Assert in 'libgomp/target.c:gomp_unmap_vars_internal' that we're not unmapping…

Assert in 'libgomp/target.c:gomp_unmap_vars_internal' that we're not unmapping 'tgt' while it's still in use

	libgomp/
	* target.c (gomp_unmap_vars_internal): Add a safeguard to
	'gomp_remove_var'.

From-SVN: r279534

libgomp/ChangeLog

 2019-12-18  Thomas Schwinge  <thomas@codesourcery.com>
 
+	* target.c (gomp_unmap_vars_internal): Add a safeguard to
+	'gomp_remove_var'.
+
 	* target.c (gomp_to_device_kind_p): Handle 'GOMP_MAP_FORCE_FROM'
 	like 'GOMP_MAP_FROM'.
 

libgomp/target.c

@@ -1225,7 +1225,15 @@ gomp_unmap_vars_internal (struct target_mem_desc *tgt, bool do_copyfrom,
 				      + tgt->list[i].offset),
 			    tgt->list[i].length);
       if (do_unmap)
-	gomp_remove_var (devicep, k);
+	{
+	  struct target_mem_desc *k_tgt = k->tgt;
+	  bool is_tgt_unmapped = gomp_remove_var (devicep, k);
+	  /* It would be bad if TGT got unmapped while we're still iterating
+	     over its LIST_COUNT, and also expect to use it in the following
+	     code.  */
+	  assert (!is_tgt_unmapped
+		  || k_tgt != tgt);
+	}
     }
 
   if (aq)