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

runtime/vm/code_descriptors.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_CODE_DESCRIPTORS_H_
 #define RUNTIME_VM_CODE_DESCRIPTORS_H_
 
 #include "vm/ast.h"
 #include "vm/code_generator.h"
 #include "vm/globals.h"
@@ skipping 56 matching lines @@
   GrowableObjectArray& list_;
   DISALLOW_COPY_AND_ASSIGN(StackMapTableBuilder);
 };
 
 
 class ExceptionHandlerList : public ZoneAllocated {
  public:
   struct HandlerDesc {
     intptr_t outer_try_index;    // Try block in which this try block is nested.
     intptr_t pc_offset;          // Handler PC offset value.
+    TokenPosition token_pos;     // Token position of handler.
+    bool is_generated;           // False if this is directly from Dart code.
     const Array* handler_types;  // Catch clause guards.
     bool needs_stacktrace;
   };
 
   ExceptionHandlerList() : list_() {}
 
   intptr_t Length() const { return list_.length(); }
 
   void AddPlaceHolder() {
     struct HandlerDesc data;
     data.outer_try_index = -1;
     data.pc_offset = ExceptionHandlers::kInvalidPcOffset;
+    data.token_pos = TokenPosition::kNoSource;
+    data.is_generated = true;
     data.handler_types = NULL;
     data.needs_stacktrace = false;
     list_.Add(data);
   }
 
   void AddHandler(intptr_t try_index,
                   intptr_t outer_try_index,
                   intptr_t pc_offset,
+                  TokenPosition token_pos,
+                  bool is_generated,
                   const Array& handler_types,
                   bool needs_stacktrace) {
     ASSERT(try_index >= 0);
     while (Length() <= try_index) {
       AddPlaceHolder();
     }
     list_[try_index].outer_try_index = outer_try_index;
     ASSERT(list_[try_index].pc_offset == ExceptionHandlers::kInvalidPcOffset);
     list_[try_index].pc_offset = pc_offset;
+    list_[try_index].token_pos = token_pos;
+    list_[try_index].is_generated = is_generated;
     ASSERT(handler_types.IsZoneHandle());
     list_[try_index].handler_types = &handler_types;
     list_[try_index].needs_stacktrace |= needs_stacktrace;
   }
 
 
   // Called by rethrows, to mark their enclosing handlers.
   void SetNeedsStackTrace(intptr_t try_index) {
     // Rethrows can be generated outside a try by the compiler.
     if (try_index == CatchClauseNode::kInvalidTryIndex) {
@@ skipping 144 matching lines @@
   const CodeSourceMap& map_;
   const Array& functions_;
   const Function& root_;
 
   DISALLOW_COPY_AND_ASSIGN(CodeSourceMapReader);
 };
 
 }  // namespace dart
 
 #endif  // RUNTIME_VM_CODE_DESCRIPTORS_H_