Questions on 'proc point splitting' again

Ben Gamari ben at
Thu Mar 3 10:32:14 UTC 2016

David Spitzenberg <spitzenb at> writes:

> Hello everyone!
> First of all, my apologies for letting you wait that long. Especially, I
> want to let you know that I really feel sorry for not following up your
> offer back in January, Simon.
Don't worry at all; life happens. Any effort your are able to contribute
is appreciated.

> I somewhat underestimated the amount of time I had to invest in
> university during the last semester. Unfortunately, I couldn't find the
> time to work out the demonstration I mentioned in my last mail back in
> December.
> At the moment, I'm making up for this showcase. In doing so, I stumbled
> across another question concerning the cmm-pipeline:
> Given a CmmGraph, is there a possibility to annotate information to a
> single node within this graph? I.e. I want to annotate to certain
> CmmCalls that they where introduced by 'proc point splitting'. I would
> like to slightly modifiy the generation of LLVM IR for such Calls later on.
My guess here would be to map the CmmGraph (which is simply a type
synonym for `GenCmmGraph CmmNode` to something of type `GenCmmGraph
AnnCmmNode` where AnnCmmNode carries a CmmNode along with whatever other
information you'd like to preserve.

This then poses the question of what you'd like to *do* with this graph,
since you'll be unable to use much of the GHC's existing machinery.
My (possibly mistaken) impression is that we don't have a terribly great
story in GHC for working with arbitrarily annotated Cmm graphs.

I'm afraid we have now scraped past the bounds of my knowledge, however;
hopefully one of the Simons will be able to set you off in the right


- Ben
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