+++ /dev/null
-%
-% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
-%
-\section[DsBinds]{Pattern-matching bindings (HsBinds and MonoBinds)}
-
-Handles @HsBinds@; those at the top level require different handling,
-in that the @Rec@/@NonRec@/etc structure is thrown away (whereas at
-lower levels it is preserved with @let@/@letrec@s).
-
-\begin{code}
-module DsBinds ( dsTopLHsBinds, dsLHsBinds, decomposeRuleLhs,
- dsCoercion,
- AutoScc(..)
- ) where
-
-#include "HsVersions.h"
-
-
-import {-# SOURCE #-} DsExpr( dsLExpr, dsExpr )
-import {-# SOURCE #-} Match( matchWrapper )
-
-import DsMonad
-import DsGRHSs ( dsGuarded )
-import DsUtils
-
-import HsSyn -- lots of things
-import CoreSyn -- lots of things
-import CoreUtils ( exprType, mkInlineMe, mkSCC )
-
-import StaticFlags ( opt_AutoSccsOnAllToplevs,
- opt_AutoSccsOnExportedToplevs )
-import OccurAnal ( occurAnalyseExpr )
-import CostCentre ( mkAutoCC, IsCafCC(..) )
-import Id ( Id, DictId, idType, idName, isExportedId, mkLocalId, setInlinePragma )
-import Rules ( addIdSpecialisations, mkLocalRule )
-import Var ( TyVar, Var, isGlobalId, setIdNotExported )
-import VarEnv
-import Type ( mkTyVarTy, substTyWith )
-import TysWiredIn ( voidTy )
-import Outputable
-import SrcLoc ( Located(..) )
-import Maybes ( isJust, catMaybes, orElse )
-import Bag ( bagToList )
-import BasicTypes ( Activation(..), InlineSpec(..), isAlwaysActive, defaultInlineSpec )
-import Monad ( foldM )
-import FastString ( mkFastString )
-import List ( (\\) )
-import Util ( mapSnd )
-\end{code}
-
-%************************************************************************
-%* *
-\subsection[dsMonoBinds]{Desugaring a @MonoBinds@}
-%* *
-%************************************************************************
-
-\begin{code}
-dsTopLHsBinds :: AutoScc -> LHsBinds Id -> DsM [(Id,CoreExpr)]
-dsTopLHsBinds auto_scc binds = ds_lhs_binds auto_scc binds
-
-dsLHsBinds :: LHsBinds Id -> DsM [(Id,CoreExpr)]
-dsLHsBinds binds = ds_lhs_binds NoSccs binds
-
-
-------------------------
-ds_lhs_binds :: AutoScc -> LHsBinds Id -> DsM [(Id,CoreExpr)]
- -- scc annotation policy (see below)
-ds_lhs_binds auto_scc binds = foldM (dsLHsBind auto_scc) [] (bagToList binds)
-
-dsLHsBind :: AutoScc
- -> [(Id,CoreExpr)] -- Put this on the end (avoid quadratic append)
- -> LHsBind Id
- -> DsM [(Id,CoreExpr)] -- Result
-dsLHsBind auto_scc rest (L loc bind)
- = putSrcSpanDs loc $ dsHsBind auto_scc rest bind
-
-dsHsBind :: AutoScc
- -> [(Id,CoreExpr)] -- Put this on the end (avoid quadratic append)
- -> HsBind Id
- -> DsM [(Id,CoreExpr)] -- Result
-
-dsHsBind auto_scc rest (VarBind var expr)
- = dsLExpr expr `thenDs` \ core_expr ->
-
- -- Dictionary bindings are always VarMonoBinds, so
- -- we only need do this here
- addDictScc var core_expr `thenDs` \ core_expr' ->
- returnDs ((var, core_expr') : rest)
-
-dsHsBind auto_scc rest (FunBind { fun_id = L _ fun, fun_matches = matches, fun_co_fn = co_fn })
- = matchWrapper (FunRhs (idName fun)) matches `thenDs` \ (args, body) ->
- dsCoercion co_fn (return (mkLams args body)) `thenDs` \ rhs ->
- addAutoScc auto_scc (fun, rhs) `thenDs` \ pair ->
- returnDs (pair : rest)
-
-dsHsBind auto_scc rest (PatBind { pat_lhs = pat, pat_rhs = grhss, pat_rhs_ty = ty })
- = dsGuarded grhss ty `thenDs` \ body_expr ->
- mkSelectorBinds pat body_expr `thenDs` \ sel_binds ->
- mappM (addAutoScc auto_scc) sel_binds `thenDs` \ sel_binds ->
- returnDs (sel_binds ++ rest)
-
- -- Common special case: no type or dictionary abstraction
- -- For the (rare) case when there are some mixed-up
- -- dictionary bindings (for which a Rec is convenient)
- -- we reply on the enclosing dsBind to wrap a Rec around.
-dsHsBind auto_scc rest (AbsBinds [] [] exports binds)
- = ds_lhs_binds (addSccs auto_scc exports) binds `thenDs` \ core_prs ->
- let
- core_prs' = addLocalInlines exports core_prs
- exports' = [(global, Var local) | (_, global, local, _) <- exports]
- in
- returnDs (core_prs' ++ exports' ++ rest)
-
- -- Another common case: one exported variable
- -- Non-recursive bindings come through this way
-dsHsBind auto_scc rest
- (AbsBinds all_tyvars dicts exports@[(tyvars, global, local, prags)] binds)
- = ASSERT( all (`elem` tyvars) all_tyvars )
- ds_lhs_binds (addSccs auto_scc exports) binds `thenDs` \ core_prs ->
- let
- -- Always treat the binds as recursive, because the typechecker
- -- makes rather mixed-up dictionary bindings
- core_bind = Rec core_prs
- in
- mappM (dsSpec all_tyvars dicts tyvars global local core_bind)
- prags `thenDs` \ mb_specs ->
- let
- (spec_binds, rules) = unzip (catMaybes mb_specs)
- global' = addIdSpecialisations global rules
- rhs' = mkLams tyvars $ mkLams dicts $ Let core_bind (Var local)
- inl = case [inl | InlinePrag inl <- prags] of
- [] -> defaultInlineSpec
- (inl:_) -> inl
- in
- returnDs (addInlineInfo inl global' rhs' : spec_binds ++ rest)
-
-dsHsBind auto_scc rest (AbsBinds all_tyvars dicts exports binds)
- = ds_lhs_binds (addSccs auto_scc exports) binds `thenDs` \ core_prs ->
- let
- -- Rec because of mixed-up dictionary bindings
- core_bind = Rec (addLocalInlines exports core_prs)
-
- tup_expr = mkTupleExpr locals
- tup_ty = exprType tup_expr
- poly_tup_expr = mkLams all_tyvars $ mkLams dicts $
- Let core_bind tup_expr
- locals = [local | (_, _, local, _) <- exports]
- local_tys = map idType locals
- in
- newSysLocalDs (exprType poly_tup_expr) `thenDs` \ poly_tup_id ->
- let
- dict_args = map Var dicts
-
- mk_bind ((tyvars, global, local, prags), n) -- locals !! n == local
- = -- Need to make fresh locals to bind in the selector, because
- -- some of the tyvars will be bound to voidTy
- newSysLocalsDs (map substitute local_tys) `thenDs` \ locals' ->
- newSysLocalDs (substitute tup_ty) `thenDs` \ tup_id ->
- mapM (dsSpec all_tyvars dicts tyvars global local core_bind)
- prags `thenDs` \ mb_specs ->
- let
- (spec_binds, rules) = unzip (catMaybes mb_specs)
- global' = addIdSpecialisations global rules
- rhs = mkLams tyvars $ mkLams dicts $
- mkTupleSelector locals' (locals' !! n) tup_id $
- mkApps (mkTyApps (Var poly_tup_id) ty_args) dict_args
- in
- returnDs ((global', rhs) : spec_binds)
- where
- mk_ty_arg all_tyvar | all_tyvar `elem` tyvars = mkTyVarTy all_tyvar
- | otherwise = voidTy
- ty_args = map mk_ty_arg all_tyvars
- substitute = substTyWith all_tyvars ty_args
- in
- mappM mk_bind (exports `zip` [0..]) `thenDs` \ export_binds_s ->
- -- don't scc (auto-)annotate the tuple itself.
-
- returnDs ((poly_tup_id, poly_tup_expr) : (concat export_binds_s ++ rest))
-
-dsSpec :: [TyVar] -> [DictId] -> [TyVar]
- -> Id -> Id -- Global, local
- -> CoreBind -> Prag
- -> DsM (Maybe ((Id,CoreExpr), -- Binding for specialised Id
- CoreRule)) -- Rule for the Global Id
-
--- Example:
--- f :: (Eq a, Ix b) => a -> b -> b
--- {-# SPECIALISE f :: Ix b => Int -> b -> b #-}
---
--- AbsBinds [ab] [d1,d2] [([ab], f, f_mono, prags)] binds
---
--- SpecPrag (/\b.\(d:Ix b). f Int b dInt d)
--- (forall b. Ix b => Int -> b -> b)
---
--- Rule: forall b,(d:Ix b). f Int b dInt d = f_spec b d
---
--- Spec bind: f_spec = Let f = /\ab \(d1:Eq a)(d2:Ix b). let binds in f_mono
--- /\b.\(d:Ix b). in f Int b dInt d
--- The idea is that f occurs just once, so it'll be
--- inlined and specialised
-
-dsSpec all_tvs dicts tvs poly_id mono_id mono_bind (InlinePrag {})
- = return Nothing
-
-dsSpec all_tvs dicts tvs poly_id mono_id mono_bind
- (SpecPrag spec_expr spec_ty const_dicts inl)
- = do { let poly_name = idName poly_id
- ; spec_name <- newLocalName poly_name
- ; ds_spec_expr <- dsExpr spec_expr
- ; let (bndrs, body) = collectBinders ds_spec_expr
- mb_lhs = decomposeRuleLhs (bndrs ++ const_dicts) body
-
- ; case mb_lhs of
- Nothing -> do { dsWarn msg; return Nothing }
-
- Just (bndrs', var, args) -> return (Just (addInlineInfo inl spec_id spec_rhs, rule))
- where
- local_poly = setIdNotExported poly_id
- -- Very important to make the 'f' non-exported,
- -- else it won't be inlined!
- spec_id = mkLocalId spec_name spec_ty
- spec_rhs = Let (NonRec local_poly poly_f_body) ds_spec_expr
- poly_f_body = mkLams (tvs ++ dicts) $
- fix_up (Let mono_bind (Var mono_id))
-
- -- Quantify over constant dicts on the LHS, since
- -- their value depends only on their type
- -- The ones we are interested in may even be imported
- -- e.g. GHC.Base.dEqInt
-
- rule = mkLocalRule (mkFastString ("SPEC " ++ showSDoc (ppr poly_name)))
- AlwaysActive poly_name
- bndrs' -- Includes constant dicts
- args
- (mkVarApps (Var spec_id) bndrs)
- }
- where
- -- Bind to voidTy any of all_ptvs that aren't
- -- relevant for this particular function
- fix_up body | null void_tvs = body
- | otherwise = mkTyApps (mkLams void_tvs body)
- (map (const voidTy) void_tvs)
- void_tvs = all_tvs \\ tvs
-
- msg = hang (ptext SLIT("Specialisation too complicated to desugar; ignored"))
- 2 (ppr spec_expr)
-\end{code}
-
-
-%************************************************************************
-%* *
-\subsection{Adding inline pragmas}
-%* *
-%************************************************************************
-
-\begin{code}
-decomposeRuleLhs :: [Var] -> CoreExpr -> Maybe ([Var], Id, [CoreExpr])
--- Returns Nothing if the LHS isn't of the expected shape
--- The argument 'all_bndrs' includes the "constant dicts" of the LHS,
--- and they may be GlobalIds, which we can't forall-ify.
--- So we substitute them out instead
-decomposeRuleLhs all_bndrs lhs
- = go init_env (occurAnalyseExpr lhs) -- Occurrence analysis sorts out the dict
- -- bindings so we know if they are recursive
- where
-
- -- all_bndrs may include top-level imported dicts,
- -- imported things with a for-all.
- -- So we localise them and subtitute them out
- bndr_prs = [ (id, Var (localise id)) | id <- all_bndrs, isGlobalId id ]
- localise d = mkLocalId (idName d) (idType d)
-
- init_env = mkVarEnv bndr_prs
- all_bndrs' = map subst_bndr all_bndrs
- subst_bndr bndr = case lookupVarEnv init_env bndr of
- Just (Var bndr') -> bndr'
- Just other -> panic "decomposeRuleLhs"
- Nothing -> bndr
-
- -- Substitute dicts in the LHS args, so that there
- -- aren't any lets getting in the way
- -- Note that we substitute the function too; we might have this as
- -- a LHS: let f71 = M.f Int in f71
- go env (Let (NonRec dict rhs) body)
- = go (extendVarEnv env dict (simpleSubst env rhs)) body
- go env body
- = case collectArgs (simpleSubst env body) of
- (Var fn, args) -> Just (all_bndrs', fn, args)
- other -> Nothing
-
-simpleSubst :: IdEnv CoreExpr -> CoreExpr -> CoreExpr
--- Similar to CoreSubst.substExpr, except that
--- (a) takes no account of capture; dictionary bindings use new names
--- (b) can have a GlobalId (imported) in its domain
--- (c) Ids only; no types are substituted
-
-simpleSubst subst expr
- = go expr
- where
- go (Var v) = lookupVarEnv subst v `orElse` Var v
- go (Type ty) = Type ty
- go (Lit lit) = Lit lit
- go (App fun arg) = App (go fun) (go arg)
- go (Note note e) = Note note (go e)
- go (Lam bndr body) = Lam bndr (go body)
- go (Let (NonRec bndr rhs) body) = Let (NonRec bndr (go rhs)) (go body)
- go (Let (Rec pairs) body) = Let (Rec (mapSnd go pairs)) (go body)
- go (Case scrut bndr ty alts) = Case (go scrut) bndr ty
- [(c,bs,go r) | (c,bs,r) <- alts]
-
-addLocalInlines exports core_prs
- = map add_inline core_prs
- where
- add_inline (bndr,rhs) | Just inl <- lookupVarEnv inline_env bndr
- = addInlineInfo inl bndr rhs
- | otherwise
- = (bndr,rhs)
- inline_env = mkVarEnv [(mono_id, prag)
- | (_, _, mono_id, prags) <- exports,
- InlinePrag prag <- prags]
-
-addInlineInfo :: InlineSpec -> Id -> CoreExpr -> (Id,CoreExpr)
-addInlineInfo (Inline phase is_inline) bndr rhs
- = (attach_phase bndr phase, wrap_inline is_inline rhs)
- where
- attach_phase bndr phase
- | isAlwaysActive phase = bndr -- Default phase
- | otherwise = bndr `setInlinePragma` phase
-
- wrap_inline True body = mkInlineMe body
- wrap_inline False body = body
-\end{code}
-
-
-%************************************************************************
-%* *
-\subsection[addAutoScc]{Adding automatic sccs}
-%* *
-%************************************************************************
-
-\begin{code}
-data AutoScc
- = TopLevel
- | TopLevelAddSccs (Id -> Maybe Id)
- | NoSccs
-
-addSccs :: AutoScc -> [(a,Id,Id,[Prag])] -> AutoScc
-addSccs auto_scc@(TopLevelAddSccs _) exports = auto_scc
-addSccs NoSccs exports = NoSccs
-addSccs TopLevel exports
- = TopLevelAddSccs (\id -> case [ exp | (_,exp,loc,_) <- exports, loc == id ] of
- (exp:_) | opt_AutoSccsOnAllToplevs ||
- (isExportedId exp &&
- opt_AutoSccsOnExportedToplevs)
- -> Just exp
- _ -> Nothing)
-
-addAutoScc :: AutoScc -- if needs be, decorate toplevs?
- -> (Id, CoreExpr)
- -> DsM (Id, CoreExpr)
-
-addAutoScc (TopLevelAddSccs auto_scc_fn) pair@(bndr, core_expr)
- | do_auto_scc
- = getModuleDs `thenDs` \ mod ->
- returnDs (bndr, mkSCC (mkAutoCC top_bndr mod NotCafCC) core_expr)
- where do_auto_scc = isJust maybe_auto_scc
- maybe_auto_scc = auto_scc_fn bndr
- (Just top_bndr) = maybe_auto_scc
-
-addAutoScc _ pair
- = returnDs pair
-\end{code}
-
-If profiling and dealing with a dict binding,
-wrap the dict in @_scc_ DICT <dict>@:
-
-\begin{code}
-addDictScc var rhs = returnDs rhs
-
-{- DISABLED for now (need to somehow make up a name for the scc) -- SDM
- | not ( opt_SccProfilingOn && opt_AutoSccsOnDicts)
- || not (isDictId var)
- = returnDs rhs -- That's easy: do nothing
-
- | otherwise
- = getModuleAndGroupDs `thenDs` \ (mod, grp) ->
- -- ToDo: do -dicts-all flag (mark dict things with individual CCs)
- returnDs (Note (SCC (mkAllDictsCC mod grp False)) rhs)
--}
-\end{code}
-
-
-%************************************************************************
-%* *
- Desugaring coercions
-%* *
-%************************************************************************
-
-
-\begin{code}
-dsCoercion :: ExprCoFn -> DsM CoreExpr -> DsM CoreExpr
-dsCoercion CoHole thing_inside = thing_inside
-dsCoercion (CoCompose c1 c2) thing_inside = dsCoercion c1 (dsCoercion c2 thing_inside)
-dsCoercion (CoLams ids c) thing_inside = do { expr <- dsCoercion c thing_inside
- ; return (mkLams ids expr) }
-dsCoercion (CoTyLams tvs c) thing_inside = do { expr <- dsCoercion c thing_inside
- ; return (mkLams tvs expr) }
-dsCoercion (CoApps c ids) thing_inside = do { expr <- dsCoercion c thing_inside
- ; return (mkVarApps expr ids) }
-dsCoercion (CoTyApps c tys) thing_inside = do { expr <- dsCoercion c thing_inside
- ; return (mkTyApps expr tys) }
-dsCoercion (CoLet bs c) thing_inside = do { prs <- dsLHsBinds bs
- ; expr <- dsCoercion c thing_inside
- ; return (Let (Rec prs) expr) }
-\end{code}
-
-
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