When looking at that code:

aa 1: stosb e2 fd loop 1b

Why doesnt jart simply use rep stosb? It would take 1 less byte and even be slightly more idiomatic.

Ok I'm not an expert here, but it seems they do [0] and in the pr [1] the comment says it's now 13 bytes (I _believe_ previously it was incorrectly stating 17 which it should have been 14)

[0] https://github.com/jart/cosmopolitan/blob/master/libc/nexgen...

[1] https://github.com/jart/cosmopolitan/commit/e96aceae41121630...