\section[DsCCall]{Desugaring \tr{_ccall_}s and \tr{_casm_}s}
\begin{code}
-#include "HsVersions.h"
-
-module DsCCall ( dsCCall ) where
+module DsCCall
+ (
+ dsCCall
+ , getIoOkDataCon
+ , unboxArg
+ , boxResult
+ , can'tSeeDataConsPanic
+ ) where
-IMP_Ubiq()
+#include "HsVersions.h"
-import CmdLineOpts (opt_PprUserLength)
import CoreSyn
import DsMonad
import DsUtils
+import TcHsSyn ( maybeBoxedPrimType )
import CoreUtils ( coreExprType )
-import Id ( dataConArgTys )
+import Id ( Id, dataConArgTys, idType )
import Maybes ( maybeToBool )
-import Outputable ( PprStyle(..), Outputable(..) )
-import PprType ( GenType{-instances-} )
-import Pretty
import PrelVals ( packStringForCId )
import PrimOp ( PrimOp(..) )
-import Type ( isPrimType, maybeAppDataTyConExpandingDicts, maybeAppTyCon,
- eqTy, maybeBoxedPrimType, SYN_IE(Type) )
-import TysPrim ( byteArrayPrimTy, realWorldTy, realWorldStatePrimTy,
+import CallConv
+import Type ( isUnpointedType, splitAlgTyConApp_maybe,
+ splitTyConApp_maybe, splitFunTys, splitForAllTys,
+ Type
+ )
+import TyCon ( tyConDataCons )
+import TysPrim ( byteArrayPrimTy, realWorldStatePrimTy,
byteArrayPrimTyCon, mutableByteArrayPrimTyCon )
import TysWiredIn ( getStatePairingConInfo,
- stRetDataCon, pairDataCon, unitDataCon,
- stringTy,
+ unitDataCon, stringTy,
realWorldStateTy, stateDataCon
)
-import Util ( pprPanic, pprError, panic )
-
+import Outputable
\end{code}
Desugaring of @ccall@s consists of adding some state manipulation,
-> [CoreExpr] -- Arguments (desugared)
-> Bool -- True <=> might cause Haskell GC
-> Bool -- True <=> really a "_casm_"
- -> Type -- Type of the result (a boxed-prim type)
+ -> Type -- Type of the result (a boxed-prim IO type)
-> DsM CoreExpr
-dsCCall label args may_gc is_asm result_ty
+dsCCall label args may_gc is_asm io_result_ty
= newSysLocalDs realWorldStatePrimTy `thenDs` \ old_s ->
mapAndUnzipDs unboxArg args `thenDs` \ (unboxed_args, arg_wrappers) ->
let
final_args = Var old_s : unboxed_args
+ (ioOkDataCon, _, result_ty) = getIoOkDataCon io_result_ty
in
- boxResult result_ty `thenDs` \ (final_result_ty, res_wrapper) ->
+ boxResult ioOkDataCon result_ty `thenDs` \ (final_result_ty, res_wrapper) ->
let
- the_ccall_op = CCallOp label is_asm may_gc
+ the_ccall_op = CCallOp (Left label) is_asm may_gc cCallConv
(map coreExprType final_args)
final_result_ty
in
-- which generates the boiler-plate box-unbox code for you, i.e., it may help
-- us nuke this very module :-)
--
- | isPrimType arg_ty
+ | isUnpointedType arg_ty
= returnDs (arg, \body -> body)
-- Strings
- | arg_ty `eqTy` stringTy
- -- ToDo (ADR): - allow synonyms of Strings too?
+ | arg_ty == stringTy
= newSysLocalDs byteArrayPrimTy `thenDs` \ prim_arg ->
mkAppDs (Var packStringForCId) [VarArg arg] `thenDs` \ pack_appn ->
returnDs (Var prim_arg,
| null data_cons
-- oops: we can't see the data constructors!!!
- = can't_see_datacons_error "argument" arg_ty
+ = can'tSeeDataConsPanic "argument" arg_ty
-- Byte-arrays, both mutable and otherwise; hack warning
| is_data_type &&
)
| otherwise
- = pprPanic "unboxArg: " (ppr PprDebug arg_ty)
+ = getSrcLocDs `thenDs` \ l ->
+ pprPanic "unboxArg: " (ppr l <+> ppr arg_ty)
where
arg_ty = coreExprType arg
maybe_boxed_prim_arg_ty = maybeBoxedPrimType arg_ty
(Just (box_data_con, the_prim_arg_ty)) = maybe_boxed_prim_arg_ty
- maybe_data_type = maybeAppDataTyConExpandingDicts arg_ty
+ maybe_data_type = splitAlgTyConApp_maybe arg_ty
is_data_type = maybeToBool maybe_data_type
(Just (tycon, tycon_arg_tys, data_cons)) = maybe_data_type
(the_data_con : other_data_cons) = data_cons
data_con_arg_tys = dataConArgTys the_data_con tycon_arg_tys
(data_con_arg_ty1 : data_con_arg_ty2 : _) = data_con_arg_tys
- maybe_arg2_tycon = maybeAppTyCon data_con_arg_ty2
+ maybe_arg2_tycon = splitTyConApp_maybe data_con_arg_ty2
Just (arg2_tycon,_) = maybe_arg2_tycon
-can't_see_datacons_error thing ty
- = pprError "ERROR: Can't see the data constructor(s) for _ccall_/_casm_ "
- (hcat [text thing, text "; type: ", ppr (PprForUser opt_PprUserLength) ty, text "(try compiling with -fno-prune-tydecls ..)\n"])
+can'tSeeDataConsPanic thing ty
+ = pprPanic "ERROR: Can't see the data constructor(s) for _ccall_/_casm_/foreign declaration"
+ (hcat [text thing, text "; type: ", ppr ty, text "(try compiling with -fno-prune-tydecls ..)\n"])
\end{code}
\begin{code}
-boxResult :: Type -- Type of desired result
+boxResult :: Id -- IOok constructor
+ -> Type -- Type of desired result
-> DsM (Type, -- Type of the result of the ccall itself
CoreExpr -> CoreExpr) -- Wrapper for the ccall
-- to box the result
-boxResult result_ty
+boxResult ioOkDataCon result_ty
| null data_cons
-- oops! can't see the data constructors
- = can't_see_datacons_error "result" result_ty
-
- -- Data types with a single constructor,
- -- which has a single, primitive-typed arg.
- | (maybeToBool maybe_data_type) && -- Data type
- (null other_data_cons) && -- Just one constr
- not (null data_con_arg_tys) && null other_args_tys && -- Just one arg
- isPrimType the_prim_result_ty -- of primitive type
+ = can'tSeeDataConsPanic "result" result_ty
+
+ -- Data types with a single constructor, which has a single, primitive-typed arg
+ | (maybeToBool maybe_data_type) && -- Data type
+ (null other_data_cons) && -- Just one constr
+ not (null data_con_arg_tys) && null other_args_tys && -- Just one arg
+ isUnpointedType the_prim_result_ty -- of primitive type
=
newSysLocalDs realWorldStatePrimTy `thenDs` \ prim_state_id ->
newSysLocalDs the_prim_result_ty `thenDs` \ prim_result_id ->
mkConDs the_data_con (map TyArg tycon_arg_tys ++ [VarArg (Var prim_result_id)]) `thenDs` \ the_result ->
- mkConDs stRetDataCon
- [TyArg realWorldTy, TyArg result_ty, VarArg (Var prim_state_id), VarArg the_result]
+ mkConDs ioOkDataCon
+ [TyArg result_ty, VarArg (Var prim_state_id), VarArg the_result]
`thenDs` \ the_pair ->
let
the_alt = (state_and_prim_datacon, [prim_state_id, prim_result_id], the_pair)
=
newSysLocalDs realWorldStatePrimTy `thenDs` \ prim_state_id ->
- mkConDs stRetDataCon
- [TyArg realWorldTy, TyArg result_ty, VarArg (Var prim_state_id), VarArg (Var unitDataCon)]
+ mkConDs ioOkDataCon
+ [TyArg result_ty, VarArg (Var prim_state_id), VarArg (Var unitDataCon)]
`thenDs` \ the_pair ->
let
)
| otherwise
- = pprPanic "boxResult: " (ppr PprDebug result_ty)
+ = pprPanic "boxResult: " (ppr result_ty)
where
- maybe_data_type = maybeAppDataTyConExpandingDicts result_ty
+ maybe_data_type = splitAlgTyConApp_maybe result_ty
Just (tycon, tycon_arg_tys, data_cons) = maybe_data_type
(the_data_con : other_data_cons) = data_cons
(state_and_prim_datacon, state_and_prim_ty) = getStatePairingConInfo the_prim_result_ty
\end{code}
+This grimy bit of code is for digging out the IOok constructor from an
+application of the the IO type. The constructor is needed for
+wrapping the result of a _ccall_. The alternative is to wire-in IO,
+which brings a whole heap of junk with it.
+
+If the representation of IO changes, this will probably have to be
+brought in line with the new definition.
+
+newtype IO a = IO (State# RealWorld -> IOResult a)
+
+the constructor IO has type (State# RealWorld -> IOResult a) -> IO a
+
+\begin{code}
+getIoOkDataCon :: Type -- IO t
+ -> (Id, Id, Type) -- Returns (IOok, IO, t)
+
+getIoOkDataCon io_ty
+ = let
+ Just (ioTyCon, [t]) = splitTyConApp_maybe io_ty
+ [ioDataCon] = tyConDataCons ioTyCon
+ ioDataConTy = idType ioDataCon
+ (_, ioDataConTy') = splitForAllTys ioDataConTy
+ ([arg_ty], _) = splitFunTys ioDataConTy'
+ (_, io_result_ty) = splitFunTys arg_ty
+ Just (io_result_tycon, _) = splitTyConApp_maybe io_result_ty
+ [ioOkDataCon,ioFailDataCon] = tyConDataCons io_result_tycon
+ in
+ (ioOkDataCon, ioDataCon, t)
+\end{code}
+
+Another way to do it, more sensitive:
+
+ case ioDataConTy of
+ ForAll _ (FunTy (FunTy _ (AppTy (TyConTy ioResultTyCon _) _)) _) ->
+ let [ioOkDataCon,ioFailDataCon] = tyConDataCons ioResultTyCon
+ in
+ (ioOkDataCon, result_ty)
+ _ -> pprPanic "getIoOkDataCon: " (ppr PprDebug ioDataConTy)
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