Wasm intrinsics look neat as a higher-level fixed size SIMD abstraction. I wonder how good the compilers can do if using them for AOT targets with libraries like simd-everywhere.

string.h is missing strstr(), there's an algorithm of similar complexity you might consider: http://0x80.pl/notesen/2016-11-28-simd-strfind.html

Yeah, so far I did exactly the ones (my build of) SQLite needed and not others.

If there's interest, the set of implemented functions can definitely be extended.