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[dart2wasm] Specialize callback wrappers.

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Change-Id: I25dd953af21b14f64d9a61fbf51095a74a800e33
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/273080
Reviewed-by: Srujan Gaddam <srujzs@google.com>
Commit-Queue: Joshua Litt <joshualitt@google.com>
This commit is contained in:
Joshua Litt 2023-01-20 01:08:51 +00:00 committed by Commit Queue
parent ae5dc9e2a9
commit d844eee251
3 changed files with 219 additions and 174 deletions
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30
pkg/dart2wasm/lib/js_runtime_blob.dart
View file

@ -71,6 +71,12 @@ export const instantiate = async (modulePromise, importObjectPromise) => {
// A special symbol attached to functions that wrap Dart functions.
const jsWrappedDartFunctionSymbol = Symbol("JSWrappedDartFunction");
function finalizeWrapper(dartFunction, wrapped) {
wrapped.dartFunction = dartFunction;
wrapped[jsWrappedDartFunctionSymbol] = true;
return wrapped;
}
// Calls a constructor with a variable number of arguments.
function callConstructorVarArgs(constructor, args) {
// Apply bind to the constructor. We pass `null` as the first argument
@ -157,30 +163,6 @@ export const instantiate = async (modulePromise, importObjectPromise) => {
},
stringFromDartString: stringFromDartString,
stringToDartString: stringToDartString,
wrapDartFunction: function(dartFunction, exportFunctionName, argCount) {
const wrapped = function (...args) {
// Compute the last defined argument so we can support default
// arguments in callbacks.
var lastDefinedArg = -1;
for (var i = args.length - 1; i >= 0; i--) {
if (args[i] !== undefined) {
lastDefinedArg = i;
break;
}
}
// Pad `undefined` for optional arguments that aren't passed so
// that the trampoline can replace these values with defaults.
while (args.length < argCount) {
args.push(undefined);
}
return dartInstance.exports[`${exportFunctionName}`](
dartFunction, lastDefinedArg, ...args.map(dartInstance.exports.$dartifyRaw));
};
wrapped.dartFunction = dartFunction;
wrapped[jsWrappedDartFunctionSymbol] = true;
return wrapped;
},
objectLength: function(o) {
return o.length;
},

318
pkg/dart2wasm/lib/js_runtime_generator.dart
View file

@ -16,6 +16,8 @@ import 'package:kernel/class_hierarchy.dart';
import 'package:kernel/core_types.dart';
import 'package:kernel/type_environment.dart';
enum _AnnotationType { import, export }
enum _MethodType {
jsObjectLiteralConstructor,
constructor,
@ -24,6 +26,9 @@ enum _MethodType {
setter,
}
bool parametersNeedParens(List<String> parameters) =>
parameters.isEmpty || parameters.length > 1;
class _MethodLoweringConfig {
final Procedure procedure;
final _MethodType type;
@ -47,7 +52,6 @@ class _MethodLoweringConfig {
String callArguments;
String functionParameters;
String object;
bool argumentsNeedParens = parameters.isEmpty || parameters.length > 1;
if (isConstructor) {
object = '';
callArguments = parameters.join(',');
@ -86,7 +90,7 @@ class _MethodLoweringConfig {
bodyString = '$object.$jsString = $callArguments';
break;
}
if (argumentsNeedParens) {
if (parametersNeedParens(parameters)) {
return '($functionParameters) => $bodyString';
} else {
return '$functionParameters => $bodyString';
@ -95,10 +99,10 @@ class _MethodLoweringConfig {
}
/// Lowers static interop to JS, generating specialized JS methods as required.
/// TODO(joshualitt): Generate specialized JS callback trampolines.
class _JSLowerer extends Transformer {
final Procedure _dartifyRawTarget;
final Procedure _jsifyRawTarget;
final Procedure _isDartFunctionWrappedTarget;
final Procedure _wrapDartFunctionTarget;
final Procedure _allowInteropTarget;
final Procedure _numToInt;
@ -110,7 +114,7 @@ class _JSLowerer extends Transformer {
// _MethodLoweringConfigs until after we run the TFA, and then only generating
// js methods for the dart stubs that remain.
final List<String> jsMethods = [];
int _jsTrampolineN = 1;
int _methodN = 1;
late Library _library;
late String _libraryJSString;
@ -123,6 +127,8 @@ class _JSLowerer extends Transformer {
.getTopLevelProcedure('dart:_js_helper', 'dartifyRaw'),
_jsifyRawTarget = _coreTypes.index
.getTopLevelProcedure('dart:_js_helper', 'jsifyRaw'),
_isDartFunctionWrappedTarget = _coreTypes.index
.getTopLevelProcedure('dart:_js_helper', '_isDartFunctionWrapped'),
_wrapDartFunctionTarget = _coreTypes.index
.getTopLevelProcedure('dart:_js_helper', '_wrapDartFunction'),
_allowInteropTarget =
@ -162,7 +168,7 @@ class _JSLowerer extends Transformer {
}
@override
StaticInvocation visitStaticInvocation(StaticInvocation node) {
Expression visitStaticInvocation(StaticInvocation node) {
node = super.visitStaticInvocation(node) as StaticInvocation;
if (node.target == _allowInteropTarget) {
Expression argument = node.arguments.positional.single;
@ -271,8 +277,9 @@ class _JSLowerer extends Transformer {
return _extensionMemberIndex!;
}
DartType get _nullableObjectType =>
_coreTypes.objectRawType(Nullability.nullable);
// We could generate something more human readable, but for now we just
// generate something short and unique.
String generateMethodName() => '_${_methodN++}';
DartType get _nonNullableObjectType =>
_coreTypes.objectRawType(Nullability.nonNullable);
@ -280,158 +287,229 @@ class _JSLowerer extends Transformer {
DartType get _nullableWasmExternRefType =>
_wasmExternRefClass.getThisType(_coreTypes, Nullability.nullable);
DartType get _nonNullableWasmExternRefType =>
_wasmExternRefClass.getThisType(_coreTypes, Nullability.nonNullable);
Expression _variableCheckConstant(
VariableDeclaration variable, Constant constant) =>
StaticInvocation(_coreTypes.identicalProcedure,
Arguments([VariableGet(variable), ConstantExpression(constant)]));
List<Expression> _generateCallbackArguments(
FunctionType function, List<VariableDeclaration> positionalParameters,
[int? requiredParameterCount]) {
List<Expression> callbackArguments = [];
int length = requiredParameterCount ?? function.positionalParameters.length;
for (int i = 0; i < length; i++) {
callbackArguments.add(AsExpression(VariableGet(positionalParameters[i]),
function.positionalParameters[i]));
Procedure _addInteropProcedure(String name, String pragmaOptionString,
FunctionNode function, Uri fileUri, _AnnotationType type,
{required bool isExternal}) {
String pragmaName;
switch (type) {
case _AnnotationType.import:
pragmaName = 'import';
break;
case _AnnotationType.export:
pragmaName = 'export';
break;
}
return callbackArguments;
final procedure = Procedure(
Name(name, _library), ProcedureKind.Method, function,
isStatic: true, isExternal: isExternal, fileUri: fileUri)
..isNonNullableByDefault = true;
procedure.addAnnotation(
ConstantExpression(InstanceConstant(_pragmaClass.reference, [], {
_pragmaName.fieldReference: StringConstant('wasm:$pragmaName'),
_pragmaOptions.fieldReference: StringConstant('$pragmaOptionString')
})));
_library.addProcedure(procedure);
return procedure;
}
Statement _generateDispatchCase(
FunctionType function,
VariableDeclaration callbackVariable,
List<VariableDeclaration> positionalParameters,
[int? requiredParameterCount]) =>
ReturnStatement(StaticInvocation(
int requiredParameterCount) {
List<Expression> callbackArguments = [];
for (int i = 0; i < requiredParameterCount; i++) {
callbackArguments.add(AsExpression(
StaticInvocation(_dartifyRawTarget,
Arguments([VariableGet(positionalParameters[i])])),
function.positionalParameters[i]));
}
return ReturnStatement(StaticInvocation(
_jsifyRawTarget,
Arguments([
FunctionInvocation(
FunctionAccessKind.FunctionType,
AsExpression(VariableGet(callbackVariable), function),
Arguments(_generateCallbackArguments(
function, positionalParameters, requiredParameterCount)),
Arguments(callbackArguments),
functionType: function),
])));
/// Builds the body of a function trampoline. To support default arguments, we
/// find the last defined argument in JS, that is the last argument which was
/// explicitly passed by the user, and then we dispatch to a Dart function
/// with the right number of arguments.
Statement _createFunctionTrampolineBody(
FunctionType function,
VariableDeclaration callbackVariable,
VariableDeclaration lastDefinedArgument,
List<VariableDeclaration> positionalParameters) {
// Handle cases where some or all arguments are undefined.
// TODO(joshualitt): Consider using a switch instead.
List<Statement> dispatchCases = [];
for (int i = function.requiredParameterCount - 1;
i < function.positionalParameters.length;
i++) {
// In this case, [i] is the last defined argument which can range from
// -1(no arguments defined), to an actual index in the positional
// parameters. [_generateDispatchCase] must also take the required
// parameter count, which is always the index of the last defined argument
// + 1, i.e. the total number of defined arguments.
int requiredParameterCount = i + 1;
dispatchCases.add(IfStatement(
_variableCheckConstant(
lastDefinedArgument, DoubleConstant(i.toDouble())),
_generateDispatchCase(function, callbackVariable,
positionalParameters, requiredParameterCount),
null));
}
// Finally handle the case where all arguments are defined.
dispatchCases.add(_generateDispatchCase(
function, callbackVariable, positionalParameters));
return Block(dispatchCases);
}
bool _needsArgumentsLength(FunctionType type) =>
type.requiredParameterCount < type.positionalParameters.length;
/// Creates a callback trampoline for the given [function]. This callback
/// trampoline expects a Dart callback as its first argument, then an integer
/// value(double type) indicating the position of the last defined argument,
/// followed by all of the arguments to the Dart callback as Dart objects. We
/// will always pad the argument list up to the maximum number of positional
/// arguments with `undefined` values. The trampoline will cast all incoming
/// Dart objects to the appropriate types, dispatch, and then `jsifyRaw` any
/// returned value. [_createFunctionTrampoline] Returns a [String] function
/// name representing the name of the wrapping function.
/// TODO(joshualitt): Share callback trampolines if the [FunctionType]
/// matches.
/// TODO(joshualitt): Simplify the trampoline in JS for the case where there
/// are no default arguments.
/// value(double type) indicating the position of the last defined
/// argument(only for callbacks that take optional parameters), followed by
/// all of the arguments to the Dart callback as JS objects. The trampoline
/// will `dartifyRaw` all incoming JS objects and then cast them to their
/// approriate types, dispatch, and then `jsifyRaw` any returned value.
/// [_createFunctionTrampoline] Returns a [String] function name representing
/// the name of the wrapping function.
String _createFunctionTrampoline(Procedure node, FunctionType function) {
int fileOffset = node.fileOffset;
// Create arguments for each positional parameter in the function. These
// arguments will be converted in JS to Dart objects. The generated wrapper
// will cast each argument to the correct type. The first argument to this
// function will be the Dart callback, which will be cast to the supplied
// [FunctionType] before being invoked. The second argument will be the
// last defined argument which is necessary to support default arguments in
// callbacks.
// arguments will be JS objects. The generated wrapper will cast each
// argument to the correct type. The first argument to this function will
// be the Dart callback, which will be cast to the supplied [FunctionType]
// before being invoked. If the callback takes optional parameters then, the
// second argument will be a `double` indicating the last defined argument.
int parameterId = 1;
final callbackVariable =
VariableDeclaration('callback', type: _nonNullableObjectType);
final lastDefinedArgument = VariableDeclaration('lastDefinedArgument',
VariableDeclaration? argumentsLength;
if (_needsArgumentsLength(function)) {
argumentsLength = VariableDeclaration('argumentsLength',
type: _coreTypes.doubleNonNullableRawType);
}
// Initialize variable declarations.
List<VariableDeclaration> positionalParameters = [];
for (int j = 0; j < function.positionalParameters.length; j++) {
positionalParameters
.add(VariableDeclaration('x$j', type: _nullableObjectType));
positionalParameters.add(VariableDeclaration('x${parameterId++}',
type: _nullableWasmExternRefType));
}
Statement functionTrampolineBody = _createFunctionTrampolineBody(
function, callbackVariable, lastDefinedArgument, positionalParameters);
// Build the body of a function trampoline. To support default arguments, we
// find the last defined argument in JS, that is the last argument which was
// explicitly passed by the user, and then we dispatch to a Dart function
// with the right number of arguments.
//
// First we handle cases where some or all arguments are undefined.
// TODO(joshualitt): Consider using a switch instead.
List<Statement> dispatchCases = [];
for (int i = function.requiredParameterCount + 1;
i <= function.positionalParameters.length;
i++) {
dispatchCases.add(IfStatement(
_variableCheckConstant(
argumentsLength!, DoubleConstant(i.toDouble())),
_generateDispatchCase(
function, callbackVariable, positionalParameters, i),
null));
}
// Finally handle the case where only required parameters are passed.
dispatchCases.add(_generateDispatchCase(function, callbackVariable,
positionalParameters, function.requiredParameterCount));
Statement functionTrampolineBody = Block(dispatchCases);
// Create a new procedure for the callback trampoline. This procedure will
// be exported from Wasm to JS so it can be called from JS. The argument
// returned from the supplied callback will be converted with `jsifyRaw` to
// a native JS value before being returned to JS.
final String libraryName = _library.name ?? 'Unnamed';
final functionTrampolineName =
'|_functionTrampoline${_jsTrampolineN++}For$libraryName';
final functionTrampolineImportName = '\$$functionTrampolineName';
final functionTrampoline = Procedure(
Name(functionTrampolineName, _library),
ProcedureKind.Method,
final functionTrampolineName = generateMethodName();
_addInteropProcedure(
functionTrampolineName,
functionTrampolineName,
FunctionNode(functionTrampolineBody,
positionalParameters: [callbackVariable, lastDefinedArgument]
.followedBy(positionalParameters)
.toList(),
positionalParameters: [
callbackVariable,
if (argumentsLength != null) argumentsLength
].followedBy(positionalParameters).toList(),
returnType: _nullableWasmExternRefType)
..fileOffset = fileOffset,
isStatic: true,
fileUri: node.fileUri)
..fileOffset = fileOffset
..isNonNullableByDefault = true;
functionTrampoline.addAnnotation(
ConstantExpression(InstanceConstant(_pragmaClass.reference, [], {
_pragmaName.fieldReference: StringConstant('wasm:export'),
_pragmaOptions.fieldReference:
StringConstant(functionTrampolineImportName)
})));
_library.addProcedure(functionTrampoline);
return functionTrampolineImportName;
..fileOffset = node.fileOffset,
node.fileUri,
_AnnotationType.export,
isExternal: false);
return functionTrampolineName;
}
/// Lowers a [StaticInvocation] of `allowInterop` to
/// [_createFunctionTrampoline] followed by `_wrapDartFunction`.
StaticInvocation _allowInterop(
/// Returns a JS method that wraps a Dart callback in a JS wrapper.
Procedure _getJSWrapperFunction(
FunctionType type, String functionTrampolineName, Uri fileUri) {
List<String> jsParameters = [];
for (int i = 0; i < type.positionalParameters.length; i++) {
jsParameters.add('x$i');
}
String jsParametersString = jsParameters.join(',');
String dartArguments = 'f';
bool needsArguments = _needsArgumentsLength(type);
if (needsArguments) {
dartArguments = '$dartArguments,arguments.length';
}
if (jsParameters.isNotEmpty) {
dartArguments = '$dartArguments,$jsParametersString';
}
// Create JS method.
// Note: We have to use a regular function for the inner closure in some
// cases because we need access to `arguments`.
final jsMethodName = functionTrampolineName;
if (needsArguments) {
jsMethods.add("$jsMethodName: f => "
"finalizeWrapper(f, function($jsParametersString) {"
" return dartInstance.exports.$functionTrampolineName($dartArguments) "
"})");
} else {
if (parametersNeedParens(jsParameters)) {
jsParametersString = '($jsParametersString)';
}
jsMethods.add("$jsMethodName: f => "
"finalizeWrapper(f,$jsParametersString => "
"dartInstance.exports.$functionTrampolineName($dartArguments))");
}
// Create Dart procedure stub.
return _addInteropProcedure(
'|$jsMethodName',
'dart2wasm.$jsMethodName',
FunctionNode(null,
positionalParameters: [
VariableDeclaration('dartFunction',
type: _nonNullableWasmExternRefType)
],
returnType: _nonNullableWasmExternRefType),
fileUri,
_AnnotationType.import,
isExternal: true);
}
/// Lowers an invocation of `allowInterop<type>(foo)` to:
///
/// let #var = foo in
/// _isDartFunctionWrapped<type>(#var) ?
/// #var :
/// _wrapDartFunction<type>(#var, jsWrapperFunction(#var));
///
/// The use of two functions here is necessary because we do not allow
/// `WasmExternRef` to be an argument or return type for a tear off.
///
/// Note: _wrapDartFunction tracks wrapped Dart functions in a map. When
/// these Dart functions flow to JS, they are replaced by their wrappers. If
/// the wrapper should ever flow back into Dart then it will be replaced by
/// the original Dart function.
Expression _allowInterop(
Procedure node, FunctionType type, Expression argument) {
String functionTrampolineName = _createFunctionTrampoline(node, type);
return StaticInvocation(
Procedure jsWrapperFunction =
_getJSWrapperFunction(type, functionTrampolineName, node.fileUri);
VariableDeclaration v =
VariableDeclaration('#var', initializer: argument, type: type);
return Let(
v,
ConditionalExpression(
StaticInvocation(_isDartFunctionWrappedTarget,
Arguments([VariableGet(v)], types: [type])),
VariableGet(v),
StaticInvocation(
_wrapDartFunctionTarget,
Arguments([
argument,
StringLiteral(functionTrampolineName),
ConstantExpression(IntConstant(type.positionalParameters.length))
VariableGet(v),
StaticInvocation(
jsWrapperFunction, Arguments([VariableGet(v)])),
], types: [
type
]));
])),
type));
}
// Specializes a JS method for a given [_MethodLoweringConfig] and returns an
@ -449,24 +527,16 @@ class _JSLowerer extends Transformer {
}
// Create Dart procedure stub for JS method.
final jsMethodName = '_${_jsTrampolineN++}';
final dartProcedureName = '|$jsMethodName';
final dartProcedure = Procedure(
Name(dartProcedureName, _library),
ProcedureKind.Method,
String jsMethodName = generateMethodName();
final dartProcedure = _addInteropProcedure(
'|$jsMethodName',
'dart2wasm.$jsMethodName',
FunctionNode(null,
positionalParameters: dartPositionalParameters,
returnType: _nullableWasmExternRefType),
isExternal: true,
isStatic: true,
fileUri: config.fileUri)
..isNonNullableByDefault = true;
dartProcedure.addAnnotation(
ConstantExpression(InstanceConstant(_pragmaClass.reference, [], {
_pragmaName.fieldReference: StringConstant('wasm:import'),
_pragmaOptions.fieldReference: StringConstant('dart2wasm.$jsMethodName')
})));
_library.addProcedure(dartProcedure);
config.fileUri,
_AnnotationType.import,
isExternal: true);
// Create JS method
jsMethods.add("$jsMethodName: ${config.generateJS(jsParameterStrings)}");

19
sdk/lib/_internal/wasm/lib/js_helper.dart
View file

@ -520,20 +520,13 @@ List<int> jsIntTypedArrayToDartIntTypedData(
List<Object?> toDartList(WasmExternRef? ref) => List<Object?>.generate(
objectLength(ref).round(), (int n) => dartifyRaw(objectReadIndex(ref, n)));
@pragma("wasm:import", "dart2wasm.wrapDartFunction")
external WasmExternRef? _wrapDartFunctionRaw(WasmExternRef? dartFunction,
WasmExternRef? trampolineName, WasmExternRef? argCount);
// These two trivial helpers are needed to work around an issue with tearing off
// functions that take / return [WasmExternRef].
bool _isDartFunctionWrapped<F extends Function>(F f) =>
functionToJSWrapper.containsKey(f);
F _wrapDartFunction<F extends Function>(
F f, String trampolineName, int argCount) {
if (functionToJSWrapper.containsKey(f)) {
return f;
}
JSValue wrappedFunction = JSValue(_wrapDartFunctionRaw(
f.toJS().toExternRef(),
trampolineName.toJS().toExternRef(),
argCount.toDouble().toJS().toExternRef())!);
functionToJSWrapper[f] = wrappedFunction;
F _wrapDartFunction<F extends Function>(F f, WasmExternRef ref) {
functionToJSWrapper[f] = JSValue(ref);
return f;
}