[lldb-dev] C++ API: Passing information from debuggee to debugger

Eugene Birukov eugenebi at hotmail.com
Tue Jun 2 08:32:47 PDT 2015

OK, thanks a lot! 
The problem is that there are complications if the target is stripped off symbols, but I probably can work around by still sending a signal (i.e. getting reliable interrupted) and inspecting registers to find my pointer. Another vague worry is if overzealous compiler would optimize it out, but of course I can compile this specific method with optimization turned off. I.e. there are some hoops to jump through instead of just getting it work.
I do not fully understand why we need mutex here... Each thread allocates data in its own memory (either allocated or on stack) and when it breaks each thread has its own local pointer (either on stack or in register). I.e. it seems this can be made lock-free.
> Date: Tue, 2 Jun 2015 11:00:47 +0100
> From: colin at codeplay.com
> To: labath at google.com; eugenebi at hotmail.com
> CC: lldb-dev at cs.uiuc.edu
> Subject: Re: [lldb-dev] C++ API: Passing information from debuggee to debugger
> comment inline
> On 02/06/2015 10:21, Pavel Labath wrote:
> > Hello,
> >
> > Yes, please file a bug. I been wanting to implement passing of the
> > struct siginfo_t from the inferior all the way up to lldb (besides
> > your use case, it is also useful for displaying more precise
> > information about segfaults, etc.). However, that is not a priority
> > now, so it may take a while (patches welcome though :) ).
> >
> >>> So, is there any other "legal" way to achieve what I need?
> > As I understand it, the way people do this kind of thing usually is to
> > have a special function in the inferior (e.g., void
> > my_debugger_interface(my_data *). Then the debugger can set a
> > breakpoint on this function and read all the data it needs from the
> > function arguments. If you want to be sure two threads don't call this
> > function simultaneously, you can protect it with a regular mutex.
> For an example, the recent r238768 implements this sort of system in the 
> RenderScript language runtime.
> >
> > pl
> > _______________________________________________
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> > lldb-dev at cs.uiuc.edu
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> -- 
> - Colin Riley
> Senior Director,
> Parallel/Graphics Debugger Systems
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