2 % (c) The AQUA Project, Glasgow University, 1994-1998
4 \section[DsCCall]{Desugaring \tr{_ccall_}s and \tr{_casm_}s}
13 , can'tSeeDataConsPanic
17 #include "HsVersions.h"
24 import TcHsSyn ( maybeBoxedPrimType )
25 import CoreUtils ( exprType )
26 import Id ( Id, mkWildId )
27 import MkId ( mkCCallOpId )
28 import Maybes ( maybeToBool )
29 import PrelInfo ( packStringForCId )
30 import PrimOp ( PrimOp(..), CCall(..), CCallTarget(..) )
31 import DataCon ( DataCon, splitProductType_maybe )
33 import Type ( isUnLiftedType, splitAlgTyConApp_maybe, mkFunTys,
34 splitTyConApp_maybe, tyVarsOfType, mkForAllTys, Type
36 import PprType ( {- instance Outputable Type -} )
37 import TysPrim ( byteArrayPrimTy, realWorldStatePrimTy,
38 byteArrayPrimTyCon, mutableByteArrayPrimTyCon )
39 import TysWiredIn ( unitDataConId, stringTy,
41 mkUnboxedTupleTy, unboxedTupleCon
43 import Unique ( Unique )
44 import VarSet ( varSetElems )
48 Desugaring of @ccall@s consists of adding some state manipulation,
49 unboxing any boxed primitive arguments and boxing the result if
52 The state stuff just consists of adding in
53 @PrimIO (\ s -> case s of { S# s# -> ... })@ in an appropriate place.
55 The unboxing is straightforward, as all information needed to unbox is
56 available from the type. For each boxed-primitive argument, we
59 _ccall_ foo [ r, t1, ... tm ] e1 ... em
63 case e1 of { T1# x1# ->
65 case em of { Tm# xm# -> xm#
66 ccall# foo [ r, t1#, ... tm# ] x1# ... xm#
70 The reboxing of a @_ccall_@ result is a bit tricker: the types don't
71 contain information about the state-pairing functions so we have to
72 keep a list of \tr{(type, s-p-function)} pairs. We transform as
75 ccall# foo [ r, t1#, ... tm# ] e1# ... em#
79 \ s# -> case (ccall# foo [ r, t1#, ... tm# ] s# e1# ... em#) of
80 (StateAnd<r># result# state#) -> (R# result#, realWorld#)
84 dsCCall :: FAST_STRING -- C routine to invoke
85 -> [CoreExpr] -- Arguments (desugared)
86 -> Bool -- True <=> might cause Haskell GC
87 -> Bool -- True <=> really a "_casm_"
88 -> Type -- Type of the result (a boxed-prim IO type)
91 dsCCall lbl args may_gc is_asm result_ty
92 = newSysLocalDs realWorldStatePrimTy `thenDs` \ old_s ->
94 mapAndUnzipDs unboxArg args `thenDs` \ (unboxed_args, arg_wrappers) ->
95 boxResult result_ty `thenDs` \ (final_result_ty, res_wrapper) ->
96 getUniqueDs `thenDs` \ uniq ->
98 val_args = Var old_s : unboxed_args
99 the_ccall = CCall (StaticTarget lbl) is_asm may_gc cCallConv
100 the_prim_app = mkCCall uniq the_ccall val_args final_result_ty
101 the_body = foldr ($) (res_wrapper the_prim_app) arg_wrappers
103 returnDs (Lam old_s the_body)
105 mkCCall :: Unique -> CCall
106 -> [CoreExpr] -- Args
107 -> Type -- Result type
109 -- Construct the ccall. The only tricky bit is that the ccall Id should have
110 -- no free vars, so if any of the arg tys do we must give it a polymorphic type.
111 -- [I forget *why* it should have no free vars!]
113 -- mkCCall ... [s::StablePtr (a->b), x::Addr, c::Char]
115 -- Here we build a ccall thus
116 -- (ccallid::(forall a b. StablePtr (a -> b) -> Addr -> Char -> IO Addr))
118 mkCCall uniq the_ccall val_args res_ty
119 = mkApps (mkVarApps (Var the_ccall_id) tyvars) val_args
121 arg_tys = map exprType val_args
122 body_ty = (mkFunTys arg_tys res_ty)
123 tyvars = varSetElems (tyVarsOfType body_ty)
124 ty = mkForAllTys tyvars body_ty
125 the_ccall_id = mkCCallOpId uniq the_ccall ty
129 unboxArg :: CoreExpr -- The supplied argument
130 -> DsM (CoreExpr, -- To pass as the actual argument
131 CoreExpr -> CoreExpr -- Wrapper to unbox the arg
136 -- ADR Question: can this ever be used? None of the PrimTypes are
137 -- instances of the CCallable class.
140 -- Oh yes they are, I've just added them :-) Having _ccall_ and _casm_
141 -- that accept unboxed arguments is a Good Thing if you have a stub generator
142 -- which generates the boiler-plate box-unbox code for you, i.e., it may help
143 -- us nuke this very module :-)
145 | isUnLiftedType arg_ty
146 = returnDs (arg, \body -> body)
150 -- ToDo (ADR): - allow synonyms of Strings too?
151 = newSysLocalDs byteArrayPrimTy `thenDs` \ prim_arg ->
152 returnDs (Var prim_arg,
153 \body -> Case (App (Var packStringForCId) arg)
154 prim_arg [(DEFAULT,[],body)])
156 -- Byte-arrays, both mutable and otherwise; hack warning
158 length data_con_arg_tys == 3 &&
159 maybeToBool maybe_arg3_tycon &&
160 (arg3_tycon == byteArrayPrimTyCon ||
161 arg3_tycon == mutableByteArrayPrimTyCon)
162 -- and, of course, it is an instance of CCallable
163 = newSysLocalDs arg_ty `thenDs` \ case_bndr ->
164 newSysLocalsDs data_con_arg_tys `thenDs` \ vars@[l_var, r_var, arr_cts_var] ->
165 returnDs (Var arr_cts_var,
166 \ body -> Case arg case_bndr [(DataAlt data_con,vars,body)]
169 -- Data types with a single constructor, which has a single, primitive-typed arg
170 | maybeToBool maybe_boxed_prim_arg_ty
171 = newSysLocalDs arg_ty `thenDs` \ case_bndr ->
172 newSysLocalDs the_prim_arg_ty `thenDs` \ prim_arg ->
173 returnDs (Var prim_arg,
174 \ body -> Case arg case_bndr [(DataAlt box_data_con,[prim_arg],body)]
178 = getSrcLocDs `thenDs` \ l ->
179 pprPanic "unboxArg: " (ppr l <+> ppr arg_ty)
181 arg_ty = exprType arg
183 maybe_boxed_prim_arg_ty = maybeBoxedPrimType arg_ty
184 (Just (box_data_con, the_prim_arg_ty)) = maybe_boxed_prim_arg_ty
186 maybe_product_type = splitProductType_maybe arg_ty
187 is_product_type = maybeToBool maybe_product_type
188 Just (tycon, _, data_con, data_con_arg_tys) = maybe_product_type
189 (data_con_arg_ty1 : data_con_arg_ty2 : data_con_arg_ty3 :_)
192 maybe_arg3_tycon = splitTyConApp_maybe data_con_arg_ty3
193 Just (arg3_tycon,_) = maybe_arg3_tycon
195 can'tSeeDataConsPanic thing ty
197 "ERROR: Can't see the data constructor(s) for _ccall_/_casm_/foreign declaration"
198 (hcat [ text thing, text "; type: ", ppr ty
199 , text "(try compiling with -fno-prune-tydecls ..)\n"])
204 boxResult :: Type -- Type of desired result
205 -> DsM (Type, -- Type of the result of the ccall itself
206 CoreExpr -> CoreExpr) -- Wrapper for the ccall
209 -- Data types with a single nullary constructor
210 | (maybeToBool maybe_product_type) && -- Data type
211 (null data_con_arg_tys)
213 newSysLocalDs realWorldStatePrimTy `thenDs` \ prim_state_id ->
215 wrapUnboxedValue result_ty `thenDs` \ (state_and_prim_datacon,
216 state_and_prim_ty, prim_result_id, the_result) ->
218 [TyArg result_ty, VarArg (Var prim_state_id), VarArg the_result]
219 `thenDs` \ the_pair ->
222 the_pair = mkConApp unboxedPairDataCon
223 [Type realWorldStatePrimTy, Type result_ty,
226 the_alt = (DataAlt (unboxedTupleCon 1), [prim_state_id], the_pair)
227 scrut_ty = mkUnboxedTupleTy 1 [realWorldStatePrimTy]
229 returnDs (scrut_ty, \prim_app -> Case prim_app (mkWildId scrut_ty) [the_alt]
232 -- Data types with a single constructor, which has a single, primitive-typed arg
233 | (maybeToBool maybe_product_type) && -- Data type
234 not (null data_con_arg_tys) && null other_args_tys && -- Just one arg
235 isUnLiftedType the_prim_result_ty -- of primitive type
237 newSysLocalDs realWorldStatePrimTy `thenDs` \ prim_state_id ->
238 newSysLocalDs the_prim_result_ty `thenDs` \ prim_result_id ->
239 newSysLocalDs ccall_res_type `thenDs` \ case_bndr ->
242 the_result = mkConApp data_con (map Type tycon_arg_tys ++ [Var prim_result_id])
243 the_pair = mkConApp unboxedPairDataCon
244 [Type realWorldStatePrimTy, Type result_ty,
245 Var prim_state_id, the_result]
246 the_alt = (DataAlt unboxedPairDataCon, [prim_state_id, prim_result_id], the_pair)
248 returnDs (ccall_res_type, \prim_app -> Case prim_app case_bndr [the_alt]
252 = pprPanic "boxResult: " (ppr result_ty)
254 maybe_product_type = splitProductType_maybe result_ty
255 Just (tycon, tycon_arg_tys, data_con, data_con_arg_tys) = maybe_product_type
256 (the_prim_result_ty : other_args_tys) = data_con_arg_tys
258 ccall_res_type = mkUnboxedTupleTy 2 [realWorldStatePrimTy, the_prim_result_ty]
260 -- wrap up an unboxed value.
261 wrapUnboxedValue :: Type -> DsM (Type, Id, CoreExpr)
263 | (maybeToBool maybe_product_type) && -- Data type
264 not (null data_con_arg_tys) && null other_args_tys && -- Just one arg
265 isUnLiftedType the_prim_result_ty -- of primitive type
267 newSysLocalDs the_prim_result_ty `thenDs` \ prim_result_id ->
269 the_result = mkConApp data_con (map Type tycon_arg_tys ++ [Var prim_result_id])
271 returnDs (ccall_res_type, prim_result_id, the_result)
273 -- Data types with a single nullary constructor
274 | (maybeToBool maybe_product_type) && -- Data type
275 (null data_con_arg_tys)
278 scrut_ty = mkUnboxedTupleTy 1 [realWorldStatePrimTy]
280 returnDs (scrut_ty, unitDataConId, Var unitDataConId)
283 = pprPanic "boxResult: " (ppr ty)
285 maybe_product_type = splitProductType_maybe ty
286 Just (tycon, tycon_arg_tys, data_con, data_con_arg_tys) = maybe_product_type
287 (the_prim_result_ty : other_args_tys) = data_con_arg_tys
288 ccall_res_type = mkUnboxedTupleTy 2 [realWorldStatePrimTy, the_prim_result_ty]