user stack support for TMP_ALLOC

Bill Allombert allomber at
Thu Oct 7 18:28:09 CEST 2004

On Thu, Oct 07, 2004 at 05:57:39PM +0200, Torbjorn Granlund wrote:
> Bill Allombert <allomber at> writes:
>   The only issue we have with this multiprecision kernel is the alloca stack
>   overflow problem.
> We are changning the use of alloca for GMP 5.  It will never allocate large
> chunks on the stack.  That change should make the stack usage very small.

That is a very good news! Also I see on your website you plan to add
more mpn_ routine, that also will be very useful to us.

>   I have written a patch [snip]
> I am unfortunately rejecting your patch.  Some usages of alloca in GMP are
> too critical for going through a mechanism such as the one you are
> proposing.

Are you implying that --enable-alloca=stack would be slower than
--enable-alloca=noreentrant, or did I seriously misunderstood how
TMP_ALLOC is used ?

Anyway, GMP 5 should make this patch useless.


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