{-# LANGUAGE CPP #-} {-# LANGUAGE ConstraintKinds #-} {-# LANGUAGE DataKinds #-} {-# LANGUAGE DeriveDataTypeable #-} {-# LANGUAGE FlexibleContexts #-} {-# LANGUAGE LambdaCase #-} {-# LANGUAGE TypeFamilies #-} {-# LANGUAGE UndecidableInstances #-} {- (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 Shared term graph (STG) syntax for spineless-tagless code generation ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ This data type represents programs just before code generation (conversion to @Cmm@): basically, what we have is a stylised form of Core syntax, the style being one that happens to be ideally suited to spineless tagless code generation. -} module GHC.Stg.Syntax ( StgArg(..), GenStgTopBinding(..), GenStgBinding(..), GenStgExpr(..), GenStgRhs(..), GenStgAlt, AltType(..), StgPass(..), BinderP, XRhsClosure, XLet, XLetNoEscape, XConApp, NoExtFieldSilent, noExtFieldSilent, OutputablePass, UpdateFlag(..), isUpdatable, ConstructorNumber(..), -- a set of synonyms for the vanilla parameterisation StgTopBinding, StgBinding, StgExpr, StgRhs, StgAlt, -- a set of synonyms for the code gen parameterisation CgStgTopBinding, CgStgBinding, CgStgExpr, CgStgRhs, CgStgAlt, -- a set of synonyms for the lambda lifting parameterisation LlStgTopBinding, LlStgBinding, LlStgExpr, LlStgRhs, LlStgAlt, -- a set of synonyms to distinguish in- and out variants InStgArg, InStgTopBinding, InStgBinding, InStgExpr, InStgRhs, InStgAlt, OutStgArg, OutStgTopBinding, OutStgBinding, OutStgExpr, OutStgRhs, OutStgAlt, -- StgOp StgOp(..), -- utils stgRhsArity, freeVarsOfRhs, isDllConApp, stgArgType, stripStgTicksTop, stripStgTicksTopE, stgCaseBndrInScope, bindersOf, bindersOfTop, bindersOfTopBinds, -- ppr StgPprOpts(..), initStgPprOpts, panicStgPprOpts, shortStgPprOpts, pprStgArg, pprStgExpr, pprStgRhs, pprStgBinding, pprGenStgTopBinding, pprStgTopBinding, pprGenStgTopBindings, pprStgTopBindings ) where #include "HsVersions.h" import GHC.Prelude import GHC.Core ( AltCon ) import GHC.Types.CostCentre ( CostCentreStack ) import Data.ByteString ( ByteString ) import Data.Data ( Data ) import Data.List ( intersperse ) import GHC.Core.DataCon import GHC.Driver.Session import GHC.Types.ForeignCall ( ForeignCall ) import GHC.Types.Id import GHC.Types.Name ( isDynLinkName ) import GHC.Types.Tickish ( StgTickish ) import GHC.Types.Var.Set import GHC.Types.Literal ( Literal, literalType ) import GHC.Unit.Module ( Module ) import GHC.Utils.Outputable import GHC.Platform import GHC.Core.Ppr( {- instances -} ) import GHC.Builtin.PrimOps ( PrimOp, PrimCall ) import GHC.Core.TyCon ( PrimRep(..), TyCon ) import GHC.Core.Type ( Type ) import GHC.Types.RepType ( typePrimRep1 ) import GHC.Utils.Misc import GHC.Utils.Panic {- ************************************************************************ * * GenStgBinding * * ************************************************************************ As usual, expressions are interesting; other things are boring. Here are the boring things (except note the @GenStgRhs@), parameterised with respect to binder and occurrence information (just as in @GHC.Core@): -} -- | A top-level binding. data GenStgTopBinding pass -- See Note [Core top-level string literals] = StgTopLifted (GenStgBinding pass) | StgTopStringLit Id ByteString data GenStgBinding pass = StgNonRec (BinderP pass) (GenStgRhs pass) | StgRec [(BinderP pass, GenStgRhs pass)] {- ************************************************************************ * * StgArg * * ************************************************************************ -} data StgArg = StgVarArg Id | StgLitArg Literal -- | Does this constructor application refer to anything in a different -- *Windows* DLL? -- If so, we can't allocate it statically isDllConApp :: DynFlags -> Module -> DataCon -> [StgArg] -> Bool isDllConApp dflags this_mod con args | not (gopt Opt_ExternalDynamicRefs dflags) = False | platformOS platform == OSMinGW32 = isDynLinkName platform this_mod (dataConName con) || any is_dll_arg args | otherwise = False where platform = targetPlatform dflags -- NB: typePrimRep1 is legit because any free variables won't have -- unlifted type (there are no unlifted things at top level) is_dll_arg :: StgArg -> Bool is_dll_arg (StgVarArg v) = isAddrRep (typePrimRep1 (idType v)) && isDynLinkName platform this_mod (idName v) is_dll_arg _ = False -- True of machine addresses; these are the things that don't work across DLLs. -- The key point here is that VoidRep comes out False, so that a top level -- nullary GADT constructor is False for isDllConApp -- -- data T a where -- T1 :: T Int -- -- gives -- -- T1 :: forall a. (a~Int) -> T a -- -- and hence the top-level binding -- -- $WT1 :: T Int -- $WT1 = T1 Int (Coercion (Refl Int)) -- -- The coercion argument here gets VoidRep isAddrRep :: PrimRep -> Bool isAddrRep AddrRep = True isAddrRep LiftedRep = True isAddrRep UnliftedRep = True isAddrRep _ = False -- | Type of an @StgArg@ -- -- Very half baked because we have lost the type arguments. stgArgType :: StgArg -> Type stgArgType (StgVarArg v) = idType v stgArgType (StgLitArg lit) = literalType lit -- | Strip ticks of a given type from an STG expression. stripStgTicksTop :: (StgTickish -> Bool) -> GenStgExpr p -> ([StgTickish], GenStgExpr p) stripStgTicksTop p = go [] where go ts (StgTick t e) | p t = go (t:ts) e go ts other = (reverse ts, other) -- | Strip ticks of a given type from an STG expression returning only the expression. stripStgTicksTopE :: (StgTickish -> Bool) -> GenStgExpr p -> GenStgExpr p stripStgTicksTopE p = go where go (StgTick t e) | p t = go e go other = other -- | Given an alt type and whether the program is unarised, return whether the -- case binder is in scope. -- -- Case binders of unboxed tuple or unboxed sum type always dead after the -- unariser has run. See Note [Post-unarisation invariants]. stgCaseBndrInScope :: AltType -> Bool {- ^ unarised? -} -> Bool stgCaseBndrInScope alt_ty unarised = case alt_ty of AlgAlt _ -> True PrimAlt _ -> True MultiValAlt _ -> not unarised PolyAlt -> True {- ************************************************************************ * * STG expressions * * ************************************************************************ The @GenStgExpr@ data type is parameterised on binder and occurrence info, as before. ************************************************************************ * * GenStgExpr * * ************************************************************************ An application is of a function to a list of atoms (not expressions). Operationally, we want to push the arguments on the stack and call the function. (If the arguments were expressions, we would have to build their closures first.) There is no constructor for a lone variable; it would appear as @StgApp var []@. -} data GenStgExpr pass = StgApp Id -- function [StgArg] -- arguments; may be empty {- ************************************************************************ * * StgConApp and StgPrimApp --- saturated applications * * ************************************************************************ There are specialised forms of application, for constructors, primitives, and literals. -} | StgLit Literal -- StgConApp is vital for returning unboxed tuples or sums -- which can't be let-bound | StgConApp DataCon (XConApp pass) [StgArg] -- Saturated [Type] -- See Note [Types in StgConApp] in GHC.Stg.Unarise | StgOpApp StgOp -- Primitive op or foreign call [StgArg] -- Saturated. Type -- Result type -- We need to know this so that we can -- assign result registers {- ************************************************************************ * * GenStgExpr: case-expressions * * ************************************************************************ This has the same boxed/unboxed business as Core case expressions. -} | StgCase (GenStgExpr pass) -- the thing to examine (BinderP pass) -- binds the result of evaluating the scrutinee AltType [GenStgAlt pass] -- The DEFAULT case is always *first* -- if it is there at all {- ************************************************************************ * * GenStgExpr: let(rec)-expressions * * ************************************************************************ The various forms of let(rec)-expression encode most of the interesting things we want to do. - let-closure x = [free-vars] [args] expr in e is equivalent to let x = (\free-vars -> \args -> expr) free-vars @args@ may be empty (and is for most closures). It isn't under circumstances like this: let x = (\y -> y+z) This gets mangled to let-closure x = [z] [y] (y+z) The idea is that we compile code for @(y+z)@ in an environment in which @z@ is bound to an offset from Node, and `y` is bound to an offset from the stack pointer. (A let-closure is an @StgLet@ with a @StgRhsClosure@ RHS.) - let-constructor x = Constructor [args] in e (A let-constructor is an @StgLet@ with a @StgRhsCon@ RHS.) - Letrec-expressions are essentially the same deal as let-closure/ let-constructor, so we use a common structure and distinguish between them with an @is_recursive@ boolean flag. - let-unboxed u = in e All the stuff on the RHS must be fully evaluated. No function calls either! (We've backed away from this toward case-expressions with suitably-magical alts ...) - Advanced stuff here! Not to start with, but makes pattern matching generate more efficient code. let-escapes-not fail = expr in e' Here the idea is that @e'@ guarantees not to put @fail@ in a data structure, or pass it to another function. All @e'@ will ever do is tail-call @fail@. Rather than build a closure for @fail@, all we need do is to record the stack level at the moment of the @let-escapes-not@; then entering @fail@ is just a matter of adjusting the stack pointer back down to that point and entering the code for it. Another example: f x y = let z = huge-expression in if y==1 then z else if y==2 then z else 1 (A let-escapes-not is an @StgLetNoEscape@.) - We may eventually want: let-literal x = Literal in e And so the code for let(rec)-things: -} | StgLet (XLet pass) (GenStgBinding pass) -- right hand sides (see below) (GenStgExpr pass) -- body | StgLetNoEscape (XLetNoEscape pass) (GenStgBinding pass) -- right hand sides (see below) (GenStgExpr pass) -- body {- ************************************************************************* * * GenStgExpr: hpc, scc and other debug annotations * * ************************************************************************* Finally for @hpc@ expressions we introduce a new STG construct. -} | StgTick StgTickish (GenStgExpr pass) -- sub expression -- END of GenStgExpr {- ************************************************************************ * * STG right-hand sides * * ************************************************************************ Here's the rest of the interesting stuff for @StgLet@s; the first flavour is for closures: -} data GenStgRhs pass = StgRhsClosure (XRhsClosure pass) -- ^ Extension point for non-global free var -- list just before 'CodeGen'. CostCentreStack -- ^ CCS to be attached (default is CurrentCCS) !UpdateFlag -- ^ 'ReEntrant' | 'Updatable' | 'SingleEntry' [BinderP pass] -- ^ arguments; if empty, then not a function; -- as above, order is important. (GenStgExpr pass) -- ^ body {- An example may be in order. Consider: let t = \x -> \y -> ... x ... y ... p ... q in e Pulling out the free vars and stylising somewhat, we get the equivalent: let t = (\[p,q] -> \[x,y] -> ... x ... y ... p ...q) p q Stg-operationally, the @[x,y]@ are on the stack, the @[p,q]@ are offsets from @Node@ into the closure, and the code ptr for the closure will be exactly that in parentheses above. The second flavour of right-hand-side is for constructors (simple but important): -} | StgRhsCon CostCentreStack -- CCS to be attached (default is CurrentCCS). -- Top-level (static) ones will end up with -- DontCareCCS, because we don't count static -- data in heap profiles, and we don't set CCCS -- from static closure. DataCon -- Constructor. Never an unboxed tuple or sum, as those -- are not allocated. ConstructorNumber [StgTickish] [StgArg] -- Args {- Note Stg Passes ~~~~~~~~~~~~~~~ Here is a short summary of the STG pipeline and where we use the different StgPass data type indexes: 1. CoreToStg.Prep performs several transformations that prepare the desugared and simplified core to be converted to STG. One of these transformations is making it so that value lambdas only exist as the RHS of a binding. 2. CoreToStg converts the prepared core to STG, specifically GenStg* parameterised by 'Vanilla. 3. Stg.Pipeline does a number of passes on the generated STG. One of these is the lambda-lifting pass, which internally uses the 'LiftLams parameterisation to store information for deciding whether or not to lift each binding. 4. Stg.FVs annotates closures with their free variables. To store these annotations we use the 'CodeGen parameterisation. 5. Stg.StgToCmm generates Cmm from the annotated STG. -} -- | Used as a data type index for the stgSyn AST data StgPass = Vanilla | LiftLams | CodeGen -- | Like 'GHC.Hs.Extension.NoExtField', but with an 'Outputable' instance that -- returns 'empty'. data NoExtFieldSilent = NoExtFieldSilent deriving (Data, Eq, Ord) instance Outputable NoExtFieldSilent where ppr _ = empty -- | Used when constructing a term with an unused extension point that should -- not appear in pretty-printed output at all. noExtFieldSilent :: NoExtFieldSilent noExtFieldSilent = NoExtFieldSilent -- TODO: Maybe move this to GHC.Hs.Extension? I'm not sure about the -- implications on build time... -- TODO: Do we really want to the extension point type families to have a closed -- domain? type family BinderP (pass :: StgPass) type instance BinderP 'Vanilla = Id type instance BinderP 'CodeGen = Id type family XRhsClosure (pass :: StgPass) type instance XRhsClosure 'Vanilla = NoExtFieldSilent -- | Code gen needs to track non-global free vars type instance XRhsClosure 'CodeGen = DIdSet type family XLet (pass :: StgPass) type instance XLet 'Vanilla = NoExtFieldSilent type instance XLet 'CodeGen = NoExtFieldSilent type family XConApp (pass :: StgPass) type instance XConApp 'Vanilla = ConstructorNumber type instance XConApp 'CodeGen = ConstructorNumber -- | When `-fdistinct-constructor-tables` is turned on then -- each usage of a constructor is given an unique number and -- an info table is generated for each different constructor. data ConstructorNumber = NoNumber | Numbered Int instance Outputable ConstructorNumber where ppr NoNumber = empty ppr (Numbered n) = text "#" <> ppr n type family XLetNoEscape (pass :: StgPass) type instance XLetNoEscape 'Vanilla = NoExtFieldSilent type instance XLetNoEscape 'CodeGen = NoExtFieldSilent stgRhsArity :: StgRhs -> Int stgRhsArity (StgRhsClosure _ _ _ bndrs _) = ASSERT( all isId bndrs ) length bndrs -- The arity never includes type parameters, but they should have gone by now stgRhsArity (StgRhsCon _ _ _ _ _) = 0 freeVarsOfRhs :: (XRhsClosure pass ~ DIdSet) => GenStgRhs pass -> DIdSet freeVarsOfRhs (StgRhsCon _ _ _ _ args) = mkDVarSet [ id | StgVarArg id <- args ] freeVarsOfRhs (StgRhsClosure fvs _ _ _ _) = fvs {- ************************************************************************ * * STG case alternatives * * ************************************************************************ Very like in Core syntax (except no type-world stuff). The type constructor is guaranteed not to be abstract; that is, we can see its representation. This is important because the code generator uses it to determine return conventions etc. But it's not trivial where there's a module loop involved, because some versions of a type constructor might not have all the constructors visible. So mkStgAlgAlts (in CoreToStg) ensures that it gets the TyCon from the constructors or literals (which are guaranteed to have the Real McCoy) rather than from the scrutinee type. -} type GenStgAlt pass = (AltCon, -- alts: data constructor, [BinderP pass], -- constructor's parameters, GenStgExpr pass) -- ...right-hand side. data AltType = PolyAlt -- Polymorphic (a boxed type variable, lifted or unlifted) | MultiValAlt Int -- Multi value of this arity (unboxed tuple or sum) -- the arity could indeed be 1 for unary unboxed tuple -- or enum-like unboxed sums | AlgAlt TyCon -- Algebraic data type; the AltCons will be DataAlts | PrimAlt PrimRep -- Primitive data type; the AltCons (if any) will be LitAlts {- ************************************************************************ * * The Plain STG parameterisation * * ************************************************************************ This happens to be the only one we use at the moment. -} type StgTopBinding = GenStgTopBinding 'Vanilla type StgBinding = GenStgBinding 'Vanilla type StgExpr = GenStgExpr 'Vanilla type StgRhs = GenStgRhs 'Vanilla type StgAlt = GenStgAlt 'Vanilla type LlStgTopBinding = GenStgTopBinding 'LiftLams type LlStgBinding = GenStgBinding 'LiftLams type LlStgExpr = GenStgExpr 'LiftLams type LlStgRhs = GenStgRhs 'LiftLams type LlStgAlt = GenStgAlt 'LiftLams type CgStgTopBinding = GenStgTopBinding 'CodeGen type CgStgBinding = GenStgBinding 'CodeGen type CgStgExpr = GenStgExpr 'CodeGen type CgStgRhs = GenStgRhs 'CodeGen type CgStgAlt = GenStgAlt 'CodeGen {- Many passes apply a substitution, and it's very handy to have type synonyms to remind us whether or not the substitution has been applied. See GHC.Core for precedence in Core land -} type InStgTopBinding = StgTopBinding type InStgBinding = StgBinding type InStgArg = StgArg type InStgExpr = StgExpr type InStgRhs = StgRhs type InStgAlt = StgAlt type OutStgTopBinding = StgTopBinding type OutStgBinding = StgBinding type OutStgArg = StgArg type OutStgExpr = StgExpr type OutStgRhs = StgRhs type OutStgAlt = StgAlt {- ************************************************************************ * * UpdateFlag * * ************************************************************************ This is also used in @LambdaFormInfo@ in the @ClosureInfo@ module. A @ReEntrant@ closure may be entered multiple times, but should not be updated or blackholed. An @Updatable@ closure should be updated after evaluation (and may be blackholed during evaluation). A @SingleEntry@ closure will only be entered once, and so need not be updated but may safely be blackholed. -} data UpdateFlag = ReEntrant | Updatable | SingleEntry instance Outputable UpdateFlag where ppr u = char $ case u of ReEntrant -> 'r' Updatable -> 'u' SingleEntry -> 's' isUpdatable :: UpdateFlag -> Bool isUpdatable ReEntrant = False isUpdatable SingleEntry = False isUpdatable Updatable = True {- ************************************************************************ * * StgOp * * ************************************************************************ An StgOp allows us to group together PrimOps and ForeignCalls. It's quite useful to move these around together, notably in StgOpApp and COpStmt. -} data StgOp = StgPrimOp PrimOp | StgPrimCallOp PrimCall | StgFCallOp ForeignCall Type -- The Type, which is obtained from the foreign import declaration -- itself, is needed by the stg-to-cmm pass to determine the offset to -- apply to unlifted boxed arguments in GHC.StgToCmm.Foreign. See Note -- [Unlifted boxed arguments to foreign calls] {- ************************************************************************ * * Utilities * * ************************************************************************ -} bindersOf :: BinderP a ~ Id => GenStgBinding a -> [Id] bindersOf (StgNonRec binder _) = [binder] bindersOf (StgRec pairs) = [binder | (binder, _) <- pairs] bindersOfTop :: BinderP a ~ Id => GenStgTopBinding a -> [Id] bindersOfTop (StgTopLifted bind) = bindersOf bind bindersOfTop (StgTopStringLit binder _) = [binder] bindersOfTopBinds :: BinderP a ~ Id => [GenStgTopBinding a] -> [Id] bindersOfTopBinds = foldr ((++) . bindersOfTop) [] {- ************************************************************************ * * Pretty-printing * * ************************************************************************ Robin Popplestone asked for semi-colon separators on STG binds; here's hoping he likes terminators instead... Ditto for case alternatives. -} type OutputablePass pass = ( Outputable (XLet pass) , Outputable (XConApp pass) , Outputable (XLetNoEscape pass) , Outputable (XRhsClosure pass) , OutputableBndr (BinderP pass) ) -- | STG pretty-printing options data StgPprOpts = StgPprOpts { stgSccEnabled :: !Bool -- ^ Enable cost-centres } -- | Initialize STG pretty-printing options from DynFlags initStgPprOpts :: DynFlags -> StgPprOpts initStgPprOpts dflags = StgPprOpts { stgSccEnabled = sccProfilingEnabled dflags } -- | STG pretty-printing options used for panic messages panicStgPprOpts :: StgPprOpts panicStgPprOpts = StgPprOpts { stgSccEnabled = True } -- | STG pretty-printing options used for short messages shortStgPprOpts :: StgPprOpts shortStgPprOpts = StgPprOpts { stgSccEnabled = False } pprGenStgTopBinding :: OutputablePass pass => StgPprOpts -> GenStgTopBinding pass -> SDoc pprGenStgTopBinding opts b = case b of StgTopStringLit bndr str -> hang (hsep [pprBndr LetBind bndr, equals]) 4 (pprHsBytes str <> semi) StgTopLifted bind -> pprGenStgBinding opts bind pprGenStgBinding :: OutputablePass pass => StgPprOpts -> GenStgBinding pass -> SDoc pprGenStgBinding opts b = case b of StgNonRec bndr rhs -> hang (hsep [pprBndr LetBind bndr, equals]) 4 (pprStgRhs opts rhs <> semi) StgRec pairs -> vcat [ text "Rec {" , vcat (intersperse blankLine (map ppr_bind pairs)) , text "end Rec }" ] where ppr_bind (bndr, expr) = hang (hsep [pprBndr LetBind bndr, equals]) 4 (pprStgRhs opts expr <> semi) pprGenStgTopBindings :: (OutputablePass pass) => StgPprOpts -> [GenStgTopBinding pass] -> SDoc pprGenStgTopBindings opts binds = vcat $ intersperse blankLine (map (pprGenStgTopBinding opts) binds) pprStgBinding :: StgPprOpts -> StgBinding -> SDoc pprStgBinding = pprGenStgBinding pprStgTopBinding :: StgPprOpts -> StgTopBinding -> SDoc pprStgTopBinding = pprGenStgTopBinding pprStgTopBindings :: StgPprOpts -> [StgTopBinding] -> SDoc pprStgTopBindings = pprGenStgTopBindings instance Outputable StgArg where ppr = pprStgArg pprStgArg :: StgArg -> SDoc pprStgArg (StgVarArg var) = ppr var pprStgArg (StgLitArg con) = ppr con pprStgExpr :: OutputablePass pass => StgPprOpts -> GenStgExpr pass -> SDoc pprStgExpr opts e = case e of -- special case StgLit lit -> ppr lit -- general case StgApp func args -> hang (ppr func) 4 (interppSP args) StgConApp con n args _ -> hsep [ ppr con, ppr n, brackets (interppSP args) ] StgOpApp op args _ -> hsep [ pprStgOp op, brackets (interppSP args)] -- special case: let v = -- in -- let ... -- in -- ... -- -- Very special! Suspicious! (SLPJ) {- StgLet srt (StgNonRec bndr (StgRhsClosure cc bi free_vars upd_flag args rhs)) expr@(StgLet _ _)) -> ($$) (hang (hcat [text "let { ", ppr bndr, ptext (sLit " = "), ppr cc, pp_binder_info bi, text " [", whenPprDebug (interppSP free_vars), ptext (sLit "] \\"), ppr upd_flag, text " [", interppSP args, char ']']) 8 (sep [hsep [ppr rhs, text "} in"]])) (ppr expr) -} -- special case: let ... in let ... StgLet ext bind expr@StgLet{} -> ($$) (sep [hang (text "let" <+> ppr ext <+> text "{") 2 (hsep [pprGenStgBinding opts bind, text "} in"])]) (pprStgExpr opts expr) -- general case StgLet ext bind expr -> sep [ hang (text "let" <+> ppr ext <+> text "{") 2 (pprGenStgBinding opts bind) , hang (text "} in ") 2 (pprStgExpr opts expr) ] StgLetNoEscape ext bind expr -> sep [ hang (text "let-no-escape" <+> ppr ext <+> text "{") 2 (pprGenStgBinding opts bind) , hang (text "} in ") 2 (pprStgExpr opts expr) ] StgTick _tickish expr -> sdocOption sdocSuppressTicks $ \case True -> pprStgExpr opts expr False -> pprStgExpr opts expr -- XXX sep [ ppr tickish, pprStgExpr opts expr ] -- Don't indent for a single case alternative. StgCase expr bndr alt_type [alt] -> sep [ sep [ text "case" , nest 4 (hsep [ pprStgExpr opts expr , whenPprDebug (dcolon <+> ppr alt_type) ]) , text "of" , pprBndr CaseBind bndr , char '{' ] , pprStgAlt opts False alt , char '}' ] StgCase expr bndr alt_type alts -> sep [ sep [ text "case" , nest 4 (hsep [ pprStgExpr opts expr , whenPprDebug (dcolon <+> ppr alt_type) ]) , text "of" , pprBndr CaseBind bndr, char '{' ] , nest 2 (vcat (map (pprStgAlt opts True) alts)) , char '}' ] pprStgAlt :: OutputablePass pass => StgPprOpts -> Bool -> GenStgAlt pass -> SDoc pprStgAlt opts indent (con, params, expr) | indent = hang altPattern 4 (pprStgExpr opts expr <> semi) | otherwise = sep [altPattern, pprStgExpr opts expr <> semi] where altPattern = (hsep [ppr con, sep (map (pprBndr CasePatBind) params), text "->"]) pprStgOp :: StgOp -> SDoc pprStgOp (StgPrimOp op) = ppr op pprStgOp (StgPrimCallOp op)= ppr op pprStgOp (StgFCallOp op _) = ppr op instance Outputable AltType where ppr PolyAlt = text "Polymorphic" ppr (MultiValAlt n) = text "MultiAlt" <+> ppr n ppr (AlgAlt tc) = text "Alg" <+> ppr tc ppr (PrimAlt tc) = text "Prim" <+> ppr tc pprStgRhs :: OutputablePass pass => StgPprOpts -> GenStgRhs pass -> SDoc pprStgRhs opts rhs = case rhs of StgRhsClosure ext cc upd_flag args body -> hang (hsep [ if stgSccEnabled opts then ppr cc else empty , ppUnlessOption sdocSuppressStgExts (ppr ext) , char '\\' <> ppr upd_flag, brackets (interppSP args) ]) 4 (pprStgExpr opts body) StgRhsCon cc con mid _ticks args -> hcat [ ppr cc, space , case mid of NoNumber -> empty Numbered n -> hcat [ppr n, space] , ppr con, text "! ", brackets (sep (map pprStgArg args))]