I totally agree we don't want multiple optimized implementations, but that is no longer necessary. Highway (mentioned below) lets you write your code once but b

I totally agree we don't want multiple optimized implementations, but that is no longer necessary. Highway (mentioned below) lets you write your code once but be compiled+specialized for the major SIMD targets. If you're writing say a thousand lines of SIMD, the binary size impact is a few dozen KiB. This is also a purely library solution, so no build system magic is required.