Right. I pointed it out because it isn't just about having portable SIMD that makes SIMD optimizations possible. Therefore, the lack of one in Rust doesn't have

Right. I pointed it out because it isn't just about having portable SIMD that makes SIMD optimizations possible. Therefore, the lack of one in Rust doesn't have much explanatory power for why Rust's standard library doesn't contain SIMD. (It does have some.) It's good enough for things like memchr (well, kinda, NEON doesn't have `movemask`[1,2]), but not for things like Teddy that do multi-substring search. When you do want to write SIMD across platforms, it's not too hard to define your own bespoke portable API[3]. I'm basically just pointing out that a portable API is somewhat oversold, because it's not uncommon to need to abandon it, especially for string related ops that make creative use of ISA extensions. And additionally, that Rust unfortunately has other reasons for why std doesn't make as much use of SIMD as it probably should (the core/alloc/std split). [1]: https://github.com/BurntSushi/memchr/blob/c6b885b870b6f1b9bfae2de482e1264d6c7aa040/src/vector.rs#L326-L333 https://github.com/BurntSushi/memchr/blob/c6b885b870b6f1b9bf... [2]: https://github.com/BurntSushi/memchr/blob/c6b885b870b6f1b9bfae2de482e1264d6c7aa040/src/vector.rs#L363-L379 https://github.com/BurntSushi/memchr/blob/c6b885b870b6f1b9bf... [3]: https://github.com/BurntSushi/aho-corasick/blob/f227162f7c56b3f28e9dd69a655316af0107b29b/src/packed/vector.rs https://github.com/BurntSushi/aho-corasick/blob/f227162f7c56...