Re: [PATCH] rs6000: Teach rs6000_opaque_type_invalid_use_p about gcall [PR108348]

["Kewen.Lin" <linkw@linux.ibm.com>]

Hi Segher!

on 2023/1/16 18:40, Segher Boessenkool wrote:
> Hi!
> 
> On Mon, Jan 16, 2023 at 05:20:56PM +0800, Kewen.Lin wrote:
>> on 2023/1/16 16:49, Segher Boessenkool wrote:
>>>> +/* { dg-require-effective-target powerpc_p9modulo_ok } */
>>>
>>> Please use a saner selector?  If one doesn't exist yet, make a new one?
>>> Something that just says "p9", not "modulo".
>>
>> The has_arch_pwr9 looks not suitable here as it doesn't check
>> the assembler behavior?
> 
> ?  What assembler behaviour?

I should have said assembler "support", selector powerpc_p9modulo_ok
checks if assembler supports some insn or not, but has_arch_pwr9
doesn't.

> 
>> Do you have some instruction in mind
>> for being used as the tested instruction mnemonic like modsw?
> 
> It should not test *any* instruction?
> 
> Ah.  There is no *_ok wanted or needed at all.  You simply are required
> to use a new enough binutils to fit your GCC.  During development you
> probably want something, but that should not end up in the public trees.
> You can always use -mcpu=power9.  If your toolchain is broken that will
> throw some pretty obvious errors your way; this is fine.  A user can
> always say -mcpu=power9.

> The *_ok things should only be used for features that can be disabled
> during configuration, or features that we *want* users to be able to
> turn off (like FP, VMX, VSX, or HMT or QP float, that kind of thing).
> That gives quite enough permutations to test already, we do not need to
> create a whole bunch extra for no reason :-)

Thanks for the explanation!!  I meant to use powerpc_p9modulo_ok to
exclude those cases where we can't use -mcpu=power9, as you explained we
should not worry about it!?  Since the test point requires altivec support
(which is implied when specifying -mcpu=power9, I didn't explicitly specify
it before), I think I could use powerpc_altivec_ok to replace
powerpc_p9modulo_ok here, does it sound good to you?

BR,
Kewen