https://gcc.gnu.org/g:2ca4602a941c1dfba2de376e3e523c7dd0491055
commit 2ca4602a941c1dfba2de376e3e523c7dd0491055
Author: Andrew Stubbs <a...@codesourcery.com>
Date: Tue Aug 3 13:45:35 2021 +0100
libgomp amdgcn: Fix issues with dynamic OpenMP thread scaling
libgomp/ChangeLog:
* config/gcn/bar.h (gomp_barrier_init): Limit thread count to the
actual physical number.
* config/gcn/team.c (gomp_team_start): Don't attempt to set up
threads that do not exist.
Diff:
---
libgomp/ChangeLog.omp | 7 +++++++
libgomp/config/gcn/bar.h | 3 +++
libgomp/config/gcn/team.c | 4 ++++
3 files changed, 14 insertions(+)
diff --git a/libgomp/ChangeLog.omp b/libgomp/ChangeLog.omp
index 2ca82622336..5bf3a8a6890 100644
--- a/libgomp/ChangeLog.omp
+++ b/libgomp/ChangeLog.omp
@@ -1,3 +1,10 @@
+2021-08-03 Andrew Stubbs <a...@codesourcery.com>
+
+ * config/gcn/bar.h (gomp_barrier_init): Limit thread count to the
+ actual physical number.
+ * config/gcn/team.c (gomp_team_start): Don't attempt to set up
+ threads that do not exist.
+
2021-02-23 Andrew Stubbs <a...@codesourcery.com>
* plugin/plugin-nvptx.c (GOMP_OFFLOAD_alloc): Remove early call to
diff --git a/libgomp/config/gcn/bar.h b/libgomp/config/gcn/bar.h
index a130c749d00..645791575e9 100644
--- a/libgomp/config/gcn/bar.h
+++ b/libgomp/config/gcn/bar.h
@@ -55,6 +55,9 @@ typedef unsigned int gomp_barrier_state_t;
static inline void gomp_barrier_init (gomp_barrier_t *bar, unsigned count)
{
+ unsigned actual_thread_count = __builtin_gcn_dim_size (1);
+ if (count > actual_thread_count)
+ count = actual_thread_count;
bar->total = count;
bar->awaited = count;
bar->awaited_final = count;
diff --git a/libgomp/config/gcn/team.c b/libgomp/config/gcn/team.c
index bd3df448b52..47bf2df55ac 100644
--- a/libgomp/config/gcn/team.c
+++ b/libgomp/config/gcn/team.c
@@ -206,6 +206,10 @@ gomp_team_start (void (*fn) (void *), void *data, unsigned
nthreads,
if (nthreads == 1)
return;
+ unsigned actual_thread_count = __builtin_gcn_dim_size (1);
+ if (nthreads > actual_thread_count)
+ nthreads = actual_thread_count;
+
/* Release existing idle threads. */
for (unsigned i = 1; i < nthreads; ++i)
{
