Re: [Patch gas/mach-o] try to specify section flags better

[Tristan Gingold <gingold at adacore dot com>]

On Feb 18, 2012, at 12:50 PM, Iain Sandoe wrote:

> I found in some tests, that:
> 	align x
> was causing the alignment padding to be zeroes - and thus broken.
> 
> This was caused by section definitions from GCC for various hot/cold/startup etc. sections which are specified the long-hand way (rather than via a canonical name).
> 
> The solution is to  examine the incoming information and try to set the section flags from that, if possible.  This is adequate for the GCC output - but, in the general case it might be wise for people to write
> 	align x,<nop>
> 
> A similar scenario causes relocation problems if we don't recognize debug sections.
> 
> OK?

Yes.  That makes sense.
I think you should add a comment here too (just the one from ChangeLog would be ok).

Tristan.

> Iain
> 
> 
> gas:
> 	* config/obj-macho.c (obj_mach_o_make_or_get_sect): In the absence of
> 	canonical information, try to determine CODE and DEBUG section flags
> 	from the mach-o section data.
> 
> --- gas/config/obj-macho.c	2012-02-12 15:42:47.000000000 +0000
> +++ gas/config/obj-macho-b.c	2012-02-18 11:42:43.000000000 +0000
> @@ -240,6 +240,16 @@ obj_mach_o_make_or_get_sect (char * segn
> 
>   if (oldflags == SEC_NO_FLAGS)
>     {
> +      if (flags == SEC_NO_FLAGS
> +	  && (specified_mask & SECT_ATTR_SPECIFIED)
> +	  && (secattr & BFD_MACH_O_S_ATTR_PURE_INSTRUCTIONS))
> +	flags |= SEC_CODE;
> +
> +      if (flags == SEC_NO_FLAGS
> +	  && (specified_mask & SECT_ATTR_SPECIFIED)
> +	  && (secattr & BFD_MACH_O_S_ATTR_DEBUG))
> +	flags |= SEC_DEBUGGING;
> +
>       /* New, so just use the defaults or what's specified.  */
>       if (! bfd_set_section_flags (stdoutput, sec, flags))
> 	as_warn (_("failed to set flags for \"%s\": %s"),
>