Initialize the async jump variable with a smi to avoid polymorphic comparison.

runtime/vm/parser.cc

 // Copyright (c) 2012, 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.
 
 #include "vm/parser.h"
 
 #include "lib/invocation_mirror.h"
 #include "platform/utils.h"
 #include "vm/ast_transformer.h"
 #include "vm/bootstrap.h"
@@ skipping 5859 matching lines @@
 SequenceNode* Parser::CloseAsyncFunction(const Function& closure,
                                          SequenceNode* closure_body) {
   TRACE_PARSER("CloseAsyncFunction");
   ASSERT(!closure.IsNull());
   ASSERT(closure_body != NULL);
   // The block for the async closure body has already been closed. Close the
   // corresponding function block.
   CloseBlock();
 
   closure_body->scope()->LookupVariable(Symbols::AwaitJumpVar(), false);
+  closure_body->scope()->LookupVariable(Symbols::AwaitContextVar(), false);
   closure_body->scope()->CaptureVariable(Symbols::AsyncCompleter());
 
   // Create and return a new future that executes a closure with the current
   // body.
 
   // No need to capture parameters or other variables, since they have already
   // been captured in the corresponding scope as the body has been parsed within
   // a nested block (contained in the async funtion's block).
   const Class& future = Class::ZoneHandle(I,
       GetClassForAsync(Symbols::Future()));
@@ skipping 19 matching lines @@
       Scanner::kNoSourcePos,
       TypeArguments::ZoneHandle(I),
       completer_constructor,
       empty_args);
   StoreLocalNode* store_completer = new (I) StoreLocalNode(
       Scanner::kNoSourcePos,
       async_completer,
       completer_constructor_node);
   current_block_->statements->Add(store_completer);
 
+  // :await_jump_var = -1;
+  LocalVariable* jump_var = current_block_->scope->LookupVariable(
+        Symbols::AwaitJumpVar(), false);
+  LiteralNode* init_value =
+    new(I) LiteralNode(Scanner::kNoSourcePos, Smi::ZoneHandle(Smi::New(-1)));
+  current_block_->statements->Add(
+      new (I) StoreLocalNode(Scanner::kNoSourcePos, jump_var, init_value));
+
   // Add to AST:
   //   :async_op = <closure>;  (containing the original body)
   LocalVariable* async_op_var = current_block_->scope->LookupVariable(
       Symbols::AsyncOperation(), false);
   ClosureNode* cn = new(I) ClosureNode(
       Scanner::kNoSourcePos, closure, NULL, closure_body->scope());
   StoreLocalNode* store_async_op = new (I) StoreLocalNode(
       Scanner::kNoSourcePos,
       async_op_var,
       cn);
@@ skipping 5879 matching lines @@
 void Parser::SkipQualIdent() {
   ASSERT(IsIdentifier());
   ConsumeToken();
   if (CurrentToken() == Token::kPERIOD) {
     ConsumeToken();  // Consume the kPERIOD token.
     ExpectIdentifier("identifier expected after '.'");
   }
 }
 
 }  // namespace dart