Index: emit-rtl.c
===================================================================
--- emit-rtl.c	(revision 193322)
+++ emit-rtl.c	(working copy)
@@ -2071,10 +2071,12 @@ adjust_address_1 (rtx memref, enum machi
   rtx new_rtx;
   enum machine_mode address_mode;
   int pbits;
-  struct mem_attrs attrs, *defattrs;
+  struct mem_attrs attrs = *get_mem_attrs (memref), *defattrs;
   unsigned HOST_WIDE_INT max_align;
-
-  attrs = *get_mem_attrs (memref);
+#ifdef POINTERS_EXTEND_UNSIGNED
+  enum machine_mode pointer_mode
+    = targetm.addr_space.pointer_mode (attrs.addrspace);
+#endif
 
   /* If there are no changes, just return the original memory reference.  */
   if (mode == GET_MODE (memref) && !offset
@@ -2109,6 +2111,18 @@ adjust_address_1 (rtx memref, enum machi
 	addr = gen_rtx_LO_SUM (address_mode, XEXP (addr, 0),
 			       plus_constant (address_mode,
 					      XEXP (addr, 1), offset));
+#ifdef POINTERS_EXTEND_UNSIGNED
+      /* If MEMREF is a ZERO_EXTEND from pointer_mode and the offset is valid
+	 in that mode, we merge it into the ZERO_EXTEND.  We take advantage of
+	 the fact that pointers are not allowed to overflow.  */
+      else if (POINTERS_EXTEND_UNSIGNED > 0
+	       && GET_CODE (addr) == ZERO_EXTEND
+	       && GET_MODE (XEXP (addr, 0)) == pointer_mode
+	       && trunc_int_for_mode (offset, pointer_mode) == offset)
+	addr = gen_rtx_ZERO_EXTEND (address_mode,
+				    plus_constant (pointer_mode,
+						   XEXP (addr, 0), offset));
+#endif
       else
 	addr = plus_constant (address_mode, addr, offset);
     }
Index: recog.c
===================================================================
--- recog.c	(revision 193322)
+++ recog.c	(working copy)
@@ -1943,6 +1943,9 @@ offsettable_address_addr_space_p (int st
     (strictp ? strict_memory_address_addr_space_p
 	     : memory_address_addr_space_p);
   unsigned int mode_sz = GET_MODE_SIZE (mode);
+#ifdef POINTERS_EXTEND_UNSIGNED
+  enum machine_mode pointer_mode = targetm.addr_space.pointer_mode (as);
+#endif
 
   if (CONSTANT_ADDRESS_P (y))
     return 1;
@@ -1992,6 +1995,15 @@ offsettable_address_addr_space_p (int st
     z = gen_rtx_LO_SUM (GET_MODE (y), XEXP (y, 0),
 			plus_constant (GET_MODE (y), XEXP (y, 1),
 				       mode_sz - 1));
+#ifdef POINTERS_EXTEND_UNSIGNED
+  /* Likewise for a ZERO_EXTEND from pointer_mode.  */
+  else if (POINTERS_EXTEND_UNSIGNED > 0
+	   && GET_CODE (y) == ZERO_EXTEND
+	   && GET_MODE (XEXP (y, 0)) == pointer_mode)
+    z = gen_rtx_ZERO_EXTEND (GET_MODE (y),
+			     plus_constant (pointer_mode, XEXP (y, 0),
+					    mode_sz - 1));
+#endif
   else
     z = plus_constant (GET_MODE (y), y, mode_sz - 1);