StgCase - are LiveVars and SRT fields going to be used?

[Simon Peyton Jones]

Those fields are dead, now that the Cmm pass deals with it.  We left it in while making the transition, but they can go now.  Go ahead!

(Lots of code should disappear along with them!)

Simon

| -----Original Message-----
| From: ghc-devs [mailto:ghc-devs-bounces at haskell.org] On Behalf Of Ömer Sinan
| Agacan
| Sent: 01 February 2016 22:06
| To: ghc-devs <ghc-devs at haskell.org>
| Subject: StgCase - are LiveVars and SRT fields going to be used?
| 
| Hi all,
| 
| This is how case expression in STG currently defined:
| 
| 
|   | StgCase
|         (GenStgExpr bndr occ)
|         (GenStgLiveVars occ)
|         (GenStgLiveVars occ)
|         bndr
|         SRT
|         AltType
|         [GenStgAlt bndr occ]
| 
| 
| The GenStgLiveVars and SRT fields are never used anywhere in the compiler
| (except the printer). So the question is, I'm assuming those were used at
| some
| point, but are they going to be used in the future? Or can I just delete
| those?
| 
| As a proof of concept, I just compiled GHC using this:
| 
| 
|   | StgCase
|         (GenStgExpr bndr occ)
|         bndr
|         AltType
|         [GenStgAlt bndr occ]
| 
| 
| Normally this is not a big deal, but I'm doing lots of STG-to-STG
| transformations nowadays, and I have to keep those field updated which is
| annoying as those are never going to be used (I can't even know if I'm doing
| it
| right), or leave those `undefined` which is not a good practice.
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