[lldb-dev] Breakpoints on inlined functions described by DW_AT_ranges

[Jim Ingham via lldb-dev]

Ah, okay.  For a while the llvm-dsymutil folks were trying to make the output of dsymutil & llvm-dsymutil identical so that they could be sure llvm-dsymutil was doing the right thing, so I'm a little surprised the two differ in this regard.  But if it works with .o files & llvm-dsymutil I think that's all we really care about at this point.

Jim


> On Sep 4, 2015, at 7:03 PM, Keno Fischer <kfischer at college.harvard.edu> wrote:
> 
> Actually, it's not a clang bug either. The info is there in the .o file. This only happens if lldb is looking in the .dSYM. If I delete that and let lldb look in the .o files, it sets the breakpoint just fine, so I'll chalk this up as a dsymutil bug. llvm-dsymutil works fine.
> 
> On Fri, Sep 4, 2015 at 9:41 PM, Keno Fischer <kfischer at college.harvard.edu> wrote:
> Hi Jim,
> 
> I tried to work on this, but everything there actually seemed correct. It now seems to me like those functions are simply missing from .apple_names (compiled with latest Clang trunk), so this might not be an LLDB bug after all.
> 
> Keno
> 
> On Fri, Sep 4, 2015 at 3:20 PM, Jim Ingham <jingham at apple.com> wrote:
> Certainly a bug.  This bit:
> 
>         if (inlined_die)
>         {
>             Block &function_block = sc.function->GetBlock (true);
>             sc.block = function_block.FindBlockByID (inlined_die.GetID());
>             if (sc.block == NULL)
>                 sc.block = function_block.FindBlockByID (inlined_die.GetOffset());
>             if (sc.block == NULL || sc.block->GetStartAddress (addr) == false)
>                 addr.Clear();
>         }
> 
> from SymbolFileDwarf::ResolveFunction is most likely responsible.  I don't remember offhand how the blocks deal with the fact that this one die actually represents multiple blocks, but it's going to be something related to that.
> 
> If you want to have a look, that would be great, otherwise file a bug and we can take a look when we get some free time.
> 
> Jim
> 
> > On Sep 4, 2015, at 12:05 PM, Keno Fischer via lldb-dev <lldb-dev at lists.llvm.org> wrote:
> >
> > I'm trying to set a breakpoint (using `b jl_apply`) on a function (jl_apply) that is inlined in a number of places. This generally works fine, but I have noticed that in certain cases LLDB fails to set a breakpoint even though when I step through manually, it does know which function the code belongs to. Investigating further, I have found that the difference comes from whether the inlined subroutine is described via DW_AT_low_pc or via DW_AT_ranges, so e.g.
> >
> > 0x0000f6c8:                   DW_TAG_inlined_subroutine [42] *
> >                                 DW_AT_abstract_origin [DW_FORM_ref4]    (cu + 0x22e7 => {0x0000d394} "jl_apply")
> >                                 DW_AT_low_pc [DW_FORM_addr]     (0x000000000000f768)
> >                                 DW_AT_high_pc [DW_FORM_addr]    (0x000000000000f776)
> >                                 DW_AT_call_file [DW_FORM_data1] ("/Users/kfischer/Projects/julia-testpatch/src/gf.c")
> >                                 DW_AT_call_line [DW_FORM_data1] (34)
> >
> > will get a  breakpoint while
> >
> > 0x0000f6ee:         DW_TAG_inlined_subroutine [53] *
> >                       DW_AT_abstract_origin [DW_FORM_ref4]      (cu + 0x22e7 => {0x0000d394} "jl_apply")
> >                       DW_AT_ranges [DW_FORM_data4]      (0x0000b790
> >                          [0x000000000000f785 - 0x000000000000f788)
> >                          [0x000000000000f79c - 0x000000000000f7b8))
> >                       DW_AT_call_file [DW_FORM_data1]   ("/Users/kfischer/Projects/julia-testpatch/src/gf.c")
> >                       DW_AT_call_line [DW_FORM_data2]   (1668)
> >
> > will not. Is this the intended behavior or a bug? If it's a bug, any ideas where to look to try to fix it?
> >
> > Thanks,
> > Keno
> > _______________________________________________
> > lldb-dev mailing list
> > lldb-dev at lists.llvm.org
> > http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev
> 
> 
>