How to get GCC on par with ICC?

[Paul Menzel]

Dear Joel,


Thank you for your quick reply.


On 06/06/18 17:57, Joel Sherrill wrote:
> On Wed, Jun 6, 2018 at 10:51 AM, Paul Menzel wrote:

>> Some scientists in our organization still want to use the Intel compiler,
>> as they say, it produces faster code, which is then executed on clusters.
>> Some resources on the Web [1][2] confirm this. (I am aware, that it’s
>> heavily dependent on the actual program.)
> 
> Do they have specific examples where icc is better for them? Or can point
> to specific GCC PRs which impact them?
> 
> GCC versions?
> 
> Are there specific CPU model variants of concern?
> 
> What flags are used to compile? Some times a bit of advice can produce
> improvements.
> 
> Without specific examples, it is hard to set goals.

I could get such examples, but it will take some time, as it’s from 
other institutes.

The clusters use exclusively Intel processors. (Hopefully, that will 
change.)

I also found the article from the German Linux-Magazin in an English 
version at the ADMIN Magazin [3]. The German article had a more strong 
statement, that they use the Intel compilers due to performance reasons.

>> My question is, is it realistic, that GCC could catch up and that the
>> scientists will start to use it over Intel’s compiler? Or will Intel
>> developers always have the lead, because they have secret documentation and
>> direct contact with the processor designers?
>>
>> If it is realistic, how can we get there? Would first the program be
>> written, and then the compiler be optimized for that? Or are just more GCC
>> developers needed?
> 
> For sure examples are needed so there are test cases to use for reference.
> 
> If you want anything improved in any free software project, sponsoring
> developers is always a good thing. If you sponsor the right developers. :)

That’s what I hoped for, but didn’t ask here. If you could point me to a 
list of possible contractors, that would be great.

Please keep in mind, that in my organization certain decisions are made 
*very* slowly. I’ll try to get answers quickly, but procuring finances 
might take longer (half a year or much longer).


Kind regards,

Paul


>> [1]: https://colfaxresearch.com/compiler-comparison/
>> [2]: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.679.1280&rep=rep1&type=pdf
[3] 
http://www.admin-magazine.com/HPC/Articles/Selecting-Compilers-for-a-Supercomputer 
    "HPC Compilers"

-------------- next part --------------
A non-text attachment was scrubbed...
Name: smime.p7s
Type: application/pkcs7-signature
Size: 5174 bytes
Desc: S/MIME Cryptographic Signature
URL: <https://gcc.gnu.org/pipermail/gcc/attachments/20180606/73685322/attachment.p7s>