I know both gcc (https://gcc.gnu.org/onlinedocs/gcc/Vector-Extensions.html) and clang (https://clang.llvm.org/docs/LanguageExtensions.html#vectors-...) have vector extensions that are intended to make it easier to write SIMD code (you can write c = a + b; instead of having to know the specific vector instruction needed to add two vectors, for example), but don’t know how well these reach that goal.

Are these helpful, or not good enough to write performant vector code?