Re: Who generate .rela.debug_info?

[Nancy <nancydreaming@gmail.com>]

>> I can't find any code in cc1 or as that generate R_X86_64_DTPOFF32 in
>> .rela.debug_info section. Did I miss something?
>
> To expand on what Nathan said: the debug info needs to refer to the
> location of the variable 'i' somehow, and as it's a TLS variable that
> location is thread specific as well, and so the normal data relocations
> can't be used.  So the dwarf info contains a location expression that uses
> this relocation and a GNU extension to push the tls address into the
> expression stack.  See e.g. the verbose asm output for the above file, the
> DIE for 'i' will contain something like this:
>
>         .uleb128 0x2    # (DIE (0x1d) DW_TAG_variable)
>         .ascii "i\0"    # DW_AT_name
>         .byte   0x1     # DW_AT_decl_file (x.c)
>         .byte   0x1     # DW_AT_decl_line
>         .long   0x31    # DW_AT_type
>                         # DW_AT_external
>         .uleb128 0xa    # DW_AT_location
>         .byte   0xe     # DW_OP_const8u
>         .long   i@dtpoff, 0
>         .byte   0xe0    # DW_OP_GNU_push_tls_address
>
> The 'i@dtpoff' is the field that causes the DTPOFF32 relocation to be
> created by the assembler.

My understand, .debug_info is generated by compiler, and that is quite
format, DIE entry, TAG, Attributes
<c1>   DW_AT_location    : 10 byte block: e 0 0 0 0 0 0 0 0 e0
(DW_OP_const8u: 0 0; DW_OP_GNU_push_tls_address or DW_OP_HP_unknown)

How ".long   i@dtpoff, 0" generated in .debug_info???  I mean that is
not that format. How it stored in DIE format?  Do you mean it not in
DIE entry, but in ASM pass adds ".long   i@dtpoff, 0" to .s, only
store in .s?

-- 
Best Regards,
Yu Rong Tan