[PATCH] Emit DWARF info for all code section in an assembly file

[Eric Christopher]

On Thu, Apr 10, 2014 at 8:24 AM, Oliver Stannard
<oliver.stannard at arm.com> wrote:
>   > You still need a DW_AT_low_pc as the offset for the for the ranges section.
>
>   I don't think we need DW_AT_low_pc when the input is assembly, as it is optional in the DWARF spec and we do not emit any debug info which could use it.
>
>   The two reasons to include DW_AT_low_pc as well as DW_AT_ranges are:
>   * Specifying the default base address for the .debug_ranges section. We do not need this as we have a base address entry for each section in .debug_ranges, so the default never gets used.
>   * Specifying the default base address for the .debug_loc section. We do not need this as we never emit the .debug_loc section for an assembly file.
>
>   > What does GCC do here?
>
>   GCC seems to do the same as I am doing:
>   * If no sections contain code, don't emit any debug info (not even .debug_abbrev)
>   * If exactly one section contains code, use low_pc and high_pc
>   * Otherwise, use .debug_ranges
>

That's weird. It's strictly larger to do it this way and using an
offset of 0 is the same effect for this case and what gcc does if you
_don't_ just assemble it. (since, of course, it's actually gas making
this decision).

More comments on the patch.

-eric