2019-07-14  Jakub Jelinek  <jakub@redhat.com>

	Backported from mainline
	2019-07-04  Jakub Jelinek  <jakub@redhat.com>

	PR middle-end/78884
	* gimplify.c (struct gimplify_omp_ctx): Add add_safelen1 member.
	(gimplify_bind_expr): If seeing TREE_ADDRESSABLE VLA inside of simd
	loop body, set ctx->add_safelen1 instead of making it GOVD_PRIVATE.
	(gimplify_adjust_omp_clauses): Add safelen (1) clause if
	ctx->add_safelen1 is set.

	* gcc.dg/gomp/pr78884.c: New test.

--- gcc/gimplify.c	(revision 273095)
+++ gcc/gimplify.c	(revision 273096)
@@ -210,6 +210,7 @@ struct gimplify_omp_ctx
   bool combined_loop;
   bool distribute;
   bool target_firstprivatize_array_bases;
+  bool add_safelen1;
   int defaultmap[4];
 };
 
@@ -1319,12 +1320,17 @@ gimplify_bind_expr (tree *expr_p, gimple
 		  || splay_tree_lookup (ctx->variables,
 					(splay_tree_key) t) == NULL))
 	    {
+	      int flag = GOVD_LOCAL;
 	      if (ctx->region_type == ORT_SIMD
 		  && TREE_ADDRESSABLE (t)
 		  && !TREE_STATIC (t))
-		omp_add_variable (ctx, t, GOVD_PRIVATE | GOVD_SEEN);
-	      else
-		omp_add_variable (ctx, t, GOVD_LOCAL | GOVD_SEEN);
+		{
+		  if (TREE_CODE (DECL_SIZE_UNIT (t)) != INTEGER_CST)
+		    ctx->add_safelen1 = true;
+		  else
+		    flag = GOVD_PRIVATE;
+		}
+	      omp_add_variable (ctx, t, flag | GOVD_SEEN);
 	    }
 
 	  DECL_SEEN_IN_BIND_EXPR_P (t) = 1;
@@ -9684,6 +9690,19 @@ gimplify_adjust_omp_clauses (gimple_seq
 			   omp_find_stores_op, &wi);
 	}
     }
+
+  if (ctx->add_safelen1)
+    {
+      /* If there are VLAs in the body of simd loop, prevent
+	 vectorization.  */
+      gcc_assert (ctx->region_type == ORT_SIMD);
+      c = build_omp_clause (UNKNOWN_LOCATION, OMP_CLAUSE_SAFELEN);
+      OMP_CLAUSE_SAFELEN_EXPR (c) = integer_one_node;
+      OMP_CLAUSE_CHAIN (c) = *list_p;
+      *list_p = c;
+      list_p = &OMP_CLAUSE_CHAIN (c);
+    }
+
   while ((c = *list_p) != NULL)
     {
       splay_tree_node n;
--- gcc/testsuite/gcc.dg/gomp/pr78884.c	(nonexistent)
+++ gcc/testsuite/gcc.dg/gomp/pr78884.c	(revision 273096)
@@ -0,0 +1,16 @@
+/* PR middle-end/78884 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fopenmp" } */
+
+void bar (int *);
+
+void
+foo (int n)
+{
+#pragma omp simd
+  for (int i = 0; i < 1024; i++)
+    {
+      int vla[n];
+      bar (vla);
+    }
+}