dart2js-kernel: implement rethrow

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, CodegenWorkItem;
 import '../common/names.dart';
@@ skipping 2196 matching lines @@
     bool old = _inExpressionOfThrow;
     try {
       _inExpressionOfThrow = true;
       expression.accept(this);
     } finally {
       _inExpressionOfThrow = old;
     }
   }
 
   @override
+  void visitRethrow(ir.Rethrow rethrowNode) {
+    HInstruction exception = rethrowableException;
+    if (exception == null) {
+      exception = graph.addConstantNull(closedWorld);
+      compiler.reporter.internalError(astAdapter.getNode(rethrowNode),
+          'rethrowableException should not be null.');
+    }
+    SourceInformation sourceInformation = null;

[Siggi Cherem (dart-lang), 2017/01/11 19:13:04]

what do we generally want to do for with source-infos at this time. Do we want
to wait and add them all later, or do we want to use the adapter to get the AST
node and then remove the adapter? For example, here we could do:

sourceInformationBuilder.buildThrow(astAdapter.getNode(rethrowNode))

[Emily Fortuna, 2017/01/11 21:19:54]

I had been avoiding them and adding TODOs, but it's probably better and less
error prone to add the machinery in now to the adapter and add the rest as we
get further along.

+    closeAndGotoExit(new HThrow(exception, sourceInformation, isRethrow: true));
+    // ir.Rethrow is an expression so we need to push a value - a constant with
+    // no type.
+    stack.add(graph.addConstantUnreachable(closedWorld));
+  }
+
+  @override
   void visitThisExpression(ir.ThisExpression thisExpression) {
     stack.add(localsHandler.readThis());
   }
 
   @override
   void visitNot(ir.Not not) {
     not.operand.accept(this);
     push(new HNot(popBoolified(), commonMasks.boolType));
   }
 
@@ skipping 259 matching lines @@
     kernelBuilder.open(exitBlock);
     enterBlock.setBlockFlow(
         new HTryBlockInformation(
             kernelBuilder.wrapStatementGraph(bodyGraph),
             exception,
             kernelBuilder.wrapStatementGraph(catchGraph),
             kernelBuilder.wrapStatementGraph(finallyGraph)),
         exitBlock);
   }
 }