2 % (c) The AQUA Project, Glasgow University, 1994-1996
4 \section[DsCCall]{Desugaring \tr{_ccall_}s and \tr{_casm_}s}
7 #include "HsVersions.h"
9 module DsCCall ( dsCCall ) where
18 import CoreUtils ( coreExprType )
19 import Id ( dataConArgTys, mkTupleCon )
20 import Maybes ( maybeToBool )
21 import PprStyle ( PprStyle(..) )
22 import PprType ( GenType{-instances-} )
24 import PrelVals ( packStringForCId )
25 import PrimOp ( PrimOp(..) )
26 import Type ( isPrimType, maybeAppDataTyConExpandingDicts, eqTy, maybeBoxedPrimType )
27 import TysPrim ( byteArrayPrimTy, realWorldTy, realWorldStatePrimTy )
28 import TysWiredIn ( getStatePairingConInfo,
29 realWorldStateTy, stateDataCon,
32 import Util ( pprPanic, pprError, panic )
35 Desugaring of @ccall@s consists of adding some state manipulation,
36 unboxing any boxed primitive arguments and boxing the result if
39 The state stuff just consists of adding in
40 @\ s -> case s of { S# s# -> ... }@ in an appropriate place.
42 The unboxing is straightforward, as all information needed to unbox is
43 available from the type. For each boxed-primitive argument, we
46 _ccall_ foo [ r, t1, ... tm ] e1 ... em
50 case e1 of { T1# x1# ->
52 case em of { Tm# xm# -> xm#
53 ccall# foo [ r, t1#, ... tm# ] x1# ... xm#
57 The reboxing of a @_ccall_@ result is a bit tricker: the types don't
58 contain information about the state-pairing functions so we have to
59 keep a list of \tr{(type, s-p-function)} pairs. We transform as
62 ccall# foo [ r, t1#, ... tm# ] e1# ... em#
66 \ s# -> case (ccall# foo [ r, t1#, ... tm# ] s# e1# ... em#) of
67 (StateAnd<r># result# state#) -> (R# result#, realWorld#)
71 dsCCall :: FAST_STRING -- C routine to invoke
72 -> [CoreExpr] -- Arguments (desugared)
73 -> Bool -- True <=> might cause Haskell GC
74 -> Bool -- True <=> really a "_casm_"
75 -> Type -- Type of the result (a boxed-prim type)
78 dsCCall label args may_gc is_asm result_ty
79 = newSysLocalDs realWorldStateTy `thenDs` \ old_s ->
81 mapAndUnzipDs unboxArg (Var old_s : args) `thenDs` \ (final_args, arg_wrappers) ->
83 boxResult result_ty `thenDs` \ (final_result_ty, res_wrapper) ->
86 the_ccall_op = CCallOp label is_asm may_gc
87 (map coreExprType final_args)
91 [] -- ***NOTE*** no ty apps; the types are inside the_ccall_op.
92 final_args `thenDs` \ the_prim_app ->
94 the_body = foldr apply (res_wrapper the_prim_app) arg_wrappers
96 returnDs (Lam (ValBinder old_s) the_body)
102 unboxArg :: CoreExpr -- The supplied argument
103 -> DsM (CoreExpr, -- To pass as the actual argument
104 CoreExpr -> CoreExpr -- Wrapper to unbox the arg
109 -- ADR Question: can this ever be used? None of the PrimTypes are
110 -- instances of the CCallable class.
112 = returnDs (arg, \body -> body)
115 | arg_ty `eqTy` stringTy
116 -- ToDo (ADR): - allow synonyms of Strings too?
117 = newSysLocalDs byteArrayPrimTy `thenDs` \ prim_arg ->
118 mkAppDs (Var packStringForCId) [] [arg] `thenDs` \ pack_appn ->
119 returnDs (Var prim_arg,
120 \body -> Case pack_appn (PrimAlts []
121 (BindDefault prim_arg body))
125 -- oops: we can't see the data constructors!!!
126 = can't_see_datacons_error "argument" arg_ty
128 -- Byte-arrays, both mutable and otherwise
129 -- (HACKy method -- but we really don't want the TyCons wired-in...) [WDP 94/10]
131 length data_con_arg_tys == 2 &&
132 not (isPrimType data_con_arg_ty1) &&
133 isPrimType data_con_arg_ty2
134 -- and, of course, it is an instance of CCallable
135 -- ( tycon == byteArrayTyCon ||
136 -- tycon == mutableByteArrayTyCon )
137 = newSysLocalsDs data_con_arg_tys `thenDs` \ vars@[ixs_var, arr_cts_var] ->
138 returnDs (Var arr_cts_var,
139 \ body -> Case arg (AlgAlts [(the_data_con,vars,body)]
143 -- Data types with a single constructor, which has a single, primitive-typed arg
144 | maybeToBool maybe_boxed_prim_arg_ty
145 = newSysLocalDs the_prim_arg_ty `thenDs` \ prim_arg ->
146 returnDs (Var prim_arg,
147 \ body -> Case arg (AlgAlts [(box_data_con,[prim_arg],body)]
152 = pprPanic "unboxArg: " (ppr PprDebug arg_ty)
154 arg_ty = coreExprType arg
156 maybe_boxed_prim_arg_ty = maybeBoxedPrimType arg_ty
157 (Just (box_data_con, the_prim_arg_ty)) = maybe_boxed_prim_arg_ty
159 maybe_data_type = maybeAppDataTyConExpandingDicts arg_ty
160 is_data_type = maybeToBool maybe_data_type
161 (Just (tycon, tycon_arg_tys, data_cons)) = maybe_data_type
162 (the_data_con : other_data_cons) = data_cons
164 data_con_arg_tys = dataConArgTys the_data_con tycon_arg_tys
165 (data_con_arg_ty1 : data_con_arg_ty2 : _) = data_con_arg_tys
167 can't_see_datacons_error thing ty
168 = pprError "ERROR: Can't see the data constructor(s) for _ccall_/_casm_ "
169 (ppBesides [ppStr thing, ppStr "; type: ", ppr PprForUser ty])
174 tuple_con_2 = mkTupleCon 2 -- out here to avoid CAF (sigh)
175 covar_tuple_con_0 = Var (mkTupleCon 0) -- ditto
177 boxResult :: Type -- Type of desired result
178 -> DsM (Type, -- Type of the result of the ccall itself
179 CoreExpr -> CoreExpr) -- Wrapper for the ccall
183 -- oops! can't see the data constructors
184 = can't_see_datacons_error "result" result_ty
186 -- Data types with a single constructor, which has a single, primitive-typed arg
187 | (maybeToBool maybe_data_type) && -- Data type
188 (null other_data_cons) && -- Just one constr
189 not (null data_con_arg_tys) && null other_args_tys && -- Just one arg
190 isPrimType the_prim_result_ty -- of primitive type
192 newSysLocalDs realWorldStatePrimTy `thenDs` \ prim_state_id ->
193 newSysLocalDs the_prim_result_ty `thenDs` \ prim_result_id ->
195 mkConDs stateDataCon [realWorldTy] [Var prim_state_id] `thenDs` \ new_state ->
196 mkConDs the_data_con tycon_arg_tys [Var prim_result_id] `thenDs` \ the_result ->
199 [result_ty, realWorldStateTy]
200 [the_result, new_state] `thenDs` \ the_pair ->
202 the_alt = (state_and_prim_datacon, [prim_state_id, prim_result_id], the_pair)
204 returnDs (state_and_prim_ty,
205 \prim_app -> Case prim_app (AlgAlts [the_alt] NoDefault)
208 -- Data types with a single nullary constructor
209 | (maybeToBool maybe_data_type) && -- Data type
210 (null other_data_cons) && -- Just one constr
211 (null data_con_arg_tys)
213 newSysLocalDs realWorldStatePrimTy `thenDs` \ prim_state_id ->
215 mkConDs stateDataCon [realWorldTy] [Var prim_state_id] `thenDs` \ new_state ->
218 [result_ty, realWorldStateTy]
219 [covar_tuple_con_0, new_state] `thenDs` \ the_pair ->
222 the_alt = (stateDataCon, [prim_state_id], the_pair)
224 returnDs (realWorldStateTy,
225 \prim_app -> Case prim_app (AlgAlts [the_alt] NoDefault)
229 = pprPanic "boxResult: " (ppr PprDebug result_ty)
232 maybe_data_type = maybeAppDataTyConExpandingDicts result_ty
233 Just (tycon, tycon_arg_tys, data_cons) = maybe_data_type
234 (the_data_con : other_data_cons) = data_cons
236 data_con_arg_tys = dataConArgTys the_data_con tycon_arg_tys
237 (the_prim_result_ty : other_args_tys) = data_con_arg_tys
239 (state_and_prim_datacon, state_and_prim_ty) = getStatePairingConInfo the_prim_result_ty