[backport from gcc-4.8/trunk r192611 <mikpe@it.uu.se>]

gcc/

2012-10-19  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/54976
	* tree-vect-stmts.c (get_vectype_for_scalar_type_and_size):
	Robustify against odd inner_mode inputs.

--- gcc-4.6.3/gcc/tree-vect-stmts.c.~1~	2012-11-03 14:38:08.000000000 +0100
+++ gcc-4.6.3/gcc/tree-vect-stmts.c	2012-11-03 14:38:15.000000000 +0100
@@ -5116,16 +5116,21 @@ get_vectype_for_scalar_type_and_size (tr
      When the component mode passes the above test simply use a type
      corresponding to that mode.  The theory is that any use that
      would cause problems with this will disable vectorization anyway.  */
-  if (!SCALAR_FLOAT_TYPE_P (scalar_type)
-      && !INTEGRAL_TYPE_P (scalar_type)
-      && !POINTER_TYPE_P (scalar_type))
+  else if (!SCALAR_FLOAT_TYPE_P (scalar_type)
+	   && !INTEGRAL_TYPE_P (scalar_type)
+	   && !POINTER_TYPE_P (scalar_type))
     scalar_type = lang_hooks.types.type_for_mode (inner_mode, 1);
 
   /* We can't build a vector type of elements with alignment bigger than
      their size.  */
-  if (nbytes < TYPE_ALIGN_UNIT (scalar_type))
+  else if (nbytes < TYPE_ALIGN_UNIT (scalar_type))
     scalar_type = lang_hooks.types.type_for_mode (inner_mode, 1);
 
+  /* If we felt back to using the mode fail if there was
+     no scalar type for it.  */
+  if (scalar_type == NULL_TREE)
+    return NULL_TREE;
+
   /* If no size was supplied use the mode the target prefers.   Otherwise
      lookup a vector mode of the specified size.  */
   if (size == 0)