Access to arrays in fortran buggy

Access to arrays in fortran buggy

[Markus Deuling]

Hi,

I see some errors in the Fortran testsuite in gdb.fortran/subarray.exp.

In subarray.f is an integer array with 7 elements which contain 1-7. The test fails when printing the
array members. The only command that works is "print array" which gives

(gdb) p array
$1 = (1, 2, 3, 4, 5, 6, 7)

whereas this
(gdb) p array(1:2)
$2 = (2, 3)

is wrong. The correct result should have been (1,2), Fortran starts counting array members with 1 instead
of 0.

This
(gdb) p array(0:1)
$3 = (1, 2)
shouldn't be possible.

Fortran language uses exp_descriptor_standard to evaluate "p array ...". 

If you for example use "p array (1:2)" GDB evaluates this expressions and sets the offset in the
corresponding "struct value" to 4 which would be correct for C language for example.

For my opinion Fortran should have its own evaluation routine for those expressions which access arrays.
If the type is not an array Fortran could fall back to the standard routines. 

What do you think about this approach? I don't want to duplicate a lot of code so I'd say I try to implemenet
a fortran specific evaluate_subexp_standard which only works for arrays. If the type is not an array it would
fall back to evaluate_subexp_standard from eval.c.

Would this be a way to go? Another idea would be to add some language specific code to evaluate_subexp_standard in eval.c
but I think this belongs to language specific callbacks.


-- 
  Markus Deuling
  GNU Toolchain for Linux on Cell BE
  deuling@de.ibm.com

Re: Access to arrays in fortran buggy

[Daniel Jacobowitz]

On Mon, Feb 11, 2008 at 01:34:15PM +0100, Markus Deuling wrote:
> For my opinion Fortran should have its own evaluation routine for
> those expressions which access arrays.  If the type is not an array
> Fortran could fall back to the standard routines.

No, this is supposed to be handled by the lower bound field in struct
type.  The test passes for me - I suspect your compiler is not
emitting correct debug info.

-- 
Daniel Jacobowitz
CodeSourcery

Re: Access to arrays in fortran buggy

[Jan Kratochvil]

On Mon, 11 Feb 2008 13:34:15 +0100, Markus Deuling wrote:
...
> (gdb) p array
> $1 = (1, 2, 3, 4, 5, 6, 7)
>
> whereas this
> (gdb) p array(1:2)
> $2 = (2, 3)
>
> is wrong. The correct result should have been (1,2), Fortran starts counting array members with 1 instead
> of 0.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22244


Regards,
Jan

Re: Access to arrays in fortran buggy

[Markus Deuling]

Hi,

Jan Kratochvil schrieb:
> On Mon, 11 Feb 2008 13:34:15 +0100, Markus Deuling wrote:
> ....
>> (gdb) p array
>> $1 = (1, 2, 3, 4, 5, 6, 7)
>>
>> whereas this
>> (gdb) p array(1:2)
>> $2 = (2, 3)
>>
>> is wrong. The correct result should have been (1,2), Fortran starts counting array members with 1 instead
>> of 0.
> 
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22244
> 

thanks for pointing me to this. I tried a g77 and now the testsuite runs fine :-)

Regards,
Markus

-- 
  Markus Deuling
  GNU Toolchain for Linux on Cell BE
  deuling@de.ibm.com