dart2js kernel: minimal recognition of external native methods

pkg/compiler/lib/src/ssa/builder_kernel.dart

 // Copyright (c) 2016, 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/ast.dart' as ir;
 
 import '../closure.dart';
 import '../common.dart';
 import '../common/codegen.dart' show CodegenRegistry;
 import '../common/names.dart';
@@ skipping 121 matching lines @@
       HInstruction.idCounter = 0;
       MemberDefinition definition =
           _elementMap.getMemberDefinition(targetElement);
 
       switch (definition.kind) {
         case MemberKind.regular:
         case MemberKind.closureCall:
           ir.Node target = definition.node;
           if (target is ir.Procedure) {
             _targetFunction = target.function;
-            buildFunctionNode(_targetFunction);
+            if (target.isExternal) {
+              buildExternalFunctionNode(_targetFunction);
+            } else {
+              buildFunctionNode(_targetFunction);
+            }
           } else if (target is ir.Field) {
             if (handleConstantField(targetElement, registry, closedWorld)) {
               // No code is generated for `targetElement`: All references inline
               // the constant value.
               return null;
             } else if (targetElement.isStatic || targetElement.isTopLevel) {
               backend.constants.registerLazyStatic(targetElement);
             }
             buildField(target);
           } else if (target is ir.FunctionExpression) {
@@ skipping 519 matching lines @@
     constructor.function.body.accept(this);
     closeFunction();
   }
 
   /// Builds a SSA graph for FunctionNodes, found in FunctionExpressions and
   /// Procedures.
   void buildFunctionNode(ir.FunctionNode functionNode) {
     openFunction(functionNode);
     ir.TreeNode parent = functionNode.parent;
     if (parent is ir.Procedure && parent.kind == ir.ProcedureKind.Factory) {
-      _addClassTypeVariablesIfNeeded(functionNode.parent);
+      _addClassTypeVariablesIfNeeded(parent);
     }
 
     // If [functionNode] is `operator==` we explicitly add a null check at the
     // beginning of the method. This is to avoid having call sites do the null
     // check.
     if (parent is ir.Procedure &&
         parent.kind == ir.ProcedureKind.Operator &&
         parent.name.name == '==') {
       FunctionEntity method = _elementMap.getMethod(parent);
       if (!_commonElements.operatorEqHandlesNullArgument(method)) {
@@ skipping 13 matching lines @@
           visitElse: null,
           // TODO(27394): Add sourceInformation via
           // `sourceInformationBuilder.buildIf(?)`.
         );
       }
     }
     functionNode.body.accept(this);
     closeFunction();
   }
 
+  /// Builds a SSA graph for FunctionNodes of external methods.
+  void buildExternalFunctionNode(ir.FunctionNode functionNode) {
+    openFunction(functionNode);
+    ir.TreeNode parent = functionNode.parent;
+    if (parent is ir.Procedure && parent.kind == ir.ProcedureKind.Factory) {
+      _addClassTypeVariablesIfNeeded(parent);
+    }
+    // TODO(sra): Generate conversion of Function typed arguments to JavaScript
+    // functions.
+    // TODO(sra): Invoke native method.
+    assert(functionNode.body == null);
+    closeFunction();
+  }
+
   void addImplicitInstantiation(DartType type) {
     if (type != null) {
       currentImplicitInstantiations.add(type);
     }
   }
 
   void removeImplicitInstantiation(DartType type) {
     if (type != null) {
       currentImplicitInstantiations.removeLast();
     }
@@ skipping 2940 matching lines @@
     enterBlock.setBlockFlow(
         new HTryBlockInformation(
             kernelBuilder.wrapStatementGraph(bodyGraph),
             exception,
             kernelBuilder.wrapStatementGraph(catchGraph),
             kernelBuilder.wrapStatementGraph(finallyGraph)),
         exitBlock);
     kernelBuilder.inTryStatement = previouslyInTryStatement;
   }
 }