I once read an awesome paper that wrote a lisp compiler as a series of lisp macros that defined more and more of the language in terms of a smaller and smaller

I once read an awesome paper that wrote a lisp compiler as a series of lisp macros that defined more and more of the language in terms of a smaller and smaller set of primitives. Then it started introducing new primitives that were lisp structured representations of assembly language, and rewrote the language in those terms. The final step of the compiler was to remove the parens and you had assembly language. I can't remember the name of this paper, any thoughts?