%
-% (c) The GRASP/AQUA Project, Glasgow University, 1992-1996
+% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
%
\section[DsUtils]{Utilities for desugaring}
This module exports some utility functions of no great interest.
\begin{code}
-#include "HsVersions.h"
-
module DsUtils (
CanItFail(..), EquationInfo(..), MatchResult(..),
+ EqnNo, EqnSet,
+
+ tidyLitPat, tidyNPat,
+
+ mkDsLet, mkDsLets,
+
+ cantFailMatchResult, extractMatchResult,
+ combineMatchResults,
+ adjustMatchResult, adjustMatchResultDs,
+ mkCoLetsMatchResult, mkGuardedMatchResult,
+ mkCoPrimCaseMatchResult, mkCoAlgCaseMatchResult,
+
+ mkErrorAppDs, mkNilExpr, mkConsExpr,
+ mkStringLit, mkStringLitFS, mkIntegerLit,
- combineGRHSMatchResults,
- combineMatchResults,
- dsExprToAtom, DsCoreArg(..),
- mkCoAlgCaseMatchResult,
- mkAppDs, mkConDs, mkPrimDs, mkErrorAppDs,
- mkCoLetsMatchResult,
- mkCoPrimCaseMatchResult,
- mkFailurePair,
- mkGuardedMatchResult,
- mkSelectorBinds,
- mkTupleBind,
- mkTupleExpr,
- selectMatchVars,
- showForErr
+ mkSelectorBinds, mkTupleExpr, mkTupleSelector,
+
+ selectMatchVar
) where
-IMP_Ubiq()
-IMPORT_DELOOPER(DsLoop) ( match, matchSimply )
+#include "HsVersions.h"
+
+import {-# SOURCE #-} Match ( matchSimply )
-import HsSyn ( HsExpr(..), OutPat(..), HsLit(..),
- Match, HsBinds, Stmt, Qualifier, PolyType, ArithSeqInfo )
-import TcHsSyn ( TypecheckedPat(..) )
-import DsHsSyn ( outPatType )
+import HsSyn
+import TcHsSyn ( TypecheckedPat, outPatType, collectTypedPatBinders )
import CoreSyn
import DsMonad
-import CoreUtils ( coreExprType, mkCoreIfThenElse )
-import PprStyle ( PprStyle(..) )
-import PrelVals ( iRREFUT_PAT_ERROR_ID, voidId )
-import Pretty ( ppShow )
-import Id ( idType, dataConArgTys, mkTupleCon,
- pprId{-ToDo:rm-},
- DataCon(..), DictVar(..), Id(..), GenId )
-import Literal ( Literal(..) )
-import TyCon ( mkTupleTyCon, isNewTyCon, tyConDataCons )
-import Type ( mkTyVarTys, mkRhoTy, mkForAllTys, mkFunTys,
- mkTheta, isUnboxedType, applyTyCon, getAppTyCon
- )
-import TysPrim ( voidTy )
-import UniqSet ( mkUniqSet, minusUniqSet, uniqSetToList, UniqSet(..) )
-import Util ( panic, assertPanic, pprTrace{-ToDo:rm-} )
-import PprCore{-ToDo:rm-}
---import PprType--ToDo:rm
-import Pretty--ToDo:rm
-import TyVar--ToDo:rm
-import Unique--ToDo:rm
-import Usage--ToDo:rm
+import CoreUtils ( exprType, mkIfThenElse )
+import PrelInfo ( iRREFUT_PAT_ERROR_ID )
+import MkId ( rebuildConArgs )
+import Id ( idType, Id, mkWildId )
+import Literal ( Literal(..), inIntRange, tARGET_MAX_INT )
+import TyCon ( isNewTyCon, tyConDataCons, isRecursiveTyCon )
+import DataCon ( DataCon, dataConStrictMarks, dataConId,
+ dataConSourceArity )
+import Type ( mkFunTy, isUnLiftedType, Type, splitTyConApp )
+import TcType ( tcTyConAppTyCon, isIntTy, isFloatTy, isDoubleTy )
+import TysPrim ( intPrimTy, charPrimTy, floatPrimTy, doublePrimTy )
+import TysWiredIn ( nilDataCon, consDataCon,
+ tupleCon,
+ unitDataConId, unitTy,
+ charTy, charDataCon,
+ 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 ( stringToUtf8 )
+import Util ( isSingleton )
+\end{code}
+
+
+
+%************************************************************************
+%* *
+\subsection{Tidying lit pats}
+%* *
+%************************************************************************
+
+\begin{code}
+tidyLitPat :: HsLit -> TypecheckedPat -> TypecheckedPat
+tidyLitPat (HsChar c) pat = ConPat charDataCon charTy [] [] [LitPat (HsCharPrim c) charPrimTy]
+tidyLitPat lit pat = pat
+
+tidyNPat :: HsLit -> Type -> TypecheckedPat -> TypecheckedPat
+tidyNPat (HsString s) _ pat
+ | _LENGTH_ s <= 1 -- Short string literals only
+ = foldr (\c pat -> ConPat consDataCon stringTy [] [] [mk_char_lit c,pat])
+ (ConPat nilDataCon stringTy [] [] []) (_UNPK_INT_ s)
+ -- The stringTy is the type of the whole pattern, not
+ -- the type to instantiate (:) or [] with!
+ where
+ mk_char_lit c = ConPat charDataCon charTy [] [] [LitPat (HsCharPrim c) charPrimTy]
+
+tidyNPat lit lit_ty default_pat
+ | isIntTy lit_ty = ConPat intDataCon lit_ty [] [] [LitPat (mk_int lit) intPrimTy]
+ | isFloatTy lit_ty = ConPat floatDataCon lit_ty [] [] [LitPat (mk_float lit) floatPrimTy]
+ | isDoubleTy lit_ty = ConPat doubleDataCon lit_ty [] [] [LitPat (mk_double lit) doublePrimTy]
+ | otherwise = default_pat
+
+ where
+ mk_int (HsInteger i) = HsIntPrim i
+
+ mk_float (HsInteger i) = HsFloatPrim (fromInteger i)
+ mk_float (HsRat f _) = HsFloatPrim f
+
+ mk_double (HsInteger i) = HsDoublePrim (fromInteger i)
+ mk_double (HsRat f _) = HsDoublePrim f
\end{code}
+
+%************************************************************************
+%* *
+\subsection{Building lets}
+%* *
+%************************************************************************
+
+Use case, not let for unlifted types. The simplifier will turn some
+back again.
+
+\begin{code}
+mkDsLet :: CoreBind -> CoreExpr -> CoreExpr
+mkDsLet (NonRec bndr rhs) body
+ | isUnLiftedType (idType bndr) = Case rhs bndr [(DEFAULT,[],body)]
+mkDsLet bind body
+ = Let bind body
+
+mkDsLets :: [CoreBind] -> CoreExpr -> CoreExpr
+mkDsLets binds body = foldr mkDsLet body binds
+\end{code}
+
+
+%************************************************************************
+%* *
+\subsection{ Selecting match variables}
+%* *
+%************************************************************************
+
+We're about to match against some patterns. We want to make some
+@Ids@ to use as match variables. If a pattern has an @Id@ readily at
+hand, which should indeed be bound to the pattern as a whole, then use it;
+otherwise, make one up.
+
+\begin{code}
+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...
+\end{code}
+
+
%************************************************************************
%* *
%* type synonym EquationInfo and access functions for its pieces *
worthy of a type synonym and a few handy functions.
\begin{code}
+
+type EqnNo = Int
+type EqnSet = UniqSet EqnNo
+
data EquationInfo
= EqnInfo
- [TypecheckedPat] -- the patterns for an eqn
+ EqnNo -- The number of the equation
+
+ DsMatchContext -- The context info is used when producing warnings
+ -- about shadowed patterns. It's the context
+ -- of the *first* thing matched in this group.
+ -- Should perhaps be a list of them all!
+
+ [TypecheckedPat] -- The patterns for an eqn
+
MatchResult -- Encapsulates the guards and bindings
\end{code}
\begin{code}
data MatchResult
= MatchResult
- CanItFail
- Type -- Type of argument expression
-
- (CoreExpr -> CoreExpr)
+ CanItFail -- Tells whether the failure expression is used
+ (CoreExpr -> DsM CoreExpr)
-- Takes a expression to plug in at the
-- failure point(s). The expression should
-- be duplicatable!
- DsMatchContext -- The context info is used when producing warnings
- -- about shadowed patterns. It's the context
- -- of the *first* thing matched in this group.
- -- Should perhaps be a list of them all!
-
data CanItFail = CanFail | CantFail
orFail CantFail CantFail = CantFail
orFail _ _ = CanFail
+\end{code}
+
+Functions on MatchResults
+
+\begin{code}
+cantFailMatchResult :: CoreExpr -> MatchResult
+cantFailMatchResult expr = MatchResult CantFail (\ ignore -> returnDs expr)
+extractMatchResult :: MatchResult -> CoreExpr -> DsM CoreExpr
+extractMatchResult (MatchResult CantFail match_fn) fail_expr
+ = match_fn (error "It can't fail!")
-mkCoLetsMatchResult :: [CoreBinding] -> MatchResult -> MatchResult
-mkCoLetsMatchResult binds (MatchResult can_it_fail ty body_fn cxt)
- = MatchResult can_it_fail ty (\body -> mkCoLetsAny binds (body_fn body)) cxt
+extractMatchResult (MatchResult CanFail match_fn) fail_expr
+ = mkFailurePair fail_expr `thenDs` \ (fail_bind, if_it_fails) ->
+ match_fn if_it_fails `thenDs` \ body ->
+ returnDs (mkDsLet fail_bind body)
-mkGuardedMatchResult :: CoreExpr -> MatchResult -> DsM MatchResult
-mkGuardedMatchResult pred_expr (MatchResult can_it_fail ty body_fn cxt)
- = returnDs (MatchResult CanFail
- ty
- (\fail -> mkCoreIfThenElse pred_expr (body_fn fail) fail)
- cxt
- )
+
+combineMatchResults :: MatchResult -> MatchResult -> MatchResult
+combineMatchResults (MatchResult CanFail body_fn1)
+ (MatchResult can_it_fail2 body_fn2)
+ = MatchResult can_it_fail2 body_fn
+ where
+ body_fn fail = body_fn2 fail `thenDs` \ body2 ->
+ mkFailurePair body2 `thenDs` \ (fail_bind, duplicatable_expr) ->
+ body_fn1 duplicatable_expr `thenDs` \ body1 ->
+ returnDs (Let fail_bind body1)
+
+combineMatchResults match_result1@(MatchResult CantFail body_fn1) match_result2
+ = match_result1
+
+
+adjustMatchResult :: (CoreExpr -> CoreExpr) -> MatchResult -> MatchResult
+adjustMatchResult encl_fn (MatchResult can_it_fail body_fn)
+ = MatchResult can_it_fail (\fail -> body_fn fail `thenDs` \ body ->
+ returnDs (encl_fn body))
+
+adjustMatchResultDs :: (CoreExpr -> DsM CoreExpr) -> MatchResult -> MatchResult
+adjustMatchResultDs encl_fn (MatchResult can_it_fail body_fn)
+ = MatchResult can_it_fail (\fail -> body_fn fail `thenDs` \ body ->
+ encl_fn body)
+
+
+mkCoLetsMatchResult :: [CoreBind] -> MatchResult -> MatchResult
+mkCoLetsMatchResult binds match_result
+ = adjustMatchResult (mkDsLets binds) match_result
+
+
+mkGuardedMatchResult :: CoreExpr -> MatchResult -> MatchResult
+mkGuardedMatchResult pred_expr (MatchResult can_it_fail body_fn)
+ = MatchResult CanFail (\fail -> body_fn fail `thenDs` \ body ->
+ returnDs (mkIfThenElse pred_expr body fail))
mkCoPrimCaseMatchResult :: Id -- Scrutinee
- -> [(Literal, MatchResult)] -- Alternatives
- -> DsM MatchResult
-mkCoPrimCaseMatchResult var alts
- = newSysLocalDs (idType var) `thenDs` \ wild ->
- returnDs (MatchResult CanFail
- ty1
- (mk_case alts wild)
- cxt1)
+ -> [(Literal, MatchResult)] -- Alternatives
+ -> MatchResult
+mkCoPrimCaseMatchResult var match_alts
+ = MatchResult CanFail mk_case
where
- ((_,MatchResult _ ty1 _ cxt1) : _) = alts
+ mk_case fail
+ = mapDs (mk_alt fail) match_alts `thenDs` \ alts ->
+ returnDs (Case (Var var) var ((DEFAULT, [], fail) : alts))
- mk_case alts wild fail_expr
- = Case (Var var) (PrimAlts final_alts (BindDefault wild fail_expr))
- where
- final_alts = [ (lit, body_fn fail_expr)
- | (lit, MatchResult _ _ body_fn _) <- alts
- ]
-
-
-mkCoAlgCaseMatchResult :: Id -- Scrutinee
- -> [(DataCon, [Id], MatchResult)] -- Alternatives
- -> DsM MatchResult
-
-mkCoAlgCaseMatchResult var alts
- | isNewTyCon tycon -- newtype case; use a let
- = ASSERT( newtype_sanity )
- returnDs (mkCoLetsMatchResult [coercion_bind] match_result)
-
- | otherwise -- datatype case
- = -- Find all the constructors in the type which aren't
- -- explicitly mentioned in the alternatives:
- case un_mentioned_constructors of
- [] -> -- All constructors mentioned, so no default needed
- returnDs (MatchResult can_any_alt_fail
- ty1
- (mk_case alts (\ignore -> NoDefault))
- cxt1)
-
- [con] -> -- Just one constructor missing, so add a case for it
- -- We need to build new locals for the args of the constructor,
- -- and figuring out their types is somewhat tiresome.
- let
- arg_tys = dataConArgTys con tycon_arg_tys
- in
- newSysLocalsDs arg_tys `thenDs` \ arg_ids ->
-
- -- Now we are ready to construct the new alternative
- let
- new_alt = (con, arg_ids, MatchResult CanFail ty1 id NoMatchContext)
- in
- returnDs (MatchResult CanFail
- ty1
- (mk_case (new_alt:alts) (\ignore -> NoDefault))
- cxt1)
-
- other -> -- Many constructors missing, so use a default case
- newSysLocalDs scrut_ty `thenDs` \ wild ->
- returnDs (MatchResult CanFail
- ty1
- (mk_case alts (\fail_expr -> BindDefault wild fail_expr))
- cxt1)
+ mk_alt fail (lit, MatchResult _ body_fn) = body_fn fail `thenDs` \ body ->
+ returnDs (LitAlt lit, [], body)
+
+
+mkCoAlgCaseMatchResult :: Id -- Scrutinee
+ -> [(DataCon, [CoreBndr], MatchResult)] -- Alternatives
+ -> MatchResult
+
+mkCoAlgCaseMatchResult var match_alts
+ | isNewTyCon tycon -- Newtype case; use a let
+ = 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) = --pprTrace "CoAlgCase:" (pprType PprDebug scrut_ty) $
- getAppTyCon scrut_ty
+ tycon = tcTyConAppTyCon scrut_ty -- Newtypes must be opaque here
-- Stuff for newtype
- (con_id, arg_ids, match_result) = head alts
- arg_id = head arg_ids
- coercion_bind = NonRec arg_id (Coerce (CoerceOut con_id)
- (idType arg_id)
- (Var var))
- newtype_sanity = null (tail alts) && null (tail arg_ids)
-
+ (_, arg_ids, match_result) = head match_alts
+ arg_id = head arg_ids
+
+ newtype_rhs | isRecursiveTyCon tycon -- Recursive case; need a case
+ = Note (Coerce (idType arg_id) scrut_ty) (Var var)
+ | otherwise -- Normal case (newtype is transparent)
+ = Var var
+
-- Stuff for data types
data_cons = tyConDataCons tycon
- un_mentioned_constructors
- = uniqSetToList (mkUniqSet data_cons `minusUniqSet` mkUniqSet [ con | (con, _, _) <- alts] )
-
- match_results = [match_result | (_,_,match_result) <- alts]
- (MatchResult _ ty1 _ cxt1 : _) = match_results
- can_any_alt_fail = foldr1 orFail [can_it_fail | MatchResult can_it_fail _ _ _ <- match_results]
+ match_results = [match_result | (_,_,match_result) <- match_alts]
- mk_case alts deflt_fn fail_expr
- = Case (Var var) (AlgAlts final_alts (deflt_fn fail_expr))
- where
- final_alts = [ (con, args, body_fn fail_expr)
- | (con, args, MatchResult _ _ body_fn _) <- alts
- ]
+ fail_flag | exhaustive_case
+ = foldr1 orFail [can_it_fail | MatchResult can_it_fail _ <- match_results]
+ | otherwise
+ = CanFail
+ wild_var = mkWildId (idType var)
+ mk_case fail = mapDs (mk_alt fail) match_alts `thenDs` \ alts ->
+ returnDs (Case (Var var) wild_var (mk_default fail ++ alts))
-combineMatchResults :: MatchResult -> MatchResult -> DsM MatchResult
-combineMatchResults (MatchResult CanFail ty1 body_fn1 cxt1)
- (MatchResult can_it_fail2 ty2 body_fn2 cxt2)
- = mkFailurePair ty1 `thenDs` \ (bind_fn, duplicatable_expr) ->
- let
- new_body_fn1 = \body1 -> Let (bind_fn body1) (body_fn1 duplicatable_expr)
- new_body_fn2 = \body2 -> new_body_fn1 (body_fn2 body2)
- in
- returnDs (MatchResult can_it_fail2 ty1 new_body_fn2 cxt1)
+ mk_alt fail (con, args, MatchResult _ body_fn)
+ = body_fn fail `thenDs` \ body ->
+ getUniquesDs `thenDs` \ us ->
+ let
+ (binds, real_args) = rebuildConArgs args (dataConStrictMarks con) us
+ in
+ returnDs (DataAlt con, real_args, mkDsLets binds body)
-combineMatchResults match_result1@(MatchResult CantFail ty body_fn1 cxt1)
- match_result2
- = returnDs match_result1
+ mk_default fail | exhaustive_case = []
+ | otherwise = [(DEFAULT, [], fail)]
-
--- The difference in combineGRHSMatchResults is that there is no
--- need to let-bind to avoid code duplication
-combineGRHSMatchResults :: MatchResult -> MatchResult -> DsM MatchResult
-combineGRHSMatchResults (MatchResult CanFail ty1 body_fn1 cxt1)
- (MatchResult can_it_fail ty2 body_fn2 cxt2)
- = returnDs (MatchResult can_it_fail ty1 (\ body -> body_fn1 (body_fn2 body)) cxt1)
-
-combineGRHSMatchResults match_result1 match_result2
- = -- Delegate to avoid duplication of code
- combineMatchResults match_result1 match_result2
+ un_mentioned_constructors
+ = mkUniqSet data_cons `minusUniqSet` mkUniqSet [ con | (con, _, _) <- match_alts]
+ exhaustive_case = isEmptyUniqSet un_mentioned_constructors
+
+ -- 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 =
+ dsLookupGlobalValue 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 ->
+ dsLookupGlobalValue 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, toInt i]
+ toInt i = mkConApp intDataCon [Lit $ MachInt i]
\end{code}
+
%************************************************************************
%* *
-\subsection[dsExprToAtom]{Take an expression and produce an atom}
+\subsection{Desugarer's versions of some Core functions}
%* *
%************************************************************************
\begin{code}
-dsExprToAtom :: DsCoreArg -- The argument expression
- -> (CoreArg -> DsM CoreExpr) -- Something taking the argument *atom*,
- -- and delivering an expression E
- -> DsM CoreExpr -- Either E or let x=arg-expr in E
-
-dsExprToAtom (UsageArg u) continue_with = continue_with (UsageArg u)
-dsExprToAtom (TyArg t) continue_with = continue_with (TyArg t)
-dsExprToAtom (LitArg l) continue_with = continue_with (LitArg l)
-
-dsExprToAtom (VarArg (Var v)) continue_with = continue_with (VarArg v)
-dsExprToAtom (VarArg (Lit v)) continue_with = continue_with (LitArg v)
+mkErrorAppDs :: Id -- The error function
+ -> Type -- Type to which it should be applied
+ -> String -- The error message string to pass
+ -> DsM CoreExpr
-dsExprToAtom (VarArg arg_expr) continue_with
- = let
- ty = coreExprType arg_expr
+mkErrorAppDs err_id ty msg
+ = getSrcLocDs `thenDs` \ src_loc ->
+ let
+ full_msg = showSDoc (hcat [ppr src_loc, text "|", text msg])
in
- newSysLocalDs ty `thenDs` \ arg_id ->
- continue_with (VarArg arg_id) `thenDs` \ body ->
- returnDs (
- if isUnboxedType ty
- then Case arg_expr (PrimAlts [] (BindDefault arg_id body))
- else Let (NonRec arg_id arg_expr) body
- )
-
-dsExprsToAtoms :: [DsCoreArg]
- -> ([CoreArg] -> DsM CoreExpr)
- -> DsM CoreExpr
-
-dsExprsToAtoms [] continue_with = continue_with []
-
-dsExprsToAtoms (arg:args) continue_with
- = dsExprToAtom arg $ \ arg_atom ->
- dsExprsToAtoms args $ \ arg_atoms ->
- continue_with (arg_atom:arg_atoms)
+ mkStringLit full_msg `thenDs` \ core_msg ->
+ returnDs (mkApps (Var err_id) [Type ty, core_msg])
\end{code}
-%************************************************************************
+
+*************************************************************
%* *
-\subsection{Desugarer's versions of some Core functions}
+\subsection{Making literals}
%* *
%************************************************************************
\begin{code}
-type DsCoreArg = GenCoreArg CoreExpr{-NB!-} TyVar UVar
+mkIntegerLit :: Integer -> DsM CoreExpr
+mkIntegerLit 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
+ = dsLookupGlobalValue plusIntegerName `thenDs` \ plus_id ->
+ dsLookupGlobalValue 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
-mkAppDs :: CoreExpr -> [DsCoreArg] -> DsM CoreExpr
-mkConDs :: Id -> [DsCoreArg] -> DsM CoreExpr
-mkPrimDs :: PrimOp -> [DsCoreArg] -> DsM CoreExpr
+ in
+ returnDs (horner tARGET_MAX_INT i)
-mkAppDs fun args
- = dsExprsToAtoms args $ \ atoms ->
- returnDs (mkGenApp fun atoms)
+mkSmallIntegerLit i = mkConApp smallIntegerDataCon [mkIntLit i]
-mkConDs con args
- = dsExprsToAtoms args $ \ atoms ->
- returnDs (Con con atoms)
+mkStringLit :: String -> DsM CoreExpr
+mkStringLit str = mkStringLitFS (_PK_ str)
-mkPrimDs op args
- = dsExprsToAtoms args $ \ atoms ->
- returnDs (Prim op atoms)
-\end{code}
+mkStringLitFS :: FAST_STRING -> DsM CoreExpr
+mkStringLitFS str
+ | _NULL_ str
+ = returnDs (mkNilExpr charTy)
-\begin{code}
-showForErr :: Outputable a => a -> String -- Boring but useful
-showForErr thing = ppShow 80 (ppr PprForUser thing)
+ | _LENGTH_ str == 1
+ = let
+ the_char = mkConApp charDataCon [mkLit (MachChar (_HEAD_INT_ str))]
+ in
+ returnDs (mkConsExpr charTy the_char (mkNilExpr charTy))
-mkErrorAppDs :: Id -- The error function
- -> Type -- Type to which it should be applied
- -> String -- The error message string to pass
- -> DsM CoreExpr
+ | all safeChar chars
+ = dsLookupGlobalValue unpackCStringName `thenDs` \ unpack_id ->
+ returnDs (App (Var unpack_id) (Lit (MachStr str)))
-mkErrorAppDs err_id ty msg
- = getSrcLocDs `thenDs` \ (file, line) ->
- let
- full_msg = file ++ "|" ++ line ++ "|" ++msg
- msg_lit = NoRepStr (_PK_ full_msg)
- in
- returnDs (mkApp (Var err_id) [] [ty] [LitArg msg_lit])
+ | otherwise
+ = dsLookupGlobalValue unpackCStringUtf8Name `thenDs` \ unpack_id ->
+ returnDs (App (Var unpack_id) (Lit (MachStr (_PK_ (stringToUtf8 chars)))))
+
+ where
+ chars = _UNPK_INT_ str
+ safeChar c = c >= 1 && c <= 0xFF
\end{code}
+
%************************************************************************
%* *
\subsection[mkSelectorBind]{Make a selector bind}
This is used in various places to do with lazy patterns.
For each binder $b$ in the pattern, we create a binding:
-
+\begin{verbatim}
b = case v of pat' -> b'
-
-where pat' is pat with each binder b cloned into b'.
+\end{verbatim}
+where @pat'@ is @pat@ with each binder @b@ cloned into @b'@.
ToDo: making these bindings should really depend on whether there's
much work to be done per binding. If the pattern is complex, it
expressions.
\begin{code}
-mkSelectorBinds :: [TyVar] -- Variables wrt which the pattern is polymorphic
- -> TypecheckedPat -- The pattern
- -> [(Id,Id)] -- Monomorphic and polymorphic binders for
- -- the pattern
- -> CoreExpr -- Expression to which the pattern is bound
+mkSelectorBinds :: TypecheckedPat -- The pattern
+ -> CoreExpr -- Expression to which the pattern is bound
-> DsM [(Id,CoreExpr)]
-mkSelectorBinds tyvars pat locals_and_globals val_expr
- = if is_simple_tuple_pat pat then
- mkTupleBind tyvars [] locals_and_globals val_expr
- else
- mkErrorAppDs iRREFUT_PAT_ERROR_ID res_ty "" `thenDs` \ error_msg ->
- matchSimply val_expr pat res_ty local_tuple error_msg `thenDs` \ tuple_expr ->
- mkTupleBind tyvars [] locals_and_globals tuple_expr
- where
- locals = [local | (local, _) <- locals_and_globals]
- local_tuple = mkTupleExpr locals
- res_ty = coreExprType local_tuple
-
- is_simple_tuple_pat (TuplePat ps) = all is_var_pat ps
- is_simple_tuple_pat other = False
-
- is_var_pat (VarPat v) = True
- is_var_pat other = False -- Even wild-card patterns aren't acceptable
-\end{code}
-
-We're about to match against some patterns. We want to make some
-@Ids@ to use as match variables. If a pattern has an @Id@ readily at
-hand, which should indeed be bound to the pattern as a whole, then use it;
-otherwise, make one up.
-\begin{code}
-selectMatchVars :: [TypecheckedPat] -> DsM [Id]
-selectMatchVars pats
- = mapDs var_from_pat_maybe pats
- where
- var_from_pat_maybe (VarPat var) = returnDs var
- var_from_pat_maybe (AsPat var pat) = returnDs var
- var_from_pat_maybe (LazyPat pat) = var_from_pat_maybe pat
- var_from_pat_maybe other_pat
- = newSysLocalDs (outPatType other_pat) -- OK, better make up one...
-\end{code}
-
-\begin{code}
-mkTupleBind :: [TyVar] -- Abstract wrt these...
- -> [DictVar] -- ... and these
-
- -> [(Id, Id)] -- Local, global pairs, equal in number
- -- to the size of the tuple. The types
- -- of the globals is the generalisation of
- -- the corresp local, wrt the tyvars and dicts
-
- -> CoreExpr -- Expr whose value is a tuple; the expression
- -- may mention the tyvars and dicts
+mkSelectorBinds (VarPat v) val_expr
+ = returnDs [(v, val_expr)]
- -> DsM [(Id, CoreExpr)] -- Bindings for the globals
-\end{code}
+mkSelectorBinds pat val_expr
+ | isSingleton binders || is_simple_pat pat
+ = newSysLocalDs (exprType val_expr) `thenDs` \ val_var ->
-The general call is
-\begin{verbatim}
- mkTupleBind tyvars dicts [(l1,g1), ..., (ln,gn)] tup_expr
-\end{verbatim}
-If $n=1$, the result is:
-\begin{verbatim}
- g1 = /\ tyvars -> \ dicts -> rhs
-\end{verbatim}
-Otherwise, the result is:
-\begin{verbatim}
- tup = /\ tyvars -> \ dicts -> tup_expr
- g1 = /\ tyvars -> \ dicts -> case (tup tyvars dicts) of
- (l1, ..., ln) -> l1
- ...etc...
-\end{verbatim}
-
-\begin{code}
-mkTupleBind tyvars dicts [(local,global)] tuple_expr
- = returnDs [(global, mkLam tyvars dicts tuple_expr)]
-\end{code}
+ -- 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
+ mkStringLit full_msg `thenDs` \ core_msg ->
+ mapDs (mk_bind val_var msg_var) binders `thenDs` \ binds ->
+ returnDs ( (val_var, val_expr) :
+ (msg_var, core_msg) :
+ binds )
-The general case:
-\begin{code}
-mkTupleBind tyvars dicts local_global_prs tuple_expr
- = --pprTrace "mkTupleBind:\n" (ppAboves [ppCat (map (pprId PprShowAll) locals), ppCat (map (pprId PprShowAll) globals), {-ppr PprDebug local_tuple, pprType PprDebug res_ty,-} ppr PprDebug tuple_expr]) $
-
- newSysLocalDs tuple_var_ty `thenDs` \ tuple_var ->
-
- zipWithDs (mk_selector (Var tuple_var))
- local_global_prs
- [(0::Int) .. (length local_global_prs - 1)]
- `thenDs` \ tup_selectors ->
- returnDs (
- (tuple_var, mkLam tyvars dicts tuple_expr)
- : tup_selectors
- )
+ | otherwise
+ = 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))
+ in
+ returnDs ( (tuple_var, tuple_expr) : map mk_tup_bind binders )
where
- locals, globals :: [Id]
- locals = [local | (local,global) <- local_global_prs]
- globals = [global | (local,global) <- local_global_prs]
-
- no_of_binders = length local_global_prs
- tyvar_tys = mkTyVarTys tyvars
-
- tuple_var_ty :: Type
- tuple_var_ty
- = mkForAllTys tyvars $
- mkRhoTy theta $
- applyTyCon (mkTupleTyCon no_of_binders)
- (map idType locals)
+ binders = collectTypedPatBinders 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 }
+ -- Remember, pat binds bv
+ = matchSimply (Var scrut_var) PatBindRhs pat
+ (Var bndr_var) error_expr `thenDs` \ rhs_expr ->
+ returnDs (bndr_var, rhs_expr)
where
- theta = mkTheta (map idType dicts)
-
- mk_selector :: CoreExpr -> (Id, Id) -> Int -> DsM (Id, CoreExpr)
-
- mk_selector tuple_var_expr (local, global) which_local
- = mapDs duplicateLocalDs locals{-the whole bunch-} `thenDs` \ binders ->
- let
- selected = binders !! which_local
- in
- returnDs (
- global,
- mkLam tyvars dicts (
- mkTupleSelector
- (mkValApp (mkTyApp tuple_var_expr tyvar_tys)
- (map VarArg dicts))
- binders
- selected)
- )
+ binder_ty = idType bndr_var
+ error_expr = mkApps (Var iRREFUT_PAT_ERROR_ID) [Type binder_ty, Var msg_var]
+
+ is_simple_pat (TuplePat ps 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_triv_pat (VarPat v) = True
+ is_triv_pat (WildPat _) = True
+ 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.
+
\begin{code}
mkTupleExpr :: [Id] -> CoreExpr
-mkTupleExpr [] = Con (mkTupleCon 0) []
+mkTupleExpr [] = Var unitDataConId
mkTupleExpr [id] = Var id
-mkTupleExpr ids = mkCon (mkTupleCon (length ids))
- [{-usages-}]
- (map idType ids)
- [ VarArg i | i <- ids ]
+mkTupleExpr ids = mkConApp (tupleCon Boxed (length ids))
+ (map (Type . idType) ids ++ [ Var i | i <- ids ])
\end{code}
just the identity.
\begin{code}
-mkTupleSelector :: CoreExpr -- Scrutinee
- -> [Id] -- The tuple args
- -> Id -- The selected one
+mkTupleSelector :: [Id] -- The tuple args
+ -> Id -- The selected one
+ -> Id -- A variable of the same type as the scrutinee
+ -> CoreExpr -- Scrutinee
-> CoreExpr
-mkTupleSelector expr [] the_var = panic "mkTupleSelector"
-
-mkTupleSelector expr [var] should_be_the_same_var
+mkTupleSelector [var] should_be_the_same_var scrut_var scrut
= ASSERT(var == should_be_the_same_var)
- expr
+ scrut
+
+mkTupleSelector vars the_var scrut_var scrut
+ = ASSERT( not (null vars) )
+ Case scrut scrut_var [(DataAlt (tupleCon Boxed (length vars)), vars, Var the_var)]
+\end{code}
+
-mkTupleSelector expr vars the_var
- = Case expr (AlgAlts [(mkTupleCon arity, vars, Var the_var)]
- NoDefault)
- where
- arity = length vars
+%************************************************************************
+%* *
+\subsection[mkFailurePair]{Code for pattern-matching and other failures}
+%* *
+%************************************************************************
+
+Call the constructor Ids when building explicit lists, so that they
+interact well with rules.
+
+\begin{code}
+mkNilExpr :: Type -> CoreExpr
+mkNilExpr ty = App (Var (dataConId nilDataCon)) (Type ty)
+
+mkConsExpr :: Type -> CoreExpr -> CoreExpr -> CoreExpr
+mkConsExpr ty hd tl = mkApps (Var (dataConId consDataCon)) [Type ty, hd, tl]
\end{code}
Then
\begin{itemize}
\item
-If the case can't fail, then there'll be no mention of fail.33, and the
+If the case can't fail, then there'll be no mention of @fail.33@, and the
simplifier will later discard it.
\item
\end{itemize}
There's a problem when the result of the case expression is of
-unboxed type. Then the type of fail.33 is unboxed too, and
+unboxed type. Then the type of @fail.33@ is unboxed too, and
there is every chance that someone will change the let into a case:
\begin{verbatim}
case error "Help" of
p4 -> ...
\end{verbatim}
-Now fail.33 is a function, so it can be let-bound.
+Now @fail.33@ is a function, so it can be let-bound.
\begin{code}
-mkFailurePair :: Type -- Result type of the whole case expression
- -> DsM (CoreExpr -> CoreBinding,
- -- Binds the newly-created fail variable
+mkFailurePair :: CoreExpr -- Result type of the whole case expression
+ -> DsM (CoreBind, -- Binds the newly-created fail variable
-- to either the expression or \ _ -> expression
CoreExpr) -- Either the fail variable, or fail variable
-- applied to unit tuple
-mkFailurePair ty
- | isUnboxedType ty
- = newFailLocalDs (mkFunTys [voidTy] ty) `thenDs` \ fail_fun_var ->
- newSysLocalDs voidTy `thenDs` \ fail_fun_arg ->
- returnDs (\ body ->
- NonRec fail_fun_var (Lam (ValBinder fail_fun_arg) body),
- App (Var fail_fun_var) (VarArg voidId))
+mkFailurePair expr
+ | isUnLiftedType ty
+ = newFailLocalDs (unitTy `mkFunTy` ty) `thenDs` \ fail_fun_var ->
+ newSysLocalDs unitTy `thenDs` \ fail_fun_arg ->
+ returnDs (NonRec fail_fun_var (Lam fail_fun_arg expr),
+ App (Var fail_fun_var) (Var unitDataConId))
| otherwise
= newFailLocalDs ty `thenDs` \ fail_var ->
- returnDs (\ body -> NonRec fail_var body, Var fail_var)
+ returnDs (NonRec fail_var expr, Var fail_var)
+ where
+ ty = exprType expr
\end{code}
-
projects / ghc-hetmet.git / blobdiff