rs6000 patch for logical operation cleanup.

[Geoff Keating]

> cc: gcc-patches@gcc.gnu.org, gcc-bugs@gcc.gnu.org
> Date: Fri, 19 May 2000 13:49:03 -0400
> From: David Edelsohn <dje@watson.ibm.com>

> 	How can we solve this once and for all so that it is not reverted
> again?

by writing something like

if (HOST_BITS_PER_WIDE_INT < GET_MODE_SIZE (mode)
    && INTVAL (x) < 0)
  return 0;

and _adding the testcase_ so that when in future someone changes this
code, and gets it wrong, they know about it.  This is the only
guaranteed way to fix a bug.

-- 
- Geoffrey Keating <geoffk@cygnus.com>