Comparing strings from the back?

[MRAB]

On 05/09/2012 03:18, Neil Hodgson wrote:
> Roy Smith:
>
>> I'm wondering if it might be faster to start at the ends of the strings
>> instead of at the beginning?  If the strings are indeed equal, it's the
>> same amount of work starting from either end.
>
>      Most people write loops that go forwards. This leads to the
> processor designers prioritizing detection mechanisms like cache
> prefetching for that case.
>
>      However, its not always the situation: a couple of years ago Intel
> contributed a memcpy implementation to glibc that went backwards for a
> performance improvement. An explanation from a related patch involves
> speculative and committed operations and address bits on some processors
> and quickly lost me:
> paragraph 3 of
> http://lists.freedesktop.org/archives/pixman/2010-August/000423.html
>
>      The memcpy patch was controversial as it broke Adobe Flash which
> assumed memcpy was safe like memmove.
>
I don't think I've ever use memcpy, only memmove.