[Bug libfortran/26890] New: SIZE parameter interacts with same variable in IO list character length specification.

[Bug libfortran/26890] New: SIZE parameter interacts with same variable in IO list character length specification.

[pault at gcc dot gnu dot org]

The program below produces the correct result for the first read and nothing
for the second.  ifort and g95 produce the same result for each.  It is my
belief that this construct is not strictly standard compliant but it is widely
used - I found this during my efforts to make iso_varying_string work.

The code looks OK, so I think that the logic in the library needs a little bit
of tweaking:

  nchars = 80;
  {
    struct __st_parameter_dt dt_parm.8;

    dt_parm.8.common.filename = "advance_io.f90";
    dt_parm.8.common.line = 21;
    dt_parm.8.common.unit = 10;
    dt_parm.8.advance = "no";
    dt_parm.8.advance_len = 2;
    dt_parm.8.format = "(a)";
    dt_parm.8.format_len = 3;
    dt_parm.8.size = &nchars;
    dt_parm.8.common.flags = 13328;
    _gfortran_st_read (&dt_parm.8);
    _gfortran_transfer_character (&dt_parm.8, &buffer, NON_LVALUE_EXPR
<nchars>) ;
    _gfortran_st_read_done (&dt_parm.8);
    switch (dt_parm.8.common.flags & 3)
      {
        case 3:;
        goto __label_000999;
      }
  }

Paul

  character(80) :: buffer, line
  integer :: nchars
  line = "The quick brown fox jumps over the lazy dog."
  open (10)
  write (10, '(a)') trim(line)
  rewind (10)
  nchars = 80
  read (10, '(a)', advance = 'no', size = nchars, eor = 998) buffer
998 print *, nchars, buffer
  rewind (10)
  buffer = ""
  nchars = 80
  read (10, '(a)', advance = 'no', size = nchars, eor = 999) buffer (:nchars)
999 print *, nchars, buffer
  close (10)
end


-- 
           Summary: SIZE parameter interacts with same variable in IO list
                    character length specification.
           Product: gcc
           Version: 4.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libfortran
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: pault at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26890

[Bug libfortran/26890] SIZE parameter interacts with same variable in IO list character length specification.

[jvdelisle at gcc dot gnu dot org]

------- Comment #1 from jvdelisle at gcc dot gnu dot org  2006-03-28 01:43 -------
I will look into this if you would like.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26890

[Bug libfortran/26890] SIZE parameter interacts with same variable in IO list character length specification.

[paulthomas2 at wanadoo dot fr]

------- Comment #2 from paulthomas2 at wanadoo dot fr  2006-03-28 04:08 -------
Subject: Re:  SIZE parameter interacts with same variable
 in IO list character length specification.

jvdelisle at gcc dot gnu dot org wrote:

>------- Comment #1 from jvdelisle at gcc dot gnu dot org  2006-03-28 01:43 -------
>I will look into this if you would like.
>  
>
Yes, indeed - you are the expert, which was why I CC'd you....

All the best,

Paul

PS I suppose that the library zeros the variable pointed too by SIZE.  
This then leads to the calculation that the destination has zero length 
and that nothing should be read?  I guess a copy of SIZE is needed to 
work with an that it should be written back on exiting the library?


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26890

[Bug libfortran/26890] SIZE parameter interacts with same variable in IO list character length specification.

[jvdelisle at gcc dot gnu dot org]

------- Comment #3 from jvdelisle at gcc dot gnu dot org  2006-03-31 05:11 -------
Subject: Bug 26890

Author: jvdelisle
Date: Fri Mar 31 05:11:03 2006
New Revision: 112570

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=112570
Log:
2006-03-30  Jerry DeLisle  <jvdelisle@gcc.gnu.org>

        PR libgfortran/26890
        * io/io.h: Add size_used to st_parameter_dt, adjust pad size.
        *io/transfer.c (data_transfer_init): Initialize size_used to zero.
        (read_sf): Use size_used.
        (read_block): Likewise.
        (read_block_direct): Likewise.
        (write_block): Likewise.
        (write_buf): Likewise and eliminate erroneous FAILURE return.
        (finalize_transfer): Assign value of size_used to *dtp->size.

Modified:
    trunk/libgfortran/ChangeLog
    trunk/libgfortran/io/io.h
    trunk/libgfortran/io/transfer.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26890

[Bug libfortran/26890] SIZE parameter interacts with same variable in IO list character length specification.

[jvdelisle at gcc dot gnu dot org]

------- Comment #4 from jvdelisle at gcc dot gnu dot org  2006-03-31 05:15 -------
Subject: Bug 26890

Author: jvdelisle
Date: Fri Mar 31 05:15:42 2006
New Revision: 112571

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=112571
Log:
2006-03-30  Jerry DeLisle  <jvdelisle@gcc.gnu.org>

        PR libgfortran/26890
        * gfortran.dg/read_size_noadvance.f90: New test.

Added:
    trunk/gcc/testsuite/gfortran.dg/read_size_noadvance.f90
Modified:
    trunk/gcc/testsuite/ChangeLog


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26890

[Bug libfortran/26890] SIZE parameter interacts with same variable in IO list character length specification.

[sje at cup dot hp dot com]

------- Comment #5 from sje at cup dot hp dot com  2006-04-07 17:02 -------
I believe this patch is causing a bunch of IO failures on ia64-hp-hpux11.23. 
Specifically, the setting of "pad" looks bad to me.  pad, in this case, is not
a padding on the end of the structure but a parallel array of chars that is in
union u and should be the same size as the structure p and using the same space
as the structure p.  I think the fix is to increase the size of pad, not
decrease it.  I will do some testing and see if I am right.


-- 

sje at cup dot hp dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |sje at cup dot hp dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26890

[Bug libfortran/26890] SIZE parameter interacts with same variable in IO list character length specification.

[jvdelisle at gcc dot gnu dot org]

------- Comment #6 from jvdelisle at gcc dot gnu dot org  2006-04-07 18:42 -------
We posted a question about that on the list.  Not knowing the purpose of pad, I
took a guess.  Let me know what you learn.  Appreciate your testing this and
reporting.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26890

[Bug libfortran/26890] SIZE parameter interacts with same variable in IO list character length specification.

[jvdelisle at gcc dot gnu dot org]

------- Comment #7 from jvdelisle at gcc dot gnu dot org  2006-04-07 18:50 -------
Another thought.  If comment #5 about size of p is true, why not set pad to
sizeof(p)?  Why was it so oddly constructed in the first place?


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26890

[Bug libfortran/26890] SIZE parameter interacts with same variable in IO list character length specification.

[sje at cup dot hp dot com]

------- Comment #8 from sje at cup dot hp dot com  2006-04-07 18:55 -------
I am not sure why it was created the way it was or why it doesn't just use
sizeof(p).  I haven't looked back into SVN/email to see if there are any
comments on why it was done the way it was done.  Do you know where structures
of type st_parameter_dt are allocated?  I looked quickly but didn't see it.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26890

[Bug libfortran/26890] SIZE parameter interacts with same variable in IO list character length specification.

[jvdelisle at gcc dot gnu dot org]

------- Comment #9 from jvdelisle at gcc dot gnu dot org  2006-04-07 19:17 -------
st_parameter_dt are declared by the front end which then passes to the library
functions.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26890

[Bug libfortran/26890] SIZE parameter interacts with same variable in IO list character length specification.

[jvdelisle at gcc dot gnu dot org]

------- Comment #10 from jvdelisle at gcc dot gnu dot org  2006-04-07 22:23 -------
I put some prints at the top of get_unit in unit.c to take a look.  After
putting the padding back where it was originally in io.h:

The DTP
Size of p: 132
Size of pad: 200
Size of char *: 4
Size if int: 4

This is OK on i686.  pad needs to be >= p

The original padding in io.h should be:

      char pad[16 * sizeof (char *) + 34 * sizeof (int)];

Steve Ellcey, could you check this on a 64 bit machine, HPUX.  I used the
following with a simple program that performed a WRITE.

gfc_unit *
get_unit (st_parameter_dt *dtp, int do_create)
{
  st_printf("The DTP\n");
  st_printf("Size of p: %d\n", sizeof(dtp->u.p));
  st_printf("Size of pad: %d\n", sizeof(dtp->u.pad));
  st_printf("Size of char *: %d\n", sizeof(char *));
  st_printf("Size if int: %d\n", sizeof(int));
...


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26890

[Bug libfortran/26890] SIZE parameter interacts with same variable in IO list character length specification.

[sje at cup dot hp dot com]

------- Comment #11 from sje at cup dot hp dot com  2006-04-07 22:36 -------
I think putting pad back to where it was is a good first step and I will see if
there is room on a 64 bit machine, I think we need some kind of test to make
sure that pad is always equal to or greater than the size of structure p and a
comment that changing the size of pad will affect compatibility.  I don't know
if we can do that check at GCC compile time though. 

I am now running into a related but slighty different problem on IA64 HP-UX. In
trans-io.c (gfc_build_st_parameter) we build the 'u' field as an array of char.
 Now in actual fact 'u' is the union of an array of char and the structure 'p'.
 On IA64 HP-UX (or any strict memory alignment machine) an array of char will
just be aligned on a 1-byte boundry, but the union would be aligned on a 4 or 8
byte boundry (whatever the largest field alignment requirement is).  So I am
accessing ->u.p.item_count and the alignment is wrong because the front-end
allocated the space based on char alignment not on int/struct alignment.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26890

[Bug libfortran/26890] SIZE parameter interacts with same variable in IO list character length specification.

[jvdelisle at gcc dot gnu dot org]

------- Comment #12 from jvdelisle at gcc dot gnu dot org  2006-04-07 23:05 -------
Subject: Bug 26890

Author: jvdelisle
Date: Fri Apr  7 23:05:12 2006
New Revision: 112769

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=112769
Log:
2006-04-07  Jerry DeLisle  <jvdelisle@gcc.gnu.org>

        PR libgfortran/26890
        * io/io.h: Revert change to pad size made on 2006-03-30.
        Add comment explaining dependency with fortran/trans-io.c.

Modified:
    trunk/libgfortran/ChangeLog
    trunk/libgfortran/io/io.h


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26890

[Bug libfortran/26890] SIZE parameter interacts with same variable in IO list character length specification.

[jvdelisle at gcc dot gnu dot org]

-- 

jvdelisle at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |jvdelisle at gcc dot gnu dot
                   |dot org                     |org
             Status|UNCONFIRMED                 |ASSIGNED
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2006-04-09 05:30:33
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26890

[Bug libfortran/26890] SIZE parameter interacts with same variable in IO list character length specification.

[sje at cup dot hp dot com]

------- Comment #13 from sje at cup dot hp dot com  2006-04-10 18:22 -------
Putting the size of pad back seems OK on IA64 in both ILP32 and LP64 modes.  In
ILP32 mode I get:

The DTP
Size of p: 136
Size of pad: 200
Size of char *: 4
Size if int: 4

In LP64 mode, both on HP-UX and Linux, I get:

The DTP
Size of p: 168
Size of pad: 264
Size of char *: 8
Size if int: 4

So we have space without changing the size of pad and by putting pad back to
the original size I do get programs to work but the alignment problem described
in comment #11 is still there waiting to hit at any time.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26890

[Bug libfortran/26890] SIZE parameter interacts with same variable in IO list character length specification.

[jvdelisle at gcc dot gnu dot org]

------- Comment #14 from jvdelisle at gcc dot gnu dot org  2006-04-14 02:31 -------
Subject: Bug 26890

Author: jvdelisle
Date: Fri Apr 14 02:31:28 2006
New Revision: 112943

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=112943
Log:
2006-04-14  Jerry DeLisle  <jvdelisle@gcc.gnu.org>

        PR libgfortran/26890
        * io/io.h: Add size_used to st_parameter_dt.
        *io/transfer.c (data_transfer_init): Initialize size_used to zero.
        (read_sf): Use size_used.
        (read_block): Likewise.
        (read_block_direct): Likewise.
        (write_block): Likewise.
        (write_buf): Likewise and eliminate erroneous FAILURE return.
        (finalize_transfer): Assign value of size_used to *dtp->size.

Modified:
    branches/gcc-4_1-branch/libgfortran/ChangeLog
    branches/gcc-4_1-branch/libgfortran/io/io.h
    branches/gcc-4_1-branch/libgfortran/io/transfer.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26890

[Bug libfortran/26890] SIZE parameter interacts with same variable in IO list character length specification.

[jvdelisle at gcc dot gnu dot org]

------- Comment #15 from jvdelisle at gcc dot gnu dot org  2006-04-14 03:14 -------
Testcase was committed to 4.1 branch as well, but I typoed the pr number so it
did not register commit here.

Fixed on 4.1 and trunk.


-- 

jvdelisle at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |4.1.1


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26890

[Bug libfortran/26890] SIZE parameter interacts with same variable in IO list character length specification.

[jvdelisle at gcc dot gnu dot org]

------- Comment #16 from jvdelisle at gcc dot gnu dot org  2006-04-14 03:16 -------
Closing


-- 

jvdelisle at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26890