[PATCH 09/10] i386: Replace assembly versions of e_log2f with generic e_log2f.c

[H.J. Lu]

On Fri, Oct 20, 2017 at 7:55 AM, Szabolcs Nagy <szabolcs.nagy@arm.com> wrote:
> On 19/10/17 20:51, H.J. Lu wrote:
>> On Thu, Oct 19, 2017 at 10:31 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
>>> This patch replaces i386 assembly versions of e_log2f with generic
>>> e_log2f.c.  For workload-spec2017.wrf, on Nehalem, it improves
>>> performance by:
>>>
>>>                            Before            After     Improvement
>>> reciprocal-throughput      92.3845          30.8752       199%
>>> latency                    112.855          54.8645       105%
>>>
>>> On Skylake, it improves performance by:
>>>
>>>                            Before            After     Improvement
>>> reciprocal-throughput      98.7488          22.7507       334%
>>> latency                    118.01           51.6083       128%
>>
>> On IvyBridge with --disable-multi-arch, it improves performance by:
>>
>>                            Before            After     Improvement
>> reciprocal-throughput      106.635          28.8596       269%
>> latency                    129.888          56.9187       128%
>>
>
> is this comparing x87 c code with x87 asm?

Yes.  I double checked.   There are no SSE instructions in libm.so.

> or did the toolchain have -fpmath=sse?
>
> i would not expect that much speedup on i386
>



-- 
H.J.