Yes, there were some pretty recent (as in, not present in 7.6) improvements to C-- syntax. Updates would be much appreciated; you can probably figure out what the changes are by snooping the changelogs for compiler/cmm. Edward Excerpts from Carter Schonwald's message of Fri Apr 05 20:37:23 -0700 2013:
Hey all, I've been staring at the cmm primop code in ghc over the past week to understand a number of things, and I was just today looking at the current cmm documentation on the ghc wiki.
specifically i've been looking at https://github.com/ghc/ghc/blob/master/compiler/cmm/Cmm.hs https://github.com/ghc/ghc/blob/master/compiler/cmm/CmmParse.y and https://github.com/ghc/ghc/blob/master/rts/PrimOps.cmm
versus the wiki docs http://hackage.haskell.org/trac/ghc/wiki/Commentary/Compiler/CmmType
it looks like CMM supports a nicer function definition convention than the wiki implies. (and presumably that also would hold for the ffi for calling user written cmm code too?)
If the wiki is out of date, i'm happy to make a first pass at trying to add this info somewhere,
thanks -Carter