(expand_decl): Don't set RTX_UNCHANGING_P.

From-SVN: r4457

gcc/stmt.c

@@ -2995,8 +2995,15 @@ expand_decl (decl)
 
   if (TREE_THIS_VOLATILE (decl))
     MEM_VOLATILE_P (DECL_RTL (decl)) = 1;
+#if 0 /* A variable is not necessarily unchanging
+	 just because it is const.  RTX_UNCHANGING_P
+	 means no change in the function,
+	 not merely no change in the variable's scope.
+	 It is correct to set RTX_UNCHANGING_P if the variable's scope
+	 is the whole function.  There's no convenient way to test that.  */
   if (TREE_READONLY (decl))
     RTX_UNCHANGING_P (DECL_RTL (decl)) = 1;
+#endif
 
   /* If doing stupid register allocation, make sure life of any
      register variable starts here, at the start of its scope.  */