Better single stepping in VM debugger

runtime/vm/dart_entry.cc

 // Copyright (c) 2011, 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/dart_entry.h"
 
 #include "vm/code_generator.h"
 #include "vm/compiler.h"
+#include "vm/debugger.h"
 #include "vm/object_store.h"
 #include "vm/resolver.h"
 #include "vm/simulator.h"
 #include "vm/stub_code.h"
 #include "vm/symbols.h"
 
 namespace dart {
 
 // A cache of VM heap allocated arguments descriptors.
 RawArray* ArgumentsDescriptor::cached_args_descriptors_[kCachedDescriptorCount];
@@ skipping 395 matching lines @@
                                        function_name,
                                        kNumArguments,
                                        Object::empty_array(),
                                        Resolver::kIsQualified);
     isolate->object_store()->set_handle_message_function(function);
   }
   const Array& args = Array::Handle(isolate, Array::New(kNumArguments));
   args.SetAt(0, receive_port);
   args.SetAt(1, Integer::Handle(isolate, Integer::New(reply_port_id)));
   args.SetAt(2, message);
+  if (isolate->debugger()->IsStepping()) {
+    // If the isolate is being debugged and the debugger was stepping
+    // through code, enable single stepping so debugger will stop
+    // at the first location the user is interested in.
+    isolate->debugger()->SetSingleStep();
+  }
   const Object& result =
       Object::Handle(isolate, DartEntry::InvokeFunction(function, args));
   ASSERT(result.IsNull() || result.IsError());
   return result.raw();
 }
 
 
 RawObject* DartLibraryCalls::NewSendPort(intptr_t port_id) {
   Library& isolate_lib = Library::Handle(Library::IsolateLibrary());
   ASSERT(!isolate_lib.IsNull());
@@ skipping 43 matching lines @@
           String::Handle(Field::GetterName(Symbols::_id()))));
   const Function& func = Function::Handle(cls.LookupDynamicFunction(func_name));
   ASSERT(!func.IsNull());
   const Array& args = Array::Handle(Array::New(1));
   args.SetAt(0, port);
   return DartEntry::InvokeFunction(func, args);
 }
 
 
 }  // namespace dart