[lldb-dev] Fwd: inability to set breakpoints in lldb

[Greg Clayton]

Because it vastly improves performance for large Objective C and C++ projects when setting file and line breakpoints. See our troubleshooting page for more details:

http://lldb.llvm.org/troubleshooting.html


> On Sep 18, 2014, at 3:38 PM, Doug Snyder <dsnyder at blueshiftinc.com> wrote:
> 
> adding that setting to .lldbinit appears to fix all three cases (ccache, preprocess and include).  this was tested in xcode with individual test cases that i created.
> 
> i wonder why that setting is not on by default?
> 
> 
> 
> 
> On Thu, Sep 18, 2014 at 1:42 PM, Todd Fiala <tfiala at google.com> wrote:
> Hey Doug,
> 
> Can you give Jim's suggestin a try and see if that affects anything?
> 
> Thanks,
> Todd
> 
> On Wed, Sep 17, 2014 at 2:39 PM, <jingham at apple.com> wrote:
> Are any of these bugs fixed by setting:
> 
> settings set target.inline-breakpoint-strategy always
> 
> in your .lldbinit file?
> 
> Jim
> 
> > On Sep 17, 2014, at 10:34 AM, Doug Snyder <dsnyder at blueshiftinc.com> wrote:
> >
> > i have been investigating several lldb bugs that seem to be related.
> >
> > bug 19974 describes lldb's inability to set a breakpoint in an included file and bug 20297 describes lldb's inability to set a breakpoint when using ccache.  i have also found a similar case where lldb is unable to set a breakpoint when a separate preprocess step has been used before compiling.
> >
> > note: ccache uses a preprocess step to determine which source files need to be rebuilt so using ccache could be considered the same as using a separate preprocess step.
> >
> > all three cases are similar in that the c/c++ preprocessor is involved and alters the way symbols are added to the object files.
> >
> > the following attached files are write-ups of some of my findings for the different cases
> >     ccache - "lldb and ccache.rtf"
> >     preprocessed files - "lldb and preprocessed files.rtf"
> >     include files - "lldb and include files.rtf"
> >
> > all three cases generate the inability to set breakpoints
> >
> > on the Mac, all three cases create object files with "SOL" symbols for preprocessed or included source files.
> >
> > the following attached file describes the object files created for the preprocessed test case on the Mac:
> >     "preprocessed object files.rtf"
> >
> > on ubuntu, it is not as obvious to spot differences in the object files when examining object files that that lldb is unable to set breakpoints.
> >
> > lldb is unable to set breakpoints on both OSX and ubuntu for all three cases.   gdb is able to set breakpoints on both OSX and ubuntu for all three cases.
> >
> > using XCode, i have tried a couple different ways of stepping through lldb to see why it is having trouble setting breakpoints.
> >
> > From top-down, i have traced setting breakpoints in Breakpoint.cpp down thru BreakpointResolver.cpp.  The intended source file does not seem to be in the list of compute units, but i don't know why.
> >
> > From bottom-up, i have tried to follow how ObjectFileMachO.cpp parses symbols, but i'm not sure that this is the correct place to look.  Also, since this is both a MachO problem and an Elf problem, the problem isn't likely to be here anyway.
> >
> > Does anyone familiar with lldb's architecture have any ideas where in the code i should be looking or have a plan-of-attack to suggest?
> >
> > thanks,
> > doug
> >
> >
> >
> >
> > <lldb and ccache.rtf><lldb and preprocessed files.rtf><preprocessed object files.rtf><lldb and include files.rtf>_______________________________________________
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> 
> -- 
> Todd Fiala |	 Software Engineer |	 tfiala at google.com |	 650-943-3180
> 
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