So I looked at these briefly without AVX512, because only a tiny fraction of people have anything like that and the claim was that this would be a great way of making portable SIMD :-) Also, obviously you cannot use -ffast-math in real code.

parse_fract seems really, really inefficient. Even on plain SSE2, you can do with unpack + sub + muladd + shuffle + add and then some scalar cleanup (plus the loads, of course). icx looks to be, what, 40 SIMD instructions?

find_unmatched is just scalar code cosplaying SIMD; 150 instructions and most of them do one byte at a time.

find_special seemingly generates _thousands_ of instructions! What you need, for each 16-byte loop, is a pshufb + compare + pmovmskb (0x80.pl is down now, but IIRC it's explained there). It helps that all of the values in question differ in one of the nibbles.

I am not that convinced by this being a usable universal technique :-) Even after switching back to supporting AVX512, the generated code is a huge mess. Seemingly these three functions together clock in at 6+ kB, which is ~10% of your entire icache.

> Sounds like you are working on some kind of parser?

All of these are for HTML/CSS, yes.