Subject: single-precision "expf" super slow on x86-64??

Paul Pluzhnikov ppluzhnikov@google.com
Sun Apr 29 15:52:00 GMT 2012


On Sat, Apr 28, 2012 at 10:38 PM, Miles Bader <miles@gnu.org> wrote:

>> This has very likely been fixed by
>> http://sources.redhat.com/git/?p=glibc.git;a=commitdiff;h=39adf059fccb7333f61a488d73172b0d8aa2d580
>
> Was there previously an optimized version of "exp", but not "expf"
> (since "exp" is already much faster)?

You can trivially answer that yourself, e.g.


gdb -q /lib/libm.so.6

Reading symbols from /lib/libm.so.6...Reading symbols from
/usr/lib/debug/lib/libm-2.11.1.so...done.
(gdb) list exp
18	../sysdeps/ieee754/dbl-64/w_exp.c: No such file or directory.

Now look at history of w_exp.c:
http://sources.redhat.com/git/?p=glibc.git;a=history;f=sysdeps/ieee754/dbl-64/w_exp.c;h=aa8ff7689ff7039cea2906e67d06264716b398e6;hb=HEAD


Cheers,
-- 
Paul Pluzhnikov



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