memory allocation

[Marc Glisse]

On Sat, 5 Jun 2010, Torbjorn Granlund wrote:

> Marc Glisse <marc.glisse at inria.fr> writes:
>
>  There are many places where the required size could be computed more
>  tightly...
>
> It is not clear how to make it more tightly in the case of
> mpz_cdiv_q_2exp, though, without adding more logic.

That's exactly what I said. You can compute a better bound, but computing 
that bound is more complicated (for this function, the mpn_add_1 can only 
require an extra limb if the shift is by a multiple of the limb size, and 
this test should be enough to never allocate more than 1 extra limb).

> What other places do you have in mind?

Last time I posted something related, your answer was:
"*If* it is a good idea, the same trick applies to dozens of other places 
in GMP."
http://gmplib.org/list-archives/gmp-bugs/2008-August/001135.html

(no, I don't have anything particular in mind)



By the way, the GMP manual already documents the memory requirements of 
several mpz functions in mpz_array_init. I am not sure it would hurt that 
much to document very conservative bounds (as opposed to tight bounds on 
the current behavior), although that's yet more work...

-- 
Marc Glisse