[wide-int] Tweak an rs6000 test

[Richard Sandiford]

This test changes from TREE_INT_CST_LOW to TREE_INT_CST_ELT.  I was going
to change it back as part of the previous patch, but using wi:: seemed
more robust.

Only compile-tested so far because of problems with gcc110.  OK for wide-int?

Richard


Index: gcc/config/rs6000/rs6000.c
===================================================================
--- gcc/config/rs6000/rs6000.c  2013-11-20 11:26:05.996351099 +0000
+++ gcc/config/rs6000/rs6000.c  2013-11-20 11:43:37.896818266 +0000
@@ -12131,16 +12131,14 @@ rs6000_expand_ternop_builtin (enum insn_
       /* Check whether the 2nd and 3rd arguments are integer constants and in
         range and prepare arguments.  */
       STRIP_NOPS (arg1);
-      if (TREE_CODE (arg1) != INTEGER_CST
-         || !IN_RANGE (TREE_INT_CST_ELT (arg1, 0), 0, 1))
+      if (TREE_CODE (arg1) != INTEGER_CST || wi::geu_p (arg1, 2))
        {
          error ("argument 2 must be 0 or 1");
          return const0_rtx;
        }
 
       STRIP_NOPS (arg2);
-      if (TREE_CODE (arg2) != INTEGER_CST
-         || !IN_RANGE (TREE_INT_CST_ELT (arg2, 0), 0, 15))
+      if (TREE_CODE (arg2) != INTEGER_CST || wi::geu_p (arg1, 16))
        {
          error ("argument 3 must be in the range 0..15");
          return const0_rtx;