RE: Garbage collection

I'm reluctant to invest much effort in a hack, when we know we are going to create an SPT anyway. Let's just go for it! Even if there are no TypeReps in it yet. Actually, I think that each entry in the SPT should have just two fields: something like Key, Value where "Key" is whatever we use as the "stable name" for the static value: a string, or something like that. The "Value" is a full Haskell value, just a pointer into the heap (these are the new GC roots). The value has type Dynamic, or something very like it: data Dynamic where MkDyn :: TTypeRep a -> a -> Dynamic Maybe the library Dynamic isn't quite what we need; e.g we may want to include the Key too: data SptEntry where SPT :: String -> TTypeRep a -> a -> SptEntry But regardless, the SPT itself is a simple key/value table, and all the interesting structure in in the Values in Haskell-land. Now all we need is - To build top-level bindings for the SPT Entries. These bindings are presumably created by the desugarer, as it desugars uses of 'static' - To collect them in an SPT This is presumably done in a similar way to the mkModuleInit stuff in StgCmm.codeGen Simon | -----Original Message----- | From: 0xbadcode@gmail.com [mailto:0xbadcode@gmail.com] On Behalf Of | Mathieu Boespflug | Sent: 18 November 2014 18:03 | To: Simon Peyton Jones | Cc: Facundo Domínguez; ghc-devs@haskell.org; Mathieu Boespflug | Subject: Re: Garbage collection | | On 18 November 2014 16:59, Simon Peyton Jones | wrote: | > Isn't it this simple: the Static Pointer Table must be a source of | roots for the garbage collector. Of course! An item in the SPT may be | looked up at any time. | | As Facundo says, the existence of the SPT would solve everything. But | we haven't quite figured out how to create a simple SPT yet, so were | wondering whether there is an existing generic mechanism to register | new GC roots. | | I guess there is no better solution but to just create an SPT, even if | we don't yet have TypeRep's to put in it. | | With an SPT, and under the assumption of everyone sharing the same | binary in the distributed system, there will be no need to hold on to | *all* CAF's - just the ones that are known to have a StaticPointer | created for them at compile time.