Hi!
On 2021-11-12T18:58:04+0100, Jakub Jelinek via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
> And finally here is a third version, [...]
... which became commit 9fa72756d90e0d9edadf6e6f5f56476029925788
"libgomp, nvptx: Honor OpenMP 5.1 num_teams lower bound".
Attached here is "GCN: Honor OpenMP 5.1 'num_teams' lower bound", which
are exactly the corresponding changes for GCN (see below Jakub's nvptx
changes for reference); OK to push?
Grüße
Thomas
> 2021-11-12 Jakub Jelinek <ja...@redhat.com>
>
> * config/nvptx/team.c (__gomp_team_num): Define as
> __attribute__((shared)) var.
> (gomp_nvptx_main): Initialize __gomp_team_num to 0.
> * config/nvptx/target.c (__gomp_team_num): Declare as
> extern __attribute__((shared)) var.
> (GOMP_teams4): Use __gomp_team_num as the team number instead of
> %ctaid.x. If first, initialize it to %ctaid.x. If num_teams_lower
> is bigger than num_blocks, use num_teams_lower teams and arrange for
> bumping of __gomp_team_num if !first and returning false once we run
> out of teams.
> * config/nvptx/teams.c (__gomp_team_num): Declare as
> extern __attribute__((shared)) var.
> (omp_get_team_num): Return __gomp_team_num value instead of %ctaid.x.
>
> --- libgomp/config/nvptx/team.c.jj 2021-05-25 13:43:02.793121350 +0200
> +++ libgomp/config/nvptx/team.c 2021-11-12 17:49:02.847341650 +0100
> @@ -32,6 +32,7 @@
> #include <string.h>
>
> struct gomp_thread *nvptx_thrs __attribute__((shared,nocommon));
> +int __gomp_team_num __attribute__((shared));
>
> static void gomp_thread_start (struct gomp_thread_pool *);
>
> @@ -57,6 +58,7 @@ gomp_nvptx_main (void (*fn) (void *), vo
> /* Starting additional threads is not supported. */
> gomp_global_icv.dyn_var = true;
>
> + __gomp_team_num = 0;
> nvptx_thrs = alloca (ntids * sizeof (*nvptx_thrs));
> memset (nvptx_thrs, 0, ntids * sizeof (*nvptx_thrs));
>
> --- libgomp/config/nvptx/target.c.jj 2021-11-12 15:57:29.400632875 +0100
> +++ libgomp/config/nvptx/target.c 2021-11-12 17:47:39.499533296 +0100
> @@ -26,28 +26,41 @@
> #include "libgomp.h"
> #include <limits.h>
>
> +extern int __gomp_team_num __attribute__((shared));
> +
> bool
> GOMP_teams4 (unsigned int num_teams_lower, unsigned int num_teams_upper,
> unsigned int thread_limit, bool first)
> {
> + unsigned int num_blocks, block_id;
> + asm ("mov.u32 %0, %%nctaid.x;" : "=r" (num_blocks));
> if (!first)
> - return false;
> + {
> + unsigned int team_num;
> + if (num_blocks > gomp_num_teams_var)
> + return false;
> + team_num = __gomp_team_num;
> + if (team_num > gomp_num_teams_var - num_blocks)
> + return false;
> + __gomp_team_num = team_num + num_blocks;
> + return true;
> + }
> if (thread_limit)
> {
> struct gomp_task_icv *icv = gomp_icv (true);
> icv->thread_limit_var
> = thread_limit > INT_MAX ? UINT_MAX : thread_limit;
> }
> - unsigned int num_blocks, block_id;
> - asm ("mov.u32 %0, %%nctaid.x;" : "=r" (num_blocks));
> - asm ("mov.u32 %0, %%ctaid.x;" : "=r" (block_id));
> - /* FIXME: If num_teams_lower > num_blocks, we want to loop multiple
> - times for some CTAs. */
> - (void) num_teams_lower;
> - if (!num_teams_upper || num_teams_upper >= num_blocks)
> + if (!num_teams_upper)
> num_teams_upper = num_blocks;
> - else if (block_id >= num_teams_upper)
> + else if (num_blocks < num_teams_lower)
> + num_teams_upper = num_teams_lower;
> + else if (num_blocks < num_teams_upper)
> + num_teams_upper = num_blocks;
> + asm ("mov.u32 %0, %%ctaid.x;" : "=r" (block_id));
> + if (block_id >= num_teams_upper)
> return false;
> + __gomp_team_num = block_id;
> gomp_num_teams_var = num_teams_upper - 1;
> return true;
> }
> --- libgomp/config/nvptx/teams.c.jj 2021-05-25 13:43:02.793121350 +0200
> +++ libgomp/config/nvptx/teams.c 2021-11-12 17:37:18.933361024 +0100
> @@ -28,6 +28,8 @@
>
> #include "libgomp.h"
>
> +extern int __gomp_team_num __attribute__((shared));
> +
> void
> GOMP_teams_reg (void (*fn) (void *), void *data, unsigned int num_teams,
> unsigned int thread_limit, unsigned int flags)
> @@ -48,9 +50,7 @@ omp_get_num_teams (void)
> int
> omp_get_team_num (void)
> {
> - int ctaid;
> - asm ("mov.u32 %0, %%ctaid.x;" : "=r" (ctaid));
> - return ctaid;
> + return __gomp_team_num;
> }
>
> ialias (omp_get_num_teams)
>
>
> Jakub
>From f078b635f033dcb80ce8cd48de3bf62ad5e285bf Mon Sep 17 00:00:00 2001
From: Thomas Schwinge <tschwi...@baylibre.com>
Date: Mon, 15 Jul 2024 11:19:28 +0200
Subject: [PATCH] GCN: Honor OpenMP 5.1 'num_teams' lower bound
Corresponding to commit 9fa72756d90e0d9edadf6e6f5f56476029925788
"libgomp, nvptx: Honor OpenMP 5.1 num_teams lower bound", these are the
GCN offloading changes to fix:
PASS: libgomp.c/../libgomp.c-c++-common/teams-2.c (test for excess errors)
[-FAIL:-]{+PASS:+} libgomp.c/../libgomp.c-c++-common/teams-2.c execution test
PASS: libgomp.c++/../libgomp.c-c++-common/teams-2.c (test for excess errors)
[-FAIL:-]{+PASS:+} libgomp.c++/../libgomp.c-c++-common/teams-2.c execution test
..., and omptests' 't-critical' test case. I've cross checked that those test
cases are the ones that regress for nvptx offloading, if I locally revert the
"libgomp, nvptx: Honor OpenMP 5.1 num_teams lower bound" changes.
libgomp/
* config/gcn/libgomp-gcn.h (GOMP_TEAM_NUM): Inject.
* config/gcn/target.c (GOMP_teams4): Handle.
* config/gcn/team.c (gomp_gcn_enter_kernel): Initialize.
* config/gcn/teams.c (omp_get_team_num): Adjust.
---
libgomp/config/gcn/libgomp-gcn.h | 9 +++++----
libgomp/config/gcn/target.c | 29 ++++++++++++++++++++---------
libgomp/config/gcn/team.c | 3 +++
libgomp/config/gcn/teams.c | 5 +++--
4 files changed, 31 insertions(+), 15 deletions(-)
diff --git a/libgomp/config/gcn/libgomp-gcn.h b/libgomp/config/gcn/libgomp-gcn.h
index e94f0c7ae68..48a3741b04d 100644
--- a/libgomp/config/gcn/libgomp-gcn.h
+++ b/libgomp/config/gcn/libgomp-gcn.h
@@ -34,10 +34,11 @@
#define DEFAULT_TEAM_ARENA_SIZE (64*1024)
/* These define the LDS location of data needed by OpenMP. */
-#define TEAM_ARENA_START 16 /* LDS offset of free pointer. */
-#define TEAM_ARENA_FREE 24 /* LDS offset of free pointer. */
-#define TEAM_ARENA_END 32 /* LDS offset of end pointer. */
-#define GCN_LOWLAT_HEAP 40 /* LDS offset of the OpenMP low-latency heap. */
+#define GOMP_TEAM_NUM 16
+#define TEAM_ARENA_START 24 /* LDS offset of free pointer. */
+#define TEAM_ARENA_FREE 32 /* LDS offset of free pointer. */
+#define TEAM_ARENA_END 40 /* LDS offset of end pointer. */
+#define GCN_LOWLAT_HEAP 48 /* LDS offset of the OpenMP low-latency heap. */
struct heap
{
diff --git a/libgomp/config/gcn/target.c b/libgomp/config/gcn/target.c
index 1d4a23cb8d2..e57d2e5f93f 100644
--- a/libgomp/config/gcn/target.c
+++ b/libgomp/config/gcn/target.c
@@ -33,26 +33,37 @@ bool
GOMP_teams4 (unsigned int num_teams_lower, unsigned int num_teams_upper,
unsigned int thread_limit, bool first)
{
+ int __lds *gomp_team_num = (int __lds *) GOMP_TEAM_NUM;
+ unsigned int num_workgroups = __builtin_gcn_dim_size (0);
if (!first)
- return false;
+ {
+ unsigned int team_num;
+ if (num_workgroups > gomp_num_teams_var)
+ return false;
+ team_num = *gomp_team_num;
+ if (team_num > gomp_num_teams_var - num_workgroups)
+ return false;
+ *gomp_team_num = team_num + num_workgroups;
+ return true;
+ }
if (thread_limit)
{
struct gomp_task_icv *icv = gomp_icv (true);
icv->thread_limit_var
= thread_limit > INT_MAX ? UINT_MAX : thread_limit;
}
- unsigned int num_workgroups, workgroup_id;
- num_workgroups = __builtin_gcn_dim_size (0);
- workgroup_id = __builtin_gcn_dim_pos (0);
- /* FIXME: If num_teams_lower > num_workgroups, we want to loop
- multiple times at least for some workgroups. */
- (void) num_teams_lower;
- if (!num_teams_upper || num_teams_upper >= num_workgroups)
+ if (!num_teams_upper)
num_teams_upper = ((GOMP_ADDITIONAL_ICVS.nteams > 0
&& num_workgroups > GOMP_ADDITIONAL_ICVS.nteams)
? GOMP_ADDITIONAL_ICVS.nteams : num_workgroups);
- else if (workgroup_id >= num_teams_upper)
+ else if (num_workgroups < num_teams_lower)
+ num_teams_upper = num_teams_lower;
+ else if (num_workgroups < num_teams_upper)
+ num_teams_upper = num_workgroups;
+ unsigned int workgroup_id = __builtin_gcn_dim_pos (0);
+ if (workgroup_id >= num_teams_upper)
return false;
+ *gomp_team_num = workgroup_id;
gomp_num_teams_var = num_teams_upper - 1;
return true;
}
diff --git a/libgomp/config/gcn/team.c b/libgomp/config/gcn/team.c
index bd3df448b52..aa68b3abe0b 100644
--- a/libgomp/config/gcn/team.c
+++ b/libgomp/config/gcn/team.c
@@ -68,6 +68,9 @@ gomp_gcn_enter_kernel (void)
/* Starting additional threads is not supported. */
gomp_global_icv.dyn_var = true;
+ int __lds *gomp_team_num = (int __lds *) GOMP_TEAM_NUM;
+ *gomp_team_num = 0;
+
/* Initialize the team arena for optimized memory allocation.
The arena has been allocated on the host side, and the address
passed in via the kernargs. Each team takes a small slice of it. */
diff --git a/libgomp/config/gcn/teams.c b/libgomp/config/gcn/teams.c
index 8a91ba8f5c1..57404184c89 100644
--- a/libgomp/config/gcn/teams.c
+++ b/libgomp/config/gcn/teams.c
@@ -44,10 +44,11 @@ omp_get_num_teams (void)
return gomp_num_teams_var + 1;
}
-int __attribute__ ((__optimize__ ("O2")))
+int
omp_get_team_num (void)
{
- return __builtin_gcn_dim_pos (0);
+ int __lds *gomp_team_num = (int __lds *) GOMP_TEAM_NUM;
+ return *gomp_team_num;
}
ialias (omp_get_num_teams)
--
2.34.1
