[Bug fortran/38319] Memory leaks in allocatable component expressions

[Bug fortran/38319] Memory leaks in allocatable component expressions

[xiaoyuanbo at yeah dot net]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38319

xiaoyuanbo <xiaoyuanbo at yeah dot net> changed:

           What    |Removed                     |Added
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                 CC|                            |xiaoyuanbo at yeah dot net

--- Comment #6 from xiaoyuanbo <xiaoyuanbo at yeah dot net> 2012-02-22 12:54:34 UTC ---
you know that title

[Bug fortran/38319] Memory leaks in allocatable component expressions

[janus at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=38319

janus at gcc dot gnu.org changed:

           What    |Removed                     |Added
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                 CC|                            |janus at gcc dot gnu.org

--- Comment #7 from janus at gcc dot gnu.org ---
I think it is indeed expected for valgrind to report leaks for the code in
comment 5, since variables in the main program are not supposed to be
auto-deallocated in F08.

Valgrind does not show any leaks if I put x into a subroutine:

  type :: thytype
    integer(4), allocatable :: h(:)
  end type thytype
  type :: mytype
    type(thytype), allocatable :: q(:)
  end type mytype
contains
  subroutine s
    type (mytype) :: x
    x = mytype ([thytype([555])])
  end subroutine
end

One should check the test cases listed in comment 0, in order to see if they
still show leaks and if those are actual bugs.

[Bug fortran/38319] Memory leaks in allocatable component expressions

[janus at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=38319

--- Comment #8 from janus at gcc dot gnu.org ---
(In reply to Paul Thomas from comment #0)
> alloc_comp_assign_4.f90      nested constructors(line 56)

With current trunk I see additional leaks in lines 28 and 29. Those are again
due to not auto-deallocating variables in the main program, which is an F08
feature, not a gfortran bug.

The leak in line 56 persists. Here is a reduced test case for that:

  type :: a
    character(4), allocatable :: ch(:)
  end type a
  call test_ab6 ()
contains
  subroutine test_ab6 ()
    type b
      type(a)  :: a
    end type b
    type c
      type(b), allocatable :: b(:) 
    end type c
    type(c)    :: p
    p = c((/b(a((/"Mary","Lamb"/)))/))
  end subroutine
end

While 4.4 shows only a single 8-byte leak, 4.6 to trunk shows two of them.

[Bug fortran/38319] Memory leaks in allocatable component expressions

[burnus at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=38319

Tobias Burnus <burnus at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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                 CC|                            |burnus at gcc dot gnu.org

--- Comment #11 from Tobias Burnus <burnus at gcc dot gnu.org> ---
Related / same issue:
https://gcc.gnu.org/pipermail/fortran/2021-January/055654.html

[Bug fortran/38319] Memory leaks in allocatable component expressions

[pault at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=38319

--- Comment #12 from Paul Thomas <pault at gcc dot gnu.org> ---
(In reply to Tobias Burnus from comment #11)
> Related / same issue:
> https://gcc.gnu.org/pipermail/fortran/2021-January/055654.html

Hi Tobias,

Over the weekend, I had a stab at fixing this recent issue. I can fix this but
at the risk of increasing the problem of leaks in the original examples in this
PR and causing some regressions.

I am going to make the testcase for PR98342 leak free so that the the specific
problems are separated.

Cheers

Paul

[Bug fortran/38319] Memory leaks in allocatable component expressions

[burnus at gcc dot gnu dot org]

------- Comment #5 from burnus at gcc dot gnu dot org  2010-02-25 13:54 -------
  type :: thytype
    integer(4), allocatable :: h(:)
  end type thytype
  type :: mytype
    type(thytype), allocatable :: q(:)
  end type mytype
  type (mytype) :: x
  x = mytype ([thytype([555])])
end

Reduced test case. If I read the dump correctly, one effectively does:

 tmp = thytype([555])
 x = mytype(tmp)

however, for "mytype(tmp)" the data is copied instead of simply assigning the
pointer "tmp.data" and "tmp.data" is never freed.

a) One creates "thytype" with the value 555:
  (*(struct thytype[1] * restrict) atmp.1.data)[0] = thytype.4;
- and recopying again:
  (*(struct thytype[1] * restrict) atmp.7.data)[S.9] = (*(struct thytype[1] *
restrict) atmp.1.data)[S.9];

b) One now assigns that data to "mytype" - but not directly but via
malloc+memcopy:
   D.1592 = (void * restrict) __builtin_malloc (MAX_EXPR <D.1591, 1>);
   (*(struct thytype[0:] * restrict) mytype.0.q.data)[S.10].h.data = D.1592;
   __builtin_memcpy ((integer(kind=4)[0:] * restrict) (*(struct thytype[0:] *
restrict) mytype.0.q.data)[S.10].h.data, (integer(kind=4)[0:] * restrict)
(*(struct thytype[1] * restrict) atmp.7.data)[S.10].h.data, D.1590 * 4);

The problem is now that "atmp.7.data.h.data" is never freed.

It would be fantastic if instead of freeing atmp.7.data.h.data one could simply
assign atmp.7.data.h.data to mytype.0.q.data[S.10].h.data without
malloc/memcpy. I am sure it is nontrivial, but I would really like to see the
number of temporaries be cut down. The dumps are pretty hard to read and we
probably give also the middle end a hard time in figuring out that we do not
need ~8 mallocs but one three - especially since the middle end does not really
optimize malloc/free (it could, but it doesn't - yet).


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38319

[Bug fortran/38319] Memory leaks in allocatable component expressions

[paul dot richard dot thomas at gmail dot com]

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------- Comment #4 from paul dot richard dot thomas at gmail dot com  2010-02-25 12:50 -------
Subject: Re:  Memory leaks in allocatable component 
        expressions

> ------- Comment #3 from burnus at gcc dot gnu dot org  2010-02-25 07:38 -------
> Paul, can you try with  valgrind --leak-check=full ? Without the =full option,
> I also do not get any line info output but just in the summary "definitely
> lost: 288 bytes in 4 blocks".

Tobias,

I cannot remember how valgrind puts it but I get the no memory leaks
possible message, even with =full.

Cheers

Possible


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38319

[Bug fortran/38319] Memory leaks in allocatable component expressions

[burnus at gcc dot gnu dot org]

------- Comment #3 from burnus at gcc dot gnu dot org  2010-02-25 07:38 -------
Paul, can you try with  valgrind --leak-check=full ? Without the =full option,
I also do not get any line info output but just in the summary "definitely
lost: 288 bytes in 4 blocks".


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38319

[Bug fortran/38319] Memory leaks in allocatable component expressions

[pault at gcc dot gnu dot org]

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------- Comment #2 from pault at gcc dot gnu dot org  2010-02-24 20:31 -------
I have been having trouble in recent times detecting these memory leaks. 
Neither FC9 nor RHEL5.2 x86_64 seem to show them with valgrind.  Since I know
that others still see them, I wonder are there any ideas what I have to do to
detect them?  It´s a tad difficult to fix the memory leaks if I cannot detect
them :-)

Paul


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38319

[Bug fortran/38319] Memory leaks in allocatable component expressions

[burnus at gcc dot gnu dot org]

------- Comment #1 from burnus at gcc dot gnu dot org  2009-07-30 19:07 -------
See also http://gcc.gnu.org/ml/fortran/2009-07/msg00260.html and PR 40899.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38319

[Bug fortran/38319] Memory leaks in allocatable component expressions

[pault at gcc dot gnu dot org]

-- 

pault at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2008-11-29 21:54:13
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38319