* Re: Local arrays of variable size are allocated
@ 2016-04-13 18:18 Dominique d'Humières
2016-04-13 19:41 ` Alberto Luaces
2016-04-13 20:44 ` Dominique d'Humières
0 siblings, 2 replies; 5+ messages in thread
From: Dominique d'Humières @ 2016-04-13 18:18 UTC (permalink / raw)
To: aluaces; +Cc: fortran
> Can adjust anything so only stack space is used?
Which options are you using? You may want to try -Ofast.
Dominique
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Local arrays of variable size are allocated
2016-04-13 18:18 Local arrays of variable size are allocated Dominique d'Humières
@ 2016-04-13 19:41 ` Alberto Luaces
2016-04-13 20:44 ` Dominique d'Humières
1 sibling, 0 replies; 5+ messages in thread
From: Alberto Luaces @ 2016-04-13 19:41 UTC (permalink / raw)
To: fortran
Dominique d'Humières writes:
>> Can adjust anything so only stack space is used?
>
> Which options are you using? You may want to try -Ofast.
Spot on, Dominique! -Ofast triggers "-fstack-arrays", which does exactly
what I need.
--
Alberto
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Local arrays of variable size are allocated
2016-04-13 18:18 Local arrays of variable size are allocated Dominique d'Humières
2016-04-13 19:41 ` Alberto Luaces
@ 2016-04-13 20:44 ` Dominique d'Humières
2016-04-13 20:52 ` Alberto Luaces
1 sibling, 1 reply; 5+ messages in thread
From: Dominique d'Humières @ 2016-04-13 20:44 UTC (permalink / raw)
To: aluaces; +Cc: fortran
> Spot on, Dominique! -Ofast triggers "-fstack-arrays", which does exactly
> what I need.
Beware of pr68829.
Dominique
> Le 13 avr. 2016 à 20:18, Dominique d'Humières <dominiq@lps.ens.fr> a écrit :
>
>> Can adjust anything so only stack space is used?
>
> Which options are you using? You may want to try -Ofast.
>
> Dominique
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Local arrays of variable size are allocated
2016-04-13 20:44 ` Dominique d'Humières
@ 2016-04-13 20:52 ` Alberto Luaces
0 siblings, 0 replies; 5+ messages in thread
From: Alberto Luaces @ 2016-04-13 20:52 UTC (permalink / raw)
To: fortran
Dominique d'Humières writes:
>> Spot on, Dominique! -Ofast triggers "-fstack-arrays", which does exactly
>> what I need.
>
> Beware of pr68829.
>
Thanks! Yes, I imagined that the default was overly-conservative in
order to avoid stack overflows. I will be watching for that, even my
arrays are pretty small. That was the reason why I had a big overhead
in small, frequent-called functions.
--
Alberto
^ permalink raw reply [flat|nested] 5+ messages in thread
* Local arrays of variable size are allocated
@ 2016-04-13 17:09 Alberto Luaces
0 siblings, 0 replies; 5+ messages in thread
From: Alberto Luaces @ 2016-04-13 17:09 UTC (permalink / raw)
To: fortran
Hello,
in a procedure as
--8<---------------cut here---------------start------------->8---
subroutine name (size)
integer, intent(in) :: size
integer:: v(3, size)
v(:,:) = 0
end subroutine name
--8<---------------cut here---------------end--------------->8---
I can see that "v" is allocated with malloc() on entry (and freed on
exit), instead of being mapped into the stack.
I imagine this is done in a general basis as a protection from stack
overflows, but in my case it is adding a significant overhead.
Can adjust anything so only stack space is used?
Thanks,
--
Alberto
^ permalink raw reply [flat|nested] 5+ messages in thread
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2016-04-13 18:18 Local arrays of variable size are allocated Dominique d'Humières
2016-04-13 19:41 ` Alberto Luaces
2016-04-13 20:44 ` Dominique d'Humières
2016-04-13 20:52 ` Alberto Luaces
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2016-04-13 17:09 Alberto Luaces
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