--- gcc/stor-layout.c	2013-10-21 08:27:09.546035668 +0200
+++ gcc/stor-layout.c	2013-10-22 10:46:49.233261818 +0200
@@ -1600,7 +1600,10 @@ compute_record_mode (tree type)
 		   && integer_zerop (TYPE_SIZE (TREE_TYPE (field)))))
 	  || ! host_integerp (bit_position (field), 1)
 	  || DECL_SIZE (field) == 0
-	  || ! host_integerp (DECL_SIZE (field), 1))
+	  || ! host_integerp (DECL_SIZE (field), 1)
+	  || (TREE_CODE (TREE_TYPE (field)) == ARRAY_TYPE
+	      && tree_low_cst (DECL_SIZE (field), 1) == 0
+	      && simple_cst_equal (TYPE_SIZE (type), bit_position (field))))
 	return;
 
       /* If this field is the whole struct, remember its mode so
--- gcc/testsuite/gcc.dg/torture/pr57748-3.c	(revision 0)
+++ gcc/testsuite/gcc.dg/torture/pr57748-3.c	(revision 0)
@@ -0,0 +1,40 @@
+/* PR middle-end/57748 */
+/* { dg-do run } */
+/* wrong code in expand_expr_real_1.  */
+
+#include <stdlib.h>
+
+extern void abort (void);
+
+typedef long long V
+  __attribute__ ((vector_size (2 * sizeof (long long)), may_alias));
+
+typedef struct S { V a; V b[0]; } P __attribute__((aligned (1)));
+
+struct __attribute__((packed)) T { char c; P s; };
+
+void __attribute__((noinline, noclone))
+check (P *p)
+{
+  if (p->b[0][0] != 3 || p->b[0][1] != 4)
+    abort ();
+}
+
+void __attribute__((noinline, noclone))
+foo (struct T *t)
+{
+  V a = { 3, 4 };
+  t->s.b[0] = a;
+}
+
+int
+main ()
+{
+  struct T *t = (struct T *) calloc (128, 1);
+
+  foo (t);
+  check (&t->s);
+
+  free (t);
+  return 0;
+}