--- trunk-orig/gcc/omp-low.c	2018-12-12 18:19:40.920852744 +0800
+++ trunk-work/gcc/omp-low.c	2018-12-13 22:28:29.149913219 +0800
@@ -2600,6 +2600,50 @@
     layout_type (ctx->record_type);
 }
 
+/* Reorder clauses so that dynamic array map clauses are placed at the very
+   front of the chain.  */
+
+static void
+reorder_dynamic_array_clauses (tree *clauses_ptr)
+{
+  tree c, clauses = *clauses_ptr;
+  tree prev_clause = NULL_TREE, next_clause;
+  tree da_clauses = NULL_TREE, da_clauses_tail = NULL_TREE;
+
+  for (c = clauses; c; c = next_clause)
+    {
+      next_clause = OMP_CLAUSE_CHAIN (c);
+
+      if (OMP_CLAUSE_CODE (c) == OMP_CLAUSE_MAP
+	  && GOMP_MAP_DYNAMIC_ARRAY_P (OMP_CLAUSE_MAP_KIND (c)))
+	{
+	  /* Unchain c from clauses.  */
+	  if (c == clauses)
+	    clauses = next_clause;
+
+	  /* Link on to da_clauses.  */
+	  if (da_clauses_tail)
+	    OMP_CLAUSE_CHAIN (da_clauses_tail) = c;
+	  else
+	    da_clauses = c;
+	  da_clauses_tail = c;
+
+	  if (prev_clause)
+	    OMP_CLAUSE_CHAIN (prev_clause) = next_clause;
+	  continue;
+	}
+
+      prev_clause = c;
+    }  
+
+  /* Place dynamic array clauses at the start of the clause list.  */
+  if (da_clauses)
+    {
+      OMP_CLAUSE_CHAIN (da_clauses_tail) = clauses;
+      *clauses_ptr = da_clauses;
+    }
+}
+
 /* Scan a GIMPLE_OMP_TARGET.  */
 
 static void
@@ -2608,7 +2652,6 @@
   omp_context *ctx;
   tree name;
   bool offloaded = is_gimple_omp_offloaded (stmt);
-  tree clauses = gimple_omp_target_clauses (stmt);
 
   ctx = new_omp_context (stmt, outer_ctx);
   ctx->field_map = splay_tree_new (splay_tree_compare_pointers, 0, 0);
@@ -2627,6 +2670,14 @@
       gimple_omp_target_set_child_fn (stmt, ctx->cb.dst_fn);
     }
 
+  /* If OpenACC construct, put dynamic array clauses (if any) in front of
+     clause chain. The runtime can then test the first to see if the
+     additional map processing for them is required.  */
+  if (is_gimple_omp_oacc (stmt))
+    reorder_dynamic_array_clauses (gimple_omp_target_clauses_ptr (stmt));
+
+  tree clauses = gimple_omp_target_clauses (stmt);
+  
   scan_sharing_clauses (clauses, ctx);
   scan_omp (gimple_omp_body_ptr (stmt), ctx);