When I read these papers I always wonder if the authors did any research into priors before doing their work. I usually see sus-af "redos" in low tier AI (the fad of the decade); so, CPU arch is original? Another commenter pointed out Mill is probably the closest one I can think of off the top of my head. I think the old rolling window Power stuff IBM published in the ... 90s? might be exactly this? I can't remember if that arch used an autowindow (STRAIGHT) or if it was more manual.

EDIT: Derp! RIP-relative x64? I've not coded x64 in 15 years, so I don't remember how pervasive the addressing mode is.

I guess the author's are trying to explore a ground-up implementation? Maybe the uarch is really exotic?