[vm] Add tests verifying AMA assumptions

See go/dart-ama

TEST=vm/cc/AMA_Test

Change-Id: If593825b7505fb8ab8ef7a74567523f43489f9be
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/304960
Reviewed-by: Slava Egorov <vegorov@google.com>
Commit-Queue: Martin Kustermann <kustermann@google.com>

runtime/tests/vm/dart/ama_test.dart

@@ -0,0 +1,69 @@
+// Copyright (c) 2023, 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:expect/expect.dart';
+import 'package:native_stack_traces/elf.dart';
+import 'package:path/path.dart' as path;
+
+import 'use_flag_test_helper.dart';
+
+main(List<String> args) async {
+  if (!isAOTRuntime) {
+    print('Skipping test due to AOT runtime not being available');
+    return; // Running in JIT: AOT binaries not available.
+  }
+
+  if (Platform.isAndroid) {
+    print('Skipping test due to being on Android where needed tools are not '
+        'available.');
+    return; // SDK tree and gen_snapshot not available on the test device.
+  }
+
+  // These are the tools we need to be available to run on a given platform:
+  if (!await testExecutable(genSnapshot)) {
+    throw "Cannot run test as $genSnapshot not available";
+  }
+  if (!await testExecutable(dartPrecompiledRuntime)) {
+    throw "Cannot run test as $dartPrecompiledRuntime not available";
+  }
+  if (!File(platformDill).existsSync()) {
+    throw "Cannot run test as $platformDill does not exist";
+  }
+
+  await withElfSnapshot((Elf elf) {
+    // NOTE: These tests validate properties we should strive to maintain.
+    // Please reach out to go/dart-ama before changing them.
+    final Symbol? symbol =
+        elf.dynamicSymbolFor('_kDartIsolateSnapshotInstructions');
+    Expect.isTrue(symbol != null && symbol.value > 0);
+  });
+}
+
+Future withElfSnapshot(Function(Elf) fun) async {
+  await withTempDir('ama-test', (String tempDir) async {
+    final scriptDart = path.join(tempDir, 'script.dart');
+    final scriptDill = path.join(tempDir, 'script.dill');
+    final scriptElf = path.join(tempDir, 'script.elf');
+    File(scriptDart).writeAsStringSync('main() => print("script");');
+
+    await run(genKernel, <String>[
+      '--aot',
+      '--platform=$platformDill',
+      '-o',
+      scriptDill,
+      scriptDart,
+    ]);
+
+    await run(genSnapshot, <String>[
+      '--snapshot-kind=app-aot-elf',
+      '--elf=$scriptElf',
+      scriptDill,
+    ]);
+
+    final elf = Elf.fromFile(scriptElf)!;
+    await fun(elf);
+  });
+}

runtime/vm/ama_test.cc

@@ -0,0 +1,26 @@
+// Copyright (c) 2023, 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.
+
+#include "platform/assert.h"
+#include "platform/globals.h"
+
+#include "include/dart_api.h"
+
+#include "vm/constants.h"
+#include "vm/unit_test.h"
+
+namespace dart {
+
+TEST_CASE(AMA_Test) {
+  // NOTE: These are expectations we should strive to maintain. Please reach out
+  // to go/dart-ama before changing them.
+#if defined(TARGET_ARCH_ARM64)
+  COMPILE_ASSERT(R27 == PP);
+  COMPILE_ASSERT(R15 == SPREG);
+  COMPILE_ASSERT(R26 == THR);
+  COMPILE_ASSERT(R21 == DISPATCH_TABLE_REG);
+#endif
+}
+
+}  // namespace dart

runtime/vm/vm_sources.gni

@@ -385,6 +385,7 @@ vm_sources = [
 
 vm_sources_tests = [
   "allocation_test.cc",
+  "ama_test.cc",
   "assert_test.cc",
   "atomic_test.cc",
   "base64_test.cc",