2 % (c) The AQUA Project, Glasgow University, 1998
4 \section[DsCCall]{Desugaring \tr{foreign} declarations}
6 Expanding out @foreign import@ and @foreign export@ declarations.
9 module DsForeign ( dsForeigns ) where
11 #include "HsVersions.h"
15 import DsCCall ( dsCCall, boxResult, unboxArg, wrapUnboxedValue )
19 import HsSyn ( ExtName(..), ForeignDecl(..), isDynamic, ForKind(..) )
21 import TcHsSyn ( TypecheckedForeignDecl )
22 import CoreUtils ( coreExprType )
23 import Const ( Con(..), mkMachInt )
24 import DataCon ( DataCon, dataConId )
25 import Id ( Id, idType, idName, mkWildId, mkUserId )
26 import Const ( Literal(..) )
27 import Name ( mkGlobalName, nameModule, nameOccName, getOccString,
29 NamedThing(..), Provenance(..), ExportFlag(..)
31 import PrelVals ( realWorldPrimId )
32 import PrelInfo ( deRefStablePtr_NAME, bindIO_NAME, makeStablePtr_NAME )
33 import Type ( splitAlgTyConApp_maybe,
34 splitTyConApp_maybe, splitFunTys, splitForAllTys,
35 Type, mkFunTys, mkForAllTys, mkTyConApp,
36 mkTyVarTy, mkFunTy, splitAppTy
38 import PrimOp ( PrimOp(..) )
40 import TysPrim ( realWorldStatePrimTy, addrPrimTy )
41 import TysWiredIn ( unitTyCon, addrTy, stablePtrTyCon,
42 unboxedTupleCon, addrDataCon
48 Desugaring of @foreign@ declarations is naturally split up into
49 parts, an @import@ and an @export@ part. A @foreign import@
52 foreign import cc nm f :: prim_args -> IO prim_res
56 f :: prim_args -> IO prim_res
57 f a1 ... an = _ccall_ nm cc a1 ... an
59 so we reuse the desugaring code in @DsCCall@ to deal with these.
62 dsForeigns :: [TypecheckedForeignDecl]
63 -> DsM ( [CoreBind] -- desugared foreign imports
64 , [CoreBind] -- helper functions for foreign exports
65 , SDoc -- Header file prototypes for "foreign exported" functions.
66 , SDoc -- C stubs to use when calling "foreign exported" funs.
68 dsForeigns fos = foldlDs combine ([],[],empty,empty) fos
70 combine (acc_fi, acc_fe, acc_h, acc_c) fo@(ForeignDecl i imp_exp _ ext_nm cconv _)
71 | isForeignImport = -- foreign import (dynamic)?
72 dsFImport i (idType i) uns ext_nm cconv `thenDs` \ b ->
73 returnDs (b:acc_fi, acc_fe, acc_h, acc_c)
75 dsFLabel i ext_nm `thenDs` \ b ->
76 returnDs (b:acc_fi, acc_fe, acc_h, acc_c)
78 dsFExportDynamic i (idType i) ext_nm cconv `thenDs` \ (fi,fe,h,c) ->
79 returnDs (fi:acc_fi, fe:acc_fe, h $$ acc_h, c $$ acc_c)
81 | otherwise = -- foreign export
82 dsFExport i (idType i) ext_nm cconv False `thenDs` \ (fe,h,c) ->
83 returnDs (acc_fi, fe:acc_fe, h $$ acc_h, c $$ acc_c)
95 (FoImport uns) = imp_exp
99 Desugaring foreign imports is just the matter of creating a binding
100 that on its RHS unboxes its arguments, performs the external call
101 (using the CCallOp primop), before boxing the result up and returning it.
105 -> Type -- Type of foreign import.
106 -> Bool -- True <=> might cause Haskell GC
110 dsFImport nm ty may_not_gc ext_name cconv =
111 newSysLocalDs realWorldStatePrimTy `thenDs` \ old_s ->
112 splitForeignTyDs ty `thenDs` \ (tvs, args, mbIoDataCon, io_res_ty) ->
115 | is_io_action = old_s
116 | otherwise = realWorldPrimId
118 arg_exprs = map (Var) args
125 mapAndUnzipDs unboxArg arg_exprs `thenDs` \ (unboxed_args, arg_wrappers) ->
126 (if not is_io_action then
127 newSysLocalDs realWorldStatePrimTy `thenDs` \ state_tok ->
128 wrapUnboxedValue io_res_ty `thenDs` \ (ccall_result_ty, v, res_v) ->
129 returnDs ( ccall_result_ty
130 , \ prim_app -> Case prim_app (mkWildId ccall_result_ty)
131 [(DataCon (unboxedTupleCon 2), [state_tok, v], res_v)])
133 boxResult io_res_ty) `thenDs` \ (final_result_ty, res_wrapper) ->
135 Dynamic -> getUniqueDs `thenDs` \ u ->
137 ExtName fs _ -> returnDs (Left fs)) `thenDs` \ label ->
139 val_args = Var the_state_arg : unboxed_args
140 final_args = Type inst_ty : val_args
142 -- A CCallOp has type (forall a. a), so we must instantiate
143 -- it at the full type, including the state argument
144 inst_ty = mkFunTys (map coreExprType val_args) final_result_ty
146 the_ccall_op = CCallOp label False (not may_not_gc) cconv
148 the_prim_app = mkPrimApp the_ccall_op (final_args :: [CoreArg])
150 body = foldr ($) (res_wrapper the_prim_app) arg_wrappers
153 | not is_io_action = body
154 | otherwise = Lam old_s body
156 newSysLocalDs (coreExprType the_body) `thenDs` \ ds ->
162 mkApps (Var (dataConId ioDataCon))
163 [Type io_res_ty, Var ds]
165 fo_rhs = mkLams (tvs ++ args)
166 (Let (NonRec ds (the_body::CoreExpr)) io_app)
168 returnDs (NonRec nm fo_rhs)
171 Given the type of a foreign import declaration, split it up into
172 its constituent parts.
175 splitForeignTyDs :: Type -> DsM ([TyVar], [Id], Maybe DataCon, Type)
176 splitForeignTyDs ty =
177 newSysLocalsDs arg_tys `thenDs` \ ds_args ->
178 case splitAlgTyConApp_maybe res_ty of
179 Just (_,(io_res_ty:_),(ioCon:_)) -> -- .... -> IO t
180 returnDs (tvs, ds_args, Just ioCon, io_res_ty)
182 returnDs (tvs, ds_args, Nothing, res_ty)
184 (arg_tys, res_ty) = splitFunTys sans_foralls
185 (tvs, sans_foralls) = splitForAllTys ty
192 dsFLabel :: Id -> ExtName -> DsM CoreBind
193 dsFLabel nm ext_name = returnDs (NonRec nm fo_rhs)
195 fo_rhs = mkConApp addrDataCon [mkLit (MachLitLit enm addrPrimTy)]
199 Dynamic -> panic "dsFLabel: Dynamic - shouldn't ever happen."
203 The function that does most of the work for 'foreign export' declarations.
204 (see below for the boilerplate code a 'foreign export' declaration expands
207 For each 'foreign export foo' in a module M we generate:
209 * a C function 'foo', which calls
210 * a Haskell stub 'M.$ffoo', which calls
212 the user-written Haskell function 'M.foo'.
216 -> Type -- Type of foreign export.
219 -> Bool -- True => invoke IO action that's hanging off
220 -- the first argument's stable pointer
225 dsFExport i ty ext_name cconv isDyn =
226 getUniqueDs `thenDs` \ uniq ->
227 getSrcLocDs `thenDs` \ src_loc ->
229 f_helper_glob = mkUserId helper_name helper_ty
232 mod = nameModule name
233 occ = mkForeignExportOcc (nameOccName name)
234 prov = LocalDef src_loc Exported
235 helper_name = mkGlobalName uniq mod occ prov
237 newSysLocalsDs fe_arg_tys `thenDs` \ fe_args ->
239 newSysLocalDs stbl_ptr_ty `thenDs` \ stbl_ptr ->
240 newSysLocalDs stbl_ptr_to_ty `thenDs` \ stbl_value ->
241 dsLookupGlobalValue deRefStablePtr_NAME `thenDs` \ deRefStablePtrId ->
243 the_deref_app = mkApps (Var deRefStablePtrId)
244 [ Type stbl_ptr_to_ty, Var stbl_ptr ]
246 newSysLocalDs (coreExprType the_deref_app) `thenDs` \ x_deref_app ->
247 dsLookupGlobalValue bindIO_NAME `thenDs` \ bindIOId ->
248 newSysLocalDs (mkFunTy stbl_ptr_to_ty
249 (mkTyConApp ioTyCon [res_ty])) `thenDs` \ x_cont ->
252 bindNonRec x_cont (mkLams [stbl_value] cont) $
253 bindNonRec x_deref_app the_deref_app
254 (mkApps (Var bindIOId)
255 [ Type stbl_ptr_to_ty
260 returnDs (stbl_value, stbl_app, stbl_ptr)
264 panic "stbl_ptr" -- should never be touched.
265 )) `thenDs` \ (i, getFun_wrapper, stbl_ptr) ->
268 | isDyn = stbl_ptr:fe_args
269 | otherwise = fe_args
272 | isDyn = stbl_ptr_ty:helper_arg_tys
273 | otherwise = helper_arg_tys
277 mkApps (Var i) (map (Type . mkTyVarTy) tvs ++ map Var fe_args)
279 getModuleAndGroupDs `thenDs` \ (mod,_) ->
280 getUniqueDs `thenDs` \ uniq ->
282 the_body = mkLams (tvs ++ wrapper_args) the_app
287 Dynamic -> panic "dsFExport: Dynamic - shouldn't ever happen."
289 (h_stub, c_stub) = fexportEntry c_nm f_helper_glob wrapper_arg_tys the_result_ty cconv isDyn
291 returnDs (NonRec f_helper_glob the_body, h_stub, c_stub)
295 (tvs,sans_foralls) = splitForAllTys ty
296 (fe_arg_tys', io_res) = splitFunTys sans_foralls
299 Just (ioTyCon, [res_ty]) = splitTyConApp_maybe io_res
301 (_, stbl_ptr_ty') = splitForAllTys stbl_ptr_ty
302 (_, stbl_ptr_to_ty) = splitAppTy stbl_ptr_ty'
305 | isDyn = tail fe_arg_tys'
306 | otherwise = fe_arg_tys'
308 (stbl_ptr_ty, helper_arg_tys) =
310 (x:xs) | isDyn -> (x,xs)
311 ls -> (error "stbl_ptr_ty", ls)
315 mkFunTys arg_tys io_res
318 | isDyn = stbl_ptr_ty : helper_arg_tys
319 | otherwise = helper_arg_tys
322 case splitTyConApp_maybe io_res of
324 case splitTyConApp_maybe res_ty of
325 Just (tc,_) | getUnique tc /= getUnique unitTyCon -> Just res_ty
331 "foreign export dynamic" lets you dress up Haskell IO actions
332 of some fixed type behind an externally callable interface (i.e.,
333 as a C function pointer). Useful for callbacks and stuff.
336 foreign export stdcall f :: (Addr -> Int -> IO Int) -> IO Addr
338 -- Haskell-visible constructor, which is generated from the
341 f :: (Addr -> Int -> IO Int) -> IO Addr
342 f cback = IO ( \ s1# ->
343 case makeStablePtr# cback s1# of { StateAndStablePtr# s2# sp# ->
344 case _ccall_ "mkAdjustor" sp# ``f_helper'' s2# of
345 StateAndAddr# s3# a# ->
355 foreign export "f_helper" f_helper :: StablePtr (Addr -> Int -> IO Int) -> Addr -> Int -> IO Int
356 -- `special' foreign export that invokes the closure pointed to by the
361 dsFExportDynamic :: Id
362 -> Type -- Type of foreign export.
365 -> DsM (CoreBind, CoreBind, SDoc, SDoc)
366 dsFExportDynamic i ty ext_name cconv =
367 newSysLocalDs ty `thenDs` \ fe_id ->
369 -- hack: need to get at the name of the C stub we're about to generate.
370 fe_nm = toCName fe_id
371 fe_ext_name = ExtName (_PK_ fe_nm) Nothing
373 dsFExport i export_ty fe_ext_name cconv True `thenDs` \ (fe@(NonRec fe_helper fe_expr), h_code, c_code) ->
374 newSysLocalDs arg_ty `thenDs` \ cback ->
375 dsLookupGlobalValue makeStablePtr_NAME `thenDs` \ makeStablePtrId ->
377 mk_stbl_ptr_app = mkApps (Var makeStablePtrId) [ Type arg_ty, Var cback ]
378 mk_stbl_ptr_app_ty = coreExprType mk_stbl_ptr_app
380 newSysLocalDs mk_stbl_ptr_app_ty `thenDs` \ x_mk_stbl_ptr_app ->
381 dsLookupGlobalValue bindIO_NAME `thenDs` \ bindIOId ->
382 newSysLocalDs (mkTyConApp stablePtrTyCon [arg_ty]) `thenDs` \ stbl_value ->
384 stbl_app = \ x_cont cont ret_ty ->
385 bindNonRec x_cont cont $
386 bindNonRec x_mk_stbl_ptr_app mk_stbl_ptr_app $
387 (mkApps (Var bindIOId)
388 [ Type (mkTyConApp stablePtrTyCon [arg_ty])
390 , Var x_mk_stbl_ptr_app
395 The arguments to the external function which will
396 create a little bit of (template) code on the fly
397 for allowing the (stable pointed) Haskell closure
398 to be entered using an external calling convention
401 adj_args = [ mkLit (mkMachInt (fromInt (callConvToInt cconv)))
403 , mkLit (MachLitLit (_PK_ fe_nm) addrPrimTy)
405 -- name of external entry point providing these services.
406 -- (probably in the RTS.)
407 adjustor = SLIT("createAdjustor")
409 dsCCall adjustor adj_args False False addrTy `thenDs` \ ccall_adj ->
410 let ccall_adj_ty = coreExprType ccall_adj
412 newSysLocalDs ccall_adj_ty `thenDs` \ x_ccall_adj ->
414 mkLams [stbl_value] $
415 bindNonRec x_ccall_adj ccall_adj $
416 Note (Coerce (mkTyConApp ioTyCon [res_ty]) ccall_adj_ty)
419 newSysLocalDs (coreExprType ccall_io_adj) `thenDs` \ x_ccall_io_adj ->
420 let io_app = mkLams tvs $
422 stbl_app x_ccall_io_adj ccall_io_adj addrTy
424 returnDs (NonRec i io_app, fe, h_code, c_code)
427 (tvs,sans_foralls) = splitForAllTys ty
428 ([arg_ty], io_res) = splitFunTys sans_foralls
430 Just (ioTyCon, [res_ty]) = splitTyConApp_maybe io_res
432 export_ty = mkFunTy (mkTyConApp stablePtrTyCon [arg_ty]) arg_ty
434 toCName :: Id -> String
435 toCName i = showSDoc (pprCode CStyle (ppr (idName i)))
441 \subsection{Generating @foreign export@ stubs}
445 For each @foreign export@ function, a C stub function is generated.
446 The C stub constructs the application of the exported Haskell function
447 using the hugs/ghc rts invocation API.
450 fexportEntry :: FAST_STRING
457 fexportEntry c_nm helper args res cc isDyn = (header_bits, c_bits)
459 -- name of the (Haskell) helper function generated by the desugarer.
460 h_nm = ppr helper <> text "_closure"
461 -- prototype for the exported function.
462 header_bits = ptext SLIT("extern") <+> fun_proto <> semi
464 fun_proto = cResType <+> pprCconv <+> ptext c_nm <>
465 parens (hsep (punctuate comma (zipWith (<+>) cParamTypes proto_args)))
472 , text "SchedulerStatus rc;"
474 -- create the application + perform it.
475 , text "rc=rts_evalIO" <>
476 parens (foldl appArg (text "(StgClosure*)&" <> h_nm) (zip args c_args) <> comma <> text "&ret") <> semi
482 text "rts_apply" <> parens (acc <> comma <> mkHObj a <> parens c_a)
484 cParamTypes = map showStgType real_args
488 Nothing -> text "void"
489 Just t -> showStgType t
492 | cc == cCallConv = empty
493 | otherwise = pprCallConv cc
495 declareResult = text "HaskellObj ret;"
497 externDecl = mkExtern (text "HaskellObj") h_nm
499 mkExtern ty nm = text "extern" <+> ty <+> nm <> semi
502 text "rts_checkSchedStatus" <>
503 parens (doubleQuotes (ptext c_nm) <> comma <> text "rc") <> semi $$
505 Nothing -> text "return"
506 Just _ -> text "return" <> parens (res_name)) <> semi
511 Just t -> unpackHObj t <> parens (text "ret")
513 c_args = mkCArgNames 0 args
516 If we're generating an entry point for a 'foreign export ccall dynamic',
517 then we receive the return address of the C function that wants to
518 invoke a Haskell function as any other C function, as second arg.
519 This arg is unused within the body of the generated C stub, but
520 needed by the Adjustor.c code to get the stack cleanup right.
522 (proto_args, real_args)
523 | cc == cCallConv && isDyn = ( text "a0" : text "a_" : mkCArgNames 1 (tail args)
524 , head args : addrTy : tail args)
525 | otherwise = (mkCArgNames 0 args, args)
527 mkCArgNames n as = zipWith (\ _ n -> text ('a':show n)) as [n..]
529 mkHObj :: Type -> SDoc
530 mkHObj t = text "rts_mk" <> showFFIType t
532 unpackHObj :: Type -> SDoc
533 unpackHObj t = text "rts_get" <> showFFIType t
535 showStgType :: Type -> SDoc
536 showStgType t = text "Stg" <> showFFIType t
538 showFFIType :: Type -> SDoc
539 showFFIType t = text (getOccString (getName tc))
541 tc = case splitTyConApp_maybe t of
543 Nothing -> pprPanic "showFFIType" (ppr t)