2 % (c) The AQUA Project, Glasgow University, 1994-1998
4 \section[DsCCall]{Desugaring \tr{_ccall_}s and \tr{_casm_}s}
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,
36 import PrimOp ( PrimOp(..) )
37 import TysPrim ( realWorldStatePrimTy, intPrimTy,
38 byteArrayPrimTyCon, mutableByteArrayPrimTyCon
40 import TyCon ( TyCon, tyConDataCons )
41 import TysWiredIn ( unitDataConId,
42 unboxedSingletonDataCon, unboxedPairDataCon,
43 unboxedSingletonTyCon, unboxedPairTyCon,
44 trueDataCon, falseDataCon,
45 trueDataConId, falseDataConId
47 import Literal ( mkMachInt )
48 import CStrings ( CLabelString )
49 import PrelNames ( Unique, hasKey, ioTyConKey, boolTyConKey, unitTyConKey,
50 int8TyConKey, int16TyConKey, int32TyConKey,
51 word8TyConKey, word16TyConKey, word32TyConKey
53 import VarSet ( varSetElems )
54 import Constants ( wORD_SIZE)
58 Desugaring of @ccall@s consists of adding some state manipulation,
59 unboxing any boxed primitive arguments and boxing the result if
62 The state stuff just consists of adding in
63 @PrimIO (\ s -> case s of { S# s# -> ... })@ in an appropriate place.
65 The unboxing is straightforward, as all information needed to unbox is
66 available from the type. For each boxed-primitive argument, we
69 _ccall_ foo [ r, t1, ... tm ] e1 ... em
73 case e1 of { T1# x1# ->
75 case em of { Tm# xm# -> xm#
76 ccall# foo [ r, t1#, ... tm# ] x1# ... xm#
80 The reboxing of a @_ccall_@ result is a bit tricker: the types don't
81 contain information about the state-pairing functions so we have to
82 keep a list of \tr{(type, s-p-function)} pairs. We transform as
85 ccall# foo [ r, t1#, ... tm# ] e1# ... em#
89 \ s# -> case (ccall# foo [ r, t1#, ... tm# ] s# e1# ... em#) of
90 (StateAnd<r># result# state#) -> (R# result#, realWorld#)
94 dsCCall :: CLabelString -- C routine to invoke
95 -> [CoreExpr] -- Arguments (desugared)
96 -> Safety -- Safety of the call
97 -> Bool -- True <=> really a "_casm_"
98 -> Type -- Type of the result: IO t
101 dsCCall lbl args may_gc is_asm result_ty
102 = mapAndUnzipDs unboxArg args `thenDs` \ (unboxed_args, arg_wrappers) ->
103 boxResult [] result_ty `thenDs` \ (ccall_result_ty, res_wrapper) ->
104 getUniqueDs `thenDs` \ uniq ->
106 target | is_asm = CasmTarget lbl
107 | otherwise = StaticTarget lbl
108 the_fcall = CCall (CCallSpec target CCallConv may_gc)
109 the_prim_app = mkFCall uniq the_fcall unboxed_args ccall_result_ty
111 returnDs (foldr ($) (res_wrapper the_prim_app) arg_wrappers)
113 mkFCall :: Unique -> ForeignCall
114 -> [CoreExpr] -- Args
115 -> Type -- Result type
117 -- Construct the ccall. The only tricky bit is that the ccall Id should have
118 -- no free vars, so if any of the arg tys do we must give it a polymorphic type.
119 -- [I forget *why* it should have no free vars!]
121 -- mkCCall ... [s::StablePtr (a->b), x::Addr, c::Char]
123 -- Here we build a ccall thus
124 -- (ccallid::(forall a b. StablePtr (a -> b) -> Addr -> Char -> IO Addr))
126 mkFCall uniq the_fcall val_args res_ty
127 = mkApps (mkVarApps (Var the_fcall_id) tyvars) val_args
129 arg_tys = map exprType val_args
130 body_ty = (mkFunTys arg_tys res_ty)
131 tyvars = varSetElems (tyVarsOfType body_ty)
132 ty = mkForAllTys tyvars body_ty
133 the_fcall_id = mkFCallId uniq the_fcall ty
137 unboxArg :: CoreExpr -- The supplied argument
138 -> DsM (CoreExpr, -- To pass as the actual argument
139 CoreExpr -> CoreExpr -- Wrapper to unbox the arg
141 -- Example: if the arg is e::Int, unboxArg will return
142 -- (x#::Int#, \W. case x of I# x# -> W)
143 -- where W is a CoreExpr that probably mentions x#
146 -- Primtive types: nothing to unbox
147 | isPrimitiveType arg_ty
148 = returnDs (arg, \body -> body)
150 -- Recursive newtypes
151 | Just rep_ty <- splitNewType_maybe arg_ty
152 = unboxArg (mkCoerce2 rep_ty arg_ty arg)
155 | Just (tc,_) <- splitTyConApp_maybe arg_ty,
156 tc `hasKey` boolTyConKey
157 = newSysLocalDs intPrimTy `thenDs` \ prim_arg ->
158 returnDs (Var prim_arg,
159 \ body -> Case (Case arg (mkWildId arg_ty)
160 [(DataAlt falseDataCon,[],mkIntLit 0),
161 (DataAlt trueDataCon, [],mkIntLit 1)])
165 -- Data types with a single constructor, which has a single, primitive-typed arg
166 -- This deals with Int, Float etc
167 | is_product_type && data_con_arity == 1
168 = ASSERT(isUnLiftedType data_con_arg_ty1 ) -- Typechecker ensures this
169 newSysLocalDs arg_ty `thenDs` \ case_bndr ->
170 newSysLocalDs data_con_arg_ty1 `thenDs` \ prim_arg ->
171 returnDs (Var prim_arg,
172 \ body -> Case arg case_bndr [(DataAlt data_con,[prim_arg],body)]
175 -- Byte-arrays, both mutable and otherwise; hack warning
176 -- We're looking for values of type ByteArray, MutableByteArray
177 -- data ByteArray ix = ByteArray ix ix ByteArray#
178 -- data MutableByteArray s ix = MutableByteArray ix ix (MutableByteArray# s)
180 data_con_arity == 3 &&
181 maybeToBool maybe_arg3_tycon &&
182 (arg3_tycon == byteArrayPrimTyCon ||
183 arg3_tycon == mutableByteArrayPrimTyCon)
184 -- and, of course, it is an instance of CCallable
185 = newSysLocalDs arg_ty `thenDs` \ case_bndr ->
186 newSysLocalsDs data_con_arg_tys `thenDs` \ vars@[l_var, r_var, arr_cts_var] ->
187 returnDs (Var arr_cts_var,
188 \ body -> Case arg case_bndr [(DataAlt data_con,vars,body)]
192 = getSrcLocDs `thenDs` \ l ->
193 pprPanic "unboxArg: " (ppr l <+> ppr arg_ty)
195 arg_ty = exprType arg
196 maybe_product_type = splitProductType_maybe arg_ty
197 is_product_type = maybeToBool maybe_product_type
198 Just (_, _, data_con, data_con_arg_tys) = maybe_product_type
199 data_con_arity = dataConSourceArity data_con
200 (data_con_arg_ty1 : _) = data_con_arg_tys
202 (_ : _ : data_con_arg_ty3 : _) = data_con_arg_tys
203 maybe_arg3_tycon = splitTyConApp_maybe data_con_arg_ty3
204 Just (arg3_tycon,_) = maybe_arg3_tycon
209 boxResult :: [Id] -> Type -> DsM (Type, CoreExpr -> CoreExpr)
211 -- Takes the result of the user-level ccall:
213 -- or maybe just t for an side-effect-free call
214 -- Returns a wrapper for the primitive ccall itself, along with the
215 -- type of the result of the primitive ccall. This result type
216 -- will be of the form
217 -- State# RealWorld -> (# State# RealWorld, t' #)
218 -- where t' is the unwrapped form of t. If t is simply (), then
219 -- the result type will be
220 -- State# RealWorld -> (# State# RealWorld #)
222 boxResult arg_ids result_ty
223 = case tcSplitTyConApp_maybe result_ty of
224 -- This split absolutely has to be a tcSplit, because we must
225 -- see the IO type; and it's a newtype which is transparent to splitTyConApp.
227 -- The result is IO t, so wrap the result in an IO constructor
228 Just (io_tycon, [io_res_ty]) | io_tycon `hasKey` ioTyConKey
229 -> mk_alt return_result
230 (resultWrapper io_res_ty) `thenDs` \ (ccall_res_ty, the_alt) ->
231 newSysLocalDs realWorldStatePrimTy `thenDs` \ state_id ->
233 io_data_con = head (tyConDataCons io_tycon)
235 mkApps (Var (dataConWrapId io_data_con))
238 Case (App the_call (Var state_id))
239 (mkWildId ccall_res_ty)
243 returnDs (realWorldStatePrimTy `mkFunTy` ccall_res_ty, wrap)
245 return_result state ans = mkConApp unboxedPairDataCon
246 [Type realWorldStatePrimTy, Type io_res_ty,
249 -- It isn't, so do unsafePerformIO
250 -- It's not conveniently available, so we inline it
251 other -> mk_alt return_result
252 (resultWrapper result_ty) `thenDs` \ (ccall_res_ty, the_alt) ->
254 wrap = \ the_call -> Case (App the_call (Var realWorldPrimId))
255 (mkWildId ccall_res_ty)
258 returnDs (realWorldStatePrimTy `mkFunTy` ccall_res_ty, wrap)
260 return_result state ans = ans
262 mk_alt return_result (Nothing, wrap_result)
263 = -- The ccall returns ()
264 newSysLocalDs realWorldStatePrimTy `thenDs` \ state_id ->
266 the_rhs = return_result (Var state_id)
267 (wrap_result (panic "boxResult"))
269 ccall_res_ty = mkTyConApp unboxedSingletonTyCon [realWorldStatePrimTy]
270 the_alt = (DataAlt unboxedSingletonDataCon, [state_id], the_rhs)
272 returnDs (ccall_res_ty, the_alt)
274 mk_alt return_result (Just prim_res_ty, wrap_result)
275 = -- The ccall returns a non-() value
276 newSysLocalDs prim_res_ty `thenDs` \ result_id ->
277 newSysLocalDs realWorldStatePrimTy `thenDs` \ state_id ->
279 the_rhs = return_result (Var state_id)
280 (wrap_result (Var result_id))
282 ccall_res_ty = mkTyConApp unboxedPairTyCon [realWorldStatePrimTy, prim_res_ty]
283 the_alt = (DataAlt unboxedPairDataCon, [state_id, result_id], the_rhs)
285 returnDs (ccall_res_ty, the_alt)
288 resultWrapper :: Type
289 -> (Maybe Type, -- Type of the expected result, if any
290 CoreExpr -> CoreExpr) -- Wrapper for the result
291 resultWrapper result_ty
292 -- Base case 1: primitive types
293 | isPrimitiveType result_ty
294 = (Just result_ty, \e -> e)
296 -- Base case 2: the unit type ()
297 | Just (tc,_) <- maybe_tc_app, tc `hasKey` unitTyConKey
298 = (Nothing, \e -> Var unitDataConId)
300 -- Base case 3: the boolean type
301 | Just (tc,_) <- maybe_tc_app, tc `hasKey` boolTyConKey
302 = (Just intPrimTy, \e -> Case e (mkWildId intPrimTy)
303 [(DEFAULT ,[],Var trueDataConId ),
304 (LitAlt (mkMachInt 0),[],Var falseDataConId)])
306 -- Recursive newtypes
307 | Just rep_ty <- splitNewType_maybe result_ty
309 (maybe_ty, wrapper) = resultWrapper rep_ty
311 (maybe_ty, \e -> mkCoerce2 result_ty rep_ty (wrapper e))
313 -- The type might contain foralls (eg. for dummy type arguments,
314 -- referring to 'Ptr a' is legal).
315 | Just (tyvar, rest) <- splitForAllTy_maybe result_ty
317 (maybe_ty, wrapper) = resultWrapper rest
319 (maybe_ty, \e -> Lam tyvar (wrapper e))
321 -- Data types with a single constructor, which has a single arg
322 | Just (tycon, tycon_arg_tys, data_con, data_con_arg_tys) <- splitProductType_maybe result_ty,
323 dataConSourceArity data_con == 1
325 (maybe_ty, wrapper) = resultWrapper unwrapped_res_ty
326 (unwrapped_res_ty : _) = data_con_arg_tys
327 narrow_wrapper = maybeNarrow tycon
329 (maybe_ty, \e -> mkApps (Var (dataConWrapId data_con))
330 (map Type tycon_arg_tys ++ [wrapper (narrow_wrapper e)]))
333 = pprPanic "resultWrapper" (ppr result_ty)
335 maybe_tc_app = splitTyConApp_maybe result_ty
337 -- When the result of a foreign call is smaller than the word size, we
338 -- need to sign- or zero-extend the result up to the word size. The C
339 -- standard appears to say that this is the responsibility of the
340 -- caller, not the callee.
342 maybeNarrow :: TyCon -> (CoreExpr -> CoreExpr)
344 | tycon `hasKey` int8TyConKey = \e -> App (Var (mkPrimOpId Narrow8IntOp)) e
345 | tycon `hasKey` int16TyConKey = \e -> App (Var (mkPrimOpId Narrow16IntOp)) e
346 | tycon `hasKey` int32TyConKey
347 && wORD_SIZE > 4 = \e -> App (Var (mkPrimOpId Narrow32IntOp)) e
349 | tycon `hasKey` word8TyConKey = \e -> App (Var (mkPrimOpId Narrow8WordOp)) e
350 | tycon `hasKey` word16TyConKey = \e -> App (Var (mkPrimOpId Narrow16WordOp)) e
351 | tycon `hasKey` word32TyConKey
352 && wORD_SIZE > 4 = \e -> App (Var (mkPrimOpId Narrow32WordOp)) e