2 % (c) The AQUA Project, Glasgow University, 1994-1998
4 \section[DsCCall]{Desugaring C calls}
15 #include "HsVersions.h"
21 import CoreUtils ( exprType, mkCoerce2 )
22 import Id ( Id, mkWildId )
23 import MkId ( mkFCallId, realWorldPrimId, mkPrimOpId )
24 import Maybes ( maybeToBool )
25 import ForeignCall ( ForeignCall(..), CCallSpec(..), CCallTarget(..), Safety, CCallConv(..) )
26 import DataCon ( splitProductType_maybe, dataConSourceArity, dataConWrapId )
27 import ForeignCall ( ForeignCall, CCallTarget(..) )
29 import TcType ( tcSplitTyConApp_maybe )
30 import Type ( Type, isUnLiftedType, mkFunTys, mkFunTy,
31 tyVarsOfType, mkForAllTys, mkTyConApp,
32 isPrimitiveType, splitTyConApp_maybe,
33 splitNewType_maybe, splitForAllTy_maybe,
37 import PrimOp ( PrimOp(..) )
38 import TysPrim ( realWorldStatePrimTy, intPrimTy,
39 byteArrayPrimTyCon, mutableByteArrayPrimTyCon,
42 import TyCon ( TyCon, tyConDataCons, tyConName )
43 import TysWiredIn ( unitDataConId,
44 unboxedSingletonDataCon, unboxedPairDataCon,
45 unboxedSingletonTyCon, unboxedPairTyCon,
46 trueDataCon, falseDataCon,
47 trueDataConId, falseDataConId,
51 import BasicTypes ( Boxity(..) )
52 import Literal ( mkMachInt )
53 import CStrings ( CLabelString )
54 import PrelNames ( Unique, hasKey, ioTyConKey, boolTyConKey, unitTyConKey,
55 int8TyConKey, int16TyConKey, int32TyConKey,
56 word8TyConKey, word16TyConKey, word32TyConKey
58 , marshalStringName, unmarshalStringName
59 , marshalObjectName, unmarshalObjectName
62 import VarSet ( varSetElems )
63 import Constants ( wORD_SIZE)
67 Desugaring of @ccall@s consists of adding some state manipulation,
68 unboxing any boxed primitive arguments and boxing the result if
71 The state stuff just consists of adding in
72 @PrimIO (\ s -> case s of { S# s# -> ... })@ in an appropriate place.
74 The unboxing is straightforward, as all information needed to unbox is
75 available from the type. For each boxed-primitive argument, we
78 _ccall_ foo [ r, t1, ... tm ] e1 ... em
82 case e1 of { T1# x1# ->
84 case em of { Tm# xm# -> xm#
85 ccall# foo [ r, t1#, ... tm# ] x1# ... xm#
89 The reboxing of a @_ccall_@ result is a bit tricker: the types don't
90 contain information about the state-pairing functions so we have to
91 keep a list of \tr{(type, s-p-function)} pairs. We transform as
94 ccall# foo [ r, t1#, ... tm# ] e1# ... em#
98 \ s# -> case (ccall# foo [ r, t1#, ... tm# ] s# e1# ... em#) of
99 (StateAnd<r># result# state#) -> (R# result#, realWorld#)
103 dsCCall :: CLabelString -- C routine to invoke
104 -> [CoreExpr] -- Arguments (desugared)
105 -> Safety -- Safety of the call
106 -> Type -- Type of the result: IO t
109 dsCCall lbl args may_gc result_ty
110 = mapAndUnzipDs unboxArg args `thenDs` \ (unboxed_args, arg_wrappers) ->
111 boxResult [] id Nothing result_ty `thenDs` \ (ccall_result_ty, res_wrapper) ->
112 getUniqueDs `thenDs` \ uniq ->
114 target = StaticTarget lbl
115 the_fcall = CCall (CCallSpec target CCallConv may_gc)
116 the_prim_app = mkFCall uniq the_fcall unboxed_args ccall_result_ty
118 returnDs (foldr ($) (res_wrapper the_prim_app) arg_wrappers)
120 mkFCall :: Unique -> ForeignCall
121 -> [CoreExpr] -- Args
122 -> Type -- Result type
124 -- Construct the ccall. The only tricky bit is that the ccall Id should have
125 -- no free vars, so if any of the arg tys do we must give it a polymorphic type.
126 -- [I forget *why* it should have no free vars!]
128 -- mkCCall ... [s::StablePtr (a->b), x::Addr, c::Char]
130 -- Here we build a ccall thus
131 -- (ccallid::(forall a b. StablePtr (a -> b) -> Addr -> Char -> IO Addr))
133 mkFCall uniq the_fcall val_args res_ty
134 = mkApps (mkVarApps (Var the_fcall_id) tyvars) val_args
136 arg_tys = map exprType val_args
137 body_ty = (mkFunTys arg_tys res_ty)
138 tyvars = varSetElems (tyVarsOfType body_ty)
139 ty = mkForAllTys tyvars body_ty
140 the_fcall_id = mkFCallId uniq the_fcall ty
144 unboxArg :: CoreExpr -- The supplied argument
145 -> DsM (CoreExpr, -- To pass as the actual argument
146 CoreExpr -> CoreExpr -- Wrapper to unbox the arg
148 -- Example: if the arg is e::Int, unboxArg will return
149 -- (x#::Int#, \W. case x of I# x# -> W)
150 -- where W is a CoreExpr that probably mentions x#
153 -- Primtive types: nothing to unbox
154 | isPrimitiveType arg_ty
155 = returnDs (arg, \body -> body)
157 -- Recursive newtypes
158 | Just rep_ty <- splitNewType_maybe arg_ty
159 = unboxArg (mkCoerce2 rep_ty arg_ty arg)
162 | Just (tc,_) <- splitTyConApp_maybe arg_ty,
163 tc `hasKey` boolTyConKey
164 = newSysLocalDs intPrimTy `thenDs` \ prim_arg ->
165 returnDs (Var prim_arg,
166 \ body -> Case (Case arg (mkWildId arg_ty)
167 [(DataAlt falseDataCon,[],mkIntLit 0),
168 (DataAlt trueDataCon, [],mkIntLit 1)])
172 -- Data types with a single constructor, which has a single, primitive-typed arg
173 -- This deals with Int, Float etc; also Ptr, ForeignPtr
174 | is_product_type && data_con_arity == 1
175 = ASSERT(isUnLiftedType data_con_arg_ty1 ) -- Typechecker ensures this
176 newSysLocalDs arg_ty `thenDs` \ case_bndr ->
177 newSysLocalDs data_con_arg_ty1 `thenDs` \ prim_arg ->
178 returnDs (Var prim_arg,
179 \ body -> Case arg case_bndr [(DataAlt data_con,[prim_arg],body)]
182 -- Byte-arrays, both mutable and otherwise; hack warning
183 -- We're looking for values of type ByteArray, MutableByteArray
184 -- data ByteArray ix = ByteArray ix ix ByteArray#
185 -- data MutableByteArray s ix = MutableByteArray ix ix (MutableByteArray# s)
187 data_con_arity == 3 &&
188 maybeToBool maybe_arg3_tycon &&
189 (arg3_tycon == byteArrayPrimTyCon ||
190 arg3_tycon == mutableByteArrayPrimTyCon)
191 -- and, of course, it is an instance of CCallable
192 = newSysLocalDs arg_ty `thenDs` \ case_bndr ->
193 newSysLocalsDs data_con_arg_tys `thenDs` \ vars@[l_var, r_var, arr_cts_var] ->
194 returnDs (Var arr_cts_var,
195 \ body -> Case arg case_bndr [(DataAlt data_con,vars,body)]
198 | Just (tc, [arg_ty]) <- splitTyConApp_maybe arg_ty,
200 Just (cc,[]) <- splitTyConApp_maybe arg_ty,
202 -- String; dotnet only
203 = dsLookupGlobalId marshalStringName `thenDs` \ unpack_id ->
204 newSysLocalDs addrPrimTy `thenDs` \ prim_string ->
205 returnDs (Var prim_string,
208 io_ty = exprType body
209 (Just (_,[io_arg])) = tcSplitTyConApp_maybe io_ty
211 mkApps (Var unpack_id)
214 , Lam prim_string body
216 | Just (tc, [arg_ty]) <- splitTyConApp_maybe arg_ty,
217 tyConName tc == objectTyConName
218 -- Object; dotnet only
219 = dsLookupGlobalId marshalObjectName `thenDs` \ unpack_id ->
220 newSysLocalDs addrPrimTy `thenDs` \ prim_obj ->
221 returnDs (Var prim_obj,
224 io_ty = exprType body
225 (Just (_,[io_arg])) = tcSplitTyConApp_maybe io_ty
227 mkApps (Var unpack_id)
234 = getSrcLocDs `thenDs` \ l ->
235 pprPanic "unboxArg: " (ppr l <+> ppr arg_ty)
237 arg_ty = exprType arg
238 maybe_product_type = splitProductType_maybe arg_ty
239 is_product_type = maybeToBool maybe_product_type
240 Just (_, _, data_con, data_con_arg_tys) = maybe_product_type
241 data_con_arity = dataConSourceArity data_con
242 (data_con_arg_ty1 : _) = data_con_arg_tys
244 (_ : _ : data_con_arg_ty3 : _) = data_con_arg_tys
245 maybe_arg3_tycon = splitTyConApp_maybe data_con_arg_ty3
246 Just (arg3_tycon,_) = maybe_arg3_tycon
252 -> ((Maybe Type, CoreExpr -> CoreExpr) -> (Maybe Type, CoreExpr -> CoreExpr))
255 -> DsM (Type, CoreExpr -> CoreExpr)
257 -- Takes the result of the user-level ccall:
259 -- or maybe just t for an side-effect-free call
260 -- Returns a wrapper for the primitive ccall itself, along with the
261 -- type of the result of the primitive ccall. This result type
262 -- will be of the form
263 -- State# RealWorld -> (# State# RealWorld, t' #)
264 -- where t' is the unwrapped form of t. If t is simply (), then
265 -- the result type will be
266 -- State# RealWorld -> (# State# RealWorld #)
268 boxResult arg_ids augment mbTopCon result_ty
269 = case tcSplitTyConApp_maybe result_ty of
270 -- This split absolutely has to be a tcSplit, because we must
271 -- see the IO type; and it's a newtype which is transparent to splitTyConApp.
273 -- The result is IO t, so wrap the result in an IO constructor
274 Just (io_tycon, [io_res_ty]) | io_tycon `hasKey` ioTyConKey
275 -> resultWrapper io_res_ty `thenDs` \ res ->
276 let aug_res = augment res
280 | isUnboxedTupleType ty ->
281 let (Just (_, ls)) = splitTyConApp_maybe ty in tail ls
284 mk_alt (return_result extra_result_tys) aug_res
285 `thenDs` \ (ccall_res_ty, the_alt) ->
286 newSysLocalDs realWorldStatePrimTy `thenDs` \ state_id ->
288 io_data_con = head (tyConDataCons io_tycon)
291 Nothing -> dataConWrapId io_data_con
297 Case (App the_call (Var state_id))
298 (mkWildId ccall_res_ty)
302 returnDs (realWorldStatePrimTy `mkFunTy` ccall_res_ty, wrap)
304 return_result ts state anss
305 = mkConApp (tupleCon Unboxed (2 + length ts))
306 (Type realWorldStatePrimTy : Type io_res_ty : map Type ts ++
308 -- It isn't, so do unsafePerformIO
309 -- It's not conveniently available, so we inline it
310 other -> resultWrapper result_ty `thenDs` \ res ->
311 mk_alt return_result (augment res) `thenDs` \ (ccall_res_ty, the_alt) ->
313 wrap = \ the_call -> Case (App the_call (Var realWorldPrimId))
314 (mkWildId ccall_res_ty)
317 returnDs (realWorldStatePrimTy `mkFunTy` ccall_res_ty, wrap)
319 return_result state [ans] = ans
320 return_result _ _ = panic "return_result: expected single result"
322 mk_alt return_result (Nothing, wrap_result)
323 = -- The ccall returns ()
324 newSysLocalDs realWorldStatePrimTy `thenDs` \ state_id ->
326 the_rhs = return_result (Var state_id)
327 [wrap_result (panic "boxResult")]
329 ccall_res_ty = mkTyConApp unboxedSingletonTyCon [realWorldStatePrimTy]
330 the_alt = (DataAlt unboxedSingletonDataCon, [state_id], the_rhs)
332 returnDs (ccall_res_ty, the_alt)
334 mk_alt return_result (Just prim_res_ty, wrap_result)
335 -- The ccall returns a non-() value
336 | isUnboxedTupleType prim_res_ty
338 (Just (_, ls@(prim_res_ty1:extras))) = splitTyConApp_maybe prim_res_ty
339 arity = 1 + length ls
341 mapDs newSysLocalDs ls `thenDs` \ args_ids@(result_id:as) ->
342 newSysLocalDs realWorldStatePrimTy `thenDs` \ state_id ->
344 the_rhs = return_result (Var state_id)
345 (wrap_result (Var result_id) : map Var as)
346 ccall_res_ty = mkTyConApp (tupleTyCon Unboxed arity)
347 (realWorldStatePrimTy : ls)
348 the_alt = ( DataAlt (tupleCon Unboxed arity)
349 , (state_id : args_ids)
353 returnDs (ccall_res_ty, the_alt)
356 newSysLocalDs prim_res_ty `thenDs` \ result_id ->
357 newSysLocalDs realWorldStatePrimTy `thenDs` \ state_id ->
359 the_rhs = return_result (Var state_id)
360 [wrap_result (Var result_id)]
362 ccall_res_ty = mkTyConApp unboxedPairTyCon [realWorldStatePrimTy, prim_res_ty]
363 the_alt = (DataAlt unboxedPairDataCon, [state_id, result_id], the_rhs)
365 returnDs (ccall_res_ty, the_alt)
368 resultWrapper :: Type
369 -> DsM (Maybe Type, -- Type of the expected result, if any
370 CoreExpr -> CoreExpr) -- Wrapper for the result
371 resultWrapper result_ty
372 -- Base case 1: primitive types
373 | isPrimitiveType result_ty
374 = returnDs (Just result_ty, \e -> e)
376 -- Base case 2: the unit type ()
377 | Just (tc,_) <- maybe_tc_app, tc `hasKey` unitTyConKey
378 = returnDs (Nothing, \e -> Var unitDataConId)
380 -- Base case 3: the boolean type
381 | Just (tc,_) <- maybe_tc_app, tc `hasKey` boolTyConKey
383 (Just intPrimTy, \e -> Case e (mkWildId intPrimTy)
384 [(DEFAULT ,[],Var trueDataConId ),
385 (LitAlt (mkMachInt 0),[],Var falseDataConId)])
387 -- Recursive newtypes
388 | Just rep_ty <- splitNewType_maybe result_ty
389 = resultWrapper rep_ty `thenDs` \ (maybe_ty, wrapper) ->
390 returnDs (maybe_ty, \e -> mkCoerce2 result_ty rep_ty (wrapper e))
392 -- The type might contain foralls (eg. for dummy type arguments,
393 -- referring to 'Ptr a' is legal).
394 | Just (tyvar, rest) <- splitForAllTy_maybe result_ty
395 = resultWrapper rest `thenDs` \ (maybe_ty, wrapper) ->
396 returnDs (maybe_ty, \e -> Lam tyvar (wrapper e))
398 -- Data types with a single constructor, which has a single arg
399 -- This includes types like Ptr and ForeignPtr
400 | Just (tycon, tycon_arg_tys, data_con, data_con_arg_tys) <- splitProductType_maybe result_ty,
401 dataConSourceArity data_con == 1
403 (unwrapped_res_ty : _) = data_con_arg_tys
404 narrow_wrapper = maybeNarrow tycon
406 resultWrapper unwrapped_res_ty `thenDs` \ (maybe_ty, wrapper) ->
408 (maybe_ty, \e -> mkApps (Var (dataConWrapId data_con))
409 (map Type tycon_arg_tys ++ [wrapper (narrow_wrapper e)]))
411 -- Strings; 'dotnet' only.
412 | Just (tc, [arg_ty]) <- maybe_tc_app, tc == listTyCon,
413 Just (cc,[]) <- splitTyConApp_maybe arg_ty, cc == charTyCon
414 = dsLookupGlobalId unmarshalStringName `thenDs` \ pack_id ->
415 returnDs (Just addrPrimTy,
416 \ e -> App (Var pack_id) e)
418 -- Objects; 'dotnet' only.
419 | Just (tc, [arg_ty]) <- maybe_tc_app,
420 tyConName tc == objectTyConName
421 = dsLookupGlobalId unmarshalObjectName `thenDs` \ pack_id ->
422 returnDs (Just addrPrimTy,
423 \ e -> App (Var pack_id) e)
426 = pprPanic "resultWrapper" (ppr result_ty)
428 maybe_tc_app = splitTyConApp_maybe result_ty
430 -- When the result of a foreign call is smaller than the word size, we
431 -- need to sign- or zero-extend the result up to the word size. The C
432 -- standard appears to say that this is the responsibility of the
433 -- caller, not the callee.
435 maybeNarrow :: TyCon -> (CoreExpr -> CoreExpr)
437 | tycon `hasKey` int8TyConKey = \e -> App (Var (mkPrimOpId Narrow8IntOp)) e
438 | tycon `hasKey` int16TyConKey = \e -> App (Var (mkPrimOpId Narrow16IntOp)) e
439 | tycon `hasKey` int32TyConKey
440 && wORD_SIZE > 4 = \e -> App (Var (mkPrimOpId Narrow32IntOp)) e
442 | tycon `hasKey` word8TyConKey = \e -> App (Var (mkPrimOpId Narrow8WordOp)) e
443 | tycon `hasKey` word16TyConKey = \e -> App (Var (mkPrimOpId Narrow16WordOp)) e
444 | tycon `hasKey` word32TyConKey
445 && wORD_SIZE > 4 = \e -> App (Var (mkPrimOpId Narrow32WordOp)) e