[backport gcc-4.8/trunk r193111 <mikpe@it.uu.se>]

gcc/

2012-11-02  Andrew Pinski  <apinski@cavium.com>

	PR rtl-opt/54524
	* simplify-rtx.c (simplify_relational_operation_1): Don't simplify
	(LTU/GEU (PLUS a 0) 0) into (GEU/LTU a 0) since they are not equivalent.

--- gcc-4.6.3/gcc/simplify-rtx.c.~1~	2011-12-23 10:16:08.000000000 +0100
+++ gcc-4.6.3/gcc/simplify-rtx.c	2012-11-03 16:34:36.000000000 +0100
@@ -4108,7 +4108,9 @@ simplify_relational_operation_1 (enum rt
       && GET_CODE (op0) == PLUS
       && CONST_INT_P (XEXP (op0, 1))
       && (rtx_equal_p (op1, XEXP (op0, 0))
-	  || rtx_equal_p (op1, XEXP (op0, 1))))
+	  || rtx_equal_p (op1, XEXP (op0, 1)))
+      /* (LTU/GEU (PLUS a 0) 0) is not the same as (GEU/LTU a 0). */
+      && XEXP (op0, 1) != const0_rtx)
     {
       rtx new_cmp
 	= simplify_gen_unary (NEG, cmp_mode, XEXP (op0, 1), cmp_mode);