Reduce the number of captured variables in async code, by only capturing local

runtime/vm/flow_graph_builder.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/flow_graph_builder.h"
 
 #include "lib/invocation_mirror.h"
 #include "vm/ast_printer.h"
 #include "vm/bit_vector.h"
 #include "vm/class_finalizer.h"
@@ skipping 2313 matching lines @@
 void EffectGraphVisitor::VisitAwaitNode(AwaitNode* node) {
   // Await nodes are temporary during parsing.
   UNREACHABLE();
 }
 
 
 void EffectGraphVisitor::VisitAwaitMarkerNode(AwaitMarkerNode* node) {
   // We need to create a new await state which involves:
   // * Increase the jump counter. Sanity check against the list of targets.
   // * Save the current context for resuming.
-  ASSERT(node->scope() != NULL);
-  LocalVariable* jump_var = node->scope()->LookupVariable(
+  ASSERT(node->async_scope() != NULL);
+  ASSERT(node->await_scope() != NULL);
+  LocalVariable* jump_var = node->async_scope()->LookupVariable(
       Symbols::AwaitJumpVar(), false);
-  LocalVariable* ctx_var = node->scope()->LookupVariable(
+  LocalVariable* ctx_var = node->async_scope()->LookupVariable(
       Symbols::AwaitContextVar(), false);
   ASSERT((jump_var != NULL) && jump_var->is_captured());
   ASSERT((ctx_var != NULL) && ctx_var->is_captured());
   const intptr_t jump_count = owner()->next_await_counter();
   ASSERT(jump_count >= 0);
   // Sanity check that we always add a JoinEntryInstr before adding a new
   // state.
   ASSERT(jump_count == owner()->await_joins()->length());
   // Store the counter in :await_jump_var.
   Value* jump_val = Bind(new(Z) ConstantInstr(
@@ skipping 2327 matching lines @@
   Report::MessageF(Report::kBailout,
                    Script::Handle(function.script()),
                    function.token_pos(),
                    "FlowGraphBuilder Bailout: %s %s",
                    String::Handle(function.name()).ToCString(),
                    reason);
   UNREACHABLE();
 }
 
 }  // namespace dart