Re: Proper Place for builtin_define(__ELF__)

[Jeff Law <jeffreyalaw@gmail.com>]

On 7/22/2021 8:12 AM, Joel Sherrill wrote:
> On Wed, Jul 21, 2021 at 10:08 PM Jeff Law <jeffreyalaw@gmail.com> wrote:
>>
>>
>> On 7/21/2021 6:31 PM, Michael Eager wrote:
>>>
>>> On 7/21/21 5:22 PM, Joel Sherrill wrote:
>>>>
>>>> On Wed, Jul 21, 2021, 7:12 PM Michael Eager <eager@eagercon.com
>>>> <mailto:eager@eagercon.com>> wrote:
>>>>
>>>>      On 7/21/21 2:28 PM, Joel Sherrill wrote:
>>>>       > Hi
>>>>       >
>>>>       > We are in the process of porting RTEMS to the Microblaze and
>>>> gcc does
>>>>       > not have __ELF__ as a predefine. In looking around at where to
>>>>      add it,
>>>>       > it looks like there are multiple ways to do it. We see
>>>> variations on
>>>>       > the following patterns:
>>>>       >
>>>>       > + dbxelf.h
>>>>       > + OS specific header in config/
>>>>       > + Arch/OS specific header
>>>>       >
>>>>       > Integrating dbxelf.h into the microblaze seems risky for one
>>>> simple
>>>>       > builtin_define(). Adding it to config/microblaze/rtems.h won't
>>>>      address
>>>>       > the microblaze-elf target.
>>>>       >
>>>>       > A suggestion on where to add the builtin_predefine is
>>>> appreciated.
>>>>
>>>>      There are very few defines for __ELF__ in the GCC target files.
>>>>
>>>>
>>>> Many  targets include dbxelf.h from the config.gcc script. There are
>>>> 130 references to that file there. That seems to be where most
>>>> architectures get it.
>>> AFAIK, no one has ever tried to build microblaze to generate stabs,
>>> and I can't see a good reason why anyone would.  Including dbxelf.h
>>> seems wrong.  I don't have an answer why other arch's do that.
>> Avoiding dbxelf would be advisable.  We're really only supporting stabs
>> for for aix anymore.  We need to start excising dbxelf from all the
>> places it's being used.
> That will take some work.
Yup.  But it's clearly the right thing to do.

>
> What about elfos.h which is referenced 168 times in config.gcc?
>
> Unfortunately, dbxelf.h and elfos.h appear to be used together a lot.
> Grep'ing for "dbxelf.h elfos.h" in config.gcc resulted in 128 hits.
I think most of elfos.h is OK, we just need to rip out the bits for 
embedded stabs contained therein.


jeff