GCN: Wait for exit value to write before exiting.

2019-05-24  Andrew Stubbs  <ams@codesourcery.com>

	gcc/
	* 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.

From-SVN: r271605

gcc/ChangeLog

+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:

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)

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 "")