[vm/bytecode] Add versioning to bytecode format

Change-Id: I35d86aec17aa0f6894a6380e4bb5ac7ca3092fac
Reviewed-on: https://dart-review.googlesource.com/c/80522
Reviewed-by: Zach Anderson <zra@google.com>
Reviewed-by: Régis Crelier <regis@google.com>
Commit-Queue: Alexander Markov <alexmarkov@google.com>

Author: alexmarkov

pkg/vm/bin/gen_kernel.dart

@@ -45,7 +45,9 @@ final ArgParser _argParser = new ArgParser(allowTrailingOptions: true)
       defaultsTo: true)
   ..addFlag('gen-bytecode', help: 'Generate bytecode', defaultsTo: false)
   ..addFlag('drop-ast',
-      help: 'Drop AST for members with bytecode', defaultsTo: false);
+      help: 'Drop AST for members with bytecode', defaultsTo: false)
+  ..addFlag('use-future-bytecode-format',
+      help: 'Generate bytecode in the bleeding edge format', defaultsTo: false);
 
 final String _usage = '''
 Usage: dart pkg/vm/bin/gen_kernel.dart --platform vm_platform_strong.dill [options] input.dart
@@ -82,6 +84,7 @@ Future<int> compile(List<String> arguments) async {
   final bool tfa = options['tfa'];
   final bool genBytecode = options['gen-bytecode'];
   final bool dropAST = options['drop-ast'];
+  final bool useFutureBytecodeFormat = options['use-future-bytecode-format'];
   final bool enableAsserts = options['enable-asserts'];
   final bool enableConstantEvaluation = options['enable-constant-evaluation'];
   final Map<String, String> environmentDefines = {};
@@ -114,6 +117,7 @@ Future<int> compile(List<String> arguments) async {
       environmentDefines: environmentDefines,
       genBytecode: genBytecode,
       dropAST: dropAST,
+      useFutureBytecodeFormat: useFutureBytecodeFormat,
       enableAsserts: enableAsserts,
       enableConstantEvaluation: enableConstantEvaluation);
 

pkg/vm/lib/bytecode/dbc.dart

@@ -6,6 +6,19 @@
 
 library vm.bytecode.dbc;
 
+/// Version of stable bytecode format, produced by default.
+/// Before bumping stable bytecode version format, make sure that
+/// all users have switched to a VM which is able to consume next
+/// version of bytecode.
+const int stableBytecodeFormatVersion = 1;
+
+/// Version of bleeding edge bytecode format.
+/// Produced by bytecode generator when --use-future-bytecode-format
+/// option is enabled.
+/// Should match kMaxSupportedBytecodeFormatVersion in
+/// runtime/vm/constants_kbc.h.
+const int futureBytecodeFormatVersion = stableBytecodeFormatVersion + 1;
+
 enum Opcode {
   kTrap,
 

pkg/vm/lib/bytecode/gen_bytecode.dart

@@ -39,6 +39,7 @@ const String symbolForTypeCast = ' in type cast';
 void generateBytecode(Component component,
     {bool dropAST: false,
     bool omitSourcePositions: false,
+    bool useFutureBytecodeFormat: false,
     Map<String, String> environmentDefines,
     ErrorReporter errorReporter}) {
   final coreTypes = new CoreTypes(component);
@@ -50,8 +51,15 @@ void generateBytecode(Component component,
   final constantsBackend =
       new VmConstantsBackend(environmentDefines, coreTypes);
   final errorReporter = new ForwardConstantEvaluationErrors(typeEnvironment);
-  new BytecodeGenerator(component, coreTypes, hierarchy, typeEnvironment,
-          constantsBackend, omitSourcePositions, errorReporter)
+  new BytecodeGenerator(
+          component,
+          coreTypes,
+          hierarchy,
+          typeEnvironment,
+          constantsBackend,
+          omitSourcePositions,
+          useFutureBytecodeFormat,
+          errorReporter)
       .visitComponent(component);
   if (dropAST) {
     new DropAST().visitComponent(component);
@@ -65,6 +73,7 @@ class BytecodeGenerator extends RecursiveVisitor<Null> {
   final TypeEnvironment typeEnvironment;
   final ConstantsBackend constantsBackend;
   final bool omitSourcePositions;
+  final bool useFutureBytecodeFormat;
   final ErrorReporter errorReporter;
   final BytecodeMetadataRepository metadata = new BytecodeMetadataRepository();
   final RecognizedMethods recognizedMethods;
@@ -101,6 +110,7 @@ class BytecodeGenerator extends RecursiveVisitor<Null> {
       this.typeEnvironment,
       this.constantsBackend,
       this.omitSourcePositions,
+      this.useFutureBytecodeFormat,
       this.errorReporter)
       : recognizedMethods = new RecognizedMethods(typeEnvironment) {
     component.addMetadataRepository(metadata);
@@ -750,8 +760,11 @@ class BytecodeGenerator extends RecursiveVisitor<Null> {
 
   void end(Member node) {
     if (!hasErrors) {
-      metadata.mapping[node] = new BytecodeMetadata(
-          cp, asm.bytecode, asm.exceptionsTable, nullableFields, closures);
+      final formatVersion = useFutureBytecodeFormat
+          ? futureBytecodeFormatVersion
+          : stableBytecodeFormatVersion;
+      metadata.mapping[node] = new BytecodeMetadata(formatVersion, cp,
+          asm.bytecode, asm.exceptionsTable, nullableFields, closures);
     }
 
     typeEnvironment.thisType = null;

pkg/vm/lib/kernel_front_end.dart

@@ -49,6 +49,7 @@ Future<Component> compileToKernel(Uri source, CompilerOptions options,
     Map<String, String> environmentDefines,
     bool genBytecode: false,
     bool dropAST: false,
+    bool useFutureBytecodeFormat: false,
     bool enableAsserts: false,
     bool enableConstantEvaluation: true}) async {
   // Replace error handler to detect if there are compilation errors.
@@ -91,7 +92,9 @@ Future<Component> compileToKernel(Uri source, CompilerOptions options,
   if (genBytecode && !errorDetector.hasCompilationErrors && component != null) {
     await runWithFrontEndCompilerContext(source, options, component, () {
       generateBytecode(component,
-          dropAST: dropAST, environmentDefines: environmentDefines);
+          dropAST: dropAST,
+          useFutureBytecodeFormat: useFutureBytecodeFormat,
+          environmentDefines: environmentDefines);
     });
   }
 

pkg/vm/lib/metadata/bytecode.dart

@@ -6,6 +6,8 @@ library vm.metadata.bytecode;
 
 import 'package:kernel/ast.dart';
 import '../bytecode/constant_pool.dart' show ConstantPool;
+import '../bytecode/dbc.dart'
+    show stableBytecodeFormatVersion, futureBytecodeFormatVersion;
 import '../bytecode/disassembler.dart' show BytecodeDisassembler;
 import '../bytecode/exceptions.dart' show ExceptionsTable;
 
@@ -14,6 +16,7 @@ import '../bytecode/exceptions.dart' show ExceptionsTable;
 /// In kernel binary, bytecode metadata is encoded as following:
 ///
 /// type BytecodeMetadata {
+///   UInt bytecodeFormatVersion
 ///   UInt flags (HasExceptionsTable, HasNullableFields, HasClosures)
 ///
 ///   ConstantPool constantPool
@@ -46,6 +49,7 @@ class BytecodeMetadata {
   static const hasNullableFieldsFlag = 1 << 1;
   static const hasClosuresFlag = 1 << 2;
 
+  final int version;
   final ConstantPool constantPool;
   final List<int> bytecodes;
   final ExceptionsTable exceptionsTable;
@@ -61,13 +65,16 @@ class BytecodeMetadata {
       (hasNullableFields ? hasNullableFieldsFlag : 0) |
       (hasClosures ? hasClosuresFlag : 0);
 
-  BytecodeMetadata(this.constantPool, this.bytecodes, this.exceptionsTable,
-      this.nullableFields, this.closures);
+  BytecodeMetadata(this.version, this.constantPool, this.bytecodes,
+      this.exceptionsTable, this.nullableFields, this.closures);
 
   // TODO(alexmarkov): Consider printing constant pool before bytecode.
   @override
   String toString() => "\n"
-      "Bytecode {\n"
+      "Bytecode"
+      " (version: "
+      "${version == stableBytecodeFormatVersion ? 'stable' : version == futureBytecodeFormatVersion ? 'future' : "v$version"}"
+      ") {\n"
       "${new BytecodeDisassembler().disassemble(bytecodes, exceptionsTable)}}\n"
       "$exceptionsTable"
       "${nullableFields.isEmpty ? '' : 'Nullable fields: ${nullableFields.map((ref) => ref.asField).toList()}\n'}"
@@ -121,6 +128,7 @@ class BytecodeMetadataRepository extends MetadataRepository<BytecodeMetadata> {
 
   @override
   void writeToBinary(BytecodeMetadata metadata, Node node, BinarySink sink) {
+    sink.writeUInt30(metadata.version);
     sink.writeUInt30(metadata.flags);
     metadata.constantPool.writeToBinary(node, sink);
     sink.writeByteList(metadata.bytecodes);
@@ -140,6 +148,11 @@ class BytecodeMetadataRepository extends MetadataRepository<BytecodeMetadata> {
 
   @override
   BytecodeMetadata readFromBinary(Node node, BinarySource source) {
+    int version = source.readUInt();
+    if (version != stableBytecodeFormatVersion &&
+        version != futureBytecodeFormatVersion) {
+      throw 'Error: unexpected bytecode version $version';
+    }
     int flags = source.readUInt();
     final ConstantPool constantPool =
         new ConstantPool.readFromBinary(node, source);
@@ -158,7 +171,7 @@ class BytecodeMetadataRepository extends MetadataRepository<BytecodeMetadata> {
             ? new List<ClosureBytecode>.generate(source.readUInt(),
                 (_) => new ClosureBytecode.readFromBinary(source))
             : const <ClosureBytecode>[];
-    return new BytecodeMetadata(
-        constantPool, bytecodes, exceptionsTable, nullableFields, closures);
+    return new BytecodeMetadata(version, constantPool, bytecodes,
+        exceptionsTable, nullableFields, closures);
   }
 }

pkg/vm/testcases/bytecode/asserts.dart.expect

@@ -3,7 +3,7 @@ import self as self;
 import "dart:core" as core;
 
 [@vm.bytecode=
-Bytecode {
+Bytecode (version: stable) {
   Entry                0
   CheckStack
   JumpIfNoAsserts      L1
@@ -28,7 +28,7 @@ ConstantPool {
   assert(condition);
 }
 [@vm.bytecode=
-Bytecode {
+Bytecode (version: stable) {
   Entry                0
   CheckStack
   JumpIfNoAsserts      L1
@@ -58,7 +58,7 @@ ConstantPool {
   assert([@vm.call-site-attributes.metadata=receiverType:() → dart.core::bool] condition.call(), [@vm.call-site-attributes.metadata=receiverType:() → dart.core::String] message.call());
 }
 [@vm.bytecode=
-Bytecode {
+Bytecode (version: stable) {
   Entry                0
   CheckStack
   PushNull

pkg/vm/testcases/bytecode/async.dart.expect

@@ -4,7 +4,7 @@ import "dart:async" as asy;
 import "dart:core" as core;
 
 [@vm.bytecode=
-Bytecode {
+Bytecode (version: stable) {
   Entry                3
   CheckStack
   Allocate             CP#19
@@ -276,7 +276,7 @@ Closure CP#0 {
   return :async_completer.{asy::Completer::future};
 };
 [@vm.bytecode=
-Bytecode {
+Bytecode (version: stable) {
   Entry                7
   CheckStack
   AllocateContext      4
@@ -463,7 +463,7 @@ L1:
   return :async_completer.{asy::Completer::future};
 }
 [@vm.bytecode=
-Bytecode {
+Bytecode (version: stable) {
   Entry                4
   CheckStack
   AllocateContext      11
@@ -746,7 +746,7 @@ L1:
   return :async_completer.{asy::Completer::future};
 }
 [@vm.bytecode=
-Bytecode {
+Bytecode (version: stable) {
   Entry                4
   CheckStack
   AllocateContext      11
@@ -1165,7 +1165,7 @@ L1:
   return :async_completer.{asy::Completer::future};
 }
 [@vm.bytecode=
-Bytecode {
+Bytecode (version: stable) {
   Entry                4
   CheckStack
   AllocateContext      16
@@ -1818,7 +1818,7 @@ L1:
   return :async_completer.{asy::Completer::future};
 }
 [@vm.bytecode=
-Bytecode {
+Bytecode (version: stable) {
   Entry                4
   CheckStack
   AllocateContext      2
@@ -2204,7 +2204,7 @@ Closure CP#0 {
   return nested;
 }
 [@vm.bytecode=
-Bytecode {
+Bytecode (version: stable) {
   Entry                4
   CheckStack
   AllocateContext      9
@@ -2460,7 +2460,7 @@ L1:
   return :async_completer.{asy::Completer::future};
 }
 [@vm.bytecode=
-Bytecode {
+Bytecode (version: stable) {
   Entry                0
   CheckStack
   PushNull