Hello, I am looking at how GHC generates STG and I am finding with a very simple piece of Haskell my usage of the API is not generating as much STG as I see when using -dump-stg option. In particular it isn't generating a binding for the nullary constructor LNull (I hope that's the correct terminology) The code is module Ex2 where data List a = LCon a (List a) | LNull -- deriving Show main :: List Int main = LCon 1 LNull Using the API I get [sat_s1pdQ = NO_CCS GHC.Base.I#! [1]; Ex2.main = NO_CCS Ex2.LCon! [sat_s1pdQ Ex2.LNull]; main = \u srt:SRT:[(s1pdS, Ex2.main)] [] Ex2.main;] with -ddump-stg I get a_r5Y = NO_CCS GHC.Base.I#! [1]; SRT(a_r5Y): [] Ex2.main = NO_CCS Ex2.LCon! [a_r5Y Ex2.LNull]; SRT(Ex2.main): [] Ex2.LCon = \r [eta_s67 eta_s68] Ex2.LCon [eta_s67 eta_s68]; SRT(Ex2.LCon): [] Ex2.LNull = NO_CCS Ex2.LNull! []; <---- This is missing SRT(Ex2.LNull): [] (in particular the Ex2.LNull is missing from the API STG) My thrown together API code is session <- GHC.newSession $ Just path (dflags,_) <- GHC.getSessionDynFlags session >>= Packages.initPackages GHC.setSessionDynFlags session dflags {GHC.hscTarget=GHC.HscAsm} core <- GHC.compileToCore session fp case core of Just core' -> do core'' <- corePrepPgm dflags core' [] stg <- coreToStg (PackageConfig.stringToPackageId "Ex2") core'' putStrLn $ (show $ (ppr stg) defaultDumpStyle) Nothing -> return () Mark
LNull is a constructor, so it has no definition in STG. How might it be defined? LNull = ??? Instead, the code generator takes the list of data types (TyCons) as well as the list of bindings. From the former it generates all the per-data-type goop, including info tables for its constructors. So the TyCons are what you want! Simon | -----Original Message----- | From: glasgow-haskell-users-bounces@haskell.org [mailto:glasgow-haskell-users-bounces@haskell.org] On | Behalf Of Mark Wassell | Sent: 15 April 2008 11:27 | To: glasgow-haskell-users | Subject: Using GHC API to generate STG | | Hello, | | I am looking at how GHC generates STG and I am finding with a very | simple piece of Haskell my usage of the API is not generating as much | STG as I see when using -dump-stg option. In particular it isn't | generating a binding for the nullary constructor LNull (I hope that's | the correct terminology) | | The code is | | module Ex2 where | | data List a = LCon a (List a) | LNull -- deriving Show | | main :: List Int | main = LCon 1 LNull | | Using the API I get | | [sat_s1pdQ = NO_CCS GHC.Base.I#! [1]; | Ex2.main = NO_CCS Ex2.LCon! [sat_s1pdQ Ex2.LNull]; | main = \u srt:SRT:[(s1pdS, Ex2.main)] [] Ex2.main;] | | with -ddump-stg I get | | a_r5Y = NO_CCS GHC.Base.I#! [1]; | SRT(a_r5Y): [] | Ex2.main = NO_CCS Ex2.LCon! [a_r5Y Ex2.LNull]; | SRT(Ex2.main): [] | Ex2.LCon = \r [eta_s67 eta_s68] Ex2.LCon [eta_s67 eta_s68]; | SRT(Ex2.LCon): [] | Ex2.LNull = NO_CCS Ex2.LNull! []; <---- This is missing | SRT(Ex2.LNull): [] | | (in particular the Ex2.LNull is missing from the API STG) | | My thrown together API code is | | session <- GHC.newSession $ Just path | (dflags,_) <- GHC.getSessionDynFlags session >>= | Packages.initPackages | GHC.setSessionDynFlags session dflags {GHC.hscTarget=GHC.HscAsm} | core <- GHC.compileToCore session fp | case core of | Just core' -> do | core'' <- corePrepPgm dflags core' [] | stg <- coreToStg | (PackageConfig.stringToPackageId "Ex2") core'' | putStrLn $ (show $ (ppr stg) | defaultDumpStyle) | Nothing -> return () | | | | Mark | _______________________________________________ | Glasgow-haskell-users mailing list | Glasgow-haskell-users@haskell.org | http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
participants (2)
-
Mark Wassell -
Simon Peyton-Jones