That sounds like PL/X[1] to me. That language will let you do things that REALLY aren't advisable on most systems like specify pointer sizes (per variable), specify address mode (arbitrary blocks, functions, nested functions, per module, whatever), specify registers for any variable. Oh an my favourite, when calling a function, you can specify an arbitrary global label for it to return to.

Or of course you can write as cleanly as possible, let the compiler do the lion's share of the work, and fix up what you need to.

[1]http://en.wikipedia.org/wiki/PL/X and http://c2.com/cgi/wiki?PlsLanguage