Add ActivationFrame_GetFramePointer method and test.

runtime/vm/debugger_api_impl.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 "include/dart_debugger_api.h"
 
 #include "vm/class_finalizer.h"
 #include "vm/compiler.h"
 #include "vm/dart_api_impl.h"
 #include "vm/dart_api_state.h"
@@ skipping 290 matching lines @@
 
   if (location != NULL) {
     location->script_url = Api::NewHandle(isolate, frame->SourceUrl());
     const Library& lib = Library::Handle(frame->Library());
     location->library_id = lib.index();
     location->token_pos = frame->TokenPos();
   }
   return Api::Success();
 }
 
+DART_EXPORT Dart_Handle Dart_ActivationFrameGetFramePointer(
+                            Dart_ActivationFrame activation_frame,
+                            uintptr_t* frame_pointer) {
+  Isolate* isolate = Isolate::Current();
+  DARTSCOPE(isolate);
+  CHECK_AND_CAST(ActivationFrame, frame, activation_frame);
+
+  if (frame_pointer != NULL) {
+    *frame_pointer = static_cast<uintptr_t>(frame->fp());

[hausner, 2014/09/05 19:16:59]

This is fine. How does it play with the V8 side of your change where you mask
the top bits so the FP fits into 53 bits? if the stack is in the top of the
address space, this would not work. (Yes, only 48 bit are used on x64, but the
only requirement is that bits 48..63 are either all 0 or all 1. So,
0xffffffff'ffff0000 for example is a valid address.

[Jacob, 2014/09/05 20:12:25]

In blink I truncate Dart stack frame values before storing them as doubles to
make it consistent with V8. I thought it was cleaner that way as there is no
need for Dart to know about a hack that is there just to work around the lack of
a 64bit int type in JS.

+  }
+  return Api::Success();
+}
+
 
 DART_EXPORT Dart_Handle Dart_GetFunctionOrigin(Dart_Handle function_in) {
   Isolate* isolate = Isolate::Current();
   DARTSCOPE(isolate);
   UNWRAP_AND_CHECK_PARAM(Function, function, function_in);
 
   const Class& cls = Class::Handle(function.origin());
   if (!cls.IsTopLevel()) {
     return Dart_NewInteger(cls.id());
   }
@@ skipping 658 matching lines @@
   return Api::CastIsolate(isolate);
 }
 
 
 DART_EXPORT Dart_IsolateId Dart_GetIsolateId(Dart_Isolate dart_isolate) {
   Isolate* isolate = reinterpret_cast<Isolate*>(dart_isolate);
   return isolate->debugger()->GetIsolateId();
 }
 
 }  // namespace dart