--- /dev/null
+%
+% (c) The AQUA Project, Glasgow University, 1994-1998
+%
+\section[DsCCall]{Desugaring C calls}
+
+\begin{code}
+module DsCCall
+ ( dsCCall
+ , mkFCall
+ , unboxArg
+ , boxResult
+ , resultWrapper
+ ) where
+
+#include "HsVersions.h"
+
+
+import CoreSyn
+
+import DsMonad
+
+import CoreUtils ( exprType, coreAltType, mkCoerce2 )
+import Id ( Id, mkWildId )
+import MkId ( mkFCallId, realWorldPrimId, mkPrimOpId )
+import Maybes ( maybeToBool )
+import ForeignCall ( ForeignCall(..), CCallSpec(..), CCallTarget(..), Safety,
+ CCallConv(..), CLabelString )
+import DataCon ( splitProductType_maybe, dataConSourceArity, dataConWrapId )
+
+import TcType ( tcSplitTyConApp_maybe )
+import Type ( Type, isUnLiftedType, mkFunTys, mkFunTy,
+ tyVarsOfType, mkForAllTys, mkTyConApp,
+ isPrimitiveType, splitTyConApp_maybe,
+ splitRecNewType_maybe, splitForAllTy_maybe,
+ isUnboxedTupleType
+ )
+
+import PrimOp ( PrimOp(..) )
+import TysPrim ( realWorldStatePrimTy, intPrimTy,
+ byteArrayPrimTyCon, mutableByteArrayPrimTyCon,
+ addrPrimTy
+ )
+import TyCon ( TyCon, tyConDataCons, tyConName )
+import TysWiredIn ( unitDataConId,
+ unboxedSingletonDataCon, unboxedPairDataCon,
+ unboxedSingletonTyCon, unboxedPairTyCon,
+ trueDataCon, falseDataCon,
+ trueDataConId, falseDataConId,
+ listTyCon, charTyCon, boolTy,
+ tupleTyCon, tupleCon
+ )
+import BasicTypes ( Boxity(..) )
+import Literal ( mkMachInt )
+import PrelNames ( Unique, hasKey, ioTyConKey, boolTyConKey, unitTyConKey,
+ int8TyConKey, int16TyConKey, int32TyConKey,
+ word8TyConKey, word16TyConKey, word32TyConKey
+ -- dotnet interop
+ , marshalStringName, unmarshalStringName
+ , marshalObjectName, unmarshalObjectName
+ , objectTyConName
+ )
+import VarSet ( varSetElems )
+import Constants ( wORD_SIZE)
+import Outputable
+
+#ifdef DEBUG
+import TypeRep
+#endif
+
+\end{code}
+
+Desugaring of @ccall@s consists of adding some state manipulation,
+unboxing any boxed primitive arguments and boxing the result if
+desired.
+
+The state stuff just consists of adding in
+@PrimIO (\ s -> case s of { S# s# -> ... })@ in an appropriate place.
+
+The unboxing is straightforward, as all information needed to unbox is
+available from the type. For each boxed-primitive argument, we
+transform:
+\begin{verbatim}
+ _ccall_ foo [ r, t1, ... tm ] e1 ... em
+ |
+ |
+ V
+ case e1 of { T1# x1# ->
+ ...
+ case em of { Tm# xm# -> xm#
+ ccall# foo [ r, t1#, ... tm# ] x1# ... xm#
+ } ... }
+\end{verbatim}
+
+The reboxing of a @_ccall_@ result is a bit tricker: the types don't
+contain information about the state-pairing functions so we have to
+keep a list of \tr{(type, s-p-function)} pairs. We transform as
+follows:
+\begin{verbatim}
+ ccall# foo [ r, t1#, ... tm# ] e1# ... em#
+ |
+ |
+ V
+ \ s# -> case (ccall# foo [ r, t1#, ... tm# ] s# e1# ... em#) of
+ (StateAnd<r># result# state#) -> (R# result#, realWorld#)
+\end{verbatim}
+
+\begin{code}
+dsCCall :: CLabelString -- C routine to invoke
+ -> [CoreExpr] -- Arguments (desugared)
+ -> Safety -- Safety of the call
+ -> Type -- Type of the result: IO t
+ -> DsM CoreExpr
+
+dsCCall lbl args may_gc result_ty
+ = mapAndUnzipDs unboxArg args `thenDs` \ (unboxed_args, arg_wrappers) ->
+ boxResult id Nothing result_ty `thenDs` \ (ccall_result_ty, res_wrapper) ->
+ newUnique `thenDs` \ uniq ->
+ let
+ target = StaticTarget lbl
+ the_fcall = CCall (CCallSpec target CCallConv may_gc)
+ the_prim_app = mkFCall uniq the_fcall unboxed_args ccall_result_ty
+ in
+ returnDs (foldr ($) (res_wrapper the_prim_app) arg_wrappers)
+
+mkFCall :: Unique -> ForeignCall
+ -> [CoreExpr] -- Args
+ -> Type -- Result type
+ -> CoreExpr
+-- Construct the ccall. The only tricky bit is that the ccall Id should have
+-- no free vars, so if any of the arg tys do we must give it a polymorphic type.
+-- [I forget *why* it should have no free vars!]
+-- For example:
+-- mkCCall ... [s::StablePtr (a->b), x::Addr, c::Char]
+--
+-- Here we build a ccall thus
+-- (ccallid::(forall a b. StablePtr (a -> b) -> Addr -> Char -> IO Addr))
+-- a b s x c
+mkFCall uniq the_fcall val_args res_ty
+ = mkApps (mkVarApps (Var the_fcall_id) tyvars) val_args
+ where
+ arg_tys = map exprType val_args
+ body_ty = (mkFunTys arg_tys res_ty)
+ tyvars = varSetElems (tyVarsOfType body_ty)
+ ty = mkForAllTys tyvars body_ty
+ the_fcall_id = mkFCallId uniq the_fcall ty
+\end{code}
+
+\begin{code}
+unboxArg :: CoreExpr -- The supplied argument
+ -> DsM (CoreExpr, -- To pass as the actual argument
+ CoreExpr -> CoreExpr -- Wrapper to unbox the arg
+ )
+-- Example: if the arg is e::Int, unboxArg will return
+-- (x#::Int#, \W. case x of I# x# -> W)
+-- where W is a CoreExpr that probably mentions x#
+
+unboxArg arg
+ -- Primtive types: nothing to unbox
+ | isPrimitiveType arg_ty
+ = returnDs (arg, \body -> body)
+
+ -- Recursive newtypes
+ | Just rep_ty <- splitRecNewType_maybe arg_ty
+ = unboxArg (mkCoerce2 rep_ty arg_ty arg)
+
+ -- Booleans
+ | Just (tc,_) <- splitTyConApp_maybe arg_ty,
+ tc `hasKey` boolTyConKey
+ = newSysLocalDs intPrimTy `thenDs` \ prim_arg ->
+ returnDs (Var prim_arg,
+ \ body -> Case (Case arg (mkWildId arg_ty) intPrimTy
+ [(DataAlt falseDataCon,[],mkIntLit 0),
+ (DataAlt trueDataCon, [],mkIntLit 1)])
+ -- In increasing tag order!
+ prim_arg
+ (exprType body)
+ [(DEFAULT,[],body)])
+
+ -- Data types with a single constructor, which has a single, primitive-typed arg
+ -- This deals with Int, Float etc; also Ptr, ForeignPtr
+ | is_product_type && data_con_arity == 1
+ = ASSERT2(isUnLiftedType data_con_arg_ty1, pprType arg_ty)
+ -- Typechecker ensures this
+ newSysLocalDs arg_ty `thenDs` \ case_bndr ->
+ newSysLocalDs data_con_arg_ty1 `thenDs` \ prim_arg ->
+ returnDs (Var prim_arg,
+ \ body -> Case arg case_bndr (exprType body) [(DataAlt data_con,[prim_arg],body)]
+ )
+
+ -- Byte-arrays, both mutable and otherwise; hack warning
+ -- We're looking for values of type ByteArray, MutableByteArray
+ -- data ByteArray ix = ByteArray ix ix ByteArray#
+ -- data MutableByteArray s ix = MutableByteArray ix ix (MutableByteArray# s)
+ | is_product_type &&
+ data_con_arity == 3 &&
+ maybeToBool maybe_arg3_tycon &&
+ (arg3_tycon == byteArrayPrimTyCon ||
+ arg3_tycon == mutableByteArrayPrimTyCon)
+ = newSysLocalDs arg_ty `thenDs` \ case_bndr ->
+ newSysLocalsDs data_con_arg_tys `thenDs` \ vars@[l_var, r_var, arr_cts_var] ->
+ returnDs (Var arr_cts_var,
+ \ body -> Case arg case_bndr (exprType body) [(DataAlt data_con,vars,body)]
+
+ )
+
+ | Just (tc, [arg_ty]) <- splitTyConApp_maybe arg_ty,
+ tc == listTyCon,
+ Just (cc,[]) <- splitTyConApp_maybe arg_ty,
+ cc == charTyCon
+ -- String; dotnet only
+ = dsLookupGlobalId marshalStringName `thenDs` \ unpack_id ->
+ newSysLocalDs addrPrimTy `thenDs` \ prim_string ->
+ returnDs (Var prim_string,
+ \ body ->
+ let
+ io_ty = exprType body
+ (Just (_,[io_arg])) = tcSplitTyConApp_maybe io_ty
+ in
+ mkApps (Var unpack_id)
+ [ Type io_arg
+ , arg
+ , Lam prim_string body
+ ])
+ | Just (tc, [arg_ty]) <- splitTyConApp_maybe arg_ty,
+ tyConName tc == objectTyConName
+ -- Object; dotnet only
+ = dsLookupGlobalId marshalObjectName `thenDs` \ unpack_id ->
+ newSysLocalDs addrPrimTy `thenDs` \ prim_obj ->
+ returnDs (Var prim_obj,
+ \ body ->
+ let
+ io_ty = exprType body
+ (Just (_,[io_arg])) = tcSplitTyConApp_maybe io_ty
+ in
+ mkApps (Var unpack_id)
+ [ Type io_arg
+ , arg
+ , Lam prim_obj body
+ ])
+
+ | otherwise
+ = getSrcSpanDs `thenDs` \ l ->
+ pprPanic "unboxArg: " (ppr l <+> ppr arg_ty)
+ where
+ arg_ty = exprType arg
+ maybe_product_type = splitProductType_maybe arg_ty
+ is_product_type = maybeToBool maybe_product_type
+ Just (_, _, data_con, data_con_arg_tys) = maybe_product_type
+ data_con_arity = dataConSourceArity data_con
+ (data_con_arg_ty1 : _) = data_con_arg_tys
+
+ (_ : _ : data_con_arg_ty3 : _) = data_con_arg_tys
+ maybe_arg3_tycon = splitTyConApp_maybe data_con_arg_ty3
+ Just (arg3_tycon,_) = maybe_arg3_tycon
+\end{code}
+
+
+\begin{code}
+boxResult :: ((Maybe Type, CoreExpr -> CoreExpr) -> (Maybe Type, CoreExpr -> CoreExpr))
+ -> Maybe Id
+ -> Type
+ -> DsM (Type, CoreExpr -> CoreExpr)
+
+-- Takes the result of the user-level ccall:
+-- either (IO t),
+-- or maybe just t for an side-effect-free call
+-- Returns a wrapper for the primitive ccall itself, along with the
+-- type of the result of the primitive ccall. This result type
+-- will be of the form
+-- State# RealWorld -> (# State# RealWorld, t' #)
+-- where t' is the unwrapped form of t. If t is simply (), then
+-- the result type will be
+-- State# RealWorld -> (# State# RealWorld #)
+
+boxResult augment mbTopCon result_ty
+ = case tcSplitTyConApp_maybe result_ty of
+ -- This split absolutely has to be a tcSplit, because we must
+ -- see the IO type; and it's a newtype which is transparent to splitTyConApp.
+
+ -- The result is IO t, so wrap the result in an IO constructor
+ Just (io_tycon, [io_res_ty]) | io_tycon `hasKey` ioTyConKey
+ -> resultWrapper io_res_ty `thenDs` \ res ->
+ let aug_res = augment res
+ extra_result_tys =
+ case aug_res of
+ (Just ty,_)
+ | isUnboxedTupleType ty ->
+ let (Just (_, ls)) = splitTyConApp_maybe ty in tail ls
+ _ -> []
+ in
+ mk_alt (return_result extra_result_tys) aug_res
+ `thenDs` \ (ccall_res_ty, the_alt) ->
+ newSysLocalDs realWorldStatePrimTy `thenDs` \ state_id ->
+ let
+ io_data_con = head (tyConDataCons io_tycon)
+ toIOCon =
+ case mbTopCon of
+ Nothing -> dataConWrapId io_data_con
+ Just x -> x
+ wrap = \ the_call ->
+ mkApps (Var toIOCon)
+ [ Type io_res_ty,
+ Lam state_id $
+ Case (App the_call (Var state_id))
+ (mkWildId ccall_res_ty)
+ (coreAltType the_alt)
+ [the_alt]
+ ]
+ in
+ returnDs (realWorldStatePrimTy `mkFunTy` ccall_res_ty, wrap)
+ where
+ return_result ts state anss
+ = mkConApp (tupleCon Unboxed (2 + length ts))
+ (Type realWorldStatePrimTy : Type io_res_ty : map Type ts ++
+ state : anss)
+ -- It isn't, so do unsafePerformIO
+ -- It's not conveniently available, so we inline it
+ other -> resultWrapper result_ty `thenDs` \ res ->
+ mk_alt return_result (augment res) `thenDs` \ (ccall_res_ty, the_alt) ->
+ let
+ wrap = \ the_call -> Case (App the_call (Var realWorldPrimId))
+ (mkWildId ccall_res_ty)
+ (coreAltType the_alt)
+ [the_alt]
+ in
+ returnDs (realWorldStatePrimTy `mkFunTy` ccall_res_ty, wrap)
+ where
+ return_result state [ans] = ans
+ return_result _ _ = panic "return_result: expected single result"
+ where
+ mk_alt return_result (Nothing, wrap_result)
+ = -- The ccall returns ()
+ newSysLocalDs realWorldStatePrimTy `thenDs` \ state_id ->
+ let
+ the_rhs = return_result (Var state_id)
+ [wrap_result (panic "boxResult")]
+
+ ccall_res_ty = mkTyConApp unboxedSingletonTyCon [realWorldStatePrimTy]
+ the_alt = (DataAlt unboxedSingletonDataCon, [state_id], the_rhs)
+ in
+ returnDs (ccall_res_ty, the_alt)
+
+ mk_alt return_result (Just prim_res_ty, wrap_result)
+ -- The ccall returns a non-() value
+ | isUnboxedTupleType prim_res_ty
+ = let
+ Just (_, ls) = splitTyConApp_maybe prim_res_ty
+ arity = 1 + length ls
+ in
+ mappM newSysLocalDs ls `thenDs` \ args_ids@(result_id:as) ->
+ newSysLocalDs realWorldStatePrimTy `thenDs` \ state_id ->
+ let
+ the_rhs = return_result (Var state_id)
+ (wrap_result (Var result_id) : map Var as)
+ ccall_res_ty = mkTyConApp (tupleTyCon Unboxed arity)
+ (realWorldStatePrimTy : ls)
+ the_alt = ( DataAlt (tupleCon Unboxed arity)
+ , (state_id : args_ids)
+ , the_rhs
+ )
+ in
+ returnDs (ccall_res_ty, the_alt)
+ | otherwise
+ = newSysLocalDs prim_res_ty `thenDs` \ result_id ->
+ newSysLocalDs realWorldStatePrimTy `thenDs` \ state_id ->
+ let
+ the_rhs = return_result (Var state_id)
+ [wrap_result (Var result_id)]
+
+ ccall_res_ty = mkTyConApp unboxedPairTyCon [realWorldStatePrimTy, prim_res_ty]
+ the_alt = (DataAlt unboxedPairDataCon, [state_id, result_id], the_rhs)
+ in
+ returnDs (ccall_res_ty, the_alt)
+
+
+resultWrapper :: Type
+ -> DsM (Maybe Type, -- Type of the expected result, if any
+ CoreExpr -> CoreExpr) -- Wrapper for the result
+resultWrapper result_ty
+ -- Base case 1: primitive types
+ | isPrimitiveType result_ty
+ = returnDs (Just result_ty, \e -> e)
+
+ -- Base case 2: the unit type ()
+ | Just (tc,_) <- maybe_tc_app, tc `hasKey` unitTyConKey
+ = returnDs (Nothing, \e -> Var unitDataConId)
+
+ -- Base case 3: the boolean type
+ | Just (tc,_) <- maybe_tc_app, tc `hasKey` boolTyConKey
+ = returnDs
+ (Just intPrimTy, \e -> Case e (mkWildId intPrimTy)
+ boolTy
+ [(DEFAULT ,[],Var trueDataConId ),
+ (LitAlt (mkMachInt 0),[],Var falseDataConId)])
+
+ -- Recursive newtypes
+ | Just rep_ty <- splitRecNewType_maybe result_ty
+ = resultWrapper rep_ty `thenDs` \ (maybe_ty, wrapper) ->
+ returnDs (maybe_ty, \e -> mkCoerce2 result_ty rep_ty (wrapper e))
+
+ -- The type might contain foralls (eg. for dummy type arguments,
+ -- referring to 'Ptr a' is legal).
+ | Just (tyvar, rest) <- splitForAllTy_maybe result_ty
+ = resultWrapper rest `thenDs` \ (maybe_ty, wrapper) ->
+ returnDs (maybe_ty, \e -> Lam tyvar (wrapper e))
+
+ -- Data types with a single constructor, which has a single arg
+ -- This includes types like Ptr and ForeignPtr
+ | Just (tycon, tycon_arg_tys, data_con, data_con_arg_tys) <- splitProductType_maybe result_ty,
+ dataConSourceArity data_con == 1
+ = let
+ (unwrapped_res_ty : _) = data_con_arg_tys
+ narrow_wrapper = maybeNarrow tycon
+ in
+ resultWrapper unwrapped_res_ty `thenDs` \ (maybe_ty, wrapper) ->
+ returnDs
+ (maybe_ty, \e -> mkApps (Var (dataConWrapId data_con))
+ (map Type tycon_arg_tys ++ [wrapper (narrow_wrapper e)]))
+
+ -- Strings; 'dotnet' only.
+ | Just (tc, [arg_ty]) <- maybe_tc_app, tc == listTyCon,
+ Just (cc,[]) <- splitTyConApp_maybe arg_ty, cc == charTyCon
+ = dsLookupGlobalId unmarshalStringName `thenDs` \ pack_id ->
+ returnDs (Just addrPrimTy,
+ \ e -> App (Var pack_id) e)
+
+ -- Objects; 'dotnet' only.
+ | Just (tc, [arg_ty]) <- maybe_tc_app,
+ tyConName tc == objectTyConName
+ = dsLookupGlobalId unmarshalObjectName `thenDs` \ pack_id ->
+ returnDs (Just addrPrimTy,
+ \ e -> App (Var pack_id) e)
+
+ | otherwise
+ = pprPanic "resultWrapper" (ppr result_ty)
+ where
+ maybe_tc_app = splitTyConApp_maybe result_ty
+
+-- When the result of a foreign call is smaller than the word size, we
+-- need to sign- or zero-extend the result up to the word size. The C
+-- standard appears to say that this is the responsibility of the
+-- caller, not the callee.
+
+maybeNarrow :: TyCon -> (CoreExpr -> CoreExpr)
+maybeNarrow tycon
+ | tycon `hasKey` int8TyConKey = \e -> App (Var (mkPrimOpId Narrow8IntOp)) e
+ | tycon `hasKey` int16TyConKey = \e -> App (Var (mkPrimOpId Narrow16IntOp)) e
+ | tycon `hasKey` int32TyConKey
+ && wORD_SIZE > 4 = \e -> App (Var (mkPrimOpId Narrow32IntOp)) e
+
+ | tycon `hasKey` word8TyConKey = \e -> App (Var (mkPrimOpId Narrow8WordOp)) e
+ | tycon `hasKey` word16TyConKey = \e -> App (Var (mkPrimOpId Narrow16WordOp)) e
+ | tycon `hasKey` word32TyConKey
+ && wORD_SIZE > 4 = \e -> App (Var (mkPrimOpId Narrow32WordOp)) e
+ | otherwise = id
+\end{code}
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