2011-07-15  Michael Hope  <michael.hope@linaro.org>

	gcc/
	Backport from mainline:
	2011-03-22  Eric Botcazou  <ebotcazou@adacore.com>

	* combine.c (simplify_set): Try harder to find the best CC mode when
	simplifying a nested COMPARE on the RHS.

=== modified file 'gcc/combine.c'
--- old/gcc/combine.c	2011-05-27 14:31:18 +0000
+++ new/gcc/combine.c	2011-07-11 03:52:31 +0000
@@ -6287,10 +6287,18 @@
       enum rtx_code new_code;
       rtx op0, op1, tmp;
       int other_changed = 0;
+      rtx inner_compare = NULL_RTX;
       enum machine_mode compare_mode = GET_MODE (dest);
 
       if (GET_CODE (src) == COMPARE)
-	op0 = XEXP (src, 0), op1 = XEXP (src, 1);
+	{
+	  op0 = XEXP (src, 0), op1 = XEXP (src, 1);
+	  if (GET_CODE (op0) == COMPARE && op1 == const0_rtx)
+	    {
+	      inner_compare = op0;
+	      op0 = XEXP (inner_compare, 0), op1 = XEXP (inner_compare, 1);
+	    }
+	}
       else
 	op0 = src, op1 = CONST0_RTX (GET_MODE (src));
 
@@ -6332,6 +6340,12 @@
 	 need to use a different CC mode here.  */
       if (GET_MODE_CLASS (GET_MODE (op0)) == MODE_CC)
 	compare_mode = GET_MODE (op0);
+      else if (inner_compare
+	       && GET_MODE_CLASS (GET_MODE (inner_compare)) == MODE_CC
+	       && new_code == old_code
+	       && op0 == XEXP (inner_compare, 0)
+	       && op1 == XEXP (inner_compare, 1))
+	compare_mode = GET_MODE (inner_compare);
       else
 	compare_mode = SELECT_CC_MODE (new_code, op0, op1);