Date: Wed, 15 May 2002 21:34:06 +0200 From: Robert Drehmel <robert@ferrari-electronic.de> To: Akinori MUSHA <knu@iDaemons.org> Cc: audit@FreeBSD.org, current@FreeBSD.org Subject: Re: moused(8): char signed-ness problem with gcc 3.1 Message-ID: <20020515213406.A30720@alpha.develop.ferrari.net> In-Reply-To: <86sn4t8fzp.wl@archon.local.idaemons.org> References: <86sn4t8fzp.wl@archon.local.idaemons.org>
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On Thu, May 16, 2002 at 02:42:34AM +0900, Akinori MUSHA wrote:
> I observed gcc 2.95.4 and gcc 3.1 interpret (or maybe optimize) the
> following code differently (CFLAGS=-O):
>
> int main(void)
> {
> unsigned char i = 127;
> printf("%d\n", ((char)(i << 1)) / 2);
> return 0;
> }
I think GCC 3.1 does a logical right shift by one to
optimize the division by two instead of an arithmetic
right shift.
ciao,
-robert
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