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

Keno Fischer via lldb-dev lldb-dev at lists.llvm.org
Fri Sep 4 12:05:36 PDT 2015


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
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