[dart2wasm] Use #ClosureBase as representation type for Function.

Also renamed the `_Function` class to `_Closure` and fixed the name of
closure structs so they aren't all called `#ClosureBase`.

Change-Id: I6b55cb9827fdffac751dfc3043f3a36e7a18f225
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/279091
Reviewed-by: Ömer Ağacan <omersa@google.com>
Commit-Queue: Aske Simon Christensen <askesc@google.com>

pkg/dart2wasm/lib/class_info.dart

@@ -61,7 +61,7 @@ class FieldIndex {
     check(translator.listBaseClass, "_data", FieldIndex.listArray);
     check(translator.hashFieldBaseClass, "_index", FieldIndex.hashBaseIndex);
     check(translator.hashFieldBaseClass, "_data", FieldIndex.hashBaseData);
-    check(translator.functionClass, "context", FieldIndex.closureContext);
+    check(translator.closureClass, "context", FieldIndex.closureContext);
     check(translator.typeClass, "isDeclaredNullable",
         FieldIndex.typeIsDeclaredNullable);
     check(translator.interfaceTypeClass, "typeArguments",
@@ -322,10 +322,10 @@ class ClassInfoCollector {
   void collect() {
     initializeTop();
 
-    // Subclasses of the `_Function` class are generated on the fly as fields
-    // with function types are encountered. Therefore, `_Function` class must
+    // Subclasses of the `_Closure` class are generated on the fly as fields
+    // with function types are encountered. Therefore, `_Closure` class must
     // be early in the initialization order.
-    initialize(translator.functionClass);
+    initialize(translator.closureClass);
 
     // Similarly `_Type` is needed for type parameter fields in classes and
     // needs to be initialized before we encounter a class with type

pkg/dart2wasm/lib/closures.dart

@@ -173,9 +173,7 @@ class ClosureLayouter extends RecursiveVisitor {
 
   // Base struct for closures.
   late final w.StructType closureBaseStruct = _makeClosureStruct(
-      "#ClosureBase",
-      _vtableBaseStructBare,
-      translator.classInfo[translator.functionClass]!.struct);
+      "#ClosureBase", _vtableBaseStructBare, translator.closureInfo.struct);
 
   late final w.RefType typeType =
       translator.classInfo[translator.typeClass]!.nonNullableType;
@@ -185,12 +183,12 @@ class ClosureLayouter extends RecursiveVisitor {
   w.StructType _makeClosureStruct(
       String name, w.StructType vtableStruct, w.StructType superType) {
     // A closure contains:
-    //  - A class ID (always the `_Function` class ID)
+    //  - A class ID (always the `_Closure` class ID)
     //  - An identity hash
     //  - A context reference (used for `this` in tear-offs)
     //  - A vtable reference
     //  - A `_FunctionType`
-    return m.addStructType("#ClosureBase",
+    return m.addStructType(name,
         fields: [
           w.FieldType(w.NumType.i32),
           w.FieldType(w.NumType.i32),
@@ -564,8 +562,6 @@ class ClosureLayouter extends RecursiveVisitor {
     ib.struct_new(instantiatedRepresentation.vtableStruct);
     ib.end();
 
-    ClassInfo info = translator.classInfo[translator.functionClass]!;
-
     w.DefinedFunction instantiationFunction = m.addFunction(functionType, name);
     w.Local preciseClosure = instantiationFunction.addLocal(genericClosureType);
     w.Instructions b = instantiationFunction.body;
@@ -575,7 +571,7 @@ class ClosureLayouter extends RecursiveVisitor {
     w.Local typeParam(int i) => instantiationFunction.locals[1 + i];
 
     // Header for the closure struct
-    b.i32_const(info.classId);
+    b.i32_const(translator.closureInfo.classId);
     b.i32_const(initialIdentityHash);
 
     // Context for the instantiated closure, containing the original closure and

pkg/dart2wasm/lib/code_generator.dart

@@ -204,7 +204,7 @@ class CodeGenerator extends ExpressionVisitor1<w.ValueType, w.ValueType>
     ClosureImplementation closure = translator.getTearOffClosure(procedure);
     w.StructType struct = closure.representation.closureStruct;
 
-    ClassInfo info = translator.classInfo[translator.functionClass]!;
+    ClassInfo info = translator.closureInfo;
     translator.functions.allocateClass(info.classId);
 
     b.i32_const(info.classId);
@@ -2345,7 +2345,7 @@ class CodeGenerator extends ExpressionVisitor1<w.ValueType, w.ValueType>
       DartType functionType, void pushContext()) {
     w.StructType struct = closure.representation.closureStruct;
 
-    ClassInfo info = translator.classInfo[translator.functionClass]!;
+    ClassInfo info = translator.closureInfo;
     translator.functions.allocateClass(info.classId);
 
     b.i32_const(info.classId);

pkg/dart2wasm/lib/constants.dart

@@ -545,7 +545,7 @@ class ConstantCreator extends ConstantVisitor<ConstantInfo?> {
     w.StructType struct = closure.representation.closureStruct;
     w.RefType type = w.RefType.def(struct, nullable: false);
     return createConstant(constant, type, (function, b) {
-      ClassInfo info = translator.classInfo[translator.functionClass]!;
+      ClassInfo info = translator.closureInfo;
       translator.functions.allocateClass(info.classId);
 
       b.i32_const(info.classId);
@@ -614,7 +614,7 @@ class ConstantCreator extends ConstantVisitor<ConstantInfo?> {
     final w.DefinedFunction dynamicCallEntry = makeDynamicCallEntry();
 
     return createConstant(constant, type, (function, b) {
-      ClassInfo info = translator.classInfo[translator.functionClass]!;
+      ClassInfo info = translator.closureInfo;
       translator.functions.allocateClass(info.classId);
 
       w.DefinedFunction makeTrampoline(

pkg/dart2wasm/lib/dynamic_forwarders.dart

@@ -524,7 +524,7 @@ class Forwarder {
 
         // Invoke "call" if the value is not a closure
         b.struct_get(translator.topInfo.struct, FieldIndex.classId);
-        b.i32_const(translator.classInfo[translator.functionClass]!.classId);
+        b.i32_const(translator.closureInfo.classId);
         b.i32_ne();
         b.if_();
         // Value is not a closure
@@ -539,8 +539,23 @@ class Forwarder {
         b.return_();
         b.end();
 
-        generateDynamicCall(translator, function, receiverLocal, typeArgsLocal,
-            positionalArgsLocal, namedArgsLocal, noSuchMethodBlock);
+        // Cast the closure to `#ClosureBase`
+        final closureBaseType = w.RefType.def(
+            translator.closureLayouter.closureBaseStruct,
+            nullable: false);
+        final closureLocal = function.addLocal(closureBaseType);
+        b.local_get(receiverLocal);
+        b.ref_cast(closureBaseType);
+        b.local_set(closureLocal);
+
+        generateDynamicFunctionCall(
+            translator,
+            function,
+            closureLocal,
+            typeArgsLocal,
+            positionalArgsLocal,
+            namedArgsLocal,
+            noSuchMethodBlock);
         b.return_();
 
         b.end(); // class ID
@@ -592,15 +607,15 @@ enum _ForwarderKind {
 /// Generate code that checks shape and type of the closure and generate a call
 /// to its dynamic call vtable entry.
 ///
-/// [closureLocal] should be a local with a closure value. Type of the local
-/// does not matter as long as it can be cast to `ref #ClosureBase`.
+/// [closureLocal] should be a local of type `ref #ClosureBase` containing a
+/// closure value.
 ///
 /// [typeArgsLocal], [posArgsLocal], [namedArgsLocal] are the locals for type,
 /// positional, and named arguments, respectively. Types of these locals must
 /// be `ref _ListBase`.
 ///
 /// [noSuchMethodBlock] is used as the `br` target when the shape check fails.
-void generateDynamicCall(
+void generateDynamicFunctionCall(
   Translator translator,
   w.DefinedFunction function,
   w.Local closureLocal,
@@ -617,19 +632,10 @@ void generateDynamicCall(
 
   final b = function.body;
 
-  // Cast the closure to `#ClosureBase`
-  final closureBaseType = w.RefType.def(
-      translator.closureLayouter.closureBaseStruct,
-      nullable: false);
-  final closureBaseLocal = function.addLocal(closureBaseType);
-  b.local_get(closureLocal);
-  b.ref_cast(closureBaseType);
-  b.local_set(closureBaseLocal);
-
   // Read the `_FunctionType` field
   final functionTypeLocal =
       function.addLocal(translator.closureLayouter.functionTypeType);
-  b.local_get(closureBaseLocal);
+  b.local_get(closureLocal);
   b.struct_get(translator.closureLayouter.closureBaseStruct,
       FieldIndex.closureRuntimeType);
   b.local_tee(functionTypeLocal);
@@ -653,13 +659,13 @@ void generateDynamicCall(
       translator.functions.getFunction(translator.checkClosureType.reference));
 
   // Type check passed, call vtable entry
-  b.local_get(closureBaseLocal);
+  b.local_get(closureLocal);
   b.local_get(typeArgsLocal);
   b.local_get(posArgsLocal);
   b.local_get(namedArgsLocal);
 
   // Get vtable
-  b.local_get(closureBaseLocal);
+  b.local_get(closureLocal);
   b.struct_get(
       translator.closureLayouter.closureBaseStruct, FieldIndex.closureVtable);
 

pkg/dart2wasm/lib/intrinsics.dart

@@ -1486,8 +1486,7 @@ class Intrinsifier {
       }
     }
 
-    if (member.enclosingClass == translator.functionClass &&
-        name == "_equals") {
+    if (member.enclosingClass == translator.closureClass && name == "_equals") {
       // Function equality works like this:
       //
       // - Function literals and local functions are only equal if they're the
@@ -1595,7 +1594,7 @@ class Intrinsifier {
         name == "apply") {
       assert(function.type.inputs.length == 3);
 
-      final closureLocal = function.locals[0]; // ref Object
+      final closureLocal = function.locals[0]; // ref #ClosureBase
       final posArgsNullableLocal = function.locals[1]; // ref null Object,
       final namedArgsLocal = function.locals[2]; // ref null Object
 
@@ -1654,8 +1653,8 @@ class Intrinsifier {
 
       final noSuchMethodBlock = b.block();
 
-      generateDynamicCall(translator, function, closureLocal, typeArgsLocal,
-          posArgsLocal, namedArgsListLocal, noSuchMethodBlock);
+      generateDynamicFunctionCall(translator, function, closureLocal,
+          typeArgsLocal, posArgsLocal, namedArgsListLocal, noSuchMethodBlock);
       b.return_();
 
       b.end(); // noSuchMethodBlock

pkg/dart2wasm/lib/kernel_nodes.dart

@@ -36,7 +36,7 @@ mixin KernelNodes {
   late final Class boxedDoubleClass =
       index.getClass("dart:core", "_BoxedDouble");
   late final Class boxedIntClass = index.getClass("dart:core", "_BoxedInt");
-  late final Class functionClass = index.getClass("dart:core", "_Function");
+  late final Class closureClass = index.getClass("dart:core", "_Closure");
   late final Class listBaseClass = index.getClass("dart:core", "_ListBase");
   late final Class fixedLengthListClass = index.getClass("dart:core", "_List");
   late final Class growableListClass =

pkg/dart2wasm/lib/translator.dart

@@ -106,6 +106,7 @@ class Translator with KernelNodes {
   // Some convenience accessors for commonly used values.
   late final ClassInfo topInfo = classes[0];
   late final ClassInfo objectInfo = classInfo[coreTypes.objectClass]!;
+  late final ClassInfo closureInfo = classInfo[closureClass]!;
   late final ClassInfo stackTraceInfo = classInfo[stackTraceClass]!;
   late final w.ArrayType listArrayType = (classInfo[listBaseClass]!
           .struct
@@ -468,6 +469,9 @@ class Translator with KernelNodes {
       } else if (isFfiCompound(cls)) {
         if (nullable) throw "FFI types can't be nullable";
         return w.NumType.i32;
+      } else if (cls == coreTypes.functionClass) {
+        return w.RefType.def(closureLayouter.closureBaseStruct,
+            nullable: nullable);
       }
     }
     return w.RefType.def(info.repr.struct, nullable: nullable);

pkg/dart2wasm/lib/types.dart

@@ -526,8 +526,7 @@ class Types {
       b.drop();
       b.i32_const(1);
     } else if (type.classNode == coreTypes.functionClass) {
-      ClassInfo functionInfo = translator.classInfo[translator.functionClass]!;
-      b.ref_test(functionInfo.nonNullableType);
+      b.ref_test(translator.closureInfo.nonNullableType);
     } else if (concrete.isEmpty) {
       b.drop();
       b.i32_const(0);

sdk/lib/_internal/wasm/lib/class_id.dart

@@ -32,8 +32,8 @@ class ClassID {
   external static int get cidFuture;
   @pragma("wasm:class-id", "dart.core#Function")
   external static int get cidFunction;
-  @pragma("wasm:class-id", "dart.core#_Function")
-  external static int get cid_Function;
+  @pragma("wasm:class-id", "dart.core#_Closure")
+  external static int get cid_Closure;
   @pragma("wasm:class-id", "dart.core#_List")
   external static int get cidFixedLengthList;
   @pragma("wasm:class-id", "dart.core#_ListBase")

sdk/lib/_internal/wasm/lib/closure.dart

@@ -1,26 +1,26 @@
-// Copyright (c) 2022, the Dart project authors.  Please see the AUTHORS file
+// 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.
 
 part of "core_patch.dart";
 
 /// Base class for closure objects.
-class _Function implements Function {
+class _Closure implements Function {
   @pragma("wasm:entry-point")
   WasmStructRef context;
 
   @pragma("wasm:entry-point")
-  _Function._(this.context);
+  _Closure._(this.context);
 
   @override
   bool operator ==(Object other) {
-    if (other is! _Function) {
+    if (other is! _Closure) {
       return false;
     }
     return _equals(this, other);
   }
 
-  external static bool _equals(_Function a, _Function b);
+  external static bool _equals(_Closure a, _Closure b);
 
   // Simple hash code for now, we can optimize later
   @override
@@ -28,5 +28,5 @@ class _Function implements Function {
 
   // Support dynamic tear-off of `.call` on functions
   @pragma("wasm:entry-point")
-  _Function get call => this;
+  _Closure get call => this;
 }

sdk/lib/_internal/wasm/lib/core_patch.dart

@@ -54,10 +54,10 @@ import "dart:typed_data" show Uint8List, Uint16List;
 import 'dart:wasm';
 
 part "bool.dart";
+part "closure.dart";
 part "date_patch.dart";
 part "double.dart";
 part "errors_patch.dart";
-part "function.dart";
 part "growable_list.dart";
 part "identical_patch.dart";
 part "int.dart";

sdk/lib/_internal/wasm/lib/object_patch.dart

@@ -50,7 +50,7 @@ class Object {
 
   @pragma("wasm:entry-point")
   _Type get _runtimeType {
-    if (ClassID.getID(this) == ClassID.cid_Function) {
+    if (ClassID.getID(this) == ClassID.cid_Closure) {
       return _getFunctionTypeRuntimeType(this);
     } else {
       return _getInterfaceTypeRuntimeType(this, _typeArguments);

sdk/lib/_internal/wasm/lib/type.dart

@@ -519,7 +519,7 @@ class _TypeUniverse {
 
   static bool isFunctionType(_Type t) =>
       isSpecificInterfaceType(t, ClassID.cidFunction) ||
-      isSpecificInterfaceType(t, ClassID.cid_Function);
+      isSpecificInterfaceType(t, ClassID.cid_Closure);
 
   static _Type substituteInterfaceTypeParameter(
       _InterfaceTypeParameterType typeParameter, List<_Type> substitutions) {