Compiler backend generated from declarative description of the architecture
Jo&atilde;o Dias; Norman Ramsey: "Automatically Generating Back Ends Using Declarative Machine Descriptions", Proc. ACM Symp. Principles of Prog. Lang., (POPL-37):403-416, 2010.

I think this goes a bit farther than you asked for, because they're actually looking for good code sequences.  For something a little more basic you could go back to some of Norm Ramsey's earlier work, like: Norman Ramsey; Mary F. Fern&aacute;ndez: "Specifying Representations of Machine Instructions", ACM T. Prog. Lang. and Sys., 19(3):492–524, May 1997.

There's a long line of research on trying to automatically generate back ends from simpler descriptions.  Look for papers by Christopher W Fraser, David R Hanson and Todd A Proebsting.