pkg/vm/lib/transformations/protobuf_aware_treeshaker/transformer.dart - sdk.git - Git at Google

 // Copyright (c) 2019, 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 'package:kernel/kernel.dart';
 import 'package:kernel/target/targets.dart';
 import 'package:kernel/core_types.dart';
 import 'package:meta/meta.dart';
 import 'package:vm/transformations/type_flow/transformer.dart' as globalTypeFlow
     show transformComponent;
 import 'package:vm/transformations/no_dynamic_invocations_annotator.dart'
     show Selector;

 class TransformationInfo {
   final List<String> removedMessageFields = <String>[];
   final List<Class> removedMessageClasses = <Class>[];
 }

 TransformationInfo transformComponent(
     Component component, Map<String, String> environment, Target target,
     {@required bool collectInfo}) {
   final coreTypes = new CoreTypes(component);

   TransformationInfo info = collectInfo ? TransformationInfo() : null;

   _treeshakeProtos(target, component, coreTypes, info);
   return info;
 }

 void _treeshakeProtos(Target target, Component component, CoreTypes coreTypes,
     TransformationInfo info) {
   globalTypeFlow.transformComponent(target, coreTypes, component,
       treeShakeSignatures: false);

   final collector = removeUnusedProtoReferences(component, coreTypes, info);
   if (collector != null) {
     globalTypeFlow.transformComponent(target, coreTypes, component,
         treeShakeSignatures: false);
     if (info != null) {
       for (Class gmSubclass in collector.gmSubclasses) {
         if (!gmSubclass.enclosingLibrary.classes.contains(gmSubclass)) {
           info.removedMessageClasses.add(gmSubclass);
         }
       }
     }
   }

   // Remove metadata added by the typeflow analysis (even if the code doesn't
   // use any protos).
   component.metadata.clear();
 }

 InfoCollector removeUnusedProtoReferences(
     Component component, CoreTypes coreTypes, TransformationInfo info) {
   final protobufUri = Uri.parse('package:protobuf/protobuf.dart');
   final protobufLibs =
       component.libraries.where((lib) => lib.importUri == protobufUri);
   if (protobufLibs.isEmpty) {
     return null;
   }
   final protobufLib = protobufLibs.single;

   final gmClass = protobufLib.classes
       .where((klass) => klass.name == 'GeneratedMessage')
       .single;
   final tagNumberClass =
       protobufLib.classes.where((klass) => klass.name == 'TagNumber').single;

   final collector = InfoCollector(gmClass);

   final biClass =
       protobufLib.classes.where((klass) => klass.name == 'BuilderInfo').single;
   final addMethod =
       biClass.members.singleWhere((Member member) => member.name.text == 'add');

   component.accept(collector);

   _UnusedFieldMetadataPruner(tagNumberClass, biClass, addMethod,
           collector.dynamicSelectors, coreTypes, info)
       .removeMetadataForUnusedFields(
     collector.gmSubclasses,
     collector.gmSubclassesInvokedMethods,
     coreTypes,
     info,
   );

   return collector;
 }

 /// For protobuf fields which are not accessed, prune away its metadata.
 class _UnusedFieldMetadataPruner extends TreeVisitor<void> {
   final Class tagNumberClass;
   final Reference tagNumberField;
   // All of those methods have the dart field name as second positional
   // parameter.
   // Method names are defined in:
   // https://github.com/dart-lang/protobuf/blob/master/protobuf/lib/src/protobuf/builder_info.dart
   // The code is generated by:
   // https://github.com/dart-lang/protobuf/blob/master/protoc_plugin/lib/protobuf_field.dart.
   static final fieldAddingMethods = Set<String>.from(const <String>[
     'a',
     'aOM',
     'aOS',
     'aQM',
     'pPS',
     'aQS',
     'aInt64',
     'aOB',
     'e',
     'p',
     'pc',
     'm',
   ]);

   final Class builderInfoClass;
   Class visitedClass;
   final names = Set<String>();
   final usedTagNumbers = Set<int>();

   final dynamicNames = Set<String>();
   final CoreTypes coreTypes;
   final TransformationInfo info;
   final Member addMethod;

   _UnusedFieldMetadataPruner(this.tagNumberClass, this.builderInfoClass,
       this.addMethod, Set<Selector> dynamicSelectors, this.coreTypes, this.info)
       : tagNumberField = tagNumberClass.fields
             .firstWhere((f) => f.name.text == 'tagNumber')
             .getterReference {
     dynamicNames.addAll(dynamicSelectors.map((sel) => sel.target.text));
   }

   /// If a proto message field is never accessed (neither read nor written to),
   /// remove its corresponding metadata in the construction of the Message._i
   /// field (i.e. the BuilderInfo metadata).
   void removeMetadataForUnusedFields(
       Set<Class> gmSubclasses,
       Map<Class, Set<Selector>> invokedMethods,
       CoreTypes coreTypes,
       TransformationInfo info) {
     for (final klass in gmSubclasses) {
       final selectors = invokedMethods[klass] ?? Set<Selector>();
       final builderInfoFields = klass.fields.where((f) => f.name.text == '_i');
       if (builderInfoFields.isEmpty) {
         continue;
       }
       final builderInfoField = builderInfoFields.single;
       _pruneBuilderInfoField(builderInfoField, selectors, klass);
     }
   }

   void _pruneBuilderInfoField(
       Field field, Set<Selector> selectors, Class gmSubclass) {
     names.clear();
     names.addAll(selectors.map((sel) => sel.target.text));
     visitedClass = gmSubclass;
     _computeUsedTagNumbers(gmSubclass);
     field.initializer.accept(this);
   }

   void _computeUsedTagNumbers(Class gmSubclass) {
     usedTagNumbers.clear();
     for (final procedure in gmSubclass.procedures) {
       for (final annotation in procedure.annotations) {
         if (annotation is ConstantExpression) {
           final constant = annotation.constant;
           if (constant is InstanceConstant &&
               constant.classReference == tagNumberClass.reference) {
             final name = procedure.name.text;
             if (dynamicNames.contains(name) || names.contains(name)) {
               usedTagNumbers.add(
                   (constant.fieldValues[tagNumberField] as IntConstant).value);
             }
           }
         }
       }
     }
   }

   @override
   visitBlockExpression(BlockExpression node) {
     // The BuilderInfo field `_i` is set up with a row of cascaded calls.
     // ```
     // static final BuilderInfo _i = BuilderInfo('MessageName')
     //     ..a(1, 'foo', PbFieldType.OM)
     //     ..a(2, 'bar', PbFieldType.OM)
     // ```
     // Each cascaded call will be represented in kernel as an entry in a
     // BlockExpression (but starts out in a Let), where each statement in block
     // is an ExpressionStatement, and where each statement will be a call to a
     // method of `builderInfo`.
     // For example:
     // ```
     // {protobuf::BuilderInfo::a}<dart.core::int*>(1, "foo", #C10)
     // ```
     // The methods enumerated in `fieldAddingMethods` are the ones that set up
     // fields (other methods do other things).
     //
     // First argument is the tag-number of the added field.
     // Second argument is the field-name.
     // Further arguments are specific to the method.
     for (Statement statement in node.body.statements) {
       if (statement is ExpressionStatement) {
         _changeCascadeEntry(statement.expression);
       }
     }
     node.body.accept(this);
   }

   @override
   visitLet(Let node) {
     // See comment in visitBlockExpression.
     node.body.accept(this);
   }

   void _changeCascadeEntry(Expression initializer) {
     if (initializer is MethodInvocation &&
         initializer.interfaceTarget?.enclosingClass == builderInfoClass &&
         fieldAddingMethods.contains(initializer.name.text)) {
       final tagNumber =
           (initializer.arguments.positional[0] as IntLiteral).value;
       if (!usedTagNumbers.contains(tagNumber)) {
         if (info != null) {
           final fieldName =
               (initializer.arguments.positional[1] as StringLiteral).value;
           info.removedMessageFields.add("${visitedClass.name}.$fieldName");
         }

         // Replace the field metadata method with a dummy call to
         // `BuilderInfo.add`. This is to preserve the index calculations when
         // removing a field.
         // Change the tag-number to 0. Otherwise the decoder will get confused.
         initializer.interfaceTarget = addMethod;
         initializer.name = addMethod.name;
         initializer.arguments.replaceWith(
           Arguments(
             <Expression>[
               IntLiteral(0), // tagNumber
               NullLiteral(), // name
               NullLiteral(), // fieldType
               NullLiteral(), // defaultOrMaker
               NullLiteral(), // subBuilder
               NullLiteral(), // valueOf
               NullLiteral(), // enumValues
             ],
             types: <DartType>[const NullType()],
           ),
         );
       }
     }
   }
 }

 /// Finds all subclasses of [GeneratedMessage] and all methods invoked on them
 /// (potentially in a dynamic call).
 class InfoCollector extends RecursiveVisitor<void> {
   final dynamicSelectors = Set<Selector>();
   final Class generatedMessageClass;
   final gmSubclasses = Set<Class>();
   final gmSubclassesInvokedMethods = Map<Class, Set<Selector>>();

   InfoCollector(this.generatedMessageClass);

   @override
   visitClass(Class klass) {
     if (isGeneratedMethodSubclass(klass)) {
       gmSubclasses.add(klass);
     }
     return super.visitClass(klass);
   }

   @override
   visitMethodInvocation(MethodInvocation node) {
     if (node.interfaceTarget == null) {
       dynamicSelectors.add(Selector.doInvoke(node.name));
     }

     final targetClass = node.interfaceTarget?.enclosingClass;
     if (isGeneratedMethodSubclass(targetClass)) {
       addInvokedMethod(targetClass, Selector.doInvoke(node.name));
     }
     super.visitMethodInvocation(node);
   }

   @override
   visitPropertyGet(PropertyGet node) {
     if (node.interfaceTarget == null) {
       dynamicSelectors.add(Selector.doGet(node.name));
     }

     final targetClass = node.interfaceTarget?.enclosingClass;
     if (isGeneratedMethodSubclass(targetClass)) {
       addInvokedMethod(targetClass, Selector.doGet(node.name));
     }
     super.visitPropertyGet(node);
   }

   @override
   visitPropertySet(PropertySet node) {
     if (node.interfaceTarget == null) {
       dynamicSelectors.add(Selector.doSet(node.name));
     }

     final targetClass = node.interfaceTarget?.enclosingClass;
     if (isGeneratedMethodSubclass(targetClass)) {
       addInvokedMethod(targetClass, Selector.doSet(node.name));
     }
     super.visitPropertySet(node);
   }

   bool isGeneratedMethodSubclass(Class klass) {
     return klass?.superclass == generatedMessageClass;
   }

   void addInvokedMethod(Class klass, Selector selector) {
     final selectors =
         gmSubclassesInvokedMethods.putIfAbsent(klass, () => Set<Selector>());
     selectors.add(selector);
   }
 }
	// Copyright (c) 2019, 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 'package:kernel/kernel.dart';
	import 'package:kernel/target/targets.dart';
	import 'package:kernel/core_types.dart';
	import 'package:meta/meta.dart';
	import 'package:vm/transformations/type_flow/transformer.dart' as globalTypeFlow
	show transformComponent;
	import 'package:vm/transformations/no_dynamic_invocations_annotator.dart'
	show Selector;

	class TransformationInfo {
	final List<String> removedMessageFields = <String>[];
	final List<Class> removedMessageClasses = <Class>[];
	}

	TransformationInfo transformComponent(
	Component component, Map<String, String> environment, Target target,
	{@required bool collectInfo}) {
	final coreTypes = new CoreTypes(component);

	TransformationInfo info = collectInfo ? TransformationInfo() : null;

	_treeshakeProtos(target, component, coreTypes, info);
	return info;
	}

	void _treeshakeProtos(Target target, Component component, CoreTypes coreTypes,
	TransformationInfo info) {
	globalTypeFlow.transformComponent(target, coreTypes, component,
	treeShakeSignatures: false);

	final collector = removeUnusedProtoReferences(component, coreTypes, info);
	if (collector != null) {
	globalTypeFlow.transformComponent(target, coreTypes, component,
	treeShakeSignatures: false);
	if (info != null) {
	for (Class gmSubclass in collector.gmSubclasses) {
	if (!gmSubclass.enclosingLibrary.classes.contains(gmSubclass)) {
	info.removedMessageClasses.add(gmSubclass);
	}
	}
	}
	}

	// Remove metadata added by the typeflow analysis (even if the code doesn't
	// use any protos).
	component.metadata.clear();
	}

	InfoCollector removeUnusedProtoReferences(
	Component component, CoreTypes coreTypes, TransformationInfo info) {
	final protobufUri = Uri.parse('package:protobuf/protobuf.dart');
	final protobufLibs =
	component.libraries.where((lib) => lib.importUri == protobufUri);
	if (protobufLibs.isEmpty) {
	return null;
	}
	final protobufLib = protobufLibs.single;

	final gmClass = protobufLib.classes
	.where((klass) => klass.name == 'GeneratedMessage')
	.single;
	final tagNumberClass =
	protobufLib.classes.where((klass) => klass.name == 'TagNumber').single;

	final collector = InfoCollector(gmClass);

	final biClass =
	protobufLib.classes.where((klass) => klass.name == 'BuilderInfo').single;
	final addMethod =
	biClass.members.singleWhere((Member member) => member.name.text == 'add');

	component.accept(collector);

	_UnusedFieldMetadataPruner(tagNumberClass, biClass, addMethod,
	collector.dynamicSelectors, coreTypes, info)
	.removeMetadataForUnusedFields(
	collector.gmSubclasses,
	collector.gmSubclassesInvokedMethods,
	coreTypes,
	info,
	);

	return collector;
	}

	/// For protobuf fields which are not accessed, prune away its metadata.
	class _UnusedFieldMetadataPruner extends TreeVisitor<void> {
	final Class tagNumberClass;
	final Reference tagNumberField;
	// All of those methods have the dart field name as second positional
	// parameter.
	// Method names are defined in:
	// https://github.com/dart-lang/protobuf/blob/master/protobuf/lib/src/protobuf/builder_info.dart
	// The code is generated by:
	// https://github.com/dart-lang/protobuf/blob/master/protoc_plugin/lib/protobuf_field.dart.
	static final fieldAddingMethods = Set<String>.from(const <String>[
	'a',
	'aOM',
	'aOS',
	'aQM',
	'pPS',
	'aQS',
	'aInt64',
	'aOB',
	'e',
	'p',
	'pc',
	'm',
	]);

	final Class builderInfoClass;
	Class visitedClass;
	final names = Set<String>();
	final usedTagNumbers = Set<int>();

	final dynamicNames = Set<String>();
	final CoreTypes coreTypes;
	final TransformationInfo info;
	final Member addMethod;

	_UnusedFieldMetadataPruner(this.tagNumberClass, this.builderInfoClass,
	this.addMethod, Set<Selector> dynamicSelectors, this.coreTypes, this.info)
	: tagNumberField = tagNumberClass.fields
	.firstWhere((f) => f.name.text == 'tagNumber')
	.getterReference {
	dynamicNames.addAll(dynamicSelectors.map((sel) => sel.target.text));
	}

	/// If a proto message field is never accessed (neither read nor written to),
	/// remove its corresponding metadata in the construction of the Message._i
	/// field (i.e. the BuilderInfo metadata).
	void removeMetadataForUnusedFields(
	Set<Class> gmSubclasses,
	Map<Class, Set<Selector>> invokedMethods,
	CoreTypes coreTypes,
	TransformationInfo info) {
	for (final klass in gmSubclasses) {
	final selectors = invokedMethods[klass] ?? Set<Selector>();
	final builderInfoFields = klass.fields.where((f) => f.name.text == '_i');
	if (builderInfoFields.isEmpty) {
	continue;
	}
	final builderInfoField = builderInfoFields.single;
	_pruneBuilderInfoField(builderInfoField, selectors, klass);
	}
	}

	void _pruneBuilderInfoField(
	Field field, Set<Selector> selectors, Class gmSubclass) {
	names.clear();
	names.addAll(selectors.map((sel) => sel.target.text));
	visitedClass = gmSubclass;
	_computeUsedTagNumbers(gmSubclass);
	field.initializer.accept(this);
	}

	void _computeUsedTagNumbers(Class gmSubclass) {
	usedTagNumbers.clear();
	for (final procedure in gmSubclass.procedures) {
	for (final annotation in procedure.annotations) {
	if (annotation is ConstantExpression) {
	final constant = annotation.constant;
	if (constant is InstanceConstant &&
	constant.classReference == tagNumberClass.reference) {
	final name = procedure.name.text;
	if (dynamicNames.contains(name) \|\| names.contains(name)) {
	usedTagNumbers.add(
	(constant.fieldValues[tagNumberField] as IntConstant).value);
	}
	}
	}
	}
	}
	}

	@override
	visitBlockExpression(BlockExpression node) {
	// The BuilderInfo field `_i` is set up with a row of cascaded calls.
	// ```
	// static final BuilderInfo _i = BuilderInfo('MessageName')
	// ..a(1, 'foo', PbFieldType.OM)
	// ..a(2, 'bar', PbFieldType.OM)
	// ```
	// Each cascaded call will be represented in kernel as an entry in a
	// BlockExpression (but starts out in a Let), where each statement in block
	// is an ExpressionStatement, and where each statement will be a call to a
	// method of `builderInfo`.
	// For example:
	// ```
	// {protobuf::BuilderInfo::a}<dart.core::int*>(1, "foo", #C10)
	// ```
	// The methods enumerated in `fieldAddingMethods` are the ones that set up
	// fields (other methods do other things).
	//
	// First argument is the tag-number of the added field.
	// Second argument is the field-name.
	// Further arguments are specific to the method.
	for (Statement statement in node.body.statements) {
	if (statement is ExpressionStatement) {
	_changeCascadeEntry(statement.expression);
	}
	}
	node.body.accept(this);
	}

	@override
	visitLet(Let node) {
	// See comment in visitBlockExpression.
	node.body.accept(this);
	}

	void _changeCascadeEntry(Expression initializer) {
	if (initializer is MethodInvocation &&
	initializer.interfaceTarget?.enclosingClass == builderInfoClass &&
	fieldAddingMethods.contains(initializer.name.text)) {
	final tagNumber =
	(initializer.arguments.positional[0] as IntLiteral).value;
	if (!usedTagNumbers.contains(tagNumber)) {
	if (info != null) {
	final fieldName =
	(initializer.arguments.positional[1] as StringLiteral).value;
	info.removedMessageFields.add("${visitedClass.name}.$fieldName");
	}

	// Replace the field metadata method with a dummy call to
	// `BuilderInfo.add`. This is to preserve the index calculations when
	// removing a field.
	// Change the tag-number to 0. Otherwise the decoder will get confused.
	initializer.interfaceTarget = addMethod;
	initializer.name = addMethod.name;
	initializer.arguments.replaceWith(
	Arguments(
	<Expression>[
	IntLiteral(0), // tagNumber
	NullLiteral(), // name
	NullLiteral(), // fieldType
	NullLiteral(), // defaultOrMaker
	NullLiteral(), // subBuilder
	NullLiteral(), // valueOf
	NullLiteral(), // enumValues
	],
	types: <DartType>[const NullType()],
	),
	);
	}
	}
	}
	}

	/// Finds all subclasses of [GeneratedMessage] and all methods invoked on them
	/// (potentially in a dynamic call).
	class InfoCollector extends RecursiveVisitor<void> {
	final dynamicSelectors = Set<Selector>();
	final Class generatedMessageClass;
	final gmSubclasses = Set<Class>();
	final gmSubclassesInvokedMethods = Map<Class, Set<Selector>>();

	InfoCollector(this.generatedMessageClass);

	@override
	visitClass(Class klass) {
	if (isGeneratedMethodSubclass(klass)) {
	gmSubclasses.add(klass);
	}
	return super.visitClass(klass);
	}

	@override
	visitMethodInvocation(MethodInvocation node) {
	if (node.interfaceTarget == null) {
	dynamicSelectors.add(Selector.doInvoke(node.name));
	}

	final targetClass = node.interfaceTarget?.enclosingClass;
	if (isGeneratedMethodSubclass(targetClass)) {
	addInvokedMethod(targetClass, Selector.doInvoke(node.name));
	}
	super.visitMethodInvocation(node);
	}

	@override
	visitPropertyGet(PropertyGet node) {
	if (node.interfaceTarget == null) {
	dynamicSelectors.add(Selector.doGet(node.name));
	}

	final targetClass = node.interfaceTarget?.enclosingClass;
	if (isGeneratedMethodSubclass(targetClass)) {
	addInvokedMethod(targetClass, Selector.doGet(node.name));
	}
	super.visitPropertyGet(node);
	}

	@override
	visitPropertySet(PropertySet node) {
	if (node.interfaceTarget == null) {
	dynamicSelectors.add(Selector.doSet(node.name));
	}

	final targetClass = node.interfaceTarget?.enclosingClass;
	if (isGeneratedMethodSubclass(targetClass)) {
	addInvokedMethod(targetClass, Selector.doSet(node.name));
	}
	super.visitPropertySet(node);
	}

	bool isGeneratedMethodSubclass(Class klass) {
	return klass?.superclass == generatedMessageClass;
	}

	void addInvokedMethod(Class klass, Selector selector) {
	final selectors =
	gmSubclassesInvokedMethods.putIfAbsent(klass, () => Set<Selector>());
	selectors.add(selector);
	}
	}