[Dwarf-discuss] Enhancement: Dynamic DW_AT_data_bit_offset

[Cary Coutant]

This is posted as Issue 250501.1:

https://dwarfstd.org/issues/250501.1.html

-cary


On Tue, Apr 29, 2025 at 10:24 AM Tom Tromey via Dwarf-discuss <
dwarf-discuss@lists.dwarfstd.org> wrote:

> >>>>> "Simon" == Simon Marchi <simark@simark.ca> writes:
>
> Simon> Just to make sure I understand, can you clarify how
> Simon> DW_AT_data_member_location and DW_AT_bit_offset are used in this
> Simon> case?  In particular, which one is constant and which one is an
> Simon> evaluated expression?
>
> Dynamic DW_AT_data_member_location, static DW_AT_bit_offset:
>
>
>  <5><117a>: Abbrev Number: 17 (DW_TAG_member)
>     <117b>   DW_AT_name        : (indirect string, offset: 0x1959):
> another_field
> ...
>     <1188>   DW_AT_bit_offset  : 6
>     <1189>   DW_AT_data_member_location: 6 byte block: 99 3d 1 0 0 22
>  (DW_OP_call4: <0x1193>; DW_OP_plus)
> ...
>  <3><1193>: Abbrev Number: 2 (DW_TAG_dwarf_procedure)
>     <1194>   DW_AT_location    : 15 byte block: 97 94 1 37 1a 32 1e 23 7
> 38 1b 31 1c 23 3       (DW_OP_push_object_address; DW_OP_deref_size: 1;
> DW_OP_lit7; DW_OP_and; DW_OP_lit2; DW_OP_mul; DW_OP_plus_uconst: 7;
> DW_OP_lit8; DW_OP_div; DW_OP_lit1; DW_OP_minus; DW_OP_plus_uconst: 3)
>
>
> This comes from the description of this gdb patch, which includes a test
> case.  (However, you'd need a patched GCC to get this output.)
>
>     https://sourceware.org/pipermail/gdb-patches/2025-April/217289.html
>
> Tom
> --
> Dwarf-discuss mailing list
> Dwarf-discuss@lists.dwarfstd.org
> https://lists.dwarfstd.org/mailman/listinfo/dwarf-discuss
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.dwarfstd.org/pipermail/dwarf-discuss/attachments/20250501/cd81168f/attachment.htm>