Re: [PATCH] powerpc: Cleanup: use actual power8 assembly mnemonics

[Adhemerval Zanella <adhemerval dot zanella at linaro dot org>]

On 28/06/2019 13:49, Gabriel F. T. Gomes wrote:
> On Thu, Jun 27 2019, Raoni Fassina Firmino wrote:
>>
>>     Does the minimum required binutils already supports
>>     ".machine power8" and related mnemonics?
>>
>> I was unable to test with binutils 2.25 (The minimum version listed on
>> INSTALL). The oldest binutils I tested was 2.26. I also failed at
>> find out on binutils repository in which version they added support for
>> power8.
>>
>> But I do have a reasonable guess to said question. Since some
>> implementations in the same folder (of my changes) already uses
>> ".machine power8" it is reasonable to assume that for some time now the
>> minimum required binutils of past glibc versions have native support for
>> power8.
> 
> I tested your patch with binutils 2.25 and it works correctly.  Your
> assumption was correct.
> 
>> Also with binutils 2.25 glibc already does not build for power because
>> the use of "xssqrtqp" which is a power9 instruction (assuming
>> --enable-multi-arch, which is the default). So 2.26 is already the "the
>> facto" minimum binutils on power.
> 
> For the sake of clarity, the problem with xssqrtqp only happens on
> powerpc64le, but I agree with your explanation.
> 
>> 2019-06-27  Raoni Fassina Firmino  <raoni@linux.ibm.com>
> 
> The patch looks good and I can commit it for you, but may I assume you
> are covered by IBM's copyright assignment?  CC'ing Tulio and Carlos,
> whom I remember understand this process.
> 

I still think it is better to add an assembler check similar to the 
compiler one on sysdeps/powerpc/powerpc64/le/configure.ac for the required
instructions.