A student from University of Illinois at Urbana-Champaign wrote a paper on transparent pointer compression in their custom GCC backend back in 2005: https://llv

A student from University of Illinois at Urbana-Champaign wrote a paper on transparent pointer compression in their custom GCC backend back in 2005: https://llvm.org/pubs/2005-06-12-MSP-PointerComp.pdf https://llvm.org/pubs/2005-06-12-MSP-PointerComp.pdf. Their compiler backend went places, but I'm not sure if the optimization described in the paper ever made it into production.