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,
40 import TysWiredIn ( unitDataConId, stringTy, boolTy,
41 falseDataCon, falseDataConId,
42 trueDataCon, trueDataConId,
44 mkUnboxedTupleTy, unboxedTupleCon
46 import Literal ( mkMachInt )
47 import CStrings ( CLabelString )
48 import Unique ( Unique )
49 import VarSet ( varSetElems )
53 Desugaring of @ccall@s consists of adding some state manipulation,
54 unboxing any boxed primitive arguments and boxing the result if
57 The state stuff just consists of adding in
58 @PrimIO (\ s -> case s of { S# s# -> ... })@ in an appropriate place.
60 The unboxing is straightforward, as all information needed to unbox is
61 available from the type. For each boxed-primitive argument, we
64 _ccall_ foo [ r, t1, ... tm ] e1 ... em
68 case e1 of { T1# x1# ->
70 case em of { Tm# xm# -> xm#
71 ccall# foo [ r, t1#, ... tm# ] x1# ... xm#
75 The reboxing of a @_ccall_@ result is a bit tricker: the types don't
76 contain information about the state-pairing functions so we have to
77 keep a list of \tr{(type, s-p-function)} pairs. We transform as
80 ccall# foo [ r, t1#, ... tm# ] e1# ... em#
84 \ s# -> case (ccall# foo [ r, t1#, ... tm# ] s# e1# ... em#) of
85 (StateAnd<r># result# state#) -> (R# result#, realWorld#)
89 dsCCall :: CLabelString -- C routine to invoke
90 -> [CoreExpr] -- Arguments (desugared)
91 -> Bool -- True <=> might cause Haskell GC
92 -> Bool -- True <=> really a "_casm_"
93 -> Type -- Type of the result (a boxed-prim IO type)
96 dsCCall lbl args may_gc is_asm result_ty
97 = newSysLocalDs realWorldStatePrimTy `thenDs` \ old_s ->
99 mapAndUnzipDs unboxArg args `thenDs` \ (unboxed_args, arg_wrappers) ->
100 boxResult result_ty `thenDs` \ (final_result_ty, res_wrapper) ->
101 getUniqueDs `thenDs` \ uniq ->
103 val_args = Var old_s : unboxed_args
104 the_ccall = CCall (StaticTarget lbl) is_asm may_gc cCallConv
105 the_prim_app = mkCCall uniq the_ccall val_args final_result_ty
106 the_body = foldr ($) (res_wrapper the_prim_app) arg_wrappers
108 returnDs (Lam old_s the_body)
110 mkCCall :: Unique -> CCall
111 -> [CoreExpr] -- Args
112 -> Type -- Result type
114 -- Construct the ccall. The only tricky bit is that the ccall Id should have
115 -- no free vars, so if any of the arg tys do we must give it a polymorphic type.
116 -- [I forget *why* it should have no free vars!]
118 -- mkCCall ... [s::StablePtr (a->b), x::Addr, c::Char]
120 -- Here we build a ccall thus
121 -- (ccallid::(forall a b. StablePtr (a -> b) -> Addr -> Char -> IO Addr))
123 mkCCall uniq the_ccall val_args res_ty
124 = mkApps (mkVarApps (Var the_ccall_id) tyvars) val_args
126 arg_tys = map exprType val_args
127 body_ty = (mkFunTys arg_tys res_ty)
128 tyvars = varSetElems (tyVarsOfType body_ty)
129 ty = mkForAllTys tyvars body_ty
130 the_ccall_id = mkCCallOpId uniq the_ccall ty
134 unboxArg :: CoreExpr -- The supplied argument
135 -> DsM (CoreExpr, -- To pass as the actual argument
136 CoreExpr -> CoreExpr -- Wrapper to unbox the arg
141 -- ADR Question: can this ever be used? None of the PrimTypes are
142 -- instances of the CCallable class.
145 -- Oh yes they are, I've just added them :-) Having _ccall_ and _casm_
146 -- that accept unboxed arguments is a Good Thing if you have a stub generator
147 -- which generates the boiler-plate box-unbox code for you, i.e., it may help
148 -- us nuke this very module :-)
150 | isUnLiftedType arg_ty
151 = returnDs (arg, \body -> body)
155 -- ToDo (ADR): - allow synonyms of Strings too?
156 = newSysLocalDs byteArrayPrimTy `thenDs` \ prim_arg ->
157 returnDs (Var prim_arg,
158 \body -> Case (App (Var packStringForCId) arg)
159 prim_arg [(DEFAULT,[],body)])
161 -- Byte-arrays, both mutable and otherwise; hack warning
163 length data_con_arg_tys == 3 &&
164 maybeToBool maybe_arg3_tycon &&
165 (arg3_tycon == byteArrayPrimTyCon ||
166 arg3_tycon == mutableByteArrayPrimTyCon)
167 -- and, of course, it is an instance of CCallable
168 = newSysLocalDs arg_ty `thenDs` \ case_bndr ->
169 newSysLocalsDs data_con_arg_tys `thenDs` \ vars@[l_var, r_var, arr_cts_var] ->
170 returnDs (Var arr_cts_var,
171 \ body -> Case arg case_bndr [(DataAlt data_con,vars,body)]
174 -- Data types with a single constructor, which has a single, primitive-typed arg
175 | maybeToBool maybe_boxed_prim_arg_ty
176 = newSysLocalDs arg_ty `thenDs` \ case_bndr ->
177 newSysLocalDs the_prim_arg_ty `thenDs` \ prim_arg ->
178 returnDs (Var prim_arg,
179 \ body -> Case arg case_bndr [(DataAlt box_data_con,[prim_arg],body)]
184 = newSysLocalDs intPrimTy `thenDs` \ prim_arg ->
185 returnDs (Var prim_arg,
186 \ body -> Case (Case arg (mkWildId arg_ty) [
187 (DataAlt falseDataCon,[],mkIntLit 0),
188 (DataAlt trueDataCon, [],mkIntLit 1)])
189 prim_arg [(DEFAULT,[],body)]
193 = getSrcLocDs `thenDs` \ l ->
194 pprPanic "unboxArg: " (ppr l <+> ppr arg_ty)
196 arg_ty = exprType arg
198 maybe_boxed_prim_arg_ty = maybeBoxedPrimType arg_ty
199 (Just (box_data_con, the_prim_arg_ty)) = maybe_boxed_prim_arg_ty
201 maybe_product_type = splitProductType_maybe arg_ty
202 is_product_type = maybeToBool maybe_product_type
203 Just (tycon, _, data_con, data_con_arg_tys) = maybe_product_type
204 (data_con_arg_ty1 : data_con_arg_ty2 : data_con_arg_ty3 :_)
207 maybe_arg3_tycon = splitTyConApp_maybe data_con_arg_ty3
208 Just (arg3_tycon,_) = maybe_arg3_tycon
210 can'tSeeDataConsPanic thing ty
212 "ERROR: Can't see the data constructor(s) for _ccall_/_casm_/foreign declaration"
213 (hcat [ text thing, text "; type: ", ppr ty
214 , text "(try compiling with -fno-prune-tydecls ..)\n"])
219 boxResult :: Type -- Type of desired result
220 -> DsM (Type, -- Type of the result of the ccall itself
221 CoreExpr -> CoreExpr) -- Wrapper for the ccall
224 -- Data types with a single nullary constructor
225 | (maybeToBool maybe_product_type) && -- Data type
226 (null data_con_arg_tys)
228 newSysLocalDs realWorldStatePrimTy `thenDs` \ prim_state_id ->
230 wrapUnboxedValue result_ty `thenDs` \ (state_and_prim_datacon,
231 state_and_prim_ty, prim_result_id, the_result) ->
233 [TyArg result_ty, VarArg (Var prim_state_id), VarArg the_result]
234 `thenDs` \ the_pair ->
237 the_pair = mkConApp unboxedPairDataCon
238 [Type realWorldStatePrimTy, Type result_ty,
241 the_alt = (DataAlt (unboxedTupleCon 1), [prim_state_id], the_pair)
242 scrut_ty = mkUnboxedTupleTy 1 [realWorldStatePrimTy]
244 returnDs (scrut_ty, \prim_app -> Case prim_app (mkWildId scrut_ty) [the_alt]
247 -- Data types with a single constructor, which has a single, primitive-typed arg
248 | (maybeToBool maybe_product_type) && -- Data type
249 not (null data_con_arg_tys) && null other_args_tys && -- Just one arg
250 isUnLiftedType the_prim_result_ty -- of primitive type
252 newSysLocalDs realWorldStatePrimTy `thenDs` \ prim_state_id ->
253 newSysLocalDs the_prim_result_ty `thenDs` \ prim_result_id ->
254 newSysLocalDs ccall_res_type `thenDs` \ case_bndr ->
257 the_result = mkConApp data_con (map Type tycon_arg_tys ++ [Var prim_result_id])
258 the_pair = mkConApp unboxedPairDataCon
259 [Type realWorldStatePrimTy, Type result_ty,
260 Var prim_state_id, the_result]
261 the_alt = (DataAlt unboxedPairDataCon, [prim_state_id, prim_result_id], the_pair)
263 returnDs (ccall_res_type, \prim_app -> Case prim_app case_bndr [the_alt]
267 | result_ty == boolTy
268 = returnDs (mkUnboxedTupleTy 2 [realWorldStatePrimTy, intPrimTy],
269 \ prim_app -> Case prim_app (mkWildId intPrimTy) [
270 (LitAlt (mkMachInt 0),[],Var falseDataConId),
271 (DEFAULT ,[],Var trueDataConId )])
274 = pprPanic "boxResult: " (ppr result_ty)
276 maybe_product_type = splitProductType_maybe result_ty
277 Just (tycon, tycon_arg_tys, data_con, data_con_arg_tys) = maybe_product_type
278 (the_prim_result_ty : other_args_tys) = data_con_arg_tys
280 ccall_res_type = mkUnboxedTupleTy 2 [realWorldStatePrimTy, the_prim_result_ty]
282 -- wrap up an unboxed value.
283 wrapUnboxedValue :: Type -> DsM (Type, Id, CoreExpr)
285 | (maybeToBool maybe_product_type) && -- Data type
286 not (null data_con_arg_tys) && null other_args_tys && -- Just one arg
287 isUnLiftedType the_prim_result_ty -- of primitive type
289 newSysLocalDs the_prim_result_ty `thenDs` \ prim_result_id ->
291 the_result = mkConApp data_con (map Type tycon_arg_tys ++ [Var prim_result_id])
293 returnDs (ccall_res_type, prim_result_id, the_result)
295 -- Data types with a single nullary constructor
296 | (maybeToBool maybe_product_type) && -- Data type
297 (null data_con_arg_tys)
300 scrut_ty = mkUnboxedTupleTy 1 [realWorldStatePrimTy]
302 returnDs (scrut_ty, unitDataConId, Var unitDataConId)
305 = pprPanic "boxResult: " (ppr ty)
307 maybe_product_type = splitProductType_maybe ty
308 Just (tycon, tycon_arg_tys, data_con, data_con_arg_tys) = maybe_product_type
309 (the_prim_result_ty : other_args_tys) = data_con_arg_tys
310 ccall_res_type = mkUnboxedTupleTy 2 [realWorldStatePrimTy, the_prim_result_ty]