From: Nathan Sidwell <nathan@codesourcery.com>
To: Dave Korn <dk@artimi.com>
Cc: gcc@gcc.gnu.org
Subject: Re: warning: right shift count >= width of type
Date: Mon, 29 Nov 2004 16:33:00 -0000 [thread overview]
Message-ID: <41AB4E8A.4020801@codesourcery.com> (raw)
In-Reply-To: <NUTMEG5kpCUsVt1IDz7000001b1@NUTMEG.CAM.ARTIMI.COM>
Dave Korn wrote:
>
> Afternoon all. Here's something that's piqued my curiosity; it's probably
> owing to some language-lawyerly issue, but it isn't obvious to me. This is
> on gcc-3.3.3, (cygwin variant, but that's probably not relevant):
>
> -------------------------<snip!>-------------------------
> dk@mace /test/shift-test> cat foo.c
>
> unsigned int bar (unsigned int baz)
> {
> unsigned int quux;
>
> quux = baz >> 32;
> return quux;
> }
>
> dk@mace /test/shift-test> gcc -S foo.c -O2 -o foo.s
> foo.c: In function `bar':
> foo.c:7: warning: right shift count >= width of type
> dk@mace /test/shift-test> cat foo.s
> Why isn't the shift operation optimised away and replaced with const_int
> 0?
It's _undefined_. Didn't you make some comment about what undefined
meant last week :)
nathan
--
Nathan Sidwell :: http://www.codesourcery.com :: CodeSourcery LLC
nathan@codesourcery.com :: http://www.planetfall.pwp.blueyonder.co.uk
next prev parent reply other threads:[~2004-11-29 16:30 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-11-29 16:30 Dave Korn
2004-11-29 16:33 ` Nathan Sidwell [this message]
2004-11-29 17:01 ` Andrew Haley
2004-11-29 17:12 ` Dale Johannesen
2004-11-29 17:14 ` Dave Korn
2004-11-29 17:26 ` Andrew Haley
2004-11-29 18:29 ` Peter Barada
2004-11-29 18:53 ` Dave Korn
2004-11-29 18:52 ` Dave Korn
2004-11-29 19:09 ` Andrew Haley
2004-11-29 19:17 ` Dale Johannesen
2004-11-29 19:54 ` Dave Korn
2004-11-29 17:38 ` Chris Jefferson
2004-11-29 18:46 ` Dave Korn
2004-11-29 19:19 ` Chris Jefferson
2004-11-29 19:46 ` Dave Korn
2004-11-29 23:49 Paul Schlie
2004-11-30 1:50 ` Andreas Schwab
2004-11-30 4:23 Paul Schlie
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