[PATCH] Automatics in equivalence statements

[Jeff Law]

On 6/24/19 2:19 AM, Bernhard Reutner-Fischer wrote:
> On Fri, 21 Jun 2019 07:10:11 -0700
> Steve Kargl <sgk@troutmask.apl.washington.edu> wrote:
> 
>> On Fri, Jun 21, 2019 at 02:31:51PM +0100, Mark Eggleston wrote:
>>> Currently variables with the AUTOMATIC attribute can not appear in an 
>>> EQUIVALENCE statement. However its counterpart, STATIC, can be used in 
>>> an EQUIVALENCE statement.
>>>
>>> Where there is a clear conflict in the attributes of variables in an 
>>> EQUIVALENCE statement an error message will be issued as is currently 
>>> the case.
>>>
>>> If there is no conflict e.g. a variable with a AUTOMATIC attribute and a 
>>> variable(s) without attributes all variables in the EQUIVALENCE will 
>>> become AUTOMATIC.
>>>
>>> Note: most of this patch was written by Jeff Law <law@redhat.com>
>>>
>>> Please review.
>>>
>>> ChangeLogs:
>>>
>>> gcc/fortran
>>>
>>>      Jeff Law  <law@redhat.com>
>>>      Mark Eggleston  <mark.eggleston@codethink.com>
>>>
>>>  Â Â Â  * gfortran.h: Add check_conflict declaration.  
>>
>> This is wrong.  By convention a routine that is not static
>> has the gfc_ prefix.
>>
> Furthermore doesn't this export indicate that you're committing a
> layering violation somehow?
Possibly.  I'm the original author, but my experience in our fortran
front-end is minimal.  I fully expected this patch to need some tweaking.

We certainly don't want to recreate all the checking that's done in
check_conflict.  We just need to defer it to a later point --
find_equivalence seemed like a good point since we've got the full
equivalence list handy and can accumulate the attributes across the
entire list, then check for conflicts.

If there's a concrete place where you think we should be doing this, I'm
all ears.


> 
>>  Â Â Â  * symbol.c (check_conflict): Remove automatic in equivalence conflict
>>  Â Â Â  check.
>>  Â Â Â  * symbol.c (save_symbol): Add check for in equivalence to stop the
>>  Â Â Â  the save attribute being added.
>>  Â Â Â  * trans-common.c (build_equiv_decl): Add is_auto parameter and
>>  Â Â Â  add !is_auto to condition where TREE_STATIC (decl) is set.
>>  Â Â Â  * trans-common.c (build_equiv_decl): Add local variable is_auto,
>>  Â Â Â  set it true if an atomatic attribute is encountered in the variable
> 
> atomatic? I read atomic but you mean automatic.
Yes.

> 
>>      list.  Call build_equiv_decl with is_auto as an additional parameter.
>>  Â Â Â  flag_dec_format_defaults is enabled.
>>  Â Â Â  * trans-common.c (accumulate_equivalence_attributes) : New subroutine.
>>  Â Â Â  * trans-common.c (find_equivalence) : New local variable dummy_symbol,
>>  Â Â Â  accumulated equivalence attributes from each symbol then check for
>>  Â Â Â  conflicts.
> 
> I'm just curious why you don't gfc_copy_attr for the most part of accumulate_equivalence_attributes?
> thanks,
Simply didn't know about it.  It could probably significantly simplify
the accumulation of attributes step.

Jeff