Customized compiler isn't really a thing in most languages. Because it implies changing the language, and everyone agreeing on what the language is was sort of the point of the whole exercise. Hence all the worries about macros.

SBCL has the right hooks. Jai probably does as well. You could build your own thing on LLVM relatively easily - so Rust _could_ do it if you gave it sufficient access to the compiler, but so could C++ or D.

SIMD bitmasks being ~0 instead of (00000001)+ is common and useful, but there's an annoying language design question in there about what type comparisons between vectors should be (if you don't have a <N x i1> as a type, say because you liked C too much). Shout out to std::vector<bool>.

There is probably interesting work in mojo for this. The library being in MLIR strongly encourages taking that sort of approach. I haven't looked at their implementation though. Happy hacking!