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, mkVanillaId )
26 import Const ( Literal(..) )
27 import Module ( Module )
28 import Name ( mkGlobalName, nameModule, nameOccName, getOccString,
29 mkForeignExportOcc, isLocalName,
30 NamedThing(..), Provenance(..), ExportFlag(..)
32 import PrelInfo ( deRefStablePtr_NAME, bindIO_NAME, makeStablePtr_NAME, realWorldPrimId )
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.
63 -> [TypecheckedForeignDecl]
64 -> DsM ( [CoreBind] -- desugared foreign imports
65 , [CoreBind] -- helper functions for foreign exports
66 , SDoc -- Header file prototypes for "foreign exported" functions.
67 , SDoc -- C stubs to use when calling "foreign exported" funs.
69 dsForeigns mod_name fos = foldlDs combine ([],[],empty,empty) fos
71 combine (acc_fi, acc_fe, acc_h, acc_c) fo@(ForeignDecl i imp_exp _ ext_nm cconv _)
72 | isForeignImport = -- foreign import (dynamic)?
73 dsFImport i (idType i) uns ext_nm cconv `thenDs` \ b ->
74 returnDs (b:acc_fi, acc_fe, acc_h, acc_c)
76 dsFLabel i ext_nm `thenDs` \ b ->
77 returnDs (b:acc_fi, acc_fe, acc_h, acc_c)
79 dsFExportDynamic i (idType i) mod_name ext_nm cconv `thenDs` \ (fi,fe,h,c) ->
80 returnDs (fi:acc_fi, fe:acc_fe, h $$ acc_h, c $$ acc_c)
82 | otherwise = -- foreign export
83 dsFExport i (idType i) mod_name ext_nm cconv False `thenDs` \ (fe,h,c) ->
84 returnDs (acc_fi, fe:acc_fe, h $$ acc_h, c $$ acc_c)
96 (FoImport uns) = imp_exp
100 Desugaring foreign imports is just the matter of creating a binding
101 that on its RHS unboxes its arguments, performs the external call
102 (using the CCallOp primop), before boxing the result up and returning it.
106 -> Type -- Type of foreign import.
107 -> Bool -- True <=> might cause Haskell GC
111 dsFImport nm ty may_not_gc ext_name cconv =
112 newSysLocalDs realWorldStatePrimTy `thenDs` \ old_s ->
113 splitForeignTyDs ty `thenDs` \ (tvs, args, mbIoDataCon, io_res_ty) ->
116 | is_io_action = old_s
117 | otherwise = realWorldPrimId
119 arg_exprs = map (Var) args
126 mapAndUnzipDs unboxArg arg_exprs `thenDs` \ (unboxed_args, arg_wrappers) ->
127 (if not is_io_action then
128 newSysLocalDs realWorldStatePrimTy `thenDs` \ state_tok ->
129 wrapUnboxedValue io_res_ty `thenDs` \ (ccall_result_ty, v, res_v) ->
130 returnDs ( ccall_result_ty
131 , \ prim_app -> Case prim_app (mkWildId ccall_result_ty)
132 [(DataCon (unboxedTupleCon 2), [state_tok, v], res_v)])
134 boxResult io_res_ty) `thenDs` \ (final_result_ty, res_wrapper) ->
136 Dynamic -> getUniqueDs `thenDs` \ u ->
138 ExtName fs _ -> returnDs (Left fs)) `thenDs` \ label ->
140 val_args = Var the_state_arg : unboxed_args
141 final_args = Type inst_ty : val_args
143 -- A CCallOp has type (forall a. a), so we must instantiate
144 -- it at the full type, including the state argument
145 inst_ty = mkFunTys (map coreExprType val_args) final_result_ty
147 the_ccall_op = CCallOp label False (not may_not_gc) cconv
149 the_prim_app = mkPrimApp the_ccall_op (final_args :: [CoreArg])
151 body = foldr ($) (res_wrapper the_prim_app) arg_wrappers
154 | not is_io_action = body
155 | otherwise = Lam old_s body
157 newSysLocalDs (coreExprType the_body) `thenDs` \ ds ->
163 mkApps (Var (dataConId ioDataCon))
164 [Type io_res_ty, Var ds]
166 fo_rhs = mkLams (tvs ++ args)
167 (mkDsLet (NonRec ds (the_body::CoreExpr)) io_app)
169 returnDs (NonRec nm fo_rhs)
172 Given the type of a foreign import declaration, split it up into
173 its constituent parts.
176 splitForeignTyDs :: Type -> DsM ([TyVar], [Id], Maybe DataCon, Type)
177 splitForeignTyDs ty =
178 newSysLocalsDs arg_tys `thenDs` \ ds_args ->
179 case splitAlgTyConApp_maybe res_ty of
180 Just (_,(io_res_ty:_),(ioCon:_)) -> -- .... -> IO t
181 returnDs (tvs, ds_args, Just ioCon, io_res_ty)
183 returnDs (tvs, ds_args, Nothing, res_ty)
185 (arg_tys, res_ty) = splitFunTys sans_foralls
186 (tvs, sans_foralls) = splitForAllTys ty
193 dsFLabel :: Id -> ExtName -> DsM CoreBind
194 dsFLabel nm ext_name = returnDs (NonRec nm fo_rhs)
196 fo_rhs = mkConApp addrDataCon [mkLit (MachLitLit enm addrPrimTy)]
200 Dynamic -> panic "dsFLabel: Dynamic - shouldn't ever happen."
204 The function that does most of the work for 'foreign export' declarations.
205 (see below for the boilerplate code a 'foreign export' declaration expands
208 For each 'foreign export foo' in a module M we generate:
210 * a C function 'foo', which calls
211 * a Haskell stub 'M.$ffoo', which calls
213 the user-written Haskell function 'M.foo'.
217 -> Type -- Type of foreign export.
221 -> Bool -- True => invoke IO action that's hanging off
222 -- the first argument's stable pointer
227 dsFExport i ty mod_name ext_name cconv isDyn =
228 getUniqueDs `thenDs` \ uniq ->
229 getSrcLocDs `thenDs` \ src_loc ->
231 f_helper_glob = mkVanillaId helper_name helper_ty
235 | isLocalName name = mod_name
236 | otherwise = nameModule name
238 occ = mkForeignExportOcc (nameOccName name)
239 prov = LocalDef src_loc Exported
240 helper_name = mkGlobalName uniq mod occ prov
242 newSysLocalsDs fe_arg_tys `thenDs` \ fe_args ->
244 newSysLocalDs stbl_ptr_ty `thenDs` \ stbl_ptr ->
245 newSysLocalDs stbl_ptr_to_ty `thenDs` \ stbl_value ->
246 dsLookupGlobalValue deRefStablePtr_NAME `thenDs` \ deRefStablePtrId ->
248 the_deref_app = mkApps (Var deRefStablePtrId)
249 [ Type stbl_ptr_to_ty, Var stbl_ptr ]
251 newSysLocalDs (coreExprType the_deref_app) `thenDs` \ x_deref_app ->
252 dsLookupGlobalValue bindIO_NAME `thenDs` \ bindIOId ->
253 newSysLocalDs (mkFunTy stbl_ptr_to_ty
254 (mkTyConApp ioTyCon [res_ty])) `thenDs` \ x_cont ->
257 bindNonRec x_cont (mkLams [stbl_value] cont) $
258 bindNonRec x_deref_app the_deref_app
259 (mkApps (Var bindIOId)
260 [ Type stbl_ptr_to_ty
265 returnDs (stbl_value, stbl_app, stbl_ptr)
269 panic "stbl_ptr" -- should never be touched.
270 )) `thenDs` \ (i, getFun_wrapper, stbl_ptr) ->
273 | isDyn = stbl_ptr:fe_args
274 | otherwise = fe_args
277 | isDyn = stbl_ptr_ty:helper_arg_tys
278 | otherwise = helper_arg_tys
282 mkApps (Var i) (map (Type . mkTyVarTy) tvs ++ map Var fe_args)
284 getModuleAndGroupDs `thenDs` \ (mod,_) ->
285 getUniqueDs `thenDs` \ uniq ->
287 the_body = mkLams (tvs ++ wrapper_args) the_app
292 Dynamic -> panic "dsFExport: Dynamic - shouldn't ever happen."
294 (h_stub, c_stub) = fexportEntry c_nm f_helper_glob wrapper_arg_tys the_result_ty cconv isDyn
296 returnDs (NonRec f_helper_glob the_body, h_stub, c_stub)
300 (tvs,sans_foralls) = splitForAllTys ty
301 (fe_arg_tys', io_res) = splitFunTys sans_foralls
304 Just (ioTyCon, [res_ty]) = splitTyConApp_maybe io_res
306 (_, stbl_ptr_ty') = splitForAllTys stbl_ptr_ty
307 (_, stbl_ptr_to_ty) = splitAppTy stbl_ptr_ty'
310 | isDyn = tail fe_arg_tys'
311 | otherwise = fe_arg_tys'
313 (stbl_ptr_ty, helper_arg_tys) =
315 (x:xs) | isDyn -> (x,xs)
316 ls -> (error "stbl_ptr_ty", ls)
320 mkFunTys arg_tys io_res
323 | isDyn = stbl_ptr_ty : helper_arg_tys
324 | otherwise = helper_arg_tys
327 case splitTyConApp_maybe io_res of
329 case splitTyConApp_maybe res_ty of
330 Just (tc,_) | getUnique tc /= getUnique unitTyCon -> Just res_ty
336 "foreign export dynamic" lets you dress up Haskell IO actions
337 of some fixed type behind an externally callable interface (i.e.,
338 as a C function pointer). Useful for callbacks and stuff.
341 foreign export stdcall f :: (Addr -> Int -> IO Int) -> IO Addr
343 -- Haskell-visible constructor, which is generated from the
346 f :: (Addr -> Int -> IO Int) -> IO Addr
347 f cback = IO ( \ s1# ->
348 case makeStablePtr# cback s1# of { StateAndStablePtr# s2# sp# ->
349 case _ccall_ "mkAdjustor" sp# ``f_helper'' s2# of
350 StateAndAddr# s3# a# ->
360 foreign export "f_helper" f_helper :: StablePtr (Addr -> Int -> IO Int) -> Addr -> Int -> IO Int
361 -- `special' foreign export that invokes the closure pointed to by the
366 dsFExportDynamic :: Id
367 -> Type -- Type of foreign export.
371 -> DsM (CoreBind, CoreBind, SDoc, SDoc)
372 dsFExportDynamic i ty mod_name ext_name cconv =
373 newSysLocalDs ty `thenDs` \ fe_id ->
375 -- hack: need to get at the name of the C stub we're about to generate.
376 fe_nm = toCName fe_id
377 fe_ext_name = ExtName (_PK_ fe_nm) Nothing
379 dsFExport i export_ty mod_name fe_ext_name cconv True `thenDs` \ (fe@(NonRec fe_helper fe_expr), h_code, c_code) ->
380 newSysLocalDs arg_ty `thenDs` \ cback ->
381 dsLookupGlobalValue makeStablePtr_NAME `thenDs` \ makeStablePtrId ->
383 mk_stbl_ptr_app = mkApps (Var makeStablePtrId) [ Type arg_ty, Var cback ]
384 mk_stbl_ptr_app_ty = coreExprType mk_stbl_ptr_app
386 newSysLocalDs mk_stbl_ptr_app_ty `thenDs` \ x_mk_stbl_ptr_app ->
387 dsLookupGlobalValue bindIO_NAME `thenDs` \ bindIOId ->
388 newSysLocalDs (mkTyConApp stablePtrTyCon [arg_ty]) `thenDs` \ stbl_value ->
390 stbl_app = \ x_cont cont ret_ty ->
391 bindNonRec x_cont cont $
392 bindNonRec x_mk_stbl_ptr_app mk_stbl_ptr_app $
393 (mkApps (Var bindIOId)
394 [ Type (mkTyConApp stablePtrTyCon [arg_ty])
396 , Var x_mk_stbl_ptr_app
401 The arguments to the external function which will
402 create a little bit of (template) code on the fly
403 for allowing the (stable pointed) Haskell closure
404 to be entered using an external calling convention
407 adj_args = [ mkLit (mkMachInt (fromInt (callConvToInt cconv)))
409 , mkLit (MachLitLit (_PK_ fe_nm) addrPrimTy)
411 -- name of external entry point providing these services.
412 -- (probably in the RTS.)
413 adjustor = SLIT("createAdjustor")
415 dsCCall adjustor adj_args False False addrTy `thenDs` \ ccall_adj ->
416 let ccall_adj_ty = coreExprType ccall_adj
418 newSysLocalDs ccall_adj_ty `thenDs` \ x_ccall_adj ->
420 mkLams [stbl_value] $
421 bindNonRec x_ccall_adj ccall_adj $
422 Note (Coerce (mkTyConApp ioTyCon [res_ty]) ccall_adj_ty)
425 newSysLocalDs (coreExprType ccall_io_adj) `thenDs` \ x_ccall_io_adj ->
426 let io_app = mkLams tvs $
428 stbl_app x_ccall_io_adj ccall_io_adj addrTy
430 returnDs (NonRec i io_app, fe, h_code, c_code)
433 (tvs,sans_foralls) = splitForAllTys ty
434 ([arg_ty], io_res) = splitFunTys sans_foralls
436 Just (ioTyCon, [res_ty]) = splitTyConApp_maybe io_res
438 export_ty = mkFunTy (mkTyConApp stablePtrTyCon [arg_ty]) arg_ty
440 toCName :: Id -> String
441 toCName i = showSDoc (pprCode CStyle (ppr (idName i)))
447 \subsection{Generating @foreign export@ stubs}
451 For each @foreign export@ function, a C stub function is generated.
452 The C stub constructs the application of the exported Haskell function
453 using the hugs/ghc rts invocation API.
456 fexportEntry :: FAST_STRING
463 fexportEntry c_nm helper args res cc isDyn = (header_bits, c_bits)
465 -- name of the (Haskell) helper function generated by the desugarer.
466 h_nm = ppr helper <> text "_closure"
467 -- prototype for the exported function.
468 header_bits = ptext SLIT("extern") <+> fun_proto <> semi
470 fun_proto = cResType <+> pprCconv <+> ptext c_nm <>
471 parens (hsep (punctuate comma (zipWith (<+>) cParamTypes proto_args)))
478 , text "SchedulerStatus rc;"
480 -- create the application + perform it.
481 , text "rc=rts_evalIO" <>
482 parens (foldl appArg (text "(StgClosure*)&" <> h_nm) (zip args c_args) <> comma <> text "&ret") <> semi
488 text "rts_apply" <> parens (acc <> comma <> mkHObj a <> parens c_a)
490 cParamTypes = map showStgType real_args
494 Nothing -> text "void"
495 Just t -> showStgType t
498 | cc == cCallConv = empty
499 | otherwise = pprCallConv cc
501 declareResult = text "HaskellObj ret;"
503 externDecl = mkExtern (text "HaskellObj") h_nm
505 mkExtern ty nm = text "extern" <+> ty <+> nm <> semi
508 text "rts_checkSchedStatus" <>
509 parens (doubleQuotes (ptext c_nm) <> comma <> text "rc") <> semi $$
511 Nothing -> text "return"
512 Just _ -> text "return" <> parens (res_name)) <> semi
517 Just t -> unpackHObj t <> parens (text "ret")
519 c_args = mkCArgNames 0 args
522 If we're generating an entry point for a 'foreign export ccall dynamic',
523 then we receive the return address of the C function that wants to
524 invoke a Haskell function as any other C function, as second arg.
525 This arg is unused within the body of the generated C stub, but
526 needed by the Adjustor.c code to get the stack cleanup right.
528 (proto_args, real_args)
529 | cc == cCallConv && isDyn = ( text "a0" : text "a_" : mkCArgNames 1 (tail args)
530 , head args : addrTy : tail args)
531 | otherwise = (mkCArgNames 0 args, args)
533 mkCArgNames :: Int -> [a] -> [SDoc]
534 mkCArgNames n as = zipWith (\ _ n -> text ('a':show n)) as [n..]
536 mkHObj :: Type -> SDoc
537 mkHObj t = text "rts_mk" <> text (showFFIType t)
539 unpackHObj :: Type -> SDoc
540 unpackHObj t = text "rts_get" <> text (showFFIType t)
542 showStgType :: Type -> SDoc
543 showStgType t = text "Stg" <> text (showFFIType t)
545 showFFIType :: Type -> String
546 showFFIType t = getOccString (getName tc)
548 tc = case splitTyConApp_maybe t of
550 Nothing -> pprPanic "showFFIType" (ppr t)