This is the mail archive of the
libc-alpha@sourceware.org
mailing list for the glibc project.
Re: [PATCH] Convert __builtin_expect to __glibc_(un)likely throughout elf/.
On Mon, Jun 4, 2018 at 10:36 AM, Joseph Myers <joseph@codesourcery.com> wrote:
> On Sat, 2 Jun 2018, Zack Weinberg wrote:
>
>> I would appreciate someone checking over this patch very carefully
>> indeed. In a whole bunch of places, __builtin_expect was used in a
>> way that did not map mechanically to the newer convention. The test
>> suite caught one mistake; I'm not confident I didn't make any more.
>
> I think this means there is a case for splitting this patch up into a part
> that doesn't change installed stripped shared libraries (on one platform -
> so at least the sense of comparisons etc. is unchanged on that platform
> after the patch, even if likely/unlikely could be wrong sometimes without
> being detected by such a comparison of installed stripped shared
> libraries), and a part that does (presumably because the mapping isn't
> purely mechanical so compiler IR changes enough to result in different
> code generated), with the latter needing more careful review that no
> semantics have changed.
I do not have time to do that in this release cycle. I think my scanf
patches are much more important and I intend to devote what little
time I do have for glibc hacking to them.
zw