X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2FdeSugar%2FDsUtils.lhs;h=47050828ec71771b82ac0b51bec3b94b821de7ad;hb=16e4ce4c0c02650082f2e11982017c903c549ad5;hp=81aaf42b535c84ce337fb0652314b8bf46fa6e3c;hpb=111cee3f1ad93816cb828e38b38521d85c3bcebb;p=ghc-hetmet.git diff --git a/ghc/compiler/deSugar/DsUtils.lhs b/ghc/compiler/deSugar/DsUtils.lhs index 81aaf42..4705082 100644 --- a/ghc/compiler/deSugar/DsUtils.lhs +++ b/ghc/compiler/deSugar/DsUtils.lhs @@ -10,7 +10,7 @@ module DsUtils ( CanItFail(..), EquationInfo(..), MatchResult(..), EqnNo, EqnSet, - tidyLitPat, + tidyLitPat, tidyNPat, mkDsLet, mkDsLets, @@ -20,107 +20,125 @@ module DsUtils ( mkCoLetsMatchResult, mkGuardedMatchResult, mkCoPrimCaseMatchResult, mkCoAlgCaseMatchResult, - mkErrorAppDs, mkNilExpr, mkConsExpr, + mkErrorAppDs, mkNilExpr, mkConsExpr, mkListExpr, + mkIntExpr, mkCharExpr, + mkStringLit, mkStringLitFS, mkIntegerExpr, - mkSelectorBinds, mkTupleExpr, mkTupleSelector, + mkSelectorBinds, mkTupleExpr, mkTupleSelector, + mkCoreTup, mkCoreSel, mkCoreTupTy, + + dsReboundNames, lookupReboundName, selectMatchVar ) where #include "HsVersions.h" -import {-# SOURCE #-} Match ( matchSimply ) +import {-# SOURCE #-} Match ( matchSimply ) +import {-# SOURCE #-} DsExpr( dsExpr ) import HsSyn -import TcHsSyn ( TypecheckedPat ) -import DsHsSyn ( outPatType, collectTypedPatBinders ) +import TcHsSyn ( TypecheckedPat, hsPatType ) import CoreSyn - +import Constants ( mAX_TUPLE_SIZE ) import DsMonad -import CoreUtils ( exprType ) -import PrelInfo ( iRREFUT_PAT_ERROR_ID ) -import Id ( idType, Id, mkWildId ) -import Literal ( Literal ) +import CoreUtils ( exprType, mkIfThenElse, mkCoerce ) +import MkId ( iRREFUT_PAT_ERROR_ID, mkReboxingAlt, mkNewTypeBody ) +import Id ( idType, Id, mkWildId, mkTemplateLocals ) +import Name ( Name ) +import Literal ( Literal(..), inIntRange, tARGET_MAX_INT ) import TyCon ( isNewTyCon, tyConDataCons ) -import DataCon ( DataCon, StrictnessMark, maybeMarkedUnboxed, - dataConStrictMarks, dataConId, splitProductType_maybe - ) -import Type ( mkFunTy, isUnLiftedType, splitAlgTyConApp, unUsgTy, - Type - ) -import TysPrim ( intPrimTy, - charPrimTy, - floatPrimTy, - doublePrimTy, - addrPrimTy, - wordPrimTy - ) +import DataCon ( DataCon, dataConSourceArity ) +import Type ( mkFunTy, isUnLiftedType, Type, splitTyConApp ) +import TcType ( tcTyConAppTyCon, isIntTy, isFloatTy, isDoubleTy ) +import TysPrim ( intPrimTy ) import TysWiredIn ( nilDataCon, consDataCon, - tupleCon, - stringTy, + tupleCon, mkTupleTy, unitDataConId, unitTy, charTy, charDataCon, - intTy, intDataCon, - floatTy, floatDataCon, - doubleTy, doubleDataCon, - addrTy, addrDataCon, - wordTy, wordDataCon - ) + intTy, intDataCon, smallIntegerDataCon, + floatDataCon, + doubleDataCon, + stringTy, isPArrFakeCon ) +import BasicTypes ( Boxity(..) ) import UniqSet ( mkUniqSet, minusUniqSet, isEmptyUniqSet, UniqSet ) +import PrelNames ( unpackCStringName, unpackCStringUtf8Name, + plusIntegerName, timesIntegerName, + lengthPName, indexPName ) import Outputable +import UnicodeUtil ( intsToUtf8, stringToUtf8 ) +import Util ( isSingleton, notNull, zipEqual ) +import ListSetOps ( assocDefault ) +import FastString \end{code} %************************************************************************ %* * -\subsection{Tidying lit pats} + Rebindable syntax %* * %************************************************************************ \begin{code} -tidyLitPat lit lit_ty default_pat - | lit_ty == charTy = ConPat charDataCon lit_ty [] [] [LitPat (mk_char lit) charPrimTy] - | lit_ty == intTy = ConPat intDataCon lit_ty [] [] [LitPat (mk_int lit) intPrimTy] - | lit_ty == wordTy = ConPat wordDataCon lit_ty [] [] [LitPat (mk_word lit) wordPrimTy] - | lit_ty == addrTy = ConPat addrDataCon lit_ty [] [] [LitPat (mk_addr lit) addrPrimTy] - | lit_ty == floatTy = ConPat floatDataCon lit_ty [] [] [LitPat (mk_float lit) floatPrimTy] - | lit_ty == doubleTy = ConPat doubleDataCon lit_ty [] [] [LitPat (mk_double lit) doublePrimTy] - - -- Convert the literal pattern "" to the constructor pattern []. - | null_str_lit lit = ConPat nilDataCon lit_ty [] [] [] - -- Similar special case for "x" - | one_str_lit lit = ConPat consDataCon lit_ty [] [] - [mk_first_char_lit lit, ConPat nilDataCon lit_ty [] [] []] - - | otherwise = default_pat +dsReboundNames :: ReboundNames Id + -> DsM ([CoreBind], -- Auxiliary bindings + [(Name,Id)]) -- Maps the standard name to its value +dsReboundNames rebound_ids + = mapAndUnzipDs mk_bind rebound_ids `thenDs` \ (binds_s, prs) -> + return (concat binds_s, prs) + where + -- The cheapo special case can happen when we + -- make an intermediate HsDo when desugaring a RecStmt + mk_bind (std_name, HsVar id) = return ([], (std_name, id)) + mk_bind (std_name, expr) = dsExpr expr `thenDs` \ rhs -> + newSysLocalDs (exprType rhs) `thenDs` \ id -> + return ([NonRec id rhs], (std_name, id)) + +lookupReboundName :: [(Name,Id)] -> Name -> CoreExpr +lookupReboundName prs std_name + = Var (assocDefault (mk_panic std_name) prs std_name) where - mk_int (HsInt i) = HsIntPrim i - mk_int l@(HsLitLit s) = l + mk_panic std_name = pprPanic "dsReboundNames" (ptext SLIT("Not found:") <+> ppr std_name) +\end{code} - mk_char (HsChar c) = HsCharPrim c - mk_char l@(HsLitLit s) = l - mk_word l@(HsLitLit s) = l +%************************************************************************ +%* * +\subsection{Tidying lit pats} +%* * +%************************************************************************ - mk_addr l@(HsLitLit s) = l +\begin{code} +tidyLitPat :: HsLit -> TypecheckedPat -> TypecheckedPat +tidyLitPat (HsChar c) pat = mkCharLitPat c +tidyLitPat lit pat = pat + +tidyNPat :: HsLit -> Type -> TypecheckedPat -> TypecheckedPat +tidyNPat (HsString s) _ pat + | lengthFS s <= 1 -- Short string literals only + = foldr (\c pat -> mkPrefixConPat consDataCon [mkCharLitPat c,pat] stringTy) + (mkNilPat stringTy) (unpackIntFS s) + -- The stringTy is the type of the whole pattern, not + -- the type to instantiate (:) or [] with! + where - mk_float (HsInt i) = HsFloatPrim (fromInteger i) - mk_float (HsFrac f) = HsFloatPrim f - mk_float l@(HsLitLit s) = l +tidyNPat lit lit_ty default_pat + | isIntTy lit_ty = mkPrefixConPat intDataCon [LitPat (mk_int lit)] lit_ty + | isFloatTy lit_ty = mkPrefixConPat floatDataCon [LitPat (mk_float lit)] lit_ty + | isDoubleTy lit_ty = mkPrefixConPat doubleDataCon [LitPat (mk_double lit)] lit_ty + | otherwise = default_pat - mk_double (HsInt i) = HsDoublePrim (fromInteger i) - mk_double (HsFrac f) = HsDoublePrim f - mk_double l@(HsLitLit s) = l + where + mk_int (HsInteger i) = HsIntPrim i - null_str_lit (HsString s) = _NULL_ s - null_str_lit other_lit = False + mk_float (HsInteger i) = HsFloatPrim (fromInteger i) + mk_float (HsRat f _) = HsFloatPrim f - one_str_lit (HsString s) = _LENGTH_ s == (1::Int) - one_str_lit other_lit = False - mk_first_char_lit (HsString s) = ConPat charDataCon charTy [] [] [LitPat (HsCharPrim (_HEAD_ s)) charPrimTy] + mk_double (HsInteger i) = HsDoublePrim (fromInteger i) + mk_double (HsRat f _) = HsDoublePrim f \end{code} @@ -161,7 +179,7 @@ selectMatchVar :: TypecheckedPat -> DsM Id selectMatchVar (VarPat var) = returnDs var selectMatchVar (AsPat var pat) = returnDs var selectMatchVar (LazyPat pat) = selectMatchVar pat -selectMatchVar other_pat = newSysLocalDs (outPatType other_pat) -- OK, better make up one... +selectMatchVar other_pat = newSysLocalDs (hsPatType other_pat) -- OK, better make up one... \end{code} @@ -268,7 +286,7 @@ mkCoPrimCaseMatchResult var match_alts where mk_case fail = mapDs (mk_alt fail) match_alts `thenDs` \ alts -> - returnDs (Case (Var var) var (alts ++ [(DEFAULT, [], fail)])) + returnDs (Case (Var var) var ((DEFAULT, [], fail) : alts)) mk_alt fail (lit, MatchResult _ body_fn) = body_fn fail `thenDs` \ body -> returnDs (LitAlt lit, [], body) @@ -280,27 +298,27 @@ mkCoAlgCaseMatchResult :: Id -- Scrutinee mkCoAlgCaseMatchResult var match_alts | isNewTyCon tycon -- Newtype case; use a let - = ASSERT( newtype_sanity ) - mkCoLetsMatchResult [coercion_bind] match_result + = ASSERT( null (tail match_alts) && null (tail arg_ids) ) + mkCoLetsMatchResult [NonRec arg_id newtype_rhs] match_result + + | isPArrFakeAlts match_alts -- Sugared parallel array; use a literal case + = MatchResult CanFail mk_parrCase | otherwise -- Datatype case; use a case = MatchResult fail_flag mk_case where -- Common stuff scrut_ty = idType var - (tycon, tycon_arg_tys, _) = splitAlgTyConApp scrut_ty + tycon = tcTyConAppTyCon scrut_ty -- Newtypes must be opaque here -- Stuff for newtype - (con_id, arg_ids, match_result) = head match_alts - arg_id = head arg_ids - coercion_bind = NonRec arg_id - (Note (Coerce (unUsgTy (idType arg_id)) (unUsgTy scrut_ty)) (Var var)) - newtype_sanity = null (tail match_alts) && null (tail arg_ids) - + (_, arg_ids, match_result) = head match_alts + arg_id = head arg_ids + newtype_rhs = mkNewTypeBody tycon (idType arg_id) (Var var) + -- Stuff for data types - data_cons = tyConDataCons tycon - - match_results = [match_result | (_,_,match_result) <- match_alts] + data_cons = tyConDataCons tycon + match_results = [match_result | (_,_,match_result) <- match_alts] fail_flag | exhaustive_case = foldr1 orFail [can_it_fail | MatchResult can_it_fail _ <- match_results] @@ -309,13 +327,12 @@ mkCoAlgCaseMatchResult var match_alts wild_var = mkWildId (idType var) mk_case fail = mapDs (mk_alt fail) match_alts `thenDs` \ alts -> - returnDs (Case (Var var) wild_var (alts ++ mk_default fail)) + returnDs (Case (Var var) wild_var (mk_default fail ++ alts)) mk_alt fail (con, args, MatchResult _ body_fn) - = body_fn fail `thenDs` \ body -> - rebuildConArgs con args (dataConStrictMarks con) body - `thenDs` \ (body', real_args) -> - returnDs (DataAlt con, real_args, body') + = body_fn fail `thenDs` \ body -> + getUniquesDs `thenDs` \ us -> + returnDs (mkReboxingAlt us con args body) mk_default fail | exhaustive_case = [] | otherwise = [(DEFAULT, [], fail)] @@ -323,41 +340,74 @@ mkCoAlgCaseMatchResult var match_alts un_mentioned_constructors = mkUniqSet data_cons `minusUniqSet` mkUniqSet [ con | (con, _, _) <- match_alts] exhaustive_case = isEmptyUniqSet un_mentioned_constructors -\end{code} -% -For each constructor we match on, we might need to re-pack some -of the strict fields if they are unpacked in the constructor. -% -\begin{code} -rebuildConArgs - :: DataCon -- the con we're matching on - -> [Id] -- the source-level args - -> [StrictnessMark] -- the strictness annotations (per-arg) - -> CoreExpr -- the body - -> DsM (CoreExpr, [Id]) - -rebuildConArgs con [] stricts body = returnDs (body, []) -rebuildConArgs con (arg:args) stricts body | isTyVar arg - = rebuildConArgs con args stricts body `thenDs` \ (body', args') -> - returnDs (body',arg:args') -rebuildConArgs con (arg:args) (str:stricts) body - = rebuildConArgs con args stricts body `thenDs` \ (body', real_args) -> - case maybeMarkedUnboxed str of - Just (pack_con1, _) -> - case splitProductType_maybe (idType arg) of - Just (_, tycon_args, pack_con, con_arg_tys) -> - ASSERT( pack_con == pack_con1 ) - newSysLocalsDs con_arg_tys `thenDs` \ unpacked_args -> - returnDs ( - mkDsLet (NonRec arg (mkConApp pack_con - (map Type tycon_args ++ - map Var unpacked_args))) body', - unpacked_args ++ real_args - ) - - _ -> returnDs (body', arg:real_args) + + -- Stuff for parallel arrays + -- + -- * the following is to desugar cases over fake constructors for + -- parallel arrays, which are introduced by `tidy1' in the `PArrPat' + -- case + -- + -- Concerning `isPArrFakeAlts': + -- + -- * it is *not* sufficient to just check the type of the type + -- constructor, as we have to be careful not to confuse the real + -- representation of parallel arrays with the fake constructors; + -- moreover, a list of alternatives must not mix fake and real + -- constructors (this is checked earlier on) + -- + -- FIXME: We actually go through the whole list and make sure that + -- either all or none of the constructors are fake parallel + -- array constructors. This is to spot equations that mix fake + -- constructors with the real representation defined in + -- `PrelPArr'. It would be nicer to spot this situation + -- earlier and raise a proper error message, but it can really + -- only happen in `PrelPArr' anyway. + -- + isPArrFakeAlts [(dcon, _, _)] = isPArrFakeCon dcon + isPArrFakeAlts ((dcon, _, _):alts) = + case (isPArrFakeCon dcon, isPArrFakeAlts alts) of + (True , True ) -> True + (False, False) -> False + _ -> + panic "DsUtils: You may not mix `[:...:]' with `PArr' patterns" + -- + mk_parrCase fail = + dsLookupGlobalId lengthPName `thenDs` \lengthP -> + unboxAlt `thenDs` \alt -> + returnDs (Case (len lengthP) (mkWildId intTy) [alt]) + where + elemTy = case splitTyConApp (idType var) of + (_, [elemTy]) -> elemTy + _ -> panic panicMsg + panicMsg = "DsUtils.mkCoAlgCaseMatchResult: not a parallel array?" + len lengthP = mkApps (Var lengthP) [Type elemTy, Var var] + -- + unboxAlt = + newSysLocalDs intPrimTy `thenDs` \l -> + dsLookupGlobalId indexPName `thenDs` \indexP -> + mapDs (mkAlt indexP) match_alts `thenDs` \alts -> + returnDs (DataAlt intDataCon, [l], (Case (Var l) wild (dft : alts))) + where + wild = mkWildId intPrimTy + dft = (DEFAULT, [], fail) + -- + -- each alternative matches one array length (corresponding to one + -- fake array constructor), so the match is on a literal; each + -- alternative's body is extended by a local binding for each + -- constructor argument, which are bound to array elements starting + -- with the first + -- + mkAlt indexP (con, args, MatchResult _ bodyFun) = + bodyFun fail `thenDs` \body -> + returnDs (LitAlt lit, [], mkDsLets binds body) + where + lit = MachInt $ toInteger (dataConSourceArity con) + binds = [NonRec arg (indexExpr i) | (i, arg) <- zip [1..] args] + -- + indexExpr i = mkApps (Var indexP) [Type elemTy, Var var, mkIntExpr i] \end{code} + %************************************************************************ %* * \subsection{Desugarer's versions of some Core functions} @@ -374,11 +424,84 @@ mkErrorAppDs err_id ty msg = getSrcLocDs `thenDs` \ src_loc -> let full_msg = showSDoc (hcat [ppr src_loc, text "|", text msg]) + core_msg = Lit (MachStr (mkFastString (stringToUtf8 full_msg))) + in + returnDs (mkApps (Var err_id) [Type ty, core_msg]) +\end{code} + + +************************************************************* +%* * +\subsection{Making literals} +%* * +%************************************************************************ + +\begin{code} +mkCharExpr :: Int -> CoreExpr -- Returns C# c :: Int +mkIntExpr :: Integer -> CoreExpr -- Returns I# i :: Int +mkIntegerExpr :: Integer -> DsM CoreExpr -- Result :: Integer +mkStringLit :: String -> DsM CoreExpr -- Result :: String +mkStringLitFS :: FastString -> DsM CoreExpr -- Result :: String + +mkIntExpr i = mkConApp intDataCon [mkIntLit i] +mkCharExpr c = mkConApp charDataCon [mkLit (MachChar c)] + +mkIntegerExpr i + | inIntRange i -- Small enough, so start from an Int + = returnDs (mkSmallIntegerLit i) + +-- Special case for integral literals with a large magnitude: +-- They are transformed into an expression involving only smaller +-- integral literals. This improves constant folding. + + | otherwise -- Big, so start from a string + = dsLookupGlobalId plusIntegerName `thenDs` \ plus_id -> + dsLookupGlobalId timesIntegerName `thenDs` \ times_id -> + let + plus a b = Var plus_id `App` a `App` b + times a b = Var times_id `App` a `App` b + + -- Transform i into (x1 + (x2 + (x3 + (...) * b) * b) * b) with abs xi <= b + horner :: Integer -> Integer -> CoreExpr + horner b i | abs q <= 1 = if r == 0 || r == i + then mkSmallIntegerLit i + else mkSmallIntegerLit r `plus` mkSmallIntegerLit (i-r) + | r == 0 = horner b q `times` mkSmallIntegerLit b + | otherwise = mkSmallIntegerLit r `plus` (horner b q `times` mkSmallIntegerLit b) + where + (q,r) = i `quotRem` b + + in + returnDs (horner tARGET_MAX_INT i) + +mkSmallIntegerLit i = mkConApp smallIntegerDataCon [mkIntLit i] + +mkStringLit str = mkStringLitFS (mkFastString str) + +mkStringLitFS str + | nullFastString str + = returnDs (mkNilExpr charTy) + + | lengthFS str == 1 + = let + the_char = mkCharExpr (headIntFS str) in - returnDs (mkApps (Var err_id) [(Type . unUsgTy) ty, mkStringLit full_msg]) - -- unUsgTy *required* -- KSW 1999-04-07 + returnDs (mkConsExpr charTy the_char (mkNilExpr charTy)) + + | all safeChar int_chars + = dsLookupGlobalId unpackCStringName `thenDs` \ unpack_id -> + returnDs (App (Var unpack_id) (Lit (MachStr str))) + + | otherwise + = dsLookupGlobalId unpackCStringUtf8Name `thenDs` \ unpack_id -> + returnDs (App (Var unpack_id) (Lit (MachStr (mkFastString (intsToUtf8 int_chars))))) + + where + int_chars = unpackIntFS str + safeChar c = c >= 1 && c <= 0xFF \end{code} + %************************************************************************ %* * \subsection[mkSelectorBind]{Make a selector bind} @@ -410,73 +533,113 @@ mkSelectorBinds (VarPat v) val_expr = returnDs [(v, val_expr)] mkSelectorBinds pat val_expr - | length binders == 1 || is_simple_pat pat - = newSysLocalDs (exprType val_expr) `thenDs` \ val_var -> - - -- For the error message we don't use mkErrorAppDs to avoid - -- duplicating the string literal each time - newSysLocalDs stringTy `thenDs` \ msg_var -> - getSrcLocDs `thenDs` \ src_loc -> - let - full_msg = showSDoc (hcat [ppr src_loc, text "|", ppr pat]) - in - mapDs (mk_bind val_var msg_var) binders `thenDs` \ binds -> + | isSingleton binders || is_simple_pat pat + = -- Given p = e, where p binds x,y + -- we are going to make + -- v = p (where v is fresh) + -- x = case v of p -> x + -- y = case v of p -> x + + -- Make up 'v' + -- NB: give it the type of *pattern* p, not the type of the *rhs* e. + -- This does not matter after desugaring, but there's a subtle + -- issue with implicit parameters. Consider + -- (x,y) = ?i + -- Then, ?i is given type {?i :: Int}, a SourceType, which is opaque + -- to the desugarer. (Why opaque? Because newtypes have to be. Why + -- does it get that type? So that when we abstract over it we get the + -- right top-level type (?i::Int) => ...) + -- + -- So to get the type of 'v', use the pattern not the rhs. Often more + -- efficient too. + newSysLocalDs (hsPatType pat) `thenDs` \ val_var -> + + -- For the error message we make one error-app, to avoid duplication. + -- But we need it at different types... so we use coerce for that + mkErrorAppDs iRREFUT_PAT_ERROR_ID + unitTy (showSDoc (ppr pat)) `thenDs` \ err_expr -> + newSysLocalDs unitTy `thenDs` \ err_var -> + mapDs (mk_bind val_var err_var) binders `thenDs` \ binds -> returnDs ( (val_var, val_expr) : - (msg_var, mkStringLit full_msg) : + (err_var, err_expr) : binds ) | otherwise - = mkErrorAppDs iRREFUT_PAT_ERROR_ID tuple_ty (showSDoc (ppr pat)) - `thenDs` \ error_expr -> - matchSimply val_expr LetMatch pat local_tuple error_expr - `thenDs` \ tuple_expr -> - newSysLocalDs tuple_ty - `thenDs` \ tuple_var -> + = mkErrorAppDs iRREFUT_PAT_ERROR_ID + tuple_ty (showSDoc (ppr pat)) `thenDs` \ error_expr -> + matchSimply val_expr PatBindRhs pat local_tuple error_expr `thenDs` \ tuple_expr -> + newSysLocalDs tuple_ty `thenDs` \ tuple_var -> let - mk_tup_bind binder = - (binder, mkTupleSelector binders binder tuple_var (Var tuple_var)) + mk_tup_bind binder + = (binder, mkTupleSelector binders binder tuple_var (Var tuple_var)) in returnDs ( (tuple_var, tuple_expr) : map mk_tup_bind binders ) where - binders = collectTypedPatBinders pat + binders = collectPatBinders pat local_tuple = mkTupleExpr binders tuple_ty = exprType local_tuple - mk_bind scrut_var msg_var bndr_var - -- (mk_bind sv bv) generates - -- bv = case sv of { pat -> bv; other -> error-msg } + mk_bind scrut_var err_var bndr_var + -- (mk_bind sv err_var) generates + -- bv = case sv of { pat -> bv; other -> coerce (type-of-bv) err_var } -- Remember, pat binds bv - = matchSimply (Var scrut_var) LetMatch pat + = matchSimply (Var scrut_var) PatBindRhs pat (Var bndr_var) error_expr `thenDs` \ rhs_expr -> returnDs (bndr_var, rhs_expr) where - binder_ty = idType bndr_var - error_expr = mkApps (Var iRREFUT_PAT_ERROR_ID) [Type binder_ty, Var msg_var] + error_expr = mkCoerce (idType bndr_var) (Var err_var) - is_simple_pat (TuplePat ps True{-boxed-}) = all is_triv_pat ps - is_simple_pat (ConPat _ _ _ _ ps) = all is_triv_pat ps - is_simple_pat (VarPat _) = True - is_simple_pat (RecPat _ _ _ _ ps) = and [is_triv_pat p | (_,p,_) <- ps] - is_simple_pat other = False + is_simple_pat (TuplePat ps Boxed) = all is_triv_pat ps + is_simple_pat (ConPatOut _ ps _ _ _) = all is_triv_pat (hsConArgs ps) + is_simple_pat (VarPat _) = True + is_simple_pat (ParPat p) = is_simple_pat p + is_simple_pat other = False is_triv_pat (VarPat v) = True is_triv_pat (WildPat _) = True + is_triv_pat (ParPat p) = is_triv_pat p is_triv_pat other = False \end{code} -@mkTupleExpr@ builds a tuple; the inverse to @mkTupleSelector@. If it -has only one element, it is the identity function. Notice we must -throw out any usage annotation on the outside of an Id. +%************************************************************************ +%* * + Tuples +%* * +%************************************************************************ + +@mkTupleExpr@ builds a tuple; the inverse to @mkTupleSelector@. + +* If it has only one element, it is the identity function. + +* If there are more elements than a big tuple can have, it nests + the tuples. + +Nesting policy. Better a 2-tuple of 10-tuples (3 objects) than +a 10-tuple of 2-tuples (11 objects). So we want the leaves to be big. \begin{code} mkTupleExpr :: [Id] -> CoreExpr - -mkTupleExpr [] = Var unitDataConId -mkTupleExpr [id] = Var id -mkTupleExpr ids = mkConApp (tupleCon (length ids)) - (map (Type . unUsgTy . idType) ids ++ [ Var i | i <- ids ]) +mkTupleExpr ids + = mk_tuple_expr (chunkify (map Var ids)) + where + mk_tuple_expr :: [[CoreExpr]] -> CoreExpr + -- Each sub-list is short enough to fit in a tuple + mk_tuple_expr [exprs] = mkCoreTup exprs + mk_tuple_expr exprs_s = mk_tuple_expr (chunkify (map mkCoreTup exprs_s)) + + +chunkify :: [a] -> [[a]] +-- The sub-lists of the result all have length <= mAX_TUPLE_SIZE +-- But there may be more than mAX_TUPLE_SIZE sub-lists +chunkify xs + | n_xs <= mAX_TUPLE_SIZE = {- pprTrace "Small" (ppr n_xs) -} [xs] + | otherwise = {- pprTrace "Big" (ppr n_xs) -} (split xs) + where + n_xs = length xs + split [] = [] + split xs = take mAX_TUPLE_SIZE xs : split (drop mAX_TUPLE_SIZE xs) \end{code} @@ -489,6 +652,19 @@ are in scope. If there is just one id in the ``tuple'', then the selector is just the identity. +If it's big, it does nesting + mkTupleSelector [a,b,c,d] b v e + = case e of v { + (p,q) -> case p of p { + (a,b) -> b }} +We use 'tpl' vars for the p,q, since shadowing does not matter. + +In fact, it's more convenient to generate it innermost first, getting + + case (case e of v + (p,q) -> p) of p + (a,b) -> b + \begin{code} mkTupleSelector :: [Id] -- The tuple args -> Id -- The selected one @@ -496,13 +672,17 @@ mkTupleSelector :: [Id] -- The tuple args -> CoreExpr -- Scrutinee -> CoreExpr -mkTupleSelector [var] should_be_the_same_var scrut_var scrut - = ASSERT(var == should_be_the_same_var) - scrut - mkTupleSelector vars the_var scrut_var scrut - = ASSERT( not (null vars) ) - Case scrut scrut_var [(DataAlt (tupleCon (length vars)), vars, Var the_var)] + = mk_tup_sel (chunkify vars) the_var + where + mk_tup_sel [vars] the_var = mkCoreSel vars the_var scrut_var scrut + mk_tup_sel vars_s the_var = mkCoreSel group the_var tpl_v $ + mk_tup_sel (chunkify tpl_vs) tpl_v + where + tpl_tys = [mkCoreTupTy (map idType gp) | gp <- vars_s] + tpl_vs = mkTemplateLocals tpl_tys + [(tpl_v, group)] = [(tpl,gp) | (tpl,gp) <- zipEqual "mkTupleSelector" tpl_vs vars_s, + the_var `elem` gp ] \end{code} @@ -517,10 +697,44 @@ interact well with rules. \begin{code} mkNilExpr :: Type -> CoreExpr -mkNilExpr ty = App (Var (dataConId nilDataCon)) (Type ty) +mkNilExpr ty = mkConApp nilDataCon [Type ty] mkConsExpr :: Type -> CoreExpr -> CoreExpr -> CoreExpr -mkConsExpr ty hd tl = mkApps (Var (dataConId consDataCon)) [Type ty, hd, tl] +mkConsExpr ty hd tl = mkConApp consDataCon [Type ty, hd, tl] + +mkListExpr :: Type -> [CoreExpr] -> CoreExpr +mkListExpr ty xs = foldr (mkConsExpr ty) (mkNilExpr ty) xs + + +-- The next three functions make tuple types, constructors and selectors, +-- with the rule that a 1-tuple is represented by the thing itselg +mkCoreTupTy :: [Type] -> Type +mkCoreTupTy [ty] = ty +mkCoreTupTy tys = mkTupleTy Boxed (length tys) tys + +mkCoreTup :: [CoreExpr] -> CoreExpr +-- Builds exactly the specified tuple. +-- No fancy business for big tuples +mkCoreTup [] = Var unitDataConId +mkCoreTup [c] = c +mkCoreTup cs = mkConApp (tupleCon Boxed (length cs)) + (map (Type . exprType) cs ++ cs) + +mkCoreSel :: [Id] -- The tuple args + -> Id -- The selected one + -> Id -- A variable of the same type as the scrutinee + -> CoreExpr -- Scrutinee + -> CoreExpr +-- mkCoreSel [x,y,z] x v e +-- ===> case e of v { (x,y,z) -> x +mkCoreSel [var] should_be_the_same_var scrut_var scrut + = ASSERT(var == should_be_the_same_var) + scrut + +mkCoreSel vars the_var scrut_var scrut + = ASSERT( notNull vars ) + Case scrut scrut_var + [(DataAlt (tupleCon Boxed (length vars)), vars, Var the_var)] \end{code} @@ -599,4 +813,3 @@ mkFailurePair expr \end{code} -