From: Thomas Schwinge <thomas@codesourcery.com>
To: Tobias Burnus <tobias@codesourcery.com>, <gcc-patches@gcc.gnu.org>
Cc: Andrew Stubbs <ams@codesourcery.com>
Subject: Fix OpenACC gang-redundant execution in 'libgomp.oacc-fortran/privatized-ref-2.f90' (was: Add 'libgomp.oacc-fortran/privatized-ref-2.f90')
Date: Tue, 22 Feb 2022 17:39:42 +0100 [thread overview]
Message-ID: <87zgmionxt.fsf@euler.schwinge.homeip.net> (raw)
In-Reply-To: <87mtsow47q.fsf@euler.schwinge.homeip.net>
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Hi!
On 2021-05-21T16:28:57+0200, I wrote:
> This came into existance internally, when the og10 branch was set up.
>
> On 2020-06-03T17:23:51+0200, Tobias Burnus <Tobias_Burnus@mentor.com> wrote:
>> This fixes [...] on OG10 (og10_prerelease); it will be
>> later applied to gcn/… to fix the issue. (Upstream is unaffected.)
>> [...]
>
> However, that means that your testcase does work on master branch (and
> would regress if certain commits got pushed there). As the testcase has
> got a property useful for a thing I'm currently working on, I've pushed
> to master branch "Add 'libgomp.oacc-fortran/privatized-ref-2.f90'" in
> commit 61796dc03befa9b7426d5bc7c336cca585944143
After commit a78b1ab1df9ca44acc5638e8f9d0ae2e62bd65ed
"amdgcn: Tune default OpenMP/OpenACC GPU utilization", we'd seen this
test case regress (only) on our AMD GPU amd-instinct1/'-march=gfx908'
system:
{+WARNING: program timed out.+}
[-PASS:-]{+FAIL:+} libgomp.oacc-fortran/privatized-ref-2.f90 -DACC_DEVICE_TYPE_radeon=1 -DACC_MEM_SHARED=0 -foffload=amdgcn-amdhsa -O0 execution test
Same for other optimization levels. Nothing more in 'libgomp.log'.
I have determined this is a latent problem in the original test case,
which contains a few instances of code as follows:
!$acc parallel copyout(array)
array = [(-i, i = 1, nn)]
!$acc loop gang private(array)
do i = 1, 10
array(i) = i
end do
if (any (array /= [(-i, i = 1, nn)])) error stop 1
!$acc end parallel
Given the '!$acc loop gang', the whole containing '!$acc parallel' region
is launched with gang parallelism. The '!$acc loop gang' executes in
gang-partitioned mode, but the 'array' assignment before and checks after
don't execute in a (hypothetical) gang-single mode, but instead in
gang-redundant mode, meaning that each gang executes these concurrently,
giving rise to data races and other mischief. Thus, we have to make sure
that we're not executing non-parallelized code in gang-redundant mode, by
putting these parts into their own 'parallel' constructs, which then
default to 'num_gangs(1)'. Pushed to master branch
commit f8187b5c0d22723c8e0a3d13d0ea5dd7ecfeff75 "Fix OpenACC
gang-redundant execution in 'libgomp.oacc-fortran/privatized-ref-2.f90'",
see attached.
Grüße
Thomas
> I confirm that "FIXME: Fails due to PR middle-end/95499" is still a
> problem.
>
> And, GCC '-O' reports:
>
> [...]/libgomp.oacc-fortran/privatized-ref-2.f90:147:21:
>
> 147 | subroutine foobar15 (scalar)
> | ^
> Warning: ‘foobar15’ defined but not used [-Wunused-function]
> [...]/libgomp.oacc-fortran/privatized-ref-2.f90: In function ‘MAIN__’:
> [...]/libgomp.oacc-fortran/privatized-ref-2.f90:31:22: warning: ‘a.offset’ is used uninitialized [-Wuninitialized]
> 31 | A = [(3*j, j=1, 10)]
> | ^
> [...]/libgomp.oacc-fortran/privatized-ref-2.f90:27:30: note: ‘a’ declared here
> 27 | integer, allocatable :: A(:)
> | ^
> [...]/libgomp.oacc-fortran/privatized-ref-2.f90:31:22: warning: ‘a.dim[0].lbound’ is used uninitialized [-Wuninitialized]
> 31 | A = [(3*j, j=1, 10)]
> | ^
> [...]/libgomp.oacc-fortran/privatized-ref-2.f90:27:30: note: ‘a’ declared here
> 27 | integer, allocatable :: A(:)
> | ^
> [...]/libgomp.oacc-fortran/privatized-ref-2.f90:31:22: warning: ‘a.dim[0].ubound’ is used uninitialized [-Wuninitialized]
> 31 | A = [(3*j, j=1, 10)]
> | ^
> [...]/libgomp.oacc-fortran/privatized-ref-2.f90:27:30: note: ‘a’ declared here
> 27 | integer, allocatable :: A(:)
> | ^
>
> I haven't looked into these.
>
>
> Grüße
> Thomas
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From f8187b5c0d22723c8e0a3d13d0ea5dd7ecfeff75 Mon Sep 17 00:00:00 2001
From: Thomas Schwinge <thomas@codesourcery.com>
Date: Fri, 21 Jan 2022 14:58:23 +0100
Subject: [PATCH] Fix OpenACC gang-redundant execution in
'libgomp.oacc-fortran/privatized-ref-2.f90'
This was a latent problem, and this commit here now resolves a regression that
after recent commit a78b1ab1df9ca44acc5638e8f9d0ae2e62bd65ed
"amdgcn: Tune default OpenMP/OpenACC GPU utilization" we had (only) seen on a
GCN offloading '-march=gfx908' system:
{+WARNING: program timed out.+}
[-PASS:-]{+FAIL:+} libgomp.oacc-fortran/privatized-ref-2.f90 -DACC_DEVICE_TYPE_radeon=1 -DACC_MEM_SHARED=0 -foffload=amdgcn-amdhsa -O0 execution test
Same for other optimization levels.
Make sure that we're not executing non-parallelized code in gang-redundant
mode, by putting these parts into their own 'parallel' constructs, which then
default to 'num_gangs(1)'.
libgomp/
* testsuite/libgomp.oacc-fortran/privatized-ref-2.f90: Fix OpenACC
gang-redundant execution.
---
.../libgomp.oacc-fortran/privatized-ref-2.f90 | 42 ++++++++++++++-----
1 file changed, 32 insertions(+), 10 deletions(-)
diff --git a/libgomp/testsuite/libgomp.oacc-fortran/privatized-ref-2.f90 b/libgomp/testsuite/libgomp.oacc-fortran/privatized-ref-2.f90
index f4a6af986e8..6bd17148911 100644
--- a/libgomp/testsuite/libgomp.oacc-fortran/privatized-ref-2.f90
+++ b/libgomp/testsuite/libgomp.oacc-fortran/privatized-ref-2.f90
@@ -53,12 +53,10 @@ contains
integer :: array(nn)
!$acc parallel copyout(array) ! { dg-line l_compute[incr c_compute] }
- ! { dg-note {variable 'atmp\.[0-9]+' declared in block isn't candidate for adjusting OpenACC privatization level: not addressable} "" { target *-*-* } l_compute$c_compute }
- ! { dg-note {variable 'shadow_loopvar\.[0-9]+' declared in block isn't candidate for adjusting OpenACC privatization level: not addressable} "" { target *-*-* } l_compute$c_compute }
- ! { dg-note {variable 'offset\.[0-9]+' declared in block isn't candidate for adjusting OpenACC privatization level: not addressable} "" { target *-*-* } l_compute$c_compute }
! { dg-note {variable 'S\.[0-9]+' declared in block isn't candidate for adjusting OpenACC privatization level: not addressable} "" { target *-*-* } l_compute$c_compute }
- ! { dg-note {variable 'test\.[0-9]+' declared in block isn't candidate for adjusting OpenACC privatization level: not addressable} "" { target *-*-* } l_compute$c_compute }
array = [(-i, i = 1, nn)]
+ !$acc end parallel
+ !$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' in 'private' clause potentially has improper OpenACC privatization level: 'parm_decl'} "" { target *-*-* } l_loop$c_loop }
@@ -66,6 +64,13 @@ contains
do i = 1, 10
array(i) = i
end do
+ !$acc end parallel
+ !$acc parallel copyin(array) ! { dg-line l_compute[incr c_compute] }
+ ! { dg-note {variable 'test\.[0-9]+' declared in block isn't candidate for adjusting OpenACC privatization level: not addressable} "" { target *-*-* } l_compute$c_compute }
+ ! { dg-note {variable 'atmp\.[0-9]+' declared in block isn't candidate for adjusting OpenACC privatization level: not addressable} "" { target *-*-* } l_compute$c_compute }
+ ! { dg-note {variable 'shadow_loopvar\.[0-9]+' declared in block isn't candidate for adjusting OpenACC privatization level: not addressable} "" { target *-*-* } l_compute$c_compute }
+ ! { dg-note {variable 'offset\.[0-9]+' declared in block isn't candidate for adjusting OpenACC privatization level: not addressable} "" { target *-*-* } l_compute$c_compute }
+ ! { dg-note {variable 'S\.[0-9]+' declared in block isn't candidate for adjusting OpenACC privatization level: not addressable} "" { target *-*-* } l_compute$c_compute }
if (any (array /= [(-i, i = 1, nn)])) error stop 1
!$acc end parallel
end subroutine foo
@@ -74,14 +79,10 @@ contains
integer :: array(:)
!$acc parallel copyout(array) ! { dg-line l_compute[incr c_compute] }
- ! { dg-note {variable 'atmp\.[0-9]+' declared in block isn't candidate for adjusting OpenACC privatization level: not addressable} "" { target *-*-* } l_compute$c_compute }
- ! { dg-note {variable 'shadow_loopvar\.[0-9]+' declared in block isn't candidate for adjusting OpenACC privatization level: not addressable} "" { target *-*-* } l_compute$c_compute }
- ! { dg-note {variable 'offset\.[0-9]+' declared in block isn't candidate for adjusting OpenACC privatization level: not addressable} "" { target *-*-* } l_compute$c_compute }
! { dg-note {variable 'S\.[0-9]+' declared in block isn't candidate for adjusting OpenACC privatization level: not addressable} "" { target *-*-* } l_compute$c_compute }
- ! { dg-note {variable 'test\.[0-9]+' declared in block isn't candidate for adjusting OpenACC privatization level: not addressable} "" { target *-*-* } l_compute$c_compute }
- ! { dg-note {variable 'parm\.[0-9]+' declared in block isn't candidate for adjusting OpenACC privatization level: not addressable} "" { target *-*-* } l_compute$c_compute }
- ! { dg-note {variable 'A\.[0-9]+' declared in block isn't candidate for adjusting OpenACC privatization level: static} "" { target *-*-* } l_compute$c_compute }
array = [(-2*i, i = 1, size(array))]
+ !$acc end parallel
+ !$acc parallel copy(array)
!$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 }
@@ -91,6 +92,11 @@ contains
do i = 1, 10
array(i) = 9*i
end do
+ !$acc end parallel
+ !$acc parallel copyin(array) ! { dg-line l_compute[incr c_compute] }
+ ! { dg-note {variable 'test\.[0-9]+' declared in block isn't candidate for adjusting OpenACC privatization level: not addressable} "" { target *-*-* } l_compute$c_compute }
+ ! { dg-note {variable 'A\.[0-9]+' declared in block isn't candidate for adjusting OpenACC privatization level: static} "" { target *-*-* } l_compute$c_compute }
+ ! { dg-note {variable 'S\.[0-9]+' declared in block isn't candidate for adjusting OpenACC privatization level: not addressable} "" { target *-*-* } l_compute$c_compute }
if (any (array /= [(-2*i, i = 1, 10)])) error stop 2
!$acc end parallel
end subroutine bar
@@ -100,6 +106,8 @@ contains
!$acc parallel copyout(str)
str = "abcdefghij"
+ !$acc end parallel
+ !$acc parallel copy(str)
!$acc loop gang private(str) ! { 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$c_loop }
! { dg-note {variable 'str' in 'private' clause potentially has improper OpenACC privatization level: 'parm_decl'} "" { target *-*-* } l_loop$c_loop }
@@ -110,6 +118,8 @@ contains
do i = 1, 10
str(i:i) = achar(ichar('A') + i)
end do
+ !$acc end parallel
+ !$acc parallel copyin(str)
if (str /= "abcdefghij") error stop 3
!$acc end parallel
end
@@ -122,10 +132,14 @@ contains
! ***************************************
!!$acc parallel copyout(str)
str = "abcdefghij"
+ !!$acc end parallel
+ !!$acc parallel copy(str)
!!$acc loop gang private(str)
!do i = 1, 10
! str(i:i) = achar(ichar('A') + i)
!end do
+ !!$acc end parallel
+ !!$acc parallel copyin(str)
if (str /= "abcdefghij") error stop 5
!!$acc end parallel
end
@@ -135,6 +149,8 @@ contains
!$acc parallel copyout(scalar)
scalar = "abcdefghi-12345"
+ !$acc end parallel
+ !$acc parallel copy(scalar)
!$acc loop gang private(scalar) ! { 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$c_loop }
! { dg-note {variable 'scalar' in 'private' clause potentially has improper OpenACC privatization level: 'parm_decl'} "" { target *-*-* } l_loop$c_loop }
@@ -145,7 +161,9 @@ contains
scalar(i:i) = achar(ichar('A') + i)
end do
!$acc end parallel
+ !$acc parallel copyin(scalar)
if (scalar /= "abcdefghi-12345") error stop 6
+ !$acc end parallel
end subroutine foobar
subroutine foobar15 (scalar)
integer :: i
@@ -153,11 +171,15 @@ contains
!$acc parallel copyout(scalar)
scalar = "abcdefghi-12345"
+ !$acc end parallel
+ !$acc parallel copy(scalar)
!$acc loop gang private(scalar)
do i = 1, 15
scalar(i:i) = achar(ichar('A') + i)
end do
!$acc end parallel
+ !$acc parallel copyin(scalar)
if (scalar /= "abcdefghi-12345") error stop 1
+ !$acc end parallel
end subroutine foobar15
end
--
2.34.1
prev parent reply other threads:[~2022-02-22 16:39 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <fc0dfbcc-0f5a-e63d-3943-80fb7b7cf03e@mentor.com>
2020-09-16 17:34 ` [PATCH] [OG10] Xfail libgomp.oacc-fortran/privatized-ref-2.f90 when offloading to nvptx Kwok Cheung Yeung
[not found] ` <0968ff25a4dc4d9895682ce0669345c5@svr-orw-mbx-02.mgc.mentorg.com>
2021-05-21 14:28 ` Add 'libgomp.oacc-fortran/privatized-ref-2.f90' Thomas Schwinge
2022-02-22 16:39 ` Thomas Schwinge [this message]
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