Fix from 2.8/egcs to handle the case where a comparison is optimized out

during a reversal.  Fixes PR 5564.

gnu/usr.bin/gcc/common/combine.c

@@ -4018,6 +4018,10 @@ simplify_if_then_else (x)
       SUBST (XEXP (x, 2), true);
 
       temp = true, true = false, false = temp, cond = XEXP (x, 0);
+
+      /* It is possible that the conditional has been simplified out.  */
+      true_code = GET_CODE (cond);
+      comparison_p = GET_RTX_CLASS (true_code) == '<';
     }
 
   /* If the two arms are identical, we don't need the comparison.  */