[Bug fortran/53521] [4.5/4.6/4.7/4.8 Regression] Zero-byte "memory leak" with zero-sized array constructor (valgrind warning)

2012-05-30 Thread Joost.VandeVondele at mat dot ethz.ch 
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53521

--- Comment #6 from Joost VandeVondele  
2012-05-30 14:37:09 UTC ---
(In reply to comment #4)
> You say not doing free (0) leaks memory?  What OS is this on?  

I'm observing on a Linux box that :

MODULE TEST
 IMPLICIT NONE
CONTAINS
 SUBROUTINE T(n1)
  INTEGER :: n1(:)
 END SUBROUTINE T
 SUBROUTINE T2(n)
   INTEGER :: n
   INTEGER :: k
   CALL T((/(k,k=1,n-1)/))
 END SUBROUTINE
END MODULE
USE TEST
  DO
CALL T2(1)
  ENDDO
END 

needs 25Gb of memory after a while (notice the endless loop around CALL T2).

[Bug fortran/53521] [4.5/4.6/4.7/4.8 Regression] Zero-byte "memory leak" with zero-sized array constructor (valgrind warning)

2012-05-30 Thread jakub at gcc dot gnu.org 
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53521

Jakub Jelinek  changed:

   What|Removed |Added

 CC||jakub at gcc dot gnu.org

--- Comment #5 from Jakub Jelinek  2012-05-30 
13:49:51 UTC ---
That is clearly a bug in the Fortran FE.
  D.1888 = (integer(kind=4)[0] * restrict) __builtin_realloc ((void *)
atmp.0.data, D.1887);
  if (D.1888 == 0B && D.1887 != 0)
{
  _gfortran_os_error (&"Allocation would exceed memory limit"[1]{lb: 1
sz: 1});
}
  if (D.1887 == 0)
{
  D.1888 = 0B;
}
means that D.1888 isn't freed.  POSIX says that realloc (x, 0) acts as free
only if x is not NULL, realloc (NULL, 0) acts as malloc (0), which can either
return NULL, or a unique pointer that needs to be freed.

[Bug fortran/53521] [4.5/4.6/4.7/4.8 Regression] Zero-byte "memory leak" with zero-sized array constructor (valgrind warning)

2012-05-30 Thread rguenth at gcc dot gnu.org 
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53521

--- Comment #4 from Richard Guenther  2012-05-30 
12:46:53 UTC ---
You say not doing free (0) leaks memory?  What OS is this on?  Note that
we fold such calls away:

case BUILT_IN_FREE:
  if (integer_zerop (arg0))
return build_empty_stmt (loc);

[Bug fortran/53521] [4.5/4.6/4.7/4.8 Regression] Zero-byte "memory leak" with zero-sized array constructor (valgrind warning)

2012-05-30 Thread Joost.VandeVondele at mat dot ethz.ch 
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53521

--- Comment #3 from Joost VandeVondele  
2012-05-30 12:31:18 UTC ---
(In reply to comment #2)
> Well, I think this is a valgrind issue and not a real "leak".  Whether you
> want to "optimize" code for the non-NULL case by omitting the NULL check is
> another question of course.  It's definitely not wrong-code IMHO.

No, definitely a real bug... not a valgrind issue. If you put a loop around
'CALL T2' the process memory usage is a >1Gb in a few seconds. This is a real
issue which causes our simulation code to crash after 24h of running.