memset and related things

[Don]

bearophile wrote:
> Don:
> 
>> It'll be interesting to see what the priorities are now -- 
>> maybe this stuff is of more interest now.
> 
> Probably removing bugs is more important still :-)
> For example your work has changed a little how compile-time functions can be used in D.
> 
> 
>> BTW the AMD manual for K7 (or might be K6 optimisation manual? don't 
>> exactly remember) goes into great detail about both memcpy() and 
>> memset(). Turns out there's about five different cases.
> 
> In the meantime Deewiant has told me that on 64 bit glibc memset is better and on more modern CPUs the timings are different (and on 64 bit my first version may not work, maybe the second one is better. I have not tested it on 64 bit LDC yet). I'm just a newbie on this stuff, while people that write the memset of 64bit glibc are expert.

Really, memset() _should_ be optimal in all cases.  On almost all 
compilers, it's not optimal, and on many (such as DMD) there's a _lot_ 
of room for improvement. So I consider this to a C standard library 
implementation issue, rather than a language weakness.