lkml.org 
[lkml]   [2008]   [Apr]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] bitops: simplify generic bit finding functions


On Sun, 27 Apr 2008, Harvey Harrison wrote:
>
> Oh, I didn't realize, I only did this because sparse started spewing out
> lots of:
> include/linux/bitops.h:166:32: warning: shift too big (65536) for type unsigned long

Well, that's really just a sparse bug/misfeature that didn't matter
before.

It happens because the warning is done as part of constant expression
evaluation, but then the expression isn't actually *used*, so when we
optimize it away - at a later date - it's too late to undo the warning.

I don't rightly know how to fix it. We do want to do the constant
evaluation early (since all the optimizations that may then make it a
non-issue depends on constants being constants!), but in order to not
output the warning we'd have to turn the constant into a "constant with
warning 'xyz' if used".

Which we have no support for in sparse yet.

Linus


\
 
 \ /
  Last update: 2008-04-27 22:41    [W:0.080 / U:0.016 seconds]
©2003-2014 Jasper Spaans. Advertise on this site