[patch, fortran] Reduce stack use in blocked matmul

[Thomas Koenig]

Am 08.05.2017 um 18:58 schrieb Jerry DeLisle:

he attached patch reduces the stack usage by the blocked
>> version of matmul for cases where we don't need the full buffer.
>> This should improve stack usage.
>>
>> OK for trunk?
>>
> 
> OK, thanks.

Is this something we should consider for backporting to gcc-7?
I think the large block size caused
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79876 .

That one was fixed by adjusting the ridiculously low
stack size for multi-threaded applications on OSX, but
the underlying problem could still bite somewhere or
somebody else.

Opinions?

Regards

	Thomas