From: Andrew Stubbs <ams@codesourcery.com>
Date: Tue, 3 Aug 2021 12:45:35 +0000 (+0100)
Subject: libgomp amdgcn: Fix issues with dynamic OpenMP thread scaling
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=64855d67f0bef461d11da03380de587cca5850e7;p=thirdparty%2Fgcc.git

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 --git a/libgomp/config/gcn/bar.h b/libgomp/config/gcn/bar.h
index bbd3141837f7..63e803bd72b0 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 627210ea4071..6aa74744315f 100644
--- a/libgomp/config/gcn/team.c
+++ b/libgomp/config/gcn/team.c
@@ -187,6 +187,10 @@ 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)
     {