=== modified file 'gcc/combine.c'
--- gcc/combine.c	2012-02-22 12:22:43 +0000
+++ gcc/combine.c	2012-07-03 19:46:18 +0000
@@ -8432,6 +8432,7 @@
 	 in OP_MODE.  */
 
       if (CONST_INT_P (XEXP (x, 1))
+	  && INTVAL (XEXP (x, 1)) >= 0
 	  && INTVAL (XEXP (x, 1)) < HOST_BITS_PER_WIDE_INT
 	  && HWI_COMPUTABLE_MODE_P (op_mode))
 	{