Due to the lack of debugging information, btjs cannot call into the the WebProcess via JSC::CallFrame::describeFrame().
Created attachment 237989 [details] Patch
Comment on attachment 237989 [details] Patch View in context: https://bugs.webkit.org/attachment.cgi?id=237989&action=review r=me, with nit: > Tools/lldb/lldb_webkit.py:135 > + JSFrameDescription = frame.EvaluateExpression("(char*)_ZN3JSC9ExecState13describeFrameEv(0x%x)" % frame.GetFP()).GetSummary() It may make sense to add an "assert" which looks up that symbol and prints a sensible error message if it can't be found.
(In reply to comment #2) > (From update of attachment 237989 [details]) > View in context: https://bugs.webkit.org/attachment.cgi?id=237989&action=review > > r=me, with nit: > > > Tools/lldb/lldb_webkit.py:135 > > + JSFrameDescription = frame.EvaluateExpression("(char*)_ZN3JSC9ExecState13describeFrameEv(0x%x)" % frame.GetFP()).GetSummary() > > It may make sense to add an "assert" which looks up that symbol and prints a sensible error message if it can't be found. I believe that EvaluateExpression() will return None if it has any problem evaluating whatever is in the quotes, including if the symbol can't be found. If the symbol isn't found or the call for some other reason, it just silently outputs the PC address. I'll create a check for both the symbols and output a once per btjs message that says JS annotated back traces isn't possible if neither form of the symbol can be found. I'll post the updated patch shortly.
Created attachment 238000 [details] Patch with suggested check for entry points
Committed r173550: <http://trac.webkit.org/changeset/173550>