Messages in this thread | | | Date | Sun, 27 Apr 2008 13:38:34 -0700 (PDT) | From | Linus Torvalds <> | Subject | Re: [PATCH] bitops: simplify generic bit finding functions |
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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
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