Bug 136760 – lldb_webkit.py:btjs doesn't work with release builds

• Component: Tools / Tests
• Status: RESOLVED FIXED

[Michael Saboff]

Due to the lack of debugging information, btjs cannot call into the the WebProcess via JSC::CallFrame::describeFrame().

[Michael Saboff]

Created attachment 237989 [details]
Patch

[Jer Noble]

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.

[Michael Saboff]

(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.

[Michael Saboff]

Created attachment 238000 [details]
Patch with suggested check for entry points

[Michael Saboff]

Committed r173550: <http://trac.webkit.org/changeset/173550>