dart2js-kernel: implement rethrow

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

Index: pkg/compiler/lib/src/ssa/builder_kernel.dart
diff --git a/pkg/compiler/lib/src/ssa/builder_kernel.dart b/pkg/compiler/lib/src/ssa/builder_kernel.dart
index d978338f5ea3b9a04ef3b261c0b045f16cec3aad..31f38f3cee49fbc166233f1e5fe541bcffa7c9a6 100644
--- a/pkg/compiler/lib/src/ssa/builder_kernel.dart
+++ b/pkg/compiler/lib/src/ssa/builder_kernel.dart
@@ -2214,6 +2214,21 @@ class KernelSsaBuilder extends ir.Visitor with GraphBuilder {
   }
 
   @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());
   }