Message-ID: <000601be1232$a9d3b000$0f00a8c0@franc.intern.dresearch.de>
From: "Michael Beck" <beck AT dresearch DOT de>
To: <djgpp-workers AT delorie DOT com>
Subject: Re: feature or bug?
Date: Tue, 17 Nov 1998 15:00:41 +0100
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Reply-To: djgpp-workers AT delorie DOT com

>Hi Workers!
>
>Just a small question:
>
>Let's say I have a 32-bit unsigned integer, and I want to clear it's
>most significant bit. I wrote this code:
>
> (x*2)/2
>
>And of course(?) it doesn't work. Is it a bug in gcc or a bug in me?
>

This seems to be a feature: Even if I did not optimize this code (gcc t.c),
the compiler
removes the *2/2 operation. For disabling the optimization, use the
following construct:

y = 2;
x = (x*y)/2;

This code work in all cases. However, why didn't you use

x & 0x7FFFFFFF ???

--
Michael Beck,                        email: beck AT dresearch DOT de
DResearch GmbH, D-10319 Berlin,  Otto-Schmirgal-Strasse 3
Fon.: +49 (030) 515932 224 Fax.: +49 (030) 515932 299