Re: [og12] OpenACC: Don't gang-privatize artificial variables: restrict to blocks (was: [PATCH] [og12] OpenACC: Don't gang-privatize artificial variables)

[Thomas Schwinge <thomas@codesourcery.com>]

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Hi!

On 2022-10-28T10:11:04+0200, I wrote:
> On 2022-10-18T15:59:24+0100, Julian Brown <julian@codesourcery.com> wrote:
>> On Tue, 18 Oct 2022 16:46:07 +0200 Thomas Schwinge <thomas@codesourcery.com> wrote:
>>> On 2022-10-14T13:38:56+0000, Julian Brown <julian@codesourcery.com> wrote:
>>> ..., but to my surprised, that did fire in one occasion:
>>>
>>> > --- a/libgomp/testsuite/libgomp.oacc-fortran/privatized-ref-2.f90
>>> > +++ b/libgomp/testsuite/libgomp.oacc-fortran/privatized-ref-2.f90
>>> > @@ -94,9 +94,7 @@ contains
>>> >      !$acc parallel copy(array)
>>> >      !$acc loop gang private(array) ! { dg-line l_loop[incr c_loop] }
>>> >      ! { dg-note {variable 'i' in 'private' clause isn't candidate for adjusting OpenACC privatization level: not addressable} "" { target *-*-* } l_loop$c_loop }
>>> > -    ! { dg-note {variable 'array\.[0-9]+' in 'private' clause is candidate for adjusting OpenACC privatization level} "" { target *-*-* } l_loop$c_loop }
>>> > -    ! { dg-note {variable 'array\.[0-9]+' ought to be adjusted for OpenACC privatization level: 'gang'} "" { target *-*-* } l_loop$c_loop }
>>> > -    ! { dg-note {variable 'array\.[0-9]+' adjusted for OpenACC privatization level: 'gang'} "" { target { ! { openacc_host_selected || { openacc_nvidia_accel_selected && __OPTIMIZE__ } } } } l_loop$c_loop }
>>> > +    ! { dg-note {variable 'array\.[0-9]+' in 'private' clause isn't candidate for adjusting OpenACC privatization level: artificial} "" { target *-*-* } l_loop$c_loop }
>>> >      ! { dg-message {sorry, unimplemented: target cannot support alloca} PR65181 { target openacc_nvidia_accel_selected } l_loop$c_loop }
>>> >      do i = 1, 10
>>> >        array(i) = 9*i
>>>
>>> ... here.  Note "variable 'array\.[0-9]+' in 'private' clause";
>>> everywhere else we have "declared in block".
>>>
>>> As part of your verification, have you already looked into whether the
>>> new behavior is correct here, or does this one need to continue to be
>>> "adjusted for OpenACC privatization level: 'gang'"?  If the latter,
>>> should we check 'if (res && block && DECL_ARTIFICIAL (decl))' instead
>>> of 'if (res && DECL_ARTIFICIAL (decl))', or is there some wrong
>>> setting of 'DECL_ARTIFICIAL' -- or are we maybe looking at an
>>> inappropriate 'decl'? (Thinking of commit
>>> r12-7580-g7a5e036b61aa088e6b8564bc9383d37dfbb4801e "[OpenACC
>>> privatization] Analyze 'lookup_decl'-translated DECL [PR90115,
>>> PR102330, PR104774]", for example.)
>>
>> I haven't looked in detail, but it seems to me that the "artificial"
>> flag isn't appropriate for that decl, which is (derived from?) a
>> user-visible symbol. So, I'm not sure what's going on there (and yes
>> the commit you mention looks like it could be relevant, I think?).
>> There are probably subtleties I'm not aware of...
>
> Until we've got that worked out, let's simply restrict the
> 'DECL_ARTIFICIAL' handling to 'block's only; pushed to devel/omp/gcc-12
> commit 9a50d282f03f7f1e1ad00de917143a2a8e0c0ee0
> "[og12] OpenACC: Don't gang-privatize artificial variables: restrict to blocks"

..., see attached now really.

Grüße
 Thomas


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From 9a50d282f03f7f1e1ad00de917143a2a8e0c0ee0 Mon Sep 17 00:00:00 2001
From: Thomas Schwinge <thomas@codesourcery.com>
Date: Tue, 18 Oct 2022 16:59:54 +0200
Subject: [PATCH] [og12] OpenACC: Don't gang-privatize artificial variables:
 restrict to blocks

Follow-up to og12 commit d4504346d2a1d6ffecb8b2d8e3e04ab8ea259785
"[og12] OpenACC: Don't gang-privatize artificial variables", to restore
the previous behavior, until we understand what it means for a
'DECL_ARTIFICIAL' to appear in a 'private' clause.

	gcc/
	* omp-low.cc (oacc_privatization_candidate_p) <DECL_ARTIFICIAL>:
	Restrict to 'block's.
	libgomp/
	* testsuite/libgomp.oacc-fortran/privatized-ref-2.f90: Adjust.
---
 gcc/omp-low.cc                                              | 2 +-
 libgomp/testsuite/libgomp.oacc-fortran/privatized-ref-2.f90 | 4 +++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/gcc/omp-low.cc b/gcc/omp-low.cc
index 002f91d930a..66aa11cd32d 100644
--- a/gcc/omp-low.cc
+++ b/gcc/omp-low.cc
@@ -11409,7 +11409,7 @@ oacc_privatization_candidate_p (const location_t loc, const tree c,
      At present, no compiler-generated artificial variables require such
      sharing semantics, so this is safe.  */
 
-  if (res && DECL_ARTIFICIAL (decl))
+  if (res && block && DECL_ARTIFICIAL (decl))
     {
       res = false;
 
diff --git a/libgomp/testsuite/libgomp.oacc-fortran/privatized-ref-2.f90 b/libgomp/testsuite/libgomp.oacc-fortran/privatized-ref-2.f90
index 936285e9f69..498ef70b63a 100644
--- a/libgomp/testsuite/libgomp.oacc-fortran/privatized-ref-2.f90
+++ b/libgomp/testsuite/libgomp.oacc-fortran/privatized-ref-2.f90
@@ -94,7 +94,9 @@ contains
     !$acc parallel copy(array)
     !$acc loop gang private(array) ! { dg-line l_loop[incr c_loop] }
     ! { dg-note {variable 'i' in 'private' clause isn't candidate for adjusting OpenACC privatization level: not addressable} "" { target *-*-* } l_loop$c_loop }
-    ! { dg-note {variable 'array\.[0-9]+' in 'private' clause isn't candidate for adjusting OpenACC privatization level: artificial} "" { target *-*-* } l_loop$c_loop }
+    ! { dg-note {variable 'array\.[0-9]+' in 'private' clause is candidate for adjusting OpenACC privatization level} "" { target *-*-* } l_loop$c_loop }
+    ! { dg-note {variable 'array\.[0-9]+' ought to be adjusted for OpenACC privatization level: 'gang'} "" { target *-*-* } l_loop$c_loop }
+    ! { dg-note {variable 'array\.[0-9]+' adjusted for OpenACC privatization level: 'gang'} "" { target { ! { openacc_host_selected || { openacc_nvidia_accel_selected && __OPTIMIZE__ } } } } l_loop$c_loop }
     ! { dg-message {sorry, unimplemented: target cannot support alloca} PR65181 { target openacc_nvidia_accel_selected } l_loop$c_loop }
     do i = 1, 10
       array(i) = 9*i
-- 
2.35.1