[patch, fortran] PR 84487

[patch, fortran] PR 84487

[Thomas Koenig]

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Hello world,

this patch makes sure that the __def_init variables, which have been
generated for normal allocatable arrays for quite some time, do not fill
up huge amounts of space in the object files with zeros. This is done by
not marking them read-only, which means that they are put into the BSS.

Setting DECL_ARTIFICIAL on the __def_init variable makes sure it
is handled as predetermined shared in gfc_omp_predetermined_sharing .

This is not an optimum solution. As the xfail shows, we are now missing
out on an optimization (as seen by the xfail that is now needed), and
having large all-zero variables seems wrong. However, this patch solves
the most urgent problem in this respect.

This is an 8/9/10 regression, so I would like to commit this to
all of these branches (waiting before gcc 9 reopens, of course).

I wold then close the PR and open an enchancement PR for the xfail
and the design improvement.

Test case... I'm not sure what to test for.

Regression-tested. OK for all affected branches?

Regards

	Thomas

2019-09-25  Thomas Koenig <tkoenig@gcc.gnu.org>

	PR fortran/84487
	* trans-decl.c (gfc_get_symbol_decl): For __def_init, set
	DECL_ARTIFICAL and do not set TREE_READONLY.

2019-09-25  Thomas Koenig <tkoenig@gcc.gnu.org>

	PR fortran/84487
	* gfortran.dg/typebound_call_22.f03: xfail.

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Index: fortran/trans-decl.c
===================================================================
--- fortran/trans-decl.c	(Revision 275719)
+++ fortran/trans-decl.c	(Arbeitskopie)
@@ -1911,9 +1911,13 @@ gfc_get_symbol_decl (gfc_symbol * sym)
   if (sym->attr.associate_var)
     GFC_DECL_ASSOCIATE_VAR_P (decl) = 1;
 
+  /* We no longer mark __def_init as read-only so it does not take up
+     space in the read-only section and dan go into the BSS instead,
+     see PR 84487.  Marking this as artificial means that OpenMP will
+     treat this as predetermined shared.  */
   if (sym->attr.vtab
       || (sym->name[0] == '_' && gfc_str_startswith (sym->name, "__def_init")))
-    TREE_READONLY (decl) = 1;
+    DECL_ARTIFICIAL (decl) = 1;
 
   return decl;
 }
Index: testsuite/gfortran.dg/typebound_call_22.f03
===================================================================
--- testsuite/gfortran.dg/typebound_call_22.f03	(Revision 275713)
+++ testsuite/gfortran.dg/typebound_call_22.f03	(Arbeitskopie)
@@ -26,4 +26,4 @@ program test
   call x%bar ()
 end program
 
-! { dg-final { scan-tree-dump-times "base \\(\\);" 1 "optimized" } }
+! { dg-final { scan-tree-dump-times "base \\(\\);" 1 "optimized" { xfail *-*-* } } }

Re: [patch, fortran] PR 84487

[Steve Kargl]

On Wed, Sep 25, 2019 at 10:24:51PM +0200, Thomas Koenig wrote:
> 
> this patch makes sure that the __def_init variables, which have been
> generated for normal allocatable arrays for quite some time, do not fill
> up huge amounts of space in the object files with zeros. This is done by
> not marking them read-only, which means that they are put into the BSS.
> 
> Setting DECL_ARTIFICIAL on the __def_init variable makes sure it
> is handled as predetermined shared in gfc_omp_predetermined_sharing .
> 
> This is not an optimum solution. As the xfail shows, we are now missing
> out on an optimization (as seen by the xfail that is now needed), and
> having large all-zero variables seems wrong. However, this patch solves
> the most urgent problem in this respect.
> 
> This is an 8/9/10 regression, so I would like to commit this to
> all of these branches (waiting before gcc 9 reopens, of course).
> 
> I wold then close the PR and open an enchancement PR for the xfail
> and the design improvement.
> 
> Test case... I'm not sure what to test for.
> 
> Regression-tested. OK for all affected branches?
> 

Your approach seems reasonable to me.  You may want to
ping Jakub or Tobias as this affects openmp.

-- 
Steve

Re: [patch, fortran] PR 84487

[Thomas Koenig]

Hi,

Jakub, do you have any comments?  After Seve's OK I plan to commit in a
couple of days unless I read anything to the contrary.

Regards

	Thomas

>> this patch makes sure that the __def_init variables, which have been
>> generated for normal allocatable arrays for quite some time, do not fill
>> up huge amounts of space in the object files with zeros. This is done by
>> not marking them read-only, which means that they are put into the BSS.
>>
>> Setting DECL_ARTIFICIAL on the __def_init variable makes sure it
>> is handled as predetermined shared in gfc_omp_predetermined_sharing .
>>
>> This is not an optimum solution. As the xfail shows, we are now missing
>> out on an optimization (as seen by the xfail that is now needed), and
>> having large all-zero variables seems wrong. However, this patch solves
>> the most urgent problem in this respect.
>>
>> This is an 8/9/10 regression, so I would like to commit this to
>> all of these branches (waiting before gcc 9 reopens, of course).
>>
>> I wold then close the PR and open an enchancement PR for the xfail
>> and the design improvement.
>>
>> Test case... I'm not sure what to test for.
>>
>> Regression-tested. OK for all affected branches?
>>
> 
> Your approach seems reasonable to me.  You may want to
> ping Jakub or Tobias as this affects openmp.
>