Update check after force_const_mem call in the plus_constant function to see if…

Update check after force_const_mem call in the plus_constant function to see if the value returned is not a NULL_RTX.

2015-06-03  Andrew Bennett  <andrew.bennett@imgtec.com>

gcc/
	* explow.c (plus_constant): Update check after force_const_mem call 
	to see if the value returned is not a NULL_RTX.

From-SVN: r224064

gcc/ChangeLog

+2015-06-03  Andrew Bennett  <andrew.bennett@imgtec.com>
+
+	* explow.c (plus_constant): Update check after force_const_mem call 
+	to see if the value returned is not a NULL_RTX.
+
 2015-06-03  Ilya Enkovich  <ilya.enkovich@intel.com>
 
 	* ipa.c (symbol_table::remove_unreachable_nodes): Don't

gcc/explow.c

@@ -132,7 +132,9 @@ plus_constant (machine_mode mode, rtx x, HOST_WIDE_INT c,
 	{
 	  tem = plus_constant (mode, get_pool_constant (XEXP (x, 0)), c);
 	  tem = force_const_mem (GET_MODE (x), tem);
-	  if (memory_address_p (GET_MODE (tem), XEXP (tem, 0)))
+	  /* Targets may disallow some constants in the constant pool, thus
+	     force_const_mem may return NULL_RTX.  */
+	  if (tem && memory_address_p (GET_MODE (tem), XEXP (tem, 0)))
 	    return tem;
 	}
       break;