Re: [Patch, fortran] PR66079 - [6 Regression] memory leak with source allocation in internal subprogram

[Andre Vehreschild <vehre at gmx dot de>]

Hi Paul,

thanks for the answers. I did not want to be nasty, but was just wondering, if
I only I had those problems. Given furthermore, that reviews are sparse lately,
I thought it might help, when a glitch was removed before a reviewer put his
head into it :-)

I am curious though, why we loose memory with the second point I mentioned. Do
you have an easy example for that?

Regards,
	Andre

PS: No hurry needed. I just started with investigation about what is needed for
submodules and am already encountering first questions marks with the example
in the F2008 standard (section C.8 I think). Just to let you know.

On Sat, 23 May 2015 21:40:08 +0200
Paul Richard Thomas <paul.richard.thomas@gmail.com> wrote:

> Dear Andre,
> 
> To answer your fist question - no, it doesn't. I was working with my
> laptop, which is over slow when it comes to
> updating. I should have realised that since you are working in this
> area that there might be a problem. I discovered it when I did an
> update on my workstation this afternoon. Of course the fixes are
> trivial.
> 
> As to your second question about the chunk that avoids creating an
> expr3. Yes, I am aware of the consequences. I am perfectly happy to
> insert a TODO that saying that we should effect all the good things
> that happen when the standard assignment is used in another block of
> code. Alternatively, we could make a temporary variable to which the
> expr3 is assigned that is used latter in the assignment to the
> allocated variables.  For the moment though, repeating evaluation of
> expressions seems like a small price to pay for avoiding memory
> leakage.
> 
> Cheers
> 
> Paul
> 
> 
> 
> On 23 May 2015 at 19:52, Andre Vehreschild <vehre@gmx.de> wrote:
> > Hi Paul,
> >
> > does this patch apply to current trunk cleanly? I get an issue with the last
> > hunk, because all of the prerequisites are gone since r223445. The string
> > copy is completely handled by the trans_assignment at the bottom of the if
> > (code->expr3) block. Therefore I doubt the patches last hunk is needed any
> > longer.
> >
> > Do you have an example why this hunk is needed?
> >
> > Index: gcc/fortran/trans-stmt.c
> > ===================================================================
> > *** gcc/fortran/trans-stmt.c    (revision 223233)
> > --- gcc/fortran/trans-stmt.c    (working copy)
> > *************** gfc_trans_allocate (gfc_code * code)
> > *** 5200,5206 ****
> >                 }
> >               /* else expr3 = NULL_TREE set above.  */
> >             }
> > !         else
> >             {
> >               /* In all other cases evaluate the expr3 and create a
> >                  temporary.  */
> > --- 5200,5207 ----
> >                 }
> >               /* else expr3 = NULL_TREE set above.  */
> >             }
> > !         else if (!(code->expr3->ts.type == BT_DERIVED
> > !                    && code->expr3->ts.u.derived->attr.alloc_comp))
> >             {
> >               /* In all other cases evaluate the expr3 and create a
> >                  temporary.  */
> >
> > When I get the code right, than all derived-typed source= expressions that
> > have an allocatable component will not be prepared for copy to the
> > allocated object. This also means, that functions returning an object of
> > such a type are called multiple times. Once for each object to allocate. Is
> > this really desired?
> >
> > I am sorry, that I have to say that, but the check2305.diff file does not
> > bring the testcase with it.
> >
> > Regards,
> >         Andre
> >
> >
> > On Sat, 23 May 2015 14:48:53 +0200
> > Paul Richard Thomas <paul.richard.thomas@gmail.com> wrote:
> >
> >> Dear All,
> >>
> >> This patch started out fixing a single source of memory leak and then
> >> went on to fix various other issues that I found upon investigation.
> >>
> >> The fortran ChangeLog entry is sufficiently descripive that I do not
> >> think that there is a need to say more.
> >>
> >> Bootstrapped and regtested on x86_64/FC21 - OK for trunk?
> >>
> >> I am rather sure that some of the issues go further back than 6.0. I
> >> will investigate what should be fixed for 5.2.
> >>
> >> Cheers
> >>
> >> Paul
> >>
> >> 2015-05-23  Paul Thomas  <pault@gcc.gnu.org>
> >>
> >>     PR fortran/66079
> >>     * trans-expr.c (gfc_conv_procedure_call): Allocatable scalar
> >>     function results must be freed and nullified after use. Create
> >>     a temporary to hold the result to prevent duplicate calls.
> >>     * trans-stmt.c (gfc_trans_allocate): Prevent memory leaks by
> >>     not evaluating expr3 for scalar derived types with allocatable
> >>     components. Fixed character length allocatable results and
> >>     dummies need to be dereferenced. Also, if al_len is NULL use
> >>     memsz for the string copy.
> >>
> >> 2015-05-23  Paul Thomas  <pault@gcc.gnu.org>
> >>
> >>     PR fortran/66079
> >>     * gfortran.dg/allocatable_scalar_13.f90: New test
> >
> >
> > --
> > Andre Vehreschild * Email: vehre ad gmx dot de
> 
> 
> 


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