X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2FdeSugar%2FDsBinds.lhs;h=8f3006d0f338295e3057b45f0fb35c3e2802dbdd;hb=28a464a75e14cece5db40f2765a29348273ff2d2;hp=e45e7bc6db1dc25e70d9ff377f0c7878158cf89b;hpb=b4255f2c320f852d7dfb0afc0bc9f64765aece0c;p=ghc-hetmet.git diff --git a/ghc/compiler/deSugar/DsBinds.lhs b/ghc/compiler/deSugar/DsBinds.lhs index e45e7bc..8f3006d 100644 --- a/ghc/compiler/deSugar/DsBinds.lhs +++ b/ghc/compiler/deSugar/DsBinds.lhs @@ -1,5 +1,5 @@ % -% (c) The GRASP/AQUA Project, Glasgow University, 1992-1996 +% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 % \section[DsBinds]{Pattern-matching bindings (HsBinds and MonoBinds)} @@ -8,553 +8,410 @@ in that the @Rec@/@NonRec@/etc structure is thrown away (whereas at lower levels it is preserved with @let@/@letrec@s). \begin{code} -#include "HsVersions.h" +module DsBinds ( dsTopLHsBinds, dsLHsBinds, decomposeRuleLhs, + dsCoercion, + AutoScc(..) + ) where -module DsBinds ( dsBinds, dsInstBinds ) where +#include "HsVersions.h" -import Ubiq -import DsLoop -- break dsExpr-ish loop -import HsSyn -- lots of things -import CoreSyn -- lots of things -import TcHsSyn ( TypecheckedHsBinds(..), TypecheckedHsExpr(..), - TypecheckedBind(..), TypecheckedMonoBinds(..) ) -import DsHsSyn ( collectTypedBinders, collectTypedPatBinders ) +import {-# SOURCE #-} DsExpr( dsLExpr, dsExpr ) +import {-# SOURCE #-} Match( matchWrapper ) import DsMonad import DsGRHSs ( dsGuarded ) import DsUtils -import Match ( matchWrapper ) - -import CmdLineOpts ( opt_SccProfilingOn, opt_CompilingPrelude ) -import CostCentre ( mkAllDictsCC, preludeDictsCostCentre ) -import Id ( idType, DictVar(..), GenId ) -import ListSetOps ( minusList, intersectLists ) -import PprType ( GenType ) -import PprStyle ( PprStyle(..) ) -import Pretty ( ppShow ) -import Type ( mkTyVarTys, splitSigmaTy, - tyVarsOfType, tyVarsOfTypes - ) -import TyVar ( tyVarSetToList, GenTyVar{-instance Eq-} ) -import Util ( isIn, panic ) - -isDictTy = panic "DsBinds.isDictTy" -quantifyTy = panic "DsBinds.quantifyTy" + +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[toplevel-and-regular-DsBinds]{Regular and top-level @dsBinds@} +\subsection[dsMonoBinds]{Desugaring a @MonoBinds@} %* * %************************************************************************ -Like @dsBinds@, @dsBind@ returns a @[CoreBinding]@, but it may be -that some of the binders are of unboxed type. This is sorted out when -the caller wraps the bindings round an expression. - \begin{code} -dsBinds :: TypecheckedHsBinds -> DsM [CoreBinding] -\end{code} - -All ``real'' bindings are expressed in terms of the -@AbsBinds@ construct, which is a massively-complicated ``shorthand'', -and its desugaring is the subject of section~9.1 in the static -semantics paper. - -(ToDo) For: -\begin{verbatim} -AbsBinds [a1, ... ,aj] -- type variables - [d1, ... ,dk] -- dict variables - [(l1,g1), ..., (lm,gm)] -- overloaded equivs [Id pairs] (later...) - [db1=..., ..., dbn=...] -- dict binds - [vb1=..., ..., vbm=...] -- val binds; note: vb_i = l_i -\end{verbatim} -we want to make, in the general case (non-Fozzie translation): -\begin{verbatim} - -- tupler-upper: - tup a1...aj d1...dk = - let in - let(rec) in (vb1,...,vbm) -- NB: == ... in (l1,...,lm) - - -- a bunch of selectors: - g1 a1...aj d1...dk = case (_tup a1...aj d1...dk) of (x1,x2,...,xm) -> x1 - ... - gm a1...aj d1...dk = case (_tup a1...aj d1...dk) of (x1,x2,...,xm) -> xm -\end{verbatim} -But there are lots of special cases. - - -%============================================== -\subsubsection{Structure cases} -%============================================== - -\begin{code} -dsBinds (BindWith _ _) = panic "dsBinds:BindWith" -dsBinds EmptyBinds = returnDs [] -dsBinds (SingleBind bind) = dsBind [] [] id [] bind - -dsBinds (ThenBinds binds_1 binds_2) - = andDs (++) (dsBinds binds_1) (dsBinds binds_2) -\end{code} - - -%============================================== -\subsubsection{AbsBind case: no overloading} -%============================================== - -Special case: no overloading. -\begin{verbatim} - x1 = e1 - x2 = e2 -\end{verbatim} -We abstract each wrt the type variables, giving -\begin{verbatim} - x1' = /\tyvars -> e1[x1' tyvars/x1, x2' tyvars/x2] - x2' = /\tyvars -> e2[x1' tyvars/x1, x2' tyvars/x2] -\end{verbatim} -There are some complications. - -(i) The @val_binds@ might mention variable not in @local_global_prs@. -In this case we need to make up new polymorphic versions of them. - -(ii) Exactly the same applies to any @inst_binds@ which may be -present. However, here we expect that mostly they will be simple constant -definitions, which don't mention the type variables at all, so making them -polymorphic is really overkill. @dsInstBinds@ deals with this case. - -\begin{code} -dsBinds (AbsBinds tyvars [] local_global_prs inst_binds val_binds) - = mapDs mk_poly_private_binder private_binders - `thenDs` \ poly_private_binders -> +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 - full_local_global_prs = (private_binders `zip` poly_private_binders) - ++ local_global_prs + core_prs' = addLocalInlines exports core_prs + exports' = [(global, Var local) | (_, global, local, _) <- exports] in - listDs [ mkSatTyApp global tyvar_tys `thenDs` \ app -> - returnDs (local, app) - | (local,global) <- full_local_global_prs - ] `thenDs` \ env -> - --- pprTrace "AbsBinds1:" (ppr PprDebug env) $ - - extendEnvDs env ( - - dsInstBinds tyvars inst_binds `thenDs` \ (inst_bind_pairs, inst_env) -> - extendEnvDs inst_env ( - - dsBind tyvars [] (lookupId full_local_global_prs) inst_bind_pairs val_binds - )) - where - -- "private_binders" is the list of binders in val_binds - -- which don't appear in the local_global_prs list - -- These only really show up in stuff produced from compiling - -- class and instance declarations. - -- We need to add suitable polymorphic versions of them to the - -- local_global_prs. - private_binders = binders `minusList` [local | (local,_) <- local_global_prs] - binders = collectTypedBinders val_binds - mk_poly_private_binder id = newSysLocalDs (snd (quantifyTy tyvars (idType id))) - - tyvar_tys = mkTyVarTys tyvars -\end{code} - - -%============================================== -\subsubsection{AbsBind case: overloading} -%============================================== - -If there is overloading we go for the general case. - -We want the global identifiers to be abstracted wrt all types and -dictionaries; and the local identifiers wrt the non-overloaded types. -That is, we try to avoid global scoping of type abstraction. Example - - f :: Eq a => a -> [(a,b)] -> b - f = ...f... - -Here, f is fully polymorphic in b. So we generate - - f ab d = let ...dict defns... - in - letrec f' b = ...(f' b)... - in f' b - -*Notice* that we don't clone type variables, and *do* make use of -shadowing. It is possible to do cloning, but it makes the code quite -a bit more complicated, and the simplifier will clone it all anyway. - -Why bother with this gloss? Because it makes it more likely that -the defn of f' can get floated out, notably if f gets specialised -to a particular type for a. - -\begin{code} -dsBinds (AbsBinds all_tyvars dicts local_global_prs dict_binds val_binds) - = -- If there is any non-overloaded polymorphism, make new locals with - -- appropriate polymorphism - (if null non_overloaded_tyvars - then - -- No non-overloaded polymorphism, so stay with current envt - returnDs (id, [], []) - else - -- Some local, non-overloaded polymorphism - cloneTyVarsDs non_overloaded_tyvars `thenDs` \ local_tyvars -> - - mapDs mk_binder binders `thenDs` \ new_binders -> - let - old_new_pairs = binders `zip` new_binders - in - - listDs [ mkSatTyApp new non_ov_tyvar_tys `thenDs` \ app -> - returnDs (old, app) - | (old,new) <- old_new_pairs - ] `thenDs` \ extra_env -> - let - local_binds = [NonRec old app | (old,app) <- extra_env, old `is_elem` locals] - is_elem = isIn "dsBinds" - in - returnDs (lookupId old_new_pairs, extra_env, local_binds) - ) - `thenDs` \ (binder_subst_fn, local_env, local_binds) -> - --- pprTrace "AbsBinds:all:" (ppAbove (ppr PprDebug local_binds) (ppr PprDebug local_env)) $ - - extendEnvDs local_env ( - - dsInstBinds non_overloaded_tyvars dict_binds `thenDs` \ (inst_bind_pairs, inst_env) -> - - extendEnvDs inst_env ( - - dsBind non_overloaded_tyvars [] binder_subst_fn inst_bind_pairs val_binds - )) `thenDs` \ core_binds -> - - let - tuple_rhs = mkCoLetsAny core_binds ( - mkCoLetsAny local_binds ( - mkTupleExpr locals )) + 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 - mkTupleBind all_tyvars dicts local_global_prs tuple_rhs `thenDs` \ core_bind_prs -> - - returnDs [ NonRec binder rhs | (binder,rhs) <- core_bind_prs ] - where - locals = [local | (local,global) <- local_global_prs] - non_ov_tyvar_tys = mkTyVarTys non_overloaded_tyvars - - overloaded_tyvars = tyVarsOfTypes (map idType dicts) - non_overloaded_tyvars = all_tyvars `minusList` (tyVarSetToList{-????-} overloaded_tyvars) - - binders = collectTypedBinders val_binds - mk_binder id = newSysLocalDs (snd (quantifyTy non_overloaded_tyvars (idType id))) -\end{code} - -@mkSatTyApp id tys@ constructs an expression whose value is (id tys). -However, sometimes id takes more type args than are in tys, and the -specialiser hates that, so we have to eta expand, to -@(/\ a b -> id tys a b)@. - -\begin{code} -mkSatTyApp :: Id -- Id to apply to the types - -> [Type] -- Types to apply it to - -> DsM CoreExpr - -mkSatTyApp id [] = returnDs (Var id) - -mkSatTyApp id tys - | null tvs - = returnDs ty_app -- Common case - | otherwise - = newTyVarsDs (drop (length tys) tvs) `thenDs` \ tyvars -> - returnDs (mkTyLam tyvars (mkTyApp ty_app (mkTyVarTys tyvars))) - where - (tvs, theta, tau_ty) = splitSigmaTy (idType id) - ty_app = mkTyApp (Var id) tys -\end{code} - -There are several places where we encounter ``inst binds,'' -@(Id, TypecheckedHsExpr)@ pairs. Many of these are ``trivial'' binds -(a var to a var or literal), which we want to substitute away; so we -return both some desugared bindings {\em and} a substitution -environment for the subbed-away ones. - -These dictionary bindings are non-recursive, and ordered, so that -later ones may mention earlier ones, but not vice versa. - -\begin{code} -dsInstBinds :: [TyVar] -- Abstract wrt these - -> [(Id, TypecheckedHsExpr)] -- From AbsBinds - -> DsM ([(Id,CoreExpr)], -- Non-trivial bindings - [(Id,CoreExpr)]) -- Trivial ones to be substituted away - -do_nothing = ([], []) -- out here to avoid dsInstBinds CAF (sigh) -prel_dicts_cc = preludeDictsCostCentre False{-not dupd-} -- ditto - -dsInstBinds tyvars [] = returnDs do_nothing - -dsInstBinds tyvars ((inst, expr@(HsVar _)) : bs) - = dsExpr expr `thenDs` \ rhs -> - let -- Need to apply dsExpr to the variable in case it - -- has a substitution in the current environment - subst_item = (inst, rhs) - in - extendEnvDs [subst_item] ( - dsInstBinds tyvars bs - ) `thenDs` \ (binds, subst_env) -> - returnDs (binds, subst_item : subst_env) - -dsInstBinds tyvars ((inst, expr@(HsLit _)) : bs) - = dsExpr expr `thenDs` \ core_lit -> + mappM (dsSpec all_tyvars dicts tyvars global local core_bind) + prags `thenDs` \ mb_specs -> let - subst_item = (inst, core_lit) + (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 - extendEnvDs [subst_item] ( - dsInstBinds tyvars bs - ) `thenDs` \ (binds, subst_env) -> - returnDs (binds, subst_item : subst_env) - -dsInstBinds tyvars ((inst, expr) : bs) - | null abs_tyvars - = dsExpr expr `thenDs` \ core_expr -> - ds_dict_cc core_expr `thenDs` \ dict_expr -> - dsInstBinds tyvars bs `thenDs` \ (core_rest, subst_env) -> - returnDs ((inst, dict_expr) : core_rest, subst_env) - - | otherwise - = -- Obscure case. - -- The inst mentions the type vars wrt which we are abstracting, - -- so we have to invent a new polymorphic version, and substitute - -- appropriately. - -- This can occur in, for example: - -- leftPoll :: [FeedBack a] -> FeedBack a - -- leftPoll xs = take poll xs - -- Here there is an instance of take at the type of elts of xs, - -- as well as the type of poll. - - dsExpr expr `thenDs` \ core_expr -> - ds_dict_cc core_expr `thenDs` \ dict_expr -> - newSysLocalDs poly_inst_ty `thenDs` \ poly_inst_id -> + 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 - subst_item = (inst, mkTyApp (Var poly_inst_id) abs_tys) + 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 - extendEnvDs [subst_item] ( - dsInstBinds tyvars bs - ) `thenDs` \ (core_rest, subst_env) -> - returnDs ((poly_inst_id, mkTyLam abs_tyvars dict_expr) : core_rest, - subst_item : subst_env) + 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 - inst_ty = idType inst - abs_tyvars = tyVarSetToList{-???sigh-} (tyVarsOfType inst_ty) `intersectLists` tyvars - abs_tys = mkTyVarTys abs_tyvars - (_, poly_inst_ty) = quantifyTy abs_tyvars inst_ty - - ------------------------ - -- Wrap a desugared expression in `_scc_ "DICT" ' if - -- appropriate. Uses "inst"'s type. - - -- if profiling, wrap the dict in "_scc_ DICT ": - ds_dict_cc expr - | not opt_SccProfilingOn || - not (isDictTy inst_ty) - = returnDs expr -- that's easy: do nothing - - | opt_CompilingPrelude - = returnDs (SCC prel_dicts_cc expr) - - | otherwise - = getModuleAndGroupDs `thenDs` \ (mod_name, grp_name) -> - -- ToDo: do -dicts-all flag (mark dict things - -- with individual CCs) - let - dict_cc = mkAllDictsCC mod_name grp_name False{-not dupd-} - in - returnDs (SCC dict_cc expr) + -- 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[dsBind]{Desugaring a @Bind@} +\subsection{Adding inline pragmas} %* * %************************************************************************ -Like @dsBinds@, @dsBind@ returns a @[CoreBinding]@, but it may be that -some of the binders are of unboxed type. +\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 -For an explanation of the first three args, see @dsMonoBinds@. + -- 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 -\begin{code} -dsBind :: [TyVar] -> [DictVar] -- Abstract wrt these - -> (Id -> Id) -- Binder substitution - -> [(Id,CoreExpr)] -- Inst bindings already dealt with - -> TypecheckedBind - -> DsM [CoreBinding] - -dsBind tyvars dicts binder_subst inst_bind_pairs EmptyBind - = returnDs [NonRec binder rhs | (binder,rhs) <- inst_bind_pairs] - -dsBind tyvars dicts binder_subst inst_bind_pairs (NonRecBind monobinds) - = dsMonoBinds False tyvars dicts binder_subst monobinds `thenDs` ( \ val_bind_pairs -> - returnDs [NonRec binder rhs | (binder,rhs) <- inst_bind_pairs ++ val_bind_pairs] ) - -dsBind tyvars dicts binder_subst inst_bind_pairs (RecBind monobinds) - = dsMonoBinds True tyvars dicts binder_subst monobinds `thenDs` ( \ val_bind_pairs -> - returnDs [Rec (inst_bind_pairs ++ val_bind_pairs)] ) + wrap_inline True body = mkInlineMe body + wrap_inline False body = body \end{code} %************************************************************************ %* * -\subsection[dsMonoBinds]{Desugaring a @MonoBinds@} +\subsection[addAutoScc]{Adding automatic sccs} %* * %************************************************************************ -@dsMonoBinds@ transforms @TypecheckedMonoBinds@ into @CoreBinds@. -In addition to desugaring pattern matching, @dsMonoBinds@ takes -a list of type variables and dicts, and adds abstractions for these -to the front of every binding. That requires that the -binders be altered too (their type has changed, -so @dsMonoBinds@ also takes a function which maps binders into binders. -This mapping gives the binder the correct new type. - -Remember, there's also a substitution in the monad which maps occurrences -of these binders into applications of the new binder to suitable type variables -and dictionaries. - \begin{code} -dsMonoBinds :: Bool -- True <=> recursive binding group - -> [TyVar] -> [DictVar] -- Abstract wrt these - -> (Id -> Id) -- Binder substitution - -> TypecheckedMonoBinds - -> DsM [(Id,CoreExpr)] +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} - - -%============================================== -\subsubsection{Structure cases} -%============================================== +If profiling and dealing with a dict binding, +wrap the dict in @_scc_ DICT @: \begin{code} -dsMonoBinds is_rec tyvars dicts binder_subst EmptyMonoBinds = returnDs [] - -dsMonoBinds is_rec tyvars dicts binder_subst (AndMonoBinds binds_1 binds_2) - = andDs (++) (dsMonoBinds is_rec tyvars dicts binder_subst binds_1) - (dsMonoBinds is_rec tyvars dicts binder_subst binds_2) -\end{code} - +addDictScc var rhs = returnDs rhs -%============================================== -\subsubsection{Simple base cases: function and variable bindings} -%============================================== +{- 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 -For the simplest bindings, we just heave them in the substitution env: - -\begin{code} -{- THESE TWO ARE PLAIN WRONG. - The extendEnvDs only scopes over the nested call! - Let the simplifier do this. - -dsMonoBinds is_rec tyvars dicts binder_subst (VarMonoBind was_var (HsVar new_var)) - | not (is_rec || isExported was_var) - = extendEnvDs [(was_var, Var new_var)] ( - returnDs [] ) - -dsMonoBinds is_rec tyvars dicts binder_subst (VarMonoBind was_var expr@(Lit _)) - | not (isExported was_var) - = dsExpr expr `thenDs` ( \ core_lit -> - extendEnvDs [(was_var, core_lit)] ( - returnDs [] )) + | otherwise + = getModuleAndGroupDs `thenDs` \ (mod, grp) -> + -- ToDo: do -dicts-all flag (mark dict things with individual CCs) + returnDs (Note (SCC (mkAllDictsCC mod grp False)) rhs) -} - -dsMonoBinds is_rec tyvars dicts binder_subst (VarMonoBind var expr) - = dsExpr expr `thenDs` \ core_expr -> - returnDs [(binder_subst var, mkLam tyvars dicts core_expr)] -\end{code} - -\begin{code} -dsMonoBinds is_rec tyvars dicts binder_subst (FunMonoBind fun _ matches locn) - = putSrcLocDs locn $ - let - new_fun = binder_subst fun - error_string = "function " ++ showForErr fun - in - matchWrapper (FunMatch fun) matches error_string `thenDs` \ (args, body) -> - returnDs [(new_fun, - mkLam tyvars (dicts ++ args) body)] - -dsMonoBinds is_rec tyvars dicts binder_subst (PatMonoBind (VarPat v) grhss_and_binds locn) - = putSrcLocDs locn $ - dsGuarded grhss_and_binds `thenDs` \ body_expr -> - returnDs [(binder_subst v, mkLam tyvars dicts body_expr)] -\end{code} - -%============================================== -\subsubsection{The general base case} -%============================================== - -Now the general case of a pattern binding. The monomorphism restriction -should ensure that if there is a non-simple pattern binding in the -group, then there is no overloading involved, so the dictionaries should -be empty. (Simple pattern bindings were handled above.) -First, the paranoia check. - -\begin{code} -dsMonoBinds is_rec tyvars (_:_) binder_subst (PatMonoBind pat grhss_and_binds locn) - = panic "Non-empty dict list in for pattern binding" \end{code} -We handle three cases for the binding - pat = rhs - -\begin{description} -\item[pat has no binders.] -Then all this is dead code and we return an empty binding. -\item[pat has exactly one binder, v.] -Then we can transform to: -\begin{verbatim} - v' = /\ tyvars -> case rhs of { pat -> v } -\end{verbatim} -where \tr{v'} is gotten by looking up \tr{v} in the \tr{binder_subst}. - -\item[pat has more than one binder.] -Then we transform to: -\begin{verbatim} - t = /\ tyvars -> case rhs of { pat -> (v1, ..., vn) } +%************************************************************************ +%* * + Desugaring coercions +%* * +%************************************************************************ - vi = /\ tyvars -> case (t tyvars) of { (v1, ..., vn) -> vi } -\end{verbatim} -\end{description} \begin{code} -dsMonoBinds is_rec tyvars [] binder_subst (PatMonoBind pat grhss_and_binds locn) - = putSrcLocDs locn $ - - dsGuarded grhss_and_binds `thenDs` \ body_expr -> - -{- KILLED by Sansom. 95/05 - -- make *sure* there are no primitive types in the pattern - if any_con_w_prim_arg pat then - error ( "ERROR: Pattern-bindings cannot involve unboxed/primitive types!\n\t" - ++ (ppShow 80 (ppr PprForUser pat)) ++ "\n" - ++ "(We apologise for not reporting this more `cleanly')\n" ) - - -- Check whether the pattern already is a simple tuple; if so, - -- we can just use the rhs directly - else --} - mkSelectorBinds tyvars pat - [(binder, binder_subst binder) | binder <- pat_binders] - body_expr - where - pat_binders = collectTypedPatBinders pat - -- NB For a simple tuple pattern, these binders - -- will appear in the right order! +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} -Wild-card patterns could be made acceptable here, but it involves some -extra work to benefit only rather unusual constructs like -\begin{verbatim} - let (_,a,b) = ... in ... -\end{verbatim} -Better to extend the whole thing for any irrefutable constructor, at least. -