Re: [PATCH v2] rs6000: Rework option -mpowerpc64 handling [PR106680]

[Sebastian Huber <sebastian.huber@embedded-brains.de>]

Hello,

On 27.12.22 11:16, Kewen.Lin via Gcc-patches wrote:
> Hi Segher,
> 
> on 2022/12/24 04:26, Segher Boessenkool wrote:
>> Hi!
>>
>> On Wed, Oct 12, 2022 at 04:12:21PM +0800, Kewen.Lin wrote:
>>> PR106680 shows that -m32 -mpowerpc64 is different from
>>> -mpowerpc64 -m32, this is determined by the way how we
>>> handle option powerpc64 in rs6000_handle_option.
>>>
>>> Segher pointed out this difference should be taken as
>>> a bug and we should ensure that option powerpc64 is
>>> independent of -m32/-m64.  So this patch removes the
>>> handlings in rs6000_handle_option and add some necessary
>>> supports in rs6000_option_override_internal instead.
>>
>> Sorry for the late review.
>>
>>> +  /* Don't expect powerpc64 enabled on those OSes with OS_MISSING_POWERPC64,
>>> +     since they don't support saving the high part of 64-bit registers on
>>> +     context switch.  If the user explicitly specifies it, we won't interfere
>>> +     with the user's specification.  */
>>
>> It depends on the OS, and what you call "context switch".  For example
>> on Linux the context switches done by the kernel are fine, only things
>> done by setjmp/longjmp and getcontext/setcontext are not.  So just be a
>> bit more vague here?  "Since they do not save and restore the high half
>> of the GPRs correctly in all cases", something like that?
>>
>> Okay for trunk like that.  Thanks!
>>
> 
> Thanks!  Adjusted as you suggested and committed in r13-4894-gacc727cf02a144.

I am a bit late, however, this broke the 32-bit support for -mcpu=e6500. 
For RTEMS, I have the following multilibs:

MULTILIB_REQUIRED += mcpu=e6500/m32
MULTILIB_REQUIRED += mcpu=e6500/m32/mvrsave
MULTILIB_REQUIRED += mcpu=e6500/m32/msoft-float/mno-altivec
MULTILIB_REQUIRED += mcpu=e6500/m64
MULTILIB_REQUIRED += mcpu=e6500/m64/mvrsave

I configured GCC as a bi-arch compiler (32-bit and 64-bit). It seems you 
removed the -m32 handling, so I am not sure how to approach this issue. 
I added a test case to the PR:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106680

-- 
embedded brains GmbH & Co. KG
Herr Sebastian HUBER
Dornierstr. 4
82178 Puchheim
Germany
email: sebastian.huber@embedded-brains.de
phone: +49-89-18 94 741 - 16
fax:   +49-89-18 94 741 - 08

Registergericht: Amtsgericht München
Registernummer: HRB 157899
Vertretungsberechtigte Geschäftsführer: Peter Rasmussen, Thomas Dörfler
Unsere Datenschutzerklärung finden Sie hier:
https://embedded-brains.de/datenschutzerklaerung/