| I am trying to understand the role of cmm files in the current GHC | compiler build process (I am guessing, they have replaced .hc files | like PrimOps and AutoApply). Yes, that's exactly right. | They are compiled by the stage1 compiler. Is ability to compile cmm | preserved in the compiler finally built at stage3 and installed? Yes it is. | What compiler flags are available for cmm files compilation? The | User's guide says nothing specific. Are -E, -C, -S available (along | with -c and -fvia-c seen in the nightly build log)? I think -C and -S are. I'm not sure about -E. Try it! You're right that it ought to say. I suspect that the whole "compile Foo.cmm" route is ill-described in the manual; even .cmm language (which is only a subset of C--) isn't described. Reason: we think of it as an internal thing. But it's fine for you to use it, and if it becomes useful to others we should document it better. If you can suggest specifically what would be helpful to you, and specifically where in the manual, and better still provide some specific words, I'll gladly paste them in. Simon