Await it!

runtime/vm/parser.cc

Index: runtime/vm/parser.cc
diff --git a/runtime/vm/parser.cc b/runtime/vm/parser.cc
index d80d951afc0fab08637eb1c456a4d57f554acaa2..ebc5308d1e8a6301b36fab2159365ad28b961ca9 100644
--- a/runtime/vm/parser.cc
+++ b/runtime/vm/parser.cc
@@ -5426,7 +5426,6 @@ void Parser::OpenFunctionBlock(const Function& func) {
 void Parser::OpenAsyncClosure() {
   TRACE_PARSER("OpenAsyncClosure");
   parsed_function()->set_await_temps_scope(current_block_->scope);
-  // TODO(mlippautz): Set up explicit jump table for await continuations.
 }
 
 
@@ -5523,6 +5522,8 @@ SequenceNode* Parser::CloseAsyncFunction(const Function& closure,
   // Add to AST:
   //   var :async_op;
   //   var :async_completer;
+  //   var :await_jump_var;
+  //   var :await_ctx_var;
   LocalVariable* async_op_var = new (I) LocalVariable(
       Scanner::kNoSourcePos,
       Symbols::AsyncOperation(),
@@ -5537,11 +5538,25 @@ SequenceNode* Parser::CloseAsyncFunction(const Function& closure,
   current_block_->scope->AddVariable(async_completer);
   found = closure_body->scope()->CaptureVariable(Symbols::AsyncCompleter());
   ASSERT(found);
+  LocalVariable* await_jump_var = new (I) LocalVariable(
+      Scanner::kNoSourcePos,
+      Symbols::AwaitJumpVar(),
+      Type::ZoneHandle(I, Type::DynamicType()));
+  current_block_->scope->AddVariable(await_jump_var);
+  found = closure_body->scope()->CaptureVariable(Symbols::AwaitJumpVar());
+  ASSERT(found);
+  LocalVariable* await_ctx_var = new (I) LocalVariable(
+      Scanner::kNoSourcePos,
+      Symbols::AwaitContextVar(),
+      Type::ZoneHandle(I, Type::DynamicType()));
+  current_block_->scope->AddVariable(await_ctx_var);
+  found = closure_body->scope()->CaptureVariable(Symbols::AwaitContextVar());
+  ASSERT(found);
 
   // Add to AST:
   //   :async_completer = new Completer();
-  ArgumentListNode* empty_args = new (I) ArgumentListNode(
-      Scanner::kNoSourcePos);
+  ArgumentListNode* empty_args =
+      new (I) ArgumentListNode(Scanner::kNoSourcePos);
   ConstructorCallNode* completer_constructor_node = new (I) ConstructorCallNode(
       Scanner::kNoSourcePos,
       TypeArguments::ZoneHandle(I),
@@ -5592,6 +5607,13 @@ void Parser::CloseAsyncClosure(SequenceNode* body) {
   TRACE_PARSER("CloseAsyncClosure");
   // We need a temporary expression to store intermediate return values.
   parsed_function()->EnsureExpressionTemp();
+  // Implicitly mark those variables below as captured. We currently mark all
+  // variables of all scopes as captured (below), but as soon as we do something
+  // smarter we rely on these internal variables to be available.
+  body->scope()->LookupVariable(Symbols::Completer(), false);
+  body->scope()->LookupVariable(Symbols::AwaitJumpVar(), false);
+  body->scope()->LookupVariable(Symbols::AwaitContextVar(), false);
+  body->scope()->RecursivelyCaptureAllVariables();
 }