app_snapshot = false;
+    dartdev_path = DartDevIsolate::TryResolveDartDevKernelPath();
+    // Clear error from app snapshot and retry from kernel.
+    if (error != nullptr && *error != nullptr) {
+      free(*error);
+      *error = nullptr;
+    }
+
+    if (app_snapshot != nullptr) {
+      delete app_snapshot;
+    }
+
+    if (dartdev_path.get() == nullptr) {
+      Syslog::PrintErr(
+          "Failed to start the Dart CLI isolate. Could not resolve DartDev "
+          "snapshot or kernel.\n");
+      delete isolate_data;
+      delete isolate_group_data;
+      return nullptr;
+    }
+
+    isolate_group_data =
+        new IsolateGroupData(DART_DEV_ISOLATE_NAME, packages_config, nullptr,
+                             isolate_run_app_snapshot);
+    uint8_t* application_kernel_buffer = NULL;
+    intptr_t application_kernel_buffer_size = 0;
+    dfe.ReadScript(dartdev_path.get(), &application_kernel_buffer,
+                   &application_kernel_buffer_size, /*decode_uri=*/false);
+    isolate_group_data->SetKernelBufferNewlyOwned(
+        application_kernel_buffer, application_kernel_buffer_size);
+
+    isolate_data = new IsolateData(isolate_group_data);
     isolate = Dart_CreateIsolateGroup(
         DART_DEV_ISOLATE_NAME, DART_DEV_ISOLATE_NAME, isolate_snapshot_data,
         isolate_snapshot_instructions, flags, isolate_group_data, isolate_data,

sdk/BUILD.gn

@@ -45,6 +45,7 @@ declare_args() {
 # ........dart2js.dart.snapshot
 # ........dart2wasm_product.snapshot (if not on ia32)
 # ........dartdev.dart.snapshot
+# ........dartdev.dill
 # ........dartdevc.dart.snapshot
 # ........dds.dart.snapshot
 # ........frontend_server.dart.snapshot
@@ -454,6 +455,17 @@ copy("copy_vm_dill_files") {
       [ "$root_out_dir/$dart_sdk_output/lib/_internal/{{source_file_part}}" ]
 }
 
+copy("copy_dartdev_dill_files") {
+  visibility = [ ":create_common_sdk" ]
+  deps = [
+    ":copy_libraries",
+    "../utils/dartdev:dartdev",
+  ]
+  sources = [ "$root_out_dir/dartdev.dill" ]
+  outputs =
+      [ "$root_out_dir/$dart_sdk_output/bin/snapshots/{{source_file_part}}" ]
+}
+
 copy("copy_dart2js_dill_files") {
   visibility = [ ":create_full_sdk" ]
   deps = [
@@ -753,6 +765,7 @@ group("create_common_sdk") {
     ":copy_analysis_summaries",
     ":copy_api_readme",
     ":copy_dart",
+    ":copy_dartdev_dill_files",
     ":copy_dartdoc_files",
     ":copy_headers",
     ":copy_libraries_dart",

utils/dartdev/BUILD.gn

@@ -7,11 +7,28 @@ import("../application_snapshot.gni")
 
 group("dartdev") {
   public_deps = [
+    ":copy_dartdev_kernel",
     ":copy_dartdev_snapshot",
     ":copy_prebuilt_devtools",
   ]
 }
 
+copy("copy_dartdev_kernel") {
+  visibility = [ ":dartdev" ]
+  public_deps = [ ":generate_dartdev_kernel" ]
+  sources = [ "$root_gen_dir/dartdev.dill" ]
+  outputs = [ "$root_out_dir/dartdev.dill" ]
+}
+
+application_snapshot("generate_dartdev_kernel") {
+  dart_snapshot_kind = "kernel"
+  main_dart = "../../pkg/dartdev/bin/dartdev.dart"
+  training_args = []
+  deps = [ "../dds:dds" ]
+  vm_args = [ "--sound-null-safety" ]
+  output = "$root_gen_dir/dartdev.dill"
+}
+
 copy("copy_dartdev_snapshot") {
   visibility = [ ":dartdev" ]
   public_deps = [ ":generate_dartdev_snapshot" ]