[acdimalev]

I didn't know it was a System V thing. Thank you for cluing me in!

I don't think of it in terms of like-vs-dislike. My observation is that it's a difficult thing to get right without a compiler, and thus avoided for introductory material.

As far as I am aware, storing values in a register requires fewer instructions. However, I have never personally confirmed the performance difference of this calling convention.

Handling of all calling conventions is one of the many things that I am personally much happier leaving up to GCC and LLVM in practice.