bug in expr.c?

[Mike Stump]

This work was put in by kenner at the FSF, he might be able to say for
sure:

Thu Nov 20 16:37:36 1997  Richard Kenner  <kenner@vlsi1.ultra.nyu.edu>
 
        * expr.c (expand_assignment): If assigning to readonly field,
        mark rtx as unchanging.

revision 1.463
date: 1997/11/20 23:38:15;  author: kenner;  state: Exp;  lines: +9 -0
(expand_assignment): If assigning to readonly field, mark rtx as unchanging.

> Date: Mon, 9 Feb 1998 23:34:14 -0600
> From: Robert Lipe <robertl@dgii.com>
> To: egcs@cygnus.com

> I was cleaning up warnings expr.c and believe this to be a bug.   Can
> anyone that actually understands this confirm or deny this?

> expand_assignment()

>       if (TREE_CODE (to) == COMPONENT_REF
>           && TREE_READONLY (TREE_OPERAND (to, 1)))
>         {
>           if (offset = 0)
>             to_rtx = copy_rtx (to_rtx);

>           RTX_UNCHANGING_P (to_rtx) = 1;
>         }

> That copy_rtx will never ever be called, right?

> Is the "obvious" fix of "offset == 0" correct?