[PATCH] LLVMSymbolizer: Use alternative method if no inlining frames found.

[Will Dietz]

Done in r193711, thanks for the fix!

~Will

On Mon, Oct 28, 2013 at 6:21 PM, Alexey Samsonov <samsonov at google.com> wrote:
>
> On Thu, Oct 17, 2013 at 11:56 AM, Will Dietz <w at wdtz.org> wrote:
>>
>> Ah, well after your DebugInfo change re:form classes lands,
>> this patch is almost certainly going about this the wrong way.
>>
>> If you'd like I can update the patch, but since you just refactored
>> things to support doing this properly it seems you should just
>> go ahead and fix this yourself (compared to overhead of managing me doing
>> it).
>>
>> The testcase is probably still useful regardless :).
>
>
> Hi Will, I think I've fixed the problem in r193555.
> Could you please commit your testcase with the following improvements:
> * Add the original source code with descriptions of how to build the object
> file (which compiler was used etc.) See
> test/DebugInfo/Inputs/dwarfdump-test.cc for inspiration.
> * Rewrite the test to use llvm-symbolizer (it will probably be shorter), or
> just extend test/DebugInfo/llvm-symbolizer.test
>
> Thanks!
>
>>
>>
>> No worries, would rather see this done properly for sure.
>> Thanks!
>>
>> ~Will
>>
>>
>> On Thu, Oct 17, 2013 at 1:20 PM, Will Dietz <w at wdtz.org> wrote:
>> > Great, thanks! You were absolutely right regarding the high_pc thing,
>> > sorry for misdiagnosing the issue (and thanks for figuring this out!).
>> >
>> > Attached is a patch that attempts to address this issue,
>> > with included test case (by far the larger time-sink after your
>> > spot-on analysis).
>> >
>> > Thanks for taking a look and letting me take a crack at fixing this
>> > properly :).
>> >
>> > ~Will
>> >
>> >
>> > On Thu, Oct 17, 2013 at 5:49 AM, Alexey Samsonov <samsonov at google.com>
>> > wrote:
>> >> Hi Will,
>> >>
>> >> On Thu, Oct 17, 2013 at 12:51 AM, Will Dietz <w at wdtz.org> wrote:
>> >>>
>> >>> Fixes bug exposed by tsan lit tests where addresses fail to be
>> >>> symbolized on my system (x86_64 linux).
>> >>>
>> >>> An example of this failure can be seen with this binary[1]:
>> >>>
>> >>> $ unxz ./thread_leak.3.c.tmp.xz
>> >>>
>> >>> Using llvm-symbolizer from ToT:
>> >>>
>> >>> $ echo ./thread_leak3.c.tmp 0x020560 |
>> >>> ~/llvm/build/bin/llvm-symbolizer
>> >>> __interceptor_pthread_create
>> >>> ??:0:0
>> >>>
>> >>> And after:
>> >>>
>> >>> $ echo ./thread_leak3.c.tmp 0x020560|~/llvm/build/bin/llvm-symbolizer
>> >>> __interceptor_pthread_create
>> >>>
>> >>>
>> >>> /home/will/llvm/latest/projects/compiler-rt/lib/tsan/rtl/tsan_interceptors.cc:876:0
>> >>>
>> >>> Proposed patch attached.
>> >>
>> >>
>> >> Interesting. I agree that llvm-symbolizer should perform at least as
>> >> good
>> >> with --inlining=true
>> >> than without it, but the fix should probably go the DWARF parser in
>> >> DebugInfo library.
>> >>
>> >> Here's the DWARF entry for __interceptor_pthread_create in your binary:
>> >>
>> >> 0x0002c37a:   DW_TAG_subprogram [182] *
>> >>                 DW_AT_external [DW_FORM_flag_present]   (true)
>> >>                 DW_AT_name [DW_FORM_strp]       (
>> >> .debug_str[0x00012957] =
>> >> "__interceptor_pthread_create")
>> >>                 DW_AT_decl_file [DW_FORM_data1] (0x01)
>> >>                 DW_AT_decl_line [DW_FORM_data2] (0x036b)
>> >>                 DW_AT_type [DW_FORM_ref4]       (cu + 0x49a0 =>
>> >> {0x00014e6e})
>> >>                 DW_AT_low_pc [DW_FORM_addr]     (0x0000000000020560)
>> >>                 DW_AT_high_pc [DW_FORM_data8]   (0x000000000000015f)
>> >> <-------------------- [1]
>> >>                 DW_AT_frame_base [DW_FORM_exprloc]      (<0x1> 9c )
>> >>                 DW_AT_Unknown_2117 [DW_FORM_flag_present]       (true)
>> >>                 DW_AT_sibling [DW_FORM_ref4]    (cu + 0x1c267 =>
>> >> {0x0002c735})
>> >>
>> >> [1] DW_AT_high_pc has different DW_FORM here and actually means the
>> >> size of
>> >> the functions, not its largest address.
>> >> My guess is DWARF parser doesn't know about this and fails to build a
>> >> correct address range for the function. I'm going
>> >> to investigate this soon.
>> >>
>> >> Thanks for the reproducer!
>> >>
>> >>>
>> >>> ~Will
>> >>>
>> >>> [1] http://wdtz.org/files/thread_leak3.c.tmp.xz
>> >>>
>> >>> _______________________________________________
>> >>> llvm-commits mailing list
>> >>> llvm-commits at cs.uiuc.edu
>> >>> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
>> >>>
>> >>
>> >>
>> >>
>> >> --
>> >> Alexey Samsonov, MSK
>
>
>
>
> --
> Alexey Samsonov, MSK