Add DAS AOT snapshot to SDK; can toggle with runtime dartdev flag

Change-Id: Idbef46ca62045022458d6d951f301ff4d6895cfe
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/424342
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Commit-Queue: Samuel Rawlins <srawlins@google.com>

pkg/dartdev/lib/src/commands/language_server.dart

@@ -35,7 +35,8 @@ For more information about the server's capabilities and configuration, see:
       usageLineLength: dartdevUsageLineLength,
       includeHelpFlag: false,
       defaultToLsp: true,
-    );
+    )..addFlag(_useAotSnapshotFlag,
+        help: 'Use the AOT analysis server snapshot', hide: true);
   }
 
   @override
@@ -48,12 +49,20 @@ For more information about the server's capabilities and configuration, see:
       args = [...args, '--$protocol=$lsp'];
     }
     try {
-      VmInteropHandler.run(
-        sdk.analysisServerSnapshot,
-        args,
-        packageConfigOverride: null,
-        useExecProcess: false,
-      );
+      if (argResults!.flag(_useAotSnapshotFlag)) {
+        args.remove('--$_useAotSnapshotFlag');
+        VmInteropHandler.run(
+          sdk.dartAotRuntime,
+          [sdk.analysisServerAotSnapshot, ...args],
+          useExecProcess: true,
+        );
+      } else {
+        VmInteropHandler.run(
+          sdk.analysisServerSnapshot,
+          args,
+          useExecProcess: false,
+        );
+      }
       return 0;
     } catch (e, st) {
       log.stderr('Error: launching language analysis server failed');
@@ -64,4 +73,6 @@ For more information about the server's capabilities and configuration, see:
       return 255;
     }
   }
+
+  static const _useAotSnapshotFlag = 'use-aot-snapshot';
 }

pkg/dartdev/lib/src/sdk.dart

@@ -66,6 +66,10 @@ class Sdk {
           Platform.isWindows ? 'dartaotruntime.exe' : 'dartaotruntime',
         );
 
+  String get analysisServerAotSnapshot => _snapshotPathFor(
+        'analysis_server_aot.dart.snapshot',
+      );
+
   String get analysisServerSnapshot => _snapshotPathFor(
         'analysis_server.dart.snapshot',
       );

sdk/BUILD.gn

@@ -130,6 +130,11 @@ _platform_sdk_snapshots = [
 ]
 if (dart_target_arch != "ia32" && dart_target_arch != "x86") {
   _platform_sdk_snapshots += [
+    [
+      "analysis_server_aot_product",
+      "../utils/analysis_server:analysis_server_aot_product",
+      "analysis_server_aot",
+    ],
     [
       "frontend_server_aot_product",
       "../utils/kernel-service:frontend_server_aot_product",