Here’s a little bit of background.
* C—started when Norman Ramsey and I decided to have a stab at designing a “portable assembly language”.
* Our primary motivation was GHC: I wanted to clearly separate the business of turning lambda calculus into an imperative language, from that of turning the imperative language into machine instructions for a particular CPU architecture. But our intention was that many compilers, not just GHC, could generate C--.
* We published a series of papers describing why this goal is less easy than it looks (tail calls, garbage collection, exception handling, lightweight threading).
* But then along came LLVM. It’s goal was the same (some differences in emphasis). And LLVM “won” – it gained mindshare, a corporate sponsor, an ecosystem. I’m quite happy about this – hundreds of person-years invested by someone else 😊.
* As a result C—is really a GHC-only language (though nothing stops other compilers from using it)
* Cmm is the GHC data type (defined in compiler/cmm) that represents C—syntax trees internally in GHC.
* We do parse foo.cmm for a few runtime system support files; e.g. rts/Apply.cmm
* But most Cmm is generated from STG by compiler/codeGen
* We do CPS conversion on Cmm
* …and then either emit LLVM, or generate assembly code directly (compiler/nativeGen)
I hope that helps a bit.
Simon
From: ghc-devs On Behalf Of Gabor Greif
Sent: 17 July 2018 07:17
To: Daniel Cartwright
Cc: ghc-devs@haskell.org
Subject: Re: Cmm learning tools
No worries! I searched for C--, which was its name back in the day. There are a bunch of other conference papers in the "GHC commentary" too.
Cheers,
Gabor
Em ter, 17 de jul de 2018 às 08:00, Daniel Cartwright mailto:chessai1996@gmail.com> escreveu:
Thanks, I'll check it out.
P.S.: Apologies if my request seemed low-effort w.r.t. searching, I did spend a good 15 minutes doing so before asking, and was unable to find the document you just produced.
On Tue, Jul 17, 2018, 1:49 AM Gabor Greif mailto:ggreif@gmail.com> wrote:
Hello Daniel,
a quick web search brought up this manual:
https://www.microsoft.com/en-us/research/wp-content/uploads/1998/01/pal-manu...https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.microsoft.com%2Fen-us%2Fresearch%2Fwp-content%2Fuploads%2F1998%2F01%2Fpal-manual.pdf&data=02%7C01%7Csimonpj%40microsoft.com%7C7bb75be5019e41da25c108d5ebace57c%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636674050179363610&sdata=FsXmfxGIxygcYNE0B%2BKEtS%2FQ%2BYVTS3FXiIkmY79avys%3D&reserved=0
Please note that Cmm is slightly different, but it should get you started.
Cheers,
Gabor
Em ter, 17 de jul de 2018 às 05:20, Daniel Cartwright mailto:chessai1996@gmail.com> escreveu:
Hello all, I've recently become interested in learning Cmm, but cannot seem to find any concrete learning resources or extensive papers. It doesn't help that the web seems to contain a lot of useless information for a newcomer to Cmm. If anyone could provide some reading material about Cmm, I would be most grateful.
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