Re: [Patch, PR Fortran/90069] Polymorphic Return Type Memory Leak Without Intermediate Variable

[Harald Anlauf <anlauf@gmx.de>]

Hi Andre,

On 5/28/24 14:10, Andre Vehreschild wrote:
> Hi all,
> 
> the attached patch fixes a memory leak with unlimited polymorphic return types.
> The leak occurred, because an expression with side-effects was evaluated twice.
> I have substituted the check for non-variable expressions followed by creating a
> SAVE_EXPR with checking for trees with side effects and creating temp. variable
> and freeing the memory.

this looks good to me.  It also solves the runtime memory leak in 
testcase pr114012.f90 .  Nice!

> Btw, I do not get the SAVE_EXPR in the old code. Is there something missing to
> manifest it or is a SAVE_EXPR not meant to be evaluated twice?

I was assuming that the comment in gcc/tree.h applies here:

/* save_expr (EXP) returns an expression equivalent to EXP
    but it can be used multiple times within context CTX
    and only evaluate EXP once.  */

I do not know what the practical difference between a SAVE_EXPR
and a temporary explicitly evaluated once (which you have now)
is, except that you can free the temporary cleanly.

> Anyway, regtested ok on Linux-x86_64-Fedora_39. Ok for master?

Yes, this is fine from my side.  If you are inclined to backport
to e.g. 14-branch after a grace period, that would be great.

> This work is funded by the Souvereign Tech Fund. Yes, the funding has been
> granted and Nicolas, Mikael and me will be working on some Fortran topics in
> the next 12-18 months.

This is really great news!

> Regards,
> 	Andre

Thanks for the patch!

Harald

> --
> Andre Vehreschild * Email: vehre ad gmx dot de