Join points

Hello all! For your consideration, I present patch D2853: Join points. https://phabricator.haskell.org/D2853 It validates* and it's ready for wider reviewing, so please help me get it to land before the freeze! It's ... sizable. There's not really any way to split it, since there are many interdependencies. I've put up a "tour" as part of the SequentCore page on the wiki: https://ghc.haskell.org/trac/ghc/wiki/SequentCore This should help with where to start. Also included on the wiki are benchmarks and lots of general information. *Modulo a few long URLs and a known bug (D2964). - Luke Maurer University of Oregon maurerl@cs.uoregon.edu