Index: gcc/stor-layout.c
===================================================================
--- gcc/stor-layout.c	2012-11-24 10:24:46.000000000 +0000
+++ gcc/stor-layout.c	2012-11-24 10:33:19.011617853 +0000
@@ -2643,15 +2643,17 @@ fixup_unsigned_type (tree type)
 			   unsigned int align, bool volatilep)
 : mode_ (GET_CLASS_NARROWEST_MODE (MODE_INT)), bitsize_ (bitsize),
   bitpos_ (bitpos), bitregion_start_ (bitregion_start),
-  bitregion_end_ (bitregion_end), align_ (MIN (align, BIGGEST_ALIGNMENT)),
+  bitregion_end_ (bitregion_end), align_ (align),
   volatilep_ (volatilep), count_ (0)
 {
   if (!bitregion_end_)
     {
-      /* We can assume that any aligned chunk of ALIGN_ bits that overlaps
+      /* We can assume that any aligned chunk of UNITS bits that overlaps
 	 the bitfield is mapped and won't trap.  */
-      bitregion_end_ = bitpos + bitsize + align_ - 1;
-      bitregion_end_ -= bitregion_end_ % align_ + 1;
+      unsigned HOST_WIDE_INT units = MIN (align, MAX (BIGGEST_ALIGNMENT,
+						      BITS_PER_WORD));
+      bitregion_end_ = bitpos + bitsize + units - 1;
+      bitregion_end_ -= bitregion_end_ % units + 1;
     }
 }
 
@@ -2808,7 +2810,7 @@ get_best_mode (int bitsize, int bitpos,
 	    causes store_bit_field to keep a 128-bit memory reference,
 	    so that the final bitfield reference still has a MEM_EXPR
 	    and MEM_OFFSET.  */
-	 && GET_MODE_BITSIZE (mode) <= align
+	 && GET_MODE_ALIGNMENT (mode) <= align
 	 && (largest_mode == VOIDmode
 	     || GET_MODE_SIZE (mode) <= GET_MODE_SIZE (largest_mode)))
     {