X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2FdeSugar%2FDsBinds.lhs;h=39e7e298abaf37d70c8e25fdaac2198e3fc95493;hp=797d55e44e596ef2be10f1f0b62a743c3c16416b;hb=d9a655dad8e013e41c74dca98fb86c4ed6f29879;hpb=7be227dcf505a16b1b63a9fe3cbea87127b70b52 diff --git a/compiler/deSugar/DsBinds.lhs b/compiler/deSugar/DsBinds.lhs index 797d55e..39e7e29 100644 --- a/compiler/deSugar/DsBinds.lhs +++ b/compiler/deSugar/DsBinds.lhs @@ -10,9 +10,9 @@ 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(..) +module DsBinds ( dsTopLHsBinds, dsLHsBinds, decomposeRuleLhs, dsSpec, + dsHsWrapper, dsTcEvBinds, dsEvBinds, wrapDsEvBinds, + DsEvBind(..), AutoScc(..) ) where #include "HsVersions.h" @@ -32,30 +32,34 @@ import CoreUtils import CoreArity ( etaExpand ) import CoreUnfold import CoreFVs +import Digraph import TcType +import Type +import Coercion import TysPrim ( anyTypeOfKind ) import CostCentre import Module import Id +import TyCon ( tyConDataCons ) +import Class +import DataCon ( dataConRepType ) import Name ( localiseName ) import MkId ( seqId ) -import Var ( Var, TyVar, tyVarKind ) -import IdInfo ( vanillaIdInfo ) +import Var import VarSet import Rules import VarEnv import Outputable import SrcLoc import Maybes +import OrdList import Bag import BasicTypes hiding ( TopLevel ) import FastString -import StaticFlags ( opt_DsMultiTyVar ) -import Util ( count, lengthExceeds ) +import Util import MonadUtils -import Control.Monad \end{code} %************************************************************************ @@ -65,33 +69,28 @@ import Control.Monad %************************************************************************ \begin{code} -dsTopLHsBinds :: AutoScc -> LHsBinds Id -> DsM [(Id,CoreExpr)] +dsTopLHsBinds :: AutoScc -> LHsBinds Id -> DsM (OrdList (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 - +dsLHsBinds binds = do { binds' <- ds_lhs_binds NoSccs binds + ; return (fromOL binds') } ------------------------ -ds_lhs_binds :: AutoScc -> LHsBinds Id -> DsM [(Id,CoreExpr)] +ds_lhs_binds :: AutoScc -> LHsBinds Id -> DsM (OrdList (Id,CoreExpr)) -- scc annotation policy (see below) -ds_lhs_binds auto_scc binds = foldM (dsLHsBind auto_scc) [] (bagToList binds) +ds_lhs_binds auto_scc binds = do { ds_bs <- mapBagM (dsLHsBind auto_scc) binds + ; return (foldBag appOL id nilOL ds_bs) } -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 +dsLHsBind :: AutoScc -> LHsBind Id -> DsM (OrdList (Id,CoreExpr)) +dsLHsBind auto_scc (L loc bind) + = putSrcSpanDs loc $ dsHsBind auto_scc bind -dsHsBind :: AutoScc - -> [(Id,CoreExpr)] -- Put this on the end (avoid quadratic append) - -> HsBind Id - -> DsM [(Id,CoreExpr)] -- Result +dsHsBind :: AutoScc -> HsBind Id -> DsM (OrdList (Id,CoreExpr)) -dsHsBind _ rest (VarBind { var_id = var, var_rhs = expr, var_inline = inline_regardless }) - = do { core_expr <- dsLExpr expr +dsHsBind _ (VarBind { var_id = var, var_rhs = expr, var_inline = inline_regardless }) + = do { core_expr <- dsLExpr expr -- Dictionary bindings are always VarBinds, -- so we only need do this here @@ -99,124 +98,71 @@ dsHsBind _ rest (VarBind { var_id = var, var_rhs = expr, var_inline = inline_reg ; let var' | inline_regardless = var `setIdUnfolding` mkCompulsoryUnfolding core_expr' | otherwise = var - ; return ((var', core_expr') : rest) } + ; return (unitOL (makeCorePair var' False 0 core_expr')) } -dsHsBind _ rest - (FunBind { fun_id = L _ fun, fun_matches = matches, - fun_co_fn = co_fn, fun_tick = tick, fun_infix = inf }) +dsHsBind auto_scc (FunBind { fun_id = L _ fun, fun_matches = matches + , fun_co_fn = co_fn, fun_tick = tick + , fun_infix = inf }) = do { (args, body) <- matchWrapper (FunRhs (idName fun) inf) matches ; body' <- mkOptTickBox tick body - ; wrap_fn' <- dsCoercion co_fn - ; return ((fun, wrap_fn' (mkLams args body')) : rest) } + ; wrap_fn' <- dsHsWrapper co_fn + ; let rhs = addAutoScc auto_scc fun $ wrap_fn' (mkLams args body') + ; return (unitOL (makeCorePair fun False 0 rhs)) } -dsHsBind _ rest - (PatBind { pat_lhs = pat, pat_rhs = grhss, pat_rhs_ty = ty }) +dsHsBind auto_scc (PatBind { pat_lhs = pat, pat_rhs = grhss, pat_rhs_ty = ty }) = do { body_expr <- dsGuarded grhss ty ; sel_binds <- mkSelectorBinds pat body_expr - ; return (sel_binds ++ rest) } + -- We silently ignore inline pragmas; no makeCorePair + -- Not so cool, but really doesn't matter + ; let sel_binds' = [ (v, addAutoScc auto_scc v expr) + | (v, expr) <- sel_binds ] + ; return (toOL sel_binds') } -dsHsBind auto_scc rest (AbsBinds [] [] exports binds) - = do { core_prs <- ds_lhs_binds NoSccs binds - ; let env = mkABEnv exports - do_one (lcl_id, rhs) - | Just (_, gbl_id, _, spec_prags) <- lookupVarEnv env lcl_id - = do { let rhs' = addAutoScc auto_scc gbl_id rhs - ; (spec_binds, rules) <- dsSpecs gbl_id (Let (Rec core_prs) rhs') spec_prags - -- See Note [Specialising in no-dict case] - ; let gbl_id' = addIdSpecialisations gbl_id rules - main_bind = makeCorePair gbl_id' False 0 rhs' - ; return (main_bind : spec_binds) } - - | otherwise = return [(lcl_id, rhs)] - - locals' = [(lcl_id, Var gbl_id) | (_, gbl_id, lcl_id, _) <- exports] - -- Note [Rules and inlining] - ; export_binds <- mapM do_one core_prs - ; return (concat export_binds ++ locals' ++ rest) } - -- No Rec needed here (contrast the other AbsBinds cases) - -- because we can rely on the enclosing dsBind to wrap in Rec - - -dsHsBind auto_scc rest (AbsBinds tyvars [] exports binds) - | opt_DsMultiTyVar -- This (static) debug flag just lets us - -- switch on and off this optimisation to - -- see if it has any impact; it is on by default - = -- Note [Abstracting over tyvars only] - do { core_prs <- ds_lhs_binds NoSccs binds - ; let arby_env = mkArbitraryTypeEnv tyvars exports - bndrs = mkVarSet (map fst core_prs) - - add_lets | core_prs `lengthExceeds` 10 = add_some - | otherwise = mkLets - add_some lg_binds rhs = mkLets [ NonRec b r | NonRec b r <- lg_binds - , b `elemVarSet` fvs] rhs - where - fvs = exprSomeFreeVars (`elemVarSet` bndrs) rhs - - env = mkABEnv exports - mk_lg_bind lcl_id gbl_id tyvars - = NonRec (setIdInfo lcl_id vanillaIdInfo) - -- Nuke the IdInfo so that no old unfoldings - -- confuse use (it might mention something not - -- even in scope at the new site - (mkTyApps (Var gbl_id) (mkTyVarTys tyvars)) - - do_one lg_binds (lcl_id, rhs) - | Just (id_tvs, gbl_id, _, spec_prags) <- lookupVarEnv env lcl_id - = do { let rhs' = addAutoScc auto_scc gbl_id $ - mkLams id_tvs $ - mkLets [ NonRec tv (Type (lookupVarEnv_NF arby_env tv)) - | tv <- tyvars, not (tv `elem` id_tvs)] $ - add_lets lg_binds rhs - ; (spec_binds, rules) <- dsSpecs gbl_id rhs' spec_prags - ; let gbl_id' = addIdSpecialisations gbl_id rules - main_bind = makeCorePair gbl_id' False 0 rhs' - ; return (mk_lg_bind lcl_id gbl_id' id_tvs, main_bind : spec_binds) } - | otherwise - = do { non_exp_gbl_id <- newUniqueId lcl_id (mkForAllTys tyvars (idType lcl_id)) - ; return (mk_lg_bind lcl_id non_exp_gbl_id tyvars, - [(non_exp_gbl_id, mkLams tyvars (add_lets lg_binds rhs))]) } - - ; (_, core_prs') <- fixDs (\ ~(lg_binds, _) -> mapAndUnzipM (do_one lg_binds) core_prs) - ; return (concat core_prs' ++ rest) } - - -- Another common case: one exported variable + -- A common case: one exported variable -- Non-recursive bindings come through this way -- So do self-recursive bindings, and recursive bindings -- that have been chopped up with type signatures -dsHsBind auto_scc rest - (AbsBinds all_tyvars dicts [(tyvars, global, local, prags)] binds) +dsHsBind auto_scc (AbsBinds { abs_tvs = all_tyvars, abs_ev_vars = dicts + , abs_exports = [(tyvars, global, local, prags)] + , abs_ev_binds = ev_binds, abs_binds = binds }) = ASSERT( all (`elem` tyvars) all_tyvars ) - do { core_prs <- ds_lhs_binds NoSccs binds + do { bind_prs <- ds_lhs_binds NoSccs binds + ; ds_ev_binds <- dsTcEvBinds ev_binds - ; let -- Always treat the binds as recursive, because the - -- typechecker makes rather mixed-up dictionary bindings - core_bind = Rec core_prs + ; let core_bind = Rec (fromOL bind_prs) rhs = addAutoScc auto_scc global $ - mkLams tyvars $ mkLams dicts $ Let core_bind (Var local) + mkLams tyvars $ mkLams dicts $ + wrapDsEvBinds ds_ev_binds $ + Let core_bind $ + Var local - ; (spec_binds, rules) <- dsSpecs global rhs prags + ; (spec_binds, rules) <- dsSpecs rhs prags ; let global' = addIdSpecialisations global rules main_bind = makeCorePair global' (isDefaultMethod prags) (dictArity dicts) rhs - ; return (main_bind : spec_binds ++ rest) } + ; return (main_bind `consOL` spec_binds) } -dsHsBind auto_scc rest (AbsBinds all_tyvars dicts exports binds) - = do { core_prs <- ds_lhs_binds NoSccs binds +dsHsBind auto_scc (AbsBinds { abs_tvs = all_tyvars, abs_ev_vars = dicts + , abs_exports = exports, abs_ev_binds = ev_binds + , abs_binds = binds }) + = do { bind_prs <- ds_lhs_binds NoSccs binds + ; ds_ev_binds <- dsTcEvBinds ev_binds ; let env = mkABEnv exports do_one (lcl_id,rhs) | Just (_, gbl_id, _, _prags) <- lookupVarEnv env lcl_id = (lcl_id, addAutoScc auto_scc gbl_id rhs) | otherwise = (lcl_id,rhs) - -- Rec because of mixed-up dictionary bindings - core_bind = Rec (map do_one core_prs) + core_bind = Rec (map do_one (fromOL bind_prs)) + -- Monomorphic recursion possible, hence Rec tup_expr = mkBigCoreVarTup locals tup_ty = exprType tup_expr poly_tup_rhs = mkLams all_tyvars $ mkLams dicts $ - Let core_bind tup_expr + wrapDsEvBinds ds_ev_binds $ + Let core_bind $ + tup_expr locals = [local | (_, _, local, _) <- exports] local_tys = map idType locals @@ -233,11 +179,11 @@ dsHsBind auto_scc rest (AbsBinds all_tyvars dicts exports binds) mkTupleSelector locals' (locals' !! n) tup_id $ mkVarApps (mkTyApps (Var poly_tup_id) ty_args) dicts - ; (spec_binds, rules) <- dsSpecs global - (Let (NonRec poly_tup_id poly_tup_rhs) rhs) - spec_prags + full_rhs = Let (NonRec poly_tup_id poly_tup_rhs) rhs + ; (spec_binds, rules) <- dsSpecs full_rhs spec_prags + ; let global' = addIdSpecialisations global rules - ; return ((global', rhs) : spec_binds) } + ; return ((global', rhs) `consOL` spec_binds) } where mk_ty_arg all_tyvar | all_tyvar `elem` tyvars = mkTyVarTy all_tyvar @@ -246,29 +192,118 @@ dsHsBind auto_scc rest (AbsBinds all_tyvars dicts exports binds) ; export_binds_s <- mapM mk_bind (exports `zip` [0..]) -- Don't scc (auto-)annotate the tuple itself. - ; return ((poly_tup_id, poly_tup_rhs) : - (concat export_binds_s ++ rest)) } + ; return ((poly_tup_id, poly_tup_rhs) `consOL` + concatOL export_binds_s) } + +-------------------------------------- +data DsEvBind + = LetEvBind -- Dictionary or coercion + CoreBind -- recursive or non-recursive + + | CaseEvBind -- Coercion binding by superclass selection + -- Desugars to case d of d { K _ g _ _ _ -> ... } + DictId -- b The dictionary + AltCon -- K Its constructor + [CoreBndr] -- _ g _ _ _ The binders in the alternative + +wrapDsEvBinds :: [DsEvBind] -> CoreExpr -> CoreExpr +wrapDsEvBinds ds_ev_binds body = foldr wrap_one body ds_ev_binds + where + body_ty = exprType body + wrap_one (LetEvBind b) body = Let b body + wrap_one (CaseEvBind x k xs) body = Case (Var x) x body_ty [(k,xs,body)] + +dsTcEvBinds :: TcEvBinds -> DsM [DsEvBind] +dsTcEvBinds (TcEvBinds {}) = panic "dsEvBinds" -- Zonker has got rid of this +dsTcEvBinds (EvBinds bs) = dsEvBinds bs + +dsEvBinds :: Bag EvBind -> DsM [DsEvBind] +dsEvBinds bs = return (map dsEvGroup sccs) + where + sccs :: [SCC EvBind] + sccs = stronglyConnCompFromEdgedVertices edges + + edges :: [(EvBind, EvVar, [EvVar])] + edges = foldrBag ((:) . mk_node) [] bs + + mk_node :: EvBind -> (EvBind, EvVar, [EvVar]) + mk_node b@(EvBind var term) = (b, var, free_vars_of term) + + free_vars_of :: EvTerm -> [EvVar] + free_vars_of (EvId v) = [v] + free_vars_of (EvCast v co) = v : varSetElems (tyCoVarsOfCo co) + free_vars_of (EvCoercion co) = varSetElems (tyCoVarsOfCo co) + free_vars_of (EvDFunApp _ _ vs) = vs + free_vars_of (EvSuperClass d _) = [d] + +dsEvGroup :: SCC EvBind -> DsEvBind +dsEvGroup (AcyclicSCC (EvBind co_var (EvSuperClass dict n))) + | isCoVar co_var -- An equality superclass + = ASSERT( null other_data_cons ) + CaseEvBind dict (DataAlt data_con) bndrs + where + (cls, tys) = getClassPredTys (evVarPred dict) + (data_con:other_data_cons) = tyConDataCons (classTyCon cls) + (ex_tvs, theta, rho) = tcSplitSigmaTy (applyTys (dataConRepType data_con) tys) + (arg_tys, _) = splitFunTys rho + bndrs = ex_tvs ++ map mk_wild_pred (theta `zip` [0..]) + ++ map mkWildValBinder arg_tys + mk_wild_pred (p, i) | i==n = ASSERT( p `eqPred` (coVarPred co_var)) + co_var + | otherwise = mkWildEvBinder p + +dsEvGroup (AcyclicSCC (EvBind v r)) + = LetEvBind (NonRec v (dsEvTerm r)) +dsEvGroup (CyclicSCC bs) + = LetEvBind (Rec (map ds_pair bs)) + where + ds_pair (EvBind v r) = (v, dsEvTerm r) + +dsEvTerm :: EvTerm -> CoreExpr +dsEvTerm (EvId v) = Var v +dsEvTerm (EvCast v co) = Cast (Var v) co +dsEvTerm (EvDFunApp df tys vars) = Var df `mkTyApps` tys `mkVarApps` vars +dsEvTerm (EvCoercion co) = Coercion co +dsEvTerm (EvSuperClass d n) + = ASSERT( isClassPred (classSCTheta cls !! n) ) + -- We can only select *dictionary* superclasses + -- in terms. Equality superclasses are dealt with + -- in dsEvGroup, where they can generate a case expression + Var sc_sel_id `mkTyApps` tys `App` Var d + where + sc_sel_id = classSCSelId cls n -- Zero-indexed + (cls, tys) = getClassPredTys (evVarPred d) + ------------------------ makeCorePair :: Id -> Bool -> Arity -> CoreExpr -> (Id, CoreExpr) makeCorePair gbl_id is_default_method dict_arity rhs | is_default_method -- Default methods are *always* inlined = (gbl_id `setIdUnfolding` mkCompulsoryUnfolding rhs, rhs) - | not (isInlinePragma inline_prag) - = (gbl_id, rhs) + | otherwise + = case inlinePragmaSpec inline_prag of + EmptyInlineSpec -> (gbl_id, rhs) + NoInline -> (gbl_id, rhs) + Inlinable -> (gbl_id `setIdUnfolding` inlinable_unf, rhs) + Inline -> inline_pair - | Just arity <- inlinePragmaSat inline_prag + where + inline_prag = idInlinePragma gbl_id + inlinable_unf = mkInlinableUnfolding rhs + inline_pair + | Just arity <- inlinePragmaSat inline_prag -- Add an Unfolding for an INLINE (but not for NOINLINE) -- And eta-expand the RHS; see Note [Eta-expanding INLINE things] - = (gbl_id `setIdUnfolding` mkInlineRule rhs (Just (dict_arity + arity)), - -- NB: The arity in the InlineRule takes account of the dictionaries - etaExpand arity rhs) + , let real_arity = dict_arity + arity + -- NB: The arity in the InlineRule takes account of the dictionaries + = ( gbl_id `setIdUnfolding` mkInlineUnfolding (Just real_arity) rhs + , etaExpand real_arity rhs) + + | otherwise + = pprTrace "makeCorePair: arity missing" (ppr gbl_id) $ + (gbl_id `setIdUnfolding` mkInlineUnfolding Nothing rhs, rhs) - | otherwise - = (gbl_id `setIdUnfolding` mkInlineRule rhs Nothing, rhs) - where - inline_prag = idInlinePragma gbl_id dictArity :: [Var] -> Arity -- Don't count coercion variables in arity @@ -308,7 +343,7 @@ This does not happen in the same way to polymorphic binds, because they desugar to M.f = /\a. let f_lcl = ...f_lcl... in f_lcl Although I'm a bit worried about whether full laziness might -float the f_lcl binding out and then inline M.f at its call site -} +float the f_lcl binding out and then inline M.f at its call site Note [Specialising in no-dict case] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ @@ -441,103 +476,176 @@ Note that \begin{code} ------------------------ -dsSpecs :: Id -- The polymorphic Id - -> CoreExpr -- Its rhs +dsSpecs :: CoreExpr -- Its rhs -> TcSpecPrags - -> DsM ( [(Id,CoreExpr)] -- Binding for specialised Ids + -> DsM ( OrdList (Id,CoreExpr) -- Binding for specialised Ids , [CoreRule] ) -- Rules for the Global Ids -- See Note [Implementing SPECIALISE pragmas] -dsSpecs poly_id poly_rhs prags - = case prags of - IsDefaultMethod -> return ([], []) - SpecPrags sps -> do { pairs <- mapMaybeM spec_one sps - ; let (spec_binds_s, rules) = unzip pairs - ; return (concat spec_binds_s, rules) } - where - spec_one :: Located TcSpecPrag -> DsM (Maybe ([(Id,CoreExpr)], CoreRule)) - spec_one (L loc (SpecPrag spec_co spec_inl)) - = putSrcSpanDs loc $ - do { let poly_name = idName poly_id - ; spec_name <- newLocalName poly_name - ; wrap_fn <- dsCoercion spec_co - ; let ds_spec_expr = wrap_fn (Var poly_id) - ; case decomposeRuleLhs ds_spec_expr of { - Nothing -> do { warnDs (decomp_msg spec_co) - ; return Nothing } ; - - Just (bndrs, _fn, args) -> - - -- Check for dead binders: Note [Unused spec binders] - case filter isDeadBinder bndrs of { - bs | not (null bs) -> do { warnDs (dead_msg bs); return Nothing } - | otherwise -> do - - { (spec_unf, unf_pairs) <- specUnfolding wrap_fn (realIdUnfolding poly_id) - - ; let spec_ty = exprType ds_spec_expr - spec_id = mkLocalId spec_name spec_ty - `setInlinePragma` inl_prag - `setIdUnfolding` spec_unf - inl_prag | isDefaultInlinePragma spec_inl = idInlinePragma poly_id - | otherwise = spec_inl - -- Get the INLINE pragma from SPECIALISE declaration, or, - -- failing that, from the original Id - - extra_dict_bndrs = [ mkLocalId (localiseName (idName d)) (idType d) - -- See Note [Constant rule dicts] - | d <- varSetElems (exprFreeVars ds_spec_expr) - , isDictId d] - - rule = mkLocalRule (mkFastString ("SPEC " ++ showSDoc (ppr poly_name))) - AlwaysActive poly_name - (extra_dict_bndrs ++ bndrs) args - (mkVarApps (Var spec_id) bndrs) - - spec_rhs = wrap_fn poly_rhs - spec_pair = makeCorePair spec_id False (dictArity bndrs) spec_rhs - - ; return (Just (spec_pair : unf_pairs, rule)) - } } } } - - dead_msg bs = vcat [ sep [ptext (sLit "Useless constraint") <> plural bs - <+> ptext (sLit "in specialied type:"), - nest 2 (pprTheta (map get_pred bs))] - , ptext (sLit "SPECIALISE pragma ignored")] - get_pred b = ASSERT( isId b ) expectJust "dsSpec" (tcSplitPredTy_maybe (idType b)) - - decomp_msg spec_co - = hang (ptext (sLit "Specialisation too complicated to desugar; ignored")) - 2 (pprHsWrapper (ppr poly_id) spec_co) - - -specUnfolding :: (CoreExpr -> CoreExpr) -> Unfolding -> DsM (Unfolding, [(Id,CoreExpr)]) -specUnfolding wrap_fn (DFunUnfolding con ops) +dsSpecs _ IsDefaultMethod = return (nilOL, []) +dsSpecs poly_rhs (SpecPrags sps) + = do { pairs <- mapMaybeM (dsSpec (Just poly_rhs)) sps + ; let (spec_binds_s, rules) = unzip pairs + ; return (concatOL spec_binds_s, rules) } + +dsSpec :: Maybe CoreExpr -- Just rhs => RULE is for a local binding + -- Nothing => RULE is for an imported Id + -- rhs is in the Id's unfolding + -> Located TcSpecPrag + -> DsM (Maybe (OrdList (Id,CoreExpr), CoreRule)) +dsSpec mb_poly_rhs (L loc (SpecPrag poly_id spec_co spec_inl)) + | isJust (isClassOpId_maybe poly_id) + = putSrcSpanDs loc $ + do { warnDs (ptext (sLit "Ignoring useless SPECIALISE pragma for class method selector") + <+> quotes (ppr poly_id)) + ; return Nothing } -- There is no point in trying to specialise a class op + -- Moreover, classops don't (currently) have an inl_sat arity set + -- (it would be Just 0) and that in turn makes makeCorePair bleat + + | otherwise + = putSrcSpanDs loc $ + do { let poly_name = idName poly_id + ; spec_name <- newLocalName poly_name + ; wrap_fn <- dsHsWrapper spec_co + ; let (bndrs, ds_lhs) = collectBinders (wrap_fn (Var poly_id)) + spec_ty = mkPiTypes bndrs (exprType ds_lhs) + ; case decomposeRuleLhs bndrs ds_lhs of { + Left msg -> do { warnDs msg; return Nothing } ; + Right (final_bndrs, _fn, args) -> do + + { (spec_unf, unf_pairs) <- specUnfolding wrap_fn spec_ty (realIdUnfolding poly_id) + + ; let spec_id = mkLocalId spec_name spec_ty + `setInlinePragma` inl_prag + `setIdUnfolding` spec_unf + inl_prag | isDefaultInlinePragma spec_inl = idInlinePragma poly_id + | otherwise = spec_inl + -- Get the INLINE pragma from SPECIALISE declaration, or, + -- failing that, from the original Id + + rule = mkRule False {- Not auto -} is_local_id + (mkFastString ("SPEC " ++ showSDoc (ppr poly_name))) + AlwaysActive poly_name + final_bndrs args + (mkVarApps (Var spec_id) bndrs) + + spec_rhs = wrap_fn poly_rhs + spec_pair = makeCorePair spec_id False (dictArity bndrs) spec_rhs + + ; return (Just (spec_pair `consOL` unf_pairs, rule)) + } } } + where + is_local_id = isJust mb_poly_rhs + poly_rhs | Just rhs <- mb_poly_rhs + = rhs -- Local Id; this is its rhs + | Just unfolding <- maybeUnfoldingTemplate (realIdUnfolding poly_id) + = unfolding -- Imported Id; this is its unfolding + -- Use realIdUnfolding so we get the unfolding + -- even when it is a loop breaker. + -- We want to specialise recursive functions! + | otherwise = pprPanic "dsImpSpecs" (ppr poly_id) + -- The type checker has checked that it *has* an unfolding + +specUnfolding :: (CoreExpr -> CoreExpr) -> Type + -> Unfolding -> DsM (Unfolding, OrdList (Id,CoreExpr)) +{- [Dec 10: TEMPORARILY commented out, until we can straighten out how to + generate unfoldings for specialised DFuns + +specUnfolding wrap_fn spec_ty (DFunUnfolding _ _ ops) = do { let spec_rhss = map wrap_fn ops ; spec_ids <- mapM (mkSysLocalM (fsLit "spec") . exprType) spec_rhss - ; return (DFunUnfolding con (map Var spec_ids), spec_ids `zip` spec_rhss) } -specUnfolding _ _ - = return (noUnfolding, []) - -mkArbitraryTypeEnv :: [TyVar] -> [([TyVar], a, b, c)] -> TyVarEnv Type --- If any of the tyvars is missing from any of the lists in --- the second arg, return a binding in the result -mkArbitraryTypeEnv tyvars exports - = go emptyVarEnv exports - where - go env [] = env - go env ((ltvs, _, _, _) : exports) - = go env' exports - where - env' = foldl extend env [tv | tv <- tyvars - , not (tv `elem` ltvs) - , not (tv `elemVarEnv` env)] - - extend env tv = extendVarEnv env tv (dsMkArbitraryType tv) + ; return (mkDFunUnfolding spec_ty (map Var spec_ids), toOL (spec_ids `zip` spec_rhss)) } +-} +specUnfolding _ _ _ + = return (noUnfolding, nilOL) dsMkArbitraryType :: TcTyVar -> Type dsMkArbitraryType tv = anyTypeOfKind (tyVarKind tv) \end{code} +%************************************************************************ +%* * +\subsection{Adding inline pragmas} +%* * +%************************************************************************ + +\begin{code} +decomposeRuleLhs :: [Var] -> CoreExpr -> Either SDoc ([Var], Id, [CoreExpr]) +-- Take apart the LHS of a RULE. It's suuposed to look like +-- /\a. f a Int dOrdInt +-- or /\a.\d:Ord a. let { dl::Ord [a] = dOrdList a d } in f [a] dl +-- That is, the RULE binders are lambda-bound +-- Returns Nothing if the LHS isn't of the expected shape +decomposeRuleLhs bndrs lhs + = -- Note [Simplifying the left-hand side of a RULE] + case collectArgs opt_lhs of + (Var fn, args) -> check_bndrs fn args + + (Case scrut bndr ty [(DEFAULT, _, body)], args) + | isDeadBinder bndr -- Note [Matching seqId] + -> check_bndrs seqId (args' ++ args) + where + args' = [Type (idType bndr), Type ty, scrut, body] + + _other -> Left bad_shape_msg + where + opt_lhs = simpleOptExpr lhs + + check_bndrs fn args + | null (dead_bndrs) = Right (extra_dict_bndrs ++ bndrs, fn, args) + | otherwise = Left (vcat (map dead_msg dead_bndrs)) + where + arg_fvs = exprsFreeVars args + + -- Check for dead binders: Note [Unused spec binders] + dead_bndrs = filterOut (`elemVarSet` arg_fvs) bndrs + + -- Add extra dict binders: Note [Constant rule dicts] + extra_dict_bndrs = [ mkLocalId (localiseName (idName d)) (idType d) + | d <- varSetElems (arg_fvs `delVarSetList` bndrs) + , isDictId d] + + + bad_shape_msg = hang (ptext (sLit "RULE left-hand side too complicated to desugar")) + 2 (ppr opt_lhs) + dead_msg bndr = hang (sep [ ptext (sLit "Forall'd") <+> pp_bndr bndr + , ptext (sLit "is not bound in RULE lhs")]) + 2 (ppr opt_lhs) + pp_bndr bndr + | isTyVar bndr = ptext (sLit "type variable") <+> quotes (ppr bndr) + | isEvVar bndr = ptext (sLit "constraint") <+> quotes (ppr (evVarPred bndr)) + | otherwise = ptext (sLit "variable") <+> quotes (ppr bndr) +\end{code} + +Note [Simplifying the left-hand side of a RULE] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +simpleOptExpr occurrence-analyses and simplifies the lhs +and thereby +(a) sorts dict bindings into NonRecs and inlines them +(b) substitute trivial lets so that they don't get in the way + Note that we substitute the function too; we might + have this as a LHS: let f71 = M.f Int in f71 +(c) does eta reduction + +For (c) consider the fold/build rule, which without simplification +looked like: + fold k z (build (/\a. g a)) ==> ... +This doesn't match unless you do eta reduction on the build argument. +Similarly for a LHS like + augment g (build h) +we do not want to get + augment (\a. g a) (build h) +otherwise we don't match when given an argument like + augment (\a. h a a) (build h) + +NB: tcSimplifyRuleLhs is very careful not to generate complicated + dictionary expressions that we might have to match + +Note [Matching seqId] +~~~~~~~~~~~~~~~~~~~ +The desugarer turns (seq e r) into (case e of _ -> r), via a special-case hack +and this code turns it back into an application of seq! +See Note [Rules for seq] in MkId for the details. + Note [Unused spec binders] ~~~~~~~~~~~~~~~~~~~~~~~~~~ Consider @@ -578,50 +686,6 @@ confused. Likewise it might have an InlineRule or something, which would be utterly bogus. So we really make a fresh Id, with the same unique and type as the old one, but with an Internal name and no IdInfo. -%************************************************************************ -%* * -\subsection{Adding inline pragmas} -%* * -%************************************************************************ - -\begin{code} -decomposeRuleLhs :: CoreExpr -> Maybe ([Var], Id, [CoreExpr]) --- Take apart the LHS of a RULE. It's suuposed to look like --- /\a. f a Int dOrdInt --- or /\a.\d:Ord a. let { dl::Ord [a] = dOrdList a d } in f [a] dl --- That is, the RULE binders are lambda-bound --- Returns Nothing if the LHS isn't of the expected shape -decomposeRuleLhs lhs - = case collectArgs body of - (Var fn, args) -> Just (bndrs, fn, args) - - (Case scrut bndr ty [(DEFAULT, _, body)], args) - | isDeadBinder bndr -- Note [Matching seqId] - -> Just (bndrs, seqId, args' ++ args) - where - args' = [Type (idType bndr), Type ty, scrut, body] - - _other -> Nothing -- Unexpected shape - where - (bndrs, body) = collectBinders (simpleOptExpr lhs) - -- simpleOptExpr occurrence-analyses and simplifies the lhs - -- and thereby - -- (a) identifies unused binders: Note [Unused spec binders] - -- (b) sorts dict bindings into NonRecs - -- so they can be inlined by 'decomp' - -- (c) substitute trivial lets so that they don't get in the way - -- Note that we substitute the function too; we might - -- have this as a LHS: let f71 = M.f Int in f71 - -- NB: tcSimplifyRuleLhs is very careful not to generate complicated - -- dictionary expressions that we might have to match -\end{code} - -Note [Matching seqId] -~~~~~~~~~~~~~~~~~~~ -The desugarer turns (seq e r) into (case e of _ -> r), via a special-case hack -and this code turns it back into an application of seq! -See Note [Rules for seq] in MkId for the details. - %************************************************************************ %* * @@ -677,19 +741,16 @@ addDictScc _ rhs = return rhs \begin{code} -dsCoercion :: HsWrapper -> DsM (CoreExpr -> CoreExpr) -dsCoercion WpHole = return (\e -> e) -dsCoercion (WpCompose c1 c2) = do { k1 <- dsCoercion c1 - ; k2 <- dsCoercion c2 - ; return (k1 . k2) } -dsCoercion (WpCast co) = return (\e -> Cast e co) -dsCoercion (WpLam id) = return (\e -> Lam id e) -dsCoercion (WpTyLam tv) = return (\e -> Lam tv e) -dsCoercion (WpApp v) | isTyVar v -- Probably a coercion var - = return (\e -> App e (Type (mkTyVarTy v))) - | otherwise - = return (\e -> App e (Var v)) -dsCoercion (WpTyApp ty) = return (\e -> App e (Type ty)) -dsCoercion (WpLet bs) = do { prs <- dsLHsBinds bs - ; return (\e -> Let (Rec prs) e) } +dsHsWrapper :: HsWrapper -> DsM (CoreExpr -> CoreExpr) +dsHsWrapper WpHole = return (\e -> e) +dsHsWrapper (WpTyApp ty) = return (\e -> App e (Type ty)) +dsHsWrapper (WpLet ev_binds) = do { ds_ev_binds <- dsTcEvBinds ev_binds + ; return (wrapDsEvBinds ds_ev_binds) } +dsHsWrapper (WpCompose c1 c2) = do { k1 <- dsHsWrapper c1 + ; k2 <- dsHsWrapper c2 + ; return (k1 . k2) } +dsHsWrapper (WpCast co) = return (\e -> Cast e co) +dsHsWrapper (WpEvLam ev) = return (\e -> Lam ev e) +dsHsWrapper (WpTyLam tv) = return (\e -> Lam tv e) +dsHsWrapper (WpEvApp evtrm) = return (\e -> App e (dsEvTerm evtrm)) \end{code}