simplify-rtx.c (simplify_relational_operation_1): Simplify (LTU (PLUS a C) C) or…

simplify-rtx.c (simplify_relational_operation_1): Simplify (LTU (PLUS a C) C) or (LTU (PLUS a C) a) to (GEU a -C)...

	* simplify-rtx.c (simplify_relational_operation_1): Simplify
	(LTU (PLUS a C) C) or (LTU (PLUS a C) a) to (GEU a -C); likewise with
	GEU/LTU reversed.

From-SVN: r145353

gcc/ChangeLog

@@ -15,6 +15,10 @@
 	and keep using them to simplify new expressions, while applying the
 	same substitutions to them as to the expression.
 
+	* simplify-rtx.c (simplify_relational_operation_1): Simplify
+	(LTU (PLUS a C) C) or (LTU (PLUS a C) a) to (GEU a -C); likewise with
+	GEU/LTU reversed.
+
 2009-03-31  Ramana Radhakrishnan  <ramana.radhakrishnan@arm.com>
 
         PR target/27237

gcc/simplify-rtx.c

@@ -3856,6 +3856,20 @@ simplify_relational_operation_1 (enum rtx_code code, enum machine_mode mode,
 	}
     }
 
+  /* (LTU/GEU (PLUS a C) C), where C is constant, can be simplified to
+     (GEU/LTU a -C).  Likewise for (LTU/GEU (PLUS a C) a).  */
+  if ((code == LTU || code == GEU)
+      && GET_CODE (op0) == PLUS
+      && GET_CODE (XEXP (op0, 1)) == CONST_INT
+      && (rtx_equal_p (op1, XEXP (op0, 0))
+	  || rtx_equal_p (op1, XEXP (op0, 1))))
+    {
+      rtx new_cmp
+	= simplify_gen_unary (NEG, cmp_mode, XEXP (op0, 1), cmp_mode);
+      return simplify_gen_relational ((code == LTU ? GEU : LTU), mode,
+				      cmp_mode, XEXP (op0, 0), new_cmp);
+    }
+
   /* Canonicalize (LTU/GEU (PLUS a b) b) as (LTU/GEU (PLUS a b) a).  */
   if ((code == LTU || code == GEU)
       && GET_CODE (op0) == PLUS