lkml.org 
[lkml]   [2016]   [May]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: linux/bitops.h
On Wed, May 04, 2016 at 03:06:04PM -0700, John Denker wrote:
> On 05/04/2016 02:56 PM, H. Peter Anvin wrote:
> >> Beware that shifting by an amount >= the number of bits in the
> >> word remains Undefined Behavior.
>
> > This construct has been supported as a rotate since at least gcc2.
>
> How then should we understand the story told in commit d7e35dfa?
> Is the story wrong?

I don't think Linux runs on a system where it would make a difference
(like a VAX), and also gcc always converts it before it could.
Even UBSan should not complain because it runs after the conversion
to ROTATE.

So it's unlikely to be a pressing issue.

-Andi

--
ak@linux.intel.com -- Speaking for myself only.

\
 
 \ /
  Last update: 2016-05-05 01:21    [W:0.086 / U:0.320 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site