On Thu, Feb 12, 2015 at 8:26 PM, Denys Vlasenko
<vda.linux@googlemail.com> wrote:
>> I'd actually like to extend the "short" range up to at least 32 bytes
>> using two 8-byte writes for the middle, unless the savings from using
>> 32-bit imul instead of 64-bit are sufficient to justify 4 4-byte
>> writes for the middle. On the cpu I tested on, the difference is 11
>> cycles vs 32 cycles for non-rep path versus rep path at size 32.
>
> The short path causes mixed feelings in me.
>
> On one hand, it's elegant in a contrived way.
>
> On the other hand, multiple
> overlaying stores must be causing hell in store unit.
> I'm thinking, maybe there's a faster way to do that.

For example, like in the attached implementation.

This one will not perform eight stores to memory
to fill 15 byte area... only two.