re PR target/14812 (ARM optimizer changes rsb/cmp to cmn, but condition codes different)

	PR target/14812
	* arm.c (arm_select_cc_mode): Return CC_Zmode when comparing against
	a negated value.

From-SVN: r97533

gcc/ChangeLog

+2005-04-04  Richard Earnshaw  <richard.earnshaw@arm.com>
+
+	PR target/14812
+	* arm.c (arm_select_cc_mode): Return CC_Zmode when comparing against
+	a negated value.
+
 2005-04-04  Richard Henderson  <rth@redhat.com>
 	    Jakub Jelinek  <jakub@redhat.com>
 

gcc/config/arm/arm.c

@@ -6100,6 +6100,13 @@ arm_select_cc_mode (enum rtx_code op, rtx x, rtx y)
 	  || GET_CODE (x) == ROTATERT))
     return CC_SWPmode;
 
+  /* This operation is performed swapped, but since we only rely on the Z
+     flag we don't need an additional mode.  */
+  if (GET_MODE (y) == SImode && REG_P (y)
+      && GET_CODE (x) == NEG
+      && (op ==	EQ || op == NE))
+    return CC_Zmode;
+
   /* This is a special case that is used by combine to allow a
      comparison of a shifted byte load to be split into a zero-extend
      followed by a comparison of the shifted integer (only valid for