[llvm-dev] GDB doesn't work with IR-originated debug info

[Jameson Nash via llvm-dev]

What version of LLVM are you using? This looks similar to a bug that I
fixed in 4.0 (R290809). I mostly only tested for `-dwarf-version 4`, so you
may get better results with using the newer format as well. But if it's
broken on the latest version of LLVM, can you post a gist/pastebin of the
LL file (e.g. `clang -S -emit-llvm`)? That'll help with reproducing it and
seeing which entry is still getting relocated incorrectly in dwarf version
2.


On Tue, Apr 4, 2017 at 11:25 AM Aliaksei Zasenka via llvm-dev <
llvm-dev at lists.llvm.org> wrote:

> Hi all,
>
> Need your help.
>
> I added some debug information to my code according to Kaleidoscope-9
> sample and got stuck with a GDB error:
>
> (gdb) info functions
> invalid dwarf2 offset 1849950870
>
>
> My module is a DLL built with llc+ld toolchain. Target triple:
> 'i686-w64-mingw32'.
> Looking this offset (1849950870 == 0x6e440296) in dwarfdump output of the
> dll gave the following:
>
> 0x00000296:   DW_TAG_base_type [10]
>                 DW_AT_name [DW_FORM_strp]    ( .debug_str[0x0000068f] =
> "void")
>                 DW_AT_encoding [DW_FORM_data1]    (0x00)
>                 DW_AT_byte_size [DW_FORM_data1]    (0x00)
> ....
> 0x00000cf8:   DW_TAG_subprogram [16] *
>                 DW_AT_low_pc [DW_FORM_addr]    (0x000000006e384c30)
>                 DW_AT_high_pc [DW_FORM_data4]    (0x000002b4)
>                 DW_AT_frame_base [DW_FORM_exprloc]    (<0x1> 54 )
>                 DW_AT_name [DW_FORM_strp]    ( .debug_str[0x00001616] =
> "FB_FPUMP at HORIZONTAL")
>                 DW_AT_type [DW_FORM_ref_addr]    (*0x000000006e440296*)
>                 DW_
> AT_external [DW_FORM_flag_present]    (true)
>
>
> In the original object file the corresponding record was:
>
> 0x00000296:   DW_TAG_base_type [10]
>                 DW_AT_name [DW_FORM_strp]    ( .debug_str[0x0000068f] =
> "void")
>                 DW_AT_encoding [DW_FORM_data1]    (0x00)
>                 DW_AT_byte_size [DW_FORM_data1]    (0x00)
> ....
>
> 0x00000cf8:   DW_TAG_subprogram [16] *
>                 DW_AT_low_pc [DW_FORM_addr]    (0x00000000000037e0)
>                 DW_AT_high_pc [DW_FORM_data4]    (0x000002b4)
>                 DW_AT_frame_base [DW_FORM_exprloc]    (<0x1> 54 )
>                 DW_AT_name [DW_FORM_strp]    ( .debug_str[0x00001616] =
> "FB_FPUMP at HORIZONTAL")
>                 DW_AT_type [DW_FORM_ref_addr]    (*0x0000000000000296*)
>                 DW_AT_external [DW_FORM_flag_present]    (true)
>
>
> There are lots of subprogram records like this.
>
> Any ideas what may be done to fix that?
>
> My debugger config:
> GNU gdb (GDB) 7.10.1
> This GDB was configured as "i686-w64-mingw32".
> OS : Win7 64-bit
>
> --
> Best regards,
> Alexey Zasenko
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
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