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Re: CVS commit: src/sys/sys
On Thu, Mar 08, 2018 at 10:25:45PM +0000, Christos Zoulas wrote:
> In article <20180308215453.GB22758%britannica.bec.de@localhost>,
> Joerg Sonnenberger <joerg%bec.de@localhost> wrote:
> >On Thu, Mar 08, 2018 at 03:32:33PM -0500, Christos Zoulas wrote:
> >> Module Name: src
> >> Committed By: christos
> >> Date: Thu Mar 8 20:32:33 UTC 2018
> >>
> >> Modified Files:
> >> src/sys/sys: bitops.h
> >>
> >> Log Message:
> >> PR/53081: Fix size of the shift to depend on the type of the bitmap so that
> >> we get the correct width.
> >
> >Please don't use __typeof__. 1ull is good enough and we can depend on
> >a non-stupid compiler to truncate the intermediate.
>
> The __typeof__ ship has already sailed:
>
> $ fgrep -r __typeof__ /usr/include/sys/ | wc -l
> 3
Of those, only the rounddown2 is non-optional. That falls into the same
category even, it doesn't really hurt to widen there.
> Doing a 64 bit calculation on a 32 bit platform when it is not needed
> is a waste (and produces narrowing warnings).
It's not a 64bit calculation if the compiler is at least trying to
create sane code. The bit masking should ensure that.
Joerg
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