[R-SIG-Mac] Debugging package code in Xcode?

Neil Tiffin neilt at neiltiffin.com
Wed Jul 8 23:41:36 CEST 2009

This has gone above my pay grade.  If it were me I would simplify and  
work all in x11 or all in xcode but not both.  Gdb works great from  
the command line or there are some gui x11 gdb front ends.

Sorry out of ideas and knowledge.


On Jul 8, 2009, at 10:53 AM, Duncan Murdoch wrote:

> On 08/07/2009 10:20 AM, Neil Tiffin wrote:
>> Duncan,
>> I am not sure that even if you answer these questions that I can  
>> help,  but I'll try.
>> How did you start gdb?  What commands?  Exactly what process did  
>> you  attach to?  What is in xcode and what is not?
> I started R in an xterm, and ran system("ps") to find its process  
> ID.  I also ran library(rgl) to get it loaded.
> I started Xcode on a project that imports a bunch of files from R  
> and rgl.
> I started gdb by menu in Xcode:  Run | Attach to process | Process  
> ID...
> This immediately breaks showing a bunch of assembler, because Xcode  
> doesn't know the connection between the R source and the binary.  (I  
> have had more success doing this on a build of R I made myself, but  
> in this case I'm using Simon's, and I get lots of warnings in the  
> gdb console that it can't find the source in directories on his  
> system named things like /Builds/Rdev-web/QA/Simon/... .  I don't  
> want to debug R this time, so I have ignored those.  I want to debug  
> rgl.
> All of the rgl source code has been added to the Xcode project,  
> using Project | Add to project.
>> How exactly are you trying to set the break point?  And what does  
>> gdb  respond with when you set it from the command line?
> I try to set the breakpoint by clicking in the left margin of one of  
> the source files.  I haven't tried doing it from the command line  
> until now, but it doesn't like the syntax I was trying.  (How do you  
> specify a source file line number?  Alternatively, how do you  
> specify a C++ method?  I can set breakpoints at C functions by name,  
> and then Xcode does find the right source line, but rgl is mostly C++.
>> Was anything compiled from xcode?
> No.
>> Was rgl.so compiled with debug symbols turned on?
> I don't know:  it was compiled by R CMD INSTALL rgl.  I was told a  
> couple of years ago that symbols were included by default, but I  
> don't know if that's still true.  I think so (based on my success  
> with C functions).
>> Was X11gui compiled with debug symbols turned on?
> It's just part of rgl, so the same answer.
>> Xcode integration with gdb is a complicated situation.  Just  
>> because  xcode can see something does not really mean that gdb can  
>> see it,  although it usually works with Apple magic.  Are you  
>> indicating that  gdb can see the source file or that xcode can see  
>> the source file?
> I'm not sure who can see what.  Here's the summary:
> - In the gdb console, I can set a breakpoint at a C function, and  
> Xcode will jump to the right source line for rgl.
> - I can't seem to set a breakpoint from the source display.
> Duncan Murdoch
>> Running x11, R, and rgl all in debug mode would seem a real   
>> challenge.  Not being an x11 expert, I would also raise the  
>> question  with people familiar with X11 debugging in Mac OS X.  I  
>> would start  with breakpoints only in rgl.so (which is probably  
>> what you are trying  to do) and not x11gui.cpp:300.
>> You might want to run gdb without xcode and see what's going on.    
>> You'll have to wade through a bunch of command line stuff, but you  
>> do  get direct feedback without it being absorbed by xcode.
>> Neil
>> On Jul 8, 2009, at 8:53 AM, Duncan Murdoch wrote:
>>> Neil Tiffin wrote:
>>>> You might research gdb fb command (future-break.)  It allows you   
>>>> to  set a breakpoint in code that is not loaded when the  
>>>> debugger  is  started.  I believe you would have to use the  
>>>> debugger console  not the  GUI with a syntax like "fb  
>>>> rgl.so:function_name".
>>> But it is loaded when I want to set the breakpoint.  I can see  
>>> the  source file, set a breakpoint in it, but it doesn't work.  I  
>>> opened  the gdb console (thanks for the suggestion),  and I see  
>>> warnings like
>>> Warning - No location found for "x11gui.cpp:300"
>>> when I try to set a breakpoint in rgl.  How do I tell it where to   
>>> find the location corresponding to that file?
>>> Duncan Murdoch
>>>> On Jul 8, 2009, at 5:57 AM, Duncan Murdoch wrote:
>>>>> I'd like to use Xcode to debug the rgl package, which is  
>>>>> crashing   sometimes in X11 on OSX.   In the past, I've done  
>>>>> this for  debugging  R itself, and have a project set up for  
>>>>> that.  I can  attach to the  process ID, and then I see rgl.so  
>>>>> is loaded, but I  can't see how to  set a breakpoint in the  
>>>>> rgl.so code.
>>>>> Has anyone else done this before?  Can you point me to step-by-  
>>>>> step  instructions?
>>>>> Duncan Murdoch
>>>>> _______________________________________________
>>>>> R-SIG-Mac mailing list
>>>>> R-SIG-Mac at stat.math.ethz.ch
>>>>> https://stat.ethz.ch/mailman/listinfo/r-sig-mac

More information about the R-SIG-Mac mailing list