[Bug fortran/83017] DO CONCURRENT not parallelizing

rguenther at suse dot de gcc-bugzilla@gcc.gnu.org
Thu Nov 16 17:30:00 GMT 2017


https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83017

--- Comment #11 from rguenther at suse dot de <rguenther at suse dot de> ---
On November 16, 2017 5:42:02 PM GMT+01:00, "dominiq at lps dot ens.fr"
<gcc-bugzilla@gcc.gnu.org> wrote:
>https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83017
>
>--- Comment #10 from Dominique d'Humieres <dominiq at lps dot ens.fr>
>---
>> Created attachment 42621 [details]
>> updated patch
>
>AFAICT the patch does not fix the problem:
>
>without the patch
>
> PI   2.98876095    
> PI   3.14159274    
>4.742u 0.015s 0:04.77 99.5%     0+0k 0+0io 36pf+0w
>
>with the patch
>
> PI   2.98876095    
> PI   3.14159274    
>4.782u 0.012s 0:04.80 99.7%     0+0k 0+0io 0pf+0w

Please use - fopt-info-loop to verify the loop is parallelized. You have to use
- floop-parallelize-all as well due to the cost model issue. 

It might be we employ the same cost model at runtime.


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