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 TysPrim ( byteArrayPrimTy, realWorldStatePrimTy,
37 byteArrayPrimTyCon, mutableByteArrayPrimTyCon )
38 import TysWiredIn ( unitDataConId, stringTy,
40 mkUnboxedTupleTy, unboxedTupleCon
42 import Unique ( Unique )
43 import VarSet ( varSetElems )
47 Desugaring of @ccall@s consists of adding some state manipulation,
48 unboxing any boxed primitive arguments and boxing the result if
51 The state stuff just consists of adding in
52 @PrimIO (\ s -> case s of { S# s# -> ... })@ in an appropriate place.
54 The unboxing is straightforward, as all information needed to unbox is
55 available from the type. For each boxed-primitive argument, we
58 _ccall_ foo [ r, t1, ... tm ] e1 ... em
62 case e1 of { T1# x1# ->
64 case em of { Tm# xm# -> xm#
65 ccall# foo [ r, t1#, ... tm# ] x1# ... xm#
69 The reboxing of a @_ccall_@ result is a bit tricker: the types don't
70 contain information about the state-pairing functions so we have to
71 keep a list of \tr{(type, s-p-function)} pairs. We transform as
74 ccall# foo [ r, t1#, ... tm# ] e1# ... em#
78 \ s# -> case (ccall# foo [ r, t1#, ... tm# ] s# e1# ... em#) of
79 (StateAnd<r># result# state#) -> (R# result#, realWorld#)
83 dsCCall :: FAST_STRING -- C routine to invoke
84 -> [CoreExpr] -- Arguments (desugared)
85 -> Bool -- True <=> might cause Haskell GC
86 -> Bool -- True <=> really a "_casm_"
87 -> Type -- Type of the result (a boxed-prim IO type)
90 dsCCall lbl args may_gc is_asm result_ty
91 = newSysLocalDs realWorldStatePrimTy `thenDs` \ old_s ->
93 mapAndUnzipDs unboxArg args `thenDs` \ (unboxed_args, arg_wrappers) ->
94 boxResult result_ty `thenDs` \ (final_result_ty, res_wrapper) ->
95 getUniqueDs `thenDs` \ uniq ->
97 val_args = Var old_s : unboxed_args
98 the_ccall = CCall (StaticTarget lbl) is_asm may_gc cCallConv
99 the_prim_app = mkCCall uniq the_ccall val_args final_result_ty
100 the_body = foldr ($) (res_wrapper the_prim_app) arg_wrappers
102 returnDs (Lam old_s the_body)
104 mkCCall :: Unique -> CCall
105 -> [CoreExpr] -- Args
106 -> Type -- Result type
108 -- Construct the ccall. The only tricky bit is that the ccall Id should have
109 -- no free vars, so if any of the arg tys do we must give it a polymorphic type.
110 -- [I forget *why* it should have no free vars!]
112 -- mkCCall ... [s::StablePtr (a->b), x::Addr, c::Char]
114 -- Here we build a ccall thus
115 -- (ccallid::(forall a b. StablePtr (a -> b) -> Addr -> Char -> IO Addr))
117 mkCCall uniq the_ccall val_args res_ty
118 = mkApps (mkVarApps (Var the_ccall_id) tyvars) val_args
120 arg_tys = map exprType val_args
121 body_ty = (mkFunTys arg_tys res_ty)
122 tyvars = varSetElems (tyVarsOfType body_ty)
123 ty = mkForAllTys tyvars body_ty
124 the_ccall_id = mkCCallOpId uniq the_ccall ty
128 unboxArg :: CoreExpr -- The supplied argument
129 -> DsM (CoreExpr, -- To pass as the actual argument
130 CoreExpr -> CoreExpr -- Wrapper to unbox the arg
135 -- ADR Question: can this ever be used? None of the PrimTypes are
136 -- instances of the CCallable class.
139 -- Oh yes they are, I've just added them :-) Having _ccall_ and _casm_
140 -- that accept unboxed arguments is a Good Thing if you have a stub generator
141 -- which generates the boiler-plate box-unbox code for you, i.e., it may help
142 -- us nuke this very module :-)
144 | isUnLiftedType arg_ty
145 = returnDs (arg, \body -> body)
149 -- ToDo (ADR): - allow synonyms of Strings too?
150 = newSysLocalDs byteArrayPrimTy `thenDs` \ prim_arg ->
151 returnDs (Var prim_arg,
152 \body -> Case (App (Var packStringForCId) arg)
153 prim_arg [(DEFAULT,[],body)])
155 -- Byte-arrays, both mutable and otherwise; hack warning
157 length data_con_arg_tys == 3 &&
158 maybeToBool maybe_arg3_tycon &&
159 (arg3_tycon == byteArrayPrimTyCon ||
160 arg3_tycon == mutableByteArrayPrimTyCon)
161 -- and, of course, it is an instance of CCallable
162 = newSysLocalDs arg_ty `thenDs` \ case_bndr ->
163 newSysLocalsDs data_con_arg_tys `thenDs` \ vars@[l_var, r_var, arr_cts_var] ->
164 returnDs (Var arr_cts_var,
165 \ body -> Case arg case_bndr [(DataAlt data_con,vars,body)]
168 -- Data types with a single constructor, which has a single, primitive-typed arg
169 | maybeToBool maybe_boxed_prim_arg_ty
170 = newSysLocalDs arg_ty `thenDs` \ case_bndr ->
171 newSysLocalDs the_prim_arg_ty `thenDs` \ prim_arg ->
172 returnDs (Var prim_arg,
173 \ body -> Case arg case_bndr [(DataAlt box_data_con,[prim_arg],body)]
177 = getSrcLocDs `thenDs` \ l ->
178 pprPanic "unboxArg: " (ppr l <+> ppr arg_ty)
180 arg_ty = exprType arg
182 maybe_boxed_prim_arg_ty = maybeBoxedPrimType arg_ty
183 (Just (box_data_con, the_prim_arg_ty)) = maybe_boxed_prim_arg_ty
185 maybe_product_type = splitProductType_maybe arg_ty
186 is_product_type = maybeToBool maybe_product_type
187 Just (tycon, _, data_con, data_con_arg_tys) = maybe_product_type
188 (data_con_arg_ty1 : data_con_arg_ty2 : data_con_arg_ty3 :_)
191 maybe_arg3_tycon = splitTyConApp_maybe data_con_arg_ty3
192 Just (arg3_tycon,_) = maybe_arg3_tycon
194 can'tSeeDataConsPanic thing ty
196 "ERROR: Can't see the data constructor(s) for _ccall_/_casm_/foreign declaration"
197 (hcat [ text thing, text "; type: ", ppr ty
198 , text "(try compiling with -fno-prune-tydecls ..)\n"])
203 boxResult :: Type -- Type of desired result
204 -> DsM (Type, -- Type of the result of the ccall itself
205 CoreExpr -> CoreExpr) -- Wrapper for the ccall
208 -- Data types with a single nullary constructor
209 | (maybeToBool maybe_product_type) && -- Data type
210 (null data_con_arg_tys)
212 newSysLocalDs realWorldStatePrimTy `thenDs` \ prim_state_id ->
214 wrapUnboxedValue result_ty `thenDs` \ (state_and_prim_datacon,
215 state_and_prim_ty, prim_result_id, the_result) ->
217 [TyArg result_ty, VarArg (Var prim_state_id), VarArg the_result]
218 `thenDs` \ the_pair ->
221 the_pair = mkConApp unboxedPairDataCon
222 [Type realWorldStatePrimTy, Type result_ty,
225 the_alt = (DataAlt (unboxedTupleCon 1), [prim_state_id], the_pair)
226 scrut_ty = mkUnboxedTupleTy 1 [realWorldStatePrimTy]
228 returnDs (scrut_ty, \prim_app -> Case prim_app (mkWildId scrut_ty) [the_alt]
231 -- Data types with a single constructor, which has a single, primitive-typed arg
232 | (maybeToBool maybe_product_type) && -- Data type
233 not (null data_con_arg_tys) && null other_args_tys && -- Just one arg
234 isUnLiftedType the_prim_result_ty -- of primitive type
236 newSysLocalDs realWorldStatePrimTy `thenDs` \ prim_state_id ->
237 newSysLocalDs the_prim_result_ty `thenDs` \ prim_result_id ->
238 newSysLocalDs ccall_res_type `thenDs` \ case_bndr ->
241 the_result = mkConApp data_con (map Type tycon_arg_tys ++ [Var prim_result_id])
242 the_pair = mkConApp unboxedPairDataCon
243 [Type realWorldStatePrimTy, Type result_ty,
244 Var prim_state_id, the_result]
245 the_alt = (DataAlt unboxedPairDataCon, [prim_state_id, prim_result_id], the_pair)
247 returnDs (ccall_res_type, \prim_app -> Case prim_app case_bndr [the_alt]
251 = pprPanic "boxResult: " (ppr result_ty)
253 maybe_product_type = splitProductType_maybe result_ty
254 Just (tycon, tycon_arg_tys, data_con, data_con_arg_tys) = maybe_product_type
255 (the_prim_result_ty : other_args_tys) = data_con_arg_tys
257 ccall_res_type = mkUnboxedTupleTy 2 [realWorldStatePrimTy, the_prim_result_ty]
259 -- wrap up an unboxed value.
260 wrapUnboxedValue :: Type -> DsM (Type, Id, CoreExpr)
262 | (maybeToBool maybe_product_type) && -- Data type
263 not (null data_con_arg_tys) && null other_args_tys && -- Just one arg
264 isUnLiftedType the_prim_result_ty -- of primitive type
266 newSysLocalDs the_prim_result_ty `thenDs` \ prim_result_id ->
268 the_result = mkConApp data_con (map Type tycon_arg_tys ++ [Var prim_result_id])
270 returnDs (ccall_res_type, prim_result_id, the_result)
272 -- Data types with a single nullary constructor
273 | (maybeToBool maybe_product_type) && -- Data type
274 (null data_con_arg_tys)
277 scrut_ty = mkUnboxedTupleTy 1 [realWorldStatePrimTy]
279 returnDs (scrut_ty, unitDataConId, Var unitDataConId)
282 = pprPanic "boxResult: " (ppr ty)
284 maybe_product_type = splitProductType_maybe ty
285 Just (tycon, tycon_arg_tys, data_con, data_con_arg_tys) = maybe_product_type
286 (the_prim_result_ty : other_args_tys) = data_con_arg_tys
287 ccall_res_type = mkUnboxedTupleTy 2 [realWorldStatePrimTy, the_prim_result_ty]