Date: Tue, 16 Nov 1999 13:23:49 +1100 From: "Andrew Reilly" <areilly@nsw.bigpond.net.au> To: Pierre Beyssac <beyssac@enst.fr> Cc: freebsd-current@FreeBSD.ORG Subject: Re: egcs -O breaks ping.c:in_cksum() Message-ID: <19991116132349.B40907@gurney.reilly.home> In-Reply-To: <19991115174831.B30139@enst.fr> References: <19991115174831.B30139@enst.fr>
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On Mon, Nov 15, 1999 at 05:48:31PM +0100, Pierre Beyssac wrote:
> The problem is apparently due to the following code fragment:
>
> register u_short answer = 0;
> [...]
> /* mop up an odd byte, if necessary */
> if (nleft == 1) {
> *(u_char *)(&answer) = *(u_char *)w ;
> sum += answer;
> }
>
> Removing the "register" declaration for 'answer' doesn't help.
That code should not even compile, since standard C says that you
_can't_ derefrence a register variable. That's about the only
genuine semantic content of the register keyword now. The fix with
a union (in another message) is the right way to do it, and doesn't
even require that "answer" be in addressable storage. (I.e., it
can now be optimised into a register).
--
Andrew
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