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Re: [Patch, fortran] PR20541 - allocatable components (TR15541)
On Fri, Oct 06, 2006 at 06:33:10AM +0200, Paul Thomas wrote:
> Tobias,
>
> >
> >Out of curiousity, why didn't you use alloca instead of doing all
> >this bookkeeping? Maybe because you would have needed bookkeeping
> >anyway for the case where the allocatable component would have been
> >> -fmax-stack-var-size? Or is there a simpler reason?
>
> Ignorance.
>
> Having looked at the spec. for alloca, you are right, we would have had
> to branch for > -fmax-stack-var-size; otherwise the warnings in the gcc
> manual would hold good. I will put a TODO in the code somewhere.
>
> It would simplify the code considerably - take a look for some of the
> testcases!
How portable is alloca? It's, as far as I know, not standard (neither
ANSI C nor POSIX). It's possible that it, in practice, is supported
everywhere where gfortran is supposed to work, but, to quote the
man-page of the GNU implementation of alloca:
BUGS
The alloca function is machine and compiler dependent. On
many systems its implementation is buggy. Its use is
discouraged.
Erik
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