diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 6bc4d1a39963df1ff7f4e0666937eb5cfe383b7d..e340675a2cfa91d2721415d7b0222ff252987ac4 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2019-05-24  Andrew Stubbs  <ams@codesourcery.com>
+
+	* config/gcn/gcn-run.c (main): Set a non-zero return value if the
+	kernel does not exit cleanly.
+	* config/gcn/gcn.md (gcn_return): Insert s_waitcnt before s_dcache_wb.
+
 2019-05-24  Jason Merrill  <jason@redhat.com>
 
 	Revert:
diff --git a/gcc/config/gcn/gcn-run.c b/gcc/config/gcn/gcn-run.c
index 84718f42846078e843f12685658515a0682e833b..21852d78bc5d726a7e30edd24e31445a3f1014d6 100644
--- a/gcc/config/gcn/gcn-run.c
+++ b/gcc/config/gcn/gcn-run.c
@@ -853,7 +853,10 @@ main (int argc, char *argv[])
 
   unsigned int upper = (return_value & ~0xffff) >> 16;
   if (upper == 0xcafe)
-    printf ("Kernel exit value was never set\n");
+    {
+      printf ("Kernel exit value was never set\n");
+      return_value = 0xff;
+    }
   else if (upper == 0xffff)
     ; /* Set by exit.  */
   else if (upper == 0)
diff --git a/gcc/config/gcn/gcn.md b/gcc/config/gcn/gcn.md
index 2b805a73c5616f5626bc902346a990c60d045444..1f06d0bd5cc91aaa105cd9d202ed520e7d82027d 100644
--- a/gcc/config/gcn/gcn.md
+++ b/gcc/config/gcn/gcn.md
@@ -784,10 +784,10 @@
     if (cfun && cfun->machine && cfun->machine->normal_function)
       return "s_setpc_b64\ts[18:19]";
     else
-      return "s_dcache_wb\;s_endpgm";
+      return "s_waitcnt\tlgkmcnt(0)\;s_dcache_wb\;s_endpgm";
   }
   [(set_attr "type" "sop1")
-   (set_attr "length" "8")])
+   (set_attr "length" "12")])
 
 (define_expand "call"
   [(parallel [(call (match_operand 0 "")