Track the 'awaiter return' call stack use it to detect uncaught exceptions in async functions

runtime/vm/flow_graph_builder.h

 // 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.
 
 #ifndef RUNTIME_VM_FLOW_GRAPH_BUILDER_H_
 #define RUNTIME_VM_FLOW_GRAPH_BUILDER_H_
 
 #include "platform/assert.h"
 #include "platform/globals.h"
 #include "vm/allocation.h"
@@ skipping 154 matching lines @@
   // OSR entry point.
   void PruneUnreachable();
 
   // Returns address where the constant 'value' is stored or 0 if not found.
   static uword FindDoubleConstant(double value);
 
   Thread* thread() const { return parsed_function().thread(); }
   Isolate* isolate() const { return parsed_function().isolate(); }
   Zone* zone() const { return parsed_function().zone(); }
 
+  void AppendAwaitTokenPosition(TokenPosition token_pos);
+
+  ZoneGrowableArray<TokenPosition>* await_token_positions() const {
+    return await_token_positions_;
+  }
+
  private:
   friend class NestedStatement;  // Explicit access to nesting_stack_.
   friend class Intrinsifier;
 
   intptr_t parameter_count() const {
     return num_copied_params_ + num_non_copied_params_;
   }
   intptr_t variable_count() const {
     return parameter_count() + num_stack_locals_;
   }
@@ skipping 20 matching lines @@
 
   // A stack of enclosing nested statements.
   NestedStatement* nesting_stack_;
 
   // The deopt id of the OSR entry orCompiler::kNoOSRDeoptId if not compiling
   // for OSR.
   const intptr_t osr_id_;
 
   intptr_t jump_count_;
   ZoneGrowableArray<JoinEntryInstr*>* await_joins_;
+  ZoneGrowableArray<TokenPosition>* await_token_positions_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(FlowGraphBuilder);
 };
 
 
 // Translate an AstNode to a control-flow graph fragment for its effects
 // (e.g., a statement or an expression in an effect context).  Implements a
 // function from an AstNode and next temporary index to a graph fragment
 // with a single entry and at most one exit.  The fragment is represented by
 // an (entry, exit) pair of Instruction pointers:
@@ skipping 331 matching lines @@
   // Output parameters.
   GrowableArray<TargetEntryInstr**> true_successor_addresses_;
   GrowableArray<TargetEntryInstr**> false_successor_addresses_;
 
   TokenPosition condition_token_pos_;
 };
 
 }  // namespace dart
 
 #endif  // RUNTIME_VM_FLOW_GRAPH_BUILDER_H_