2 % (c) The University of Glasgow 2006
3 % (c) The AQUA Project, Glasgow University, 1998
6 Desugaring foreign declarations (see also DsCCall).
9 module DsForeign ( dsForeigns ) where
11 #include "HsVersions.h"
12 import TcRnMonad -- temp
50 Desugaring of @foreign@ declarations is naturally split up into
51 parts, an @import@ and an @export@ part. A @foreign import@
54 foreign import cc nm f :: prim_args -> IO prim_res
58 f :: prim_args -> IO prim_res
59 f a1 ... an = _ccall_ nm cc a1 ... an
61 so we reuse the desugaring code in @DsCCall@ to deal with these.
64 type Binding = (Id, CoreExpr) -- No rec/nonrec structure;
65 -- the occurrence analyser will sort it all out
67 dsForeigns :: [LForeignDecl Id]
68 -> DsM (ForeignStubs, [Binding])
70 = return (NoStubs, [])
72 fives <- mapM do_ldecl fos
74 (hs, cs, idss, bindss) = unzip4 fives
76 fe_init_code = map foreignExportInitialiser fe_ids
80 (vcat cs $$ vcat fe_init_code),
83 do_ldecl (L loc decl) = putSrcSpanDs loc (do_decl decl)
85 do_decl (ForeignImport id _ spec) = do
86 traceIf (text "fi start" <+> ppr id)
87 (bs, h, c) <- dsFImport (unLoc id) spec
88 traceIf (text "fi end" <+> ppr id)
91 do_decl (ForeignExport (L _ id) _ (CExport (CExportStatic ext_nm cconv))) = do
92 (h, c, _, _) <- dsFExport id (idType id) ext_nm cconv False
93 return (h, c, [id], [])
95 do_decl d = pprPanic "dsForeigns/do_decl" (ppr d)
99 %************************************************************************
101 \subsection{Foreign import}
103 %************************************************************************
105 Desugaring foreign imports is just the matter of creating a binding
106 that on its RHS unboxes its arguments, performs the external call
107 (using the @CCallOp@ primop), before boxing the result up and returning it.
109 However, we create a worker/wrapper pair, thus:
111 foreign import f :: Int -> IO Int
113 f x = IO ( \s -> case x of { I# x# ->
114 case fw s x# of { (# s1, y# #) ->
117 fw s x# = ccall f s x#
119 The strictness/CPR analyser won't do this automatically because it doesn't look
120 inside returned tuples; but inlining this wrapper is a Really Good Idea
121 because it exposes the boxing to the call site.
126 -> DsM ([Binding], SDoc, SDoc)
127 dsFImport id (CImport cconv safety _ _ spec) = do
128 (ids, h, c) <- dsCImport id spec cconv safety
131 -- FIXME: the `lib' field is needed for .NET ILX generation when invoking
132 -- routines that are external to the .NET runtime, but GHC doesn't
133 -- support such calls yet; if `nullFastString lib', the value was not given
134 dsFImport id (DNImport spec) = do
135 (ids, h, c) <- dsFCall id (DNCall spec)
142 -> DsM ([Binding], SDoc, SDoc)
143 dsCImport id (CLabel cid) cconv _ = do
145 (resTy, foRhs) <- resultWrapper ty
146 ASSERT(fromJust resTy `coreEqType` addrPrimTy) -- typechecker ensures this
148 rhs = foRhs (mkLit (MachLabel cid stdcall_info))
149 stdcall_info = fun_type_arg_stdcall_info cconv ty
151 return ([(id, rhs)], empty, empty)
153 dsCImport id (CFunction target) cconv safety
154 = dsFCall id (CCall (CCallSpec target cconv safety))
155 dsCImport id CWrapper cconv _
156 = dsFExportDynamic id cconv
158 -- For stdcall labels, if the type was a FunPtr or newtype thereof,
159 -- then we need to calculate the size of the arguments in order to add
160 -- the @n suffix to the label.
161 fun_type_arg_stdcall_info :: CCallConv -> Type -> Maybe Int
162 fun_type_arg_stdcall_info StdCallConv ty
163 | Just (tc,[arg_ty]) <- splitTyConApp_maybe (repType ty),
164 tyConUnique tc == funPtrTyConKey
166 (_tvs,sans_foralls) = tcSplitForAllTys arg_ty
167 (fe_arg_tys, _orig_res_ty) = tcSplitFunTys sans_foralls
169 Just $ sum (map (machRepByteWidth . typeMachRep . getPrimTyOf) fe_arg_tys)
170 fun_type_arg_stdcall_info _other_conv _
175 %************************************************************************
177 \subsection{Foreign calls}
179 %************************************************************************
182 dsFCall :: Id -> ForeignCall -> DsM ([(Id, Expr TyVar)], SDoc, SDoc)
183 dsFCall fn_id fcall = do
186 (tvs, fun_ty) = tcSplitForAllTys ty
187 (arg_tys, io_res_ty) = tcSplitFunTys fun_ty
188 -- Must use tcSplit* functions because we want to
189 -- see that (IO t) in the corner
191 args <- newSysLocalsDs arg_tys
192 (val_args, arg_wrappers) <- mapAndUnzipM unboxArg (map Var args)
195 work_arg_ids = [v | Var v <- val_args] -- All guaranteed to be vars
203 | forDotnet = Just <$> dsLookupGlobalId checkDotnetResName
204 | otherwise = return Nothing
208 return (\ (mb_res_ty, resWrap) ->
210 Nothing -> (Just (mkTyConApp (tupleTyCon Unboxed 1)
213 Just x -> (Just (mkTyConApp (tupleTyCon Unboxed 2)
216 | otherwise = return id
218 augment <- augmentResultDs
220 (ccall_result_ty, res_wrapper) <- boxResult augment topCon io_res_ty
222 ccall_uniq <- newUnique
223 work_uniq <- newUnique
226 worker_ty = mkForAllTys tvs (mkFunTys (map idType work_arg_ids) ccall_result_ty)
227 the_ccall_app = mkFCall ccall_uniq fcall val_args ccall_result_ty
228 work_rhs = mkLams tvs (mkLams work_arg_ids the_ccall_app)
229 work_id = mkSysLocal (fsLit "$wccall") work_uniq worker_ty
232 work_app = mkApps (mkVarApps (Var work_id) tvs) val_args
233 wrapper_body = foldr ($) (res_wrapper work_app) arg_wrappers
234 wrap_rhs = mkInlineMe (mkLams (tvs ++ args) wrapper_body)
236 return ([(work_id, work_rhs), (fn_id, wrap_rhs)], empty, empty)
240 %************************************************************************
242 \subsection{Foreign export}
244 %************************************************************************
246 The function that does most of the work for `@foreign export@' declarations.
247 (see below for the boilerplate code a `@foreign export@' declaration expands
250 For each `@foreign export foo@' in a module M we generate:
252 \item a C function `@foo@', which calls
253 \item a Haskell stub `@M.$ffoo@', which calls
255 the user-written Haskell function `@M.foo@'.
258 dsFExport :: Id -- Either the exported Id,
259 -- or the foreign-export-dynamic constructor
260 -> Type -- The type of the thing callable from C
261 -> CLabelString -- The name to export to C land
263 -> Bool -- True => foreign export dynamic
264 -- so invoke IO action that's hanging off
265 -- the first argument's stable pointer
266 -> DsM ( SDoc -- contents of Module_stub.h
267 , SDoc -- contents of Module_stub.c
268 , String -- string describing type to pass to createAdj.
269 , Int -- size of args to stub function
272 dsFExport fn_id ty ext_name cconv isDyn= do
274 (_tvs,sans_foralls) = tcSplitForAllTys ty
275 (fe_arg_tys', orig_res_ty) = tcSplitFunTys sans_foralls
276 -- We must use tcSplits here, because we want to see
277 -- the (IO t) in the corner of the type!
278 fe_arg_tys | isDyn = tail fe_arg_tys'
279 | otherwise = fe_arg_tys'
281 -- Look at the result type of the exported function, orig_res_ty
282 -- If it's IO t, return (t, True)
283 -- If it's plain t, return (t, False)
285 is_IO_res_ty) <- -- Bool
286 case tcSplitIOType_maybe orig_res_ty of
287 Just (_ioTyCon, res_ty, _co) -> return (res_ty, True)
288 -- The function already returns IO t
289 -- ToDo: what about the coercion?
290 Nothing -> return (orig_res_ty, False)
291 -- The function returns t
294 mkFExportCBits ext_name
295 (if isDyn then Nothing else Just fn_id)
296 fe_arg_tys res_ty is_IO_res_ty cconv
299 @foreign import "wrapper"@ (previously "foreign export dynamic") lets
300 you dress up Haskell IO actions of some fixed type behind an
301 externally callable interface (i.e., as a C function pointer). Useful
302 for callbacks and stuff.
305 type Fun = Bool -> Int -> IO Int
306 foreign import "wrapper" f :: Fun -> IO (FunPtr Fun)
308 -- Haskell-visible constructor, which is generated from the above:
309 -- SUP: No check for NULL from createAdjustor anymore???
311 f :: Fun -> IO (FunPtr Fun)
313 bindIO (newStablePtr cback)
314 (\StablePtr sp# -> IO (\s1# ->
315 case _ccall_ createAdjustor cconv sp# ``f_helper'' <arg info> s1# of
316 (# s2#, a# #) -> (# s2#, A# a# #)))
318 foreign import "&f_helper" f_helper :: FunPtr (StablePtr Fun -> Fun)
320 -- and the helper in C:
322 f_helper(StablePtr s, HsBool b, HsInt i)
324 rts_evalIO(rts_apply(rts_apply(deRefStablePtr(s),
325 rts_mkBool(b)), rts_mkInt(i)));
330 dsFExportDynamic :: Id
332 -> DsM ([Binding], SDoc, SDoc)
333 dsFExportDynamic id cconv = do
334 fe_id <- newSysLocalDs ty
337 -- hack: need to get at the name of the C stub we're about to generate.
338 fe_nm = mkFastString (unpackFS (zEncodeFS (moduleNameFS (moduleName mod))) ++ "_" ++ toCName fe_id)
340 cback <- newSysLocalDs arg_ty
341 newStablePtrId <- dsLookupGlobalId newStablePtrName
342 stable_ptr_tycon <- dsLookupTyCon stablePtrTyConName
344 stable_ptr_ty = mkTyConApp stable_ptr_tycon [arg_ty]
345 export_ty = mkFunTy stable_ptr_ty arg_ty
346 bindIOId <- dsLookupGlobalId bindIOName
347 stbl_value <- newSysLocalDs stable_ptr_ty
348 (h_code, c_code, typestring, args_size) <- dsFExport id export_ty fe_nm cconv True
351 The arguments to the external function which will
352 create a little bit of (template) code on the fly
353 for allowing the (stable pointed) Haskell closure
354 to be entered using an external calling convention
357 adj_args = [ mkIntLitInt (ccallConvToInt cconv)
359 , mkLit (MachLabel fe_nm mb_sz_args)
360 , mkLit (mkStringLit typestring)
362 -- name of external entry point providing these services.
363 -- (probably in the RTS.)
364 adjustor = fsLit "createAdjustor"
366 -- Determine the number of bytes of arguments to the stub function,
367 -- so that we can attach the '@N' suffix to its label if it is a
368 -- stdcall on Windows.
369 mb_sz_args = case cconv of
370 StdCallConv -> Just args_size
373 ccall_adj <- dsCCall adjustor adj_args PlayRisky (mkTyConApp io_tc [res_ty])
374 -- PlayRisky: the adjustor doesn't allocate in the Haskell heap or do a callback
376 let io_app = mkLams tvs $
378 mkCoerceI (mkSymCoI co) $
379 mkApps (Var bindIOId)
382 , mkApps (Var newStablePtrId) [ Type arg_ty, Var cback ]
383 , Lam stbl_value ccall_adj
386 fed = (id `setInlinePragma` NeverActive, io_app)
387 -- Never inline the f.e.d. function, because the litlit
388 -- might not be in scope in other modules.
390 return ([fed], h_code, c_code)
394 (tvs,sans_foralls) = tcSplitForAllTys ty
395 ([arg_ty], fn_res_ty) = tcSplitFunTys sans_foralls
396 Just (io_tc, res_ty, co) = tcSplitIOType_maybe fn_res_ty
397 -- Must have an IO type; hence Just
398 -- co : fn_res_ty ~ IO res_ty
400 toCName :: Id -> String
401 toCName i = showSDoc (pprCode CStyle (ppr (idName i)))
406 \subsection{Generating @foreign export@ stubs}
410 For each @foreign export@ function, a C stub function is generated.
411 The C stub constructs the application of the exported Haskell function
412 using the hugs/ghc rts invocation API.
415 mkFExportCBits :: FastString
416 -> Maybe Id -- Just==static, Nothing==dynamic
419 -> Bool -- True <=> returns an IO type
423 String, -- the argument reps
424 Int -- total size of arguments
426 mkFExportCBits c_nm maybe_target arg_htys res_hty is_IO_res_ty cc
427 = (header_bits, c_bits, type_string,
428 sum [ machRepByteWidth rep | (_,_,_,rep) <- aug_arg_info] -- all the args
431 -- list the arguments to the C function
432 arg_info :: [(SDoc, -- arg name
434 Type, -- Haskell type
435 MachRep)] -- the MachRep
436 arg_info = [ let stg_type = showStgType ty in
437 (arg_cname n stg_type,
440 typeMachRep (getPrimTyOf ty))
441 | (ty,n) <- zip arg_htys [1::Int ..] ]
444 | libffi = char '*' <> parens (stg_ty <> char '*') <>
445 ptext (sLit "args") <> brackets (int (n-1))
446 | otherwise = text ('a':show n)
448 -- generate a libffi-style stub if this is a "wrapper" and libffi is enabled
449 libffi = cLibFFI && isNothing maybe_target
452 -- libffi needs to know the result type too:
453 | libffi = primTyDescChar res_hty : arg_type_string
454 | otherwise = arg_type_string
456 arg_type_string = [primTyDescChar ty | (_,_,ty,_) <- arg_info]
457 -- just the real args
459 -- add some auxiliary args; the stable ptr in the wrapper case, and
460 -- a slot for the dummy return address in the wrapper + ccall case
462 | isNothing maybe_target = stable_ptr_arg : insertRetAddr cc arg_info
463 | otherwise = arg_info
466 (text "the_stableptr", text "StgStablePtr", undefined,
467 typeMachRep (mkStablePtrPrimTy alphaTy))
469 -- stuff to do with the return type of the C function
470 res_hty_is_unit = res_hty `coreEqType` unitTy -- Look through any newtypes
472 cResType | res_hty_is_unit = text "void"
473 | otherwise = showStgType res_hty
475 -- Now we can cook up the prototype for the exported function.
476 pprCconv = case cc of
478 StdCallConv -> text (ccallConvAttribute cc)
479 CmmCallConv -> panic "mkFExportCBits/pprCconv CmmCallConv"
481 header_bits = ptext (sLit "extern") <+> fun_proto <> semi
484 | null aug_arg_info = text "void"
485 | otherwise = hsep $ punctuate comma
486 $ map (\(nm,ty,_,_) -> ty <+> nm) aug_arg_info
490 = ptext (sLit "void") <+> ftext c_nm <>
491 parens (ptext (sLit "void *cif STG_UNUSED, void* resp, void** args, void* the_stableptr"))
493 = cResType <+> pprCconv <+> ftext c_nm <> parens fun_args
495 -- the target which will form the root of what we ask rts_evalIO to run
497 = case maybe_target of
498 Nothing -> text "(StgClosure*)deRefStablePtr(the_stableptr)"
499 Just hs_fn -> char '&' <> ppr hs_fn <> text "_closure"
501 cap = text "cap" <> comma
503 -- the expression we give to rts_evalIO
505 = foldl appArg the_cfun arg_info -- NOT aug_arg_info
507 appArg acc (arg_cname, _, arg_hty, _)
509 <> parens (cap <> acc <> comma <> mkHObj arg_hty <> parens (cap <> arg_cname))
511 -- various other bits for inside the fn
512 declareResult = text "HaskellObj ret;"
513 declareCResult | res_hty_is_unit = empty
514 | otherwise = cResType <+> text "cret;"
516 assignCResult | res_hty_is_unit = empty
518 text "cret=" <> unpackHObj res_hty <> parens (text "ret") <> semi
520 -- an extern decl for the fn being called
522 = case maybe_target of
524 Just hs_fn -> text "extern StgClosure " <> ppr hs_fn <> text "_closure" <> semi
527 -- finally, the whole darn thing
534 , ptext (sLit "Capability *cap;")
537 , text "cap = rts_lock();"
538 -- create the application + perform it.
539 , ptext (sLit "cap=rts_evalIO") <> parens (
541 ptext (sLit "rts_apply") <> parens (
544 <> ptext (if is_IO_res_ty
545 then (sLit "runIO_closure")
546 else (sLit "runNonIO_closure"))
552 , ptext (sLit "rts_checkSchedStatus") <> parens (doubleQuotes (ftext c_nm)
553 <> comma <> text "cap") <> semi
555 , ptext (sLit "rts_unlock(cap);")
556 , if res_hty_is_unit then empty
558 then char '*' <> parens (cResType <> char '*') <>
559 ptext (sLit "resp = cret;")
560 else ptext (sLit "return cret;")
565 foreignExportInitialiser :: Id -> SDoc
566 foreignExportInitialiser hs_fn =
567 -- Initialise foreign exports by registering a stable pointer from an
568 -- __attribute__((constructor)) function.
569 -- The alternative is to do this from stginit functions generated in
570 -- codeGen/CodeGen.lhs; however, stginit functions have a negative impact
571 -- on binary sizes and link times because the static linker will think that
572 -- all modules that are imported directly or indirectly are actually used by
574 -- (this is bad for big umbrella modules like Graphics.Rendering.OpenGL)
576 [ text "static void stginit_export_" <> ppr hs_fn
577 <> text "() __attribute__((constructor));"
578 , text "static void stginit_export_" <> ppr hs_fn <> text "()"
579 , braces (text "getStablePtr"
580 <> parens (text "(StgPtr) &" <> ppr hs_fn <> text "_closure")
585 -- NB. the calculation here isn't strictly speaking correct.
586 -- We have a primitive Haskell type (eg. Int#, Double#), and
587 -- we want to know the size, when passed on the C stack, of
588 -- the associated C type (eg. HsInt, HsDouble). We don't have
589 -- this information to hand, but we know what GHC's conventions
590 -- are for passing around the primitive Haskell types, so we
591 -- use that instead. I hope the two coincide --SDM
592 typeMachRep :: Type -> MachRep
593 typeMachRep ty = argMachRep (typeCgRep ty)
595 mkHObj :: Type -> SDoc
596 mkHObj t = text "rts_mk" <> text (showFFIType t)
598 unpackHObj :: Type -> SDoc
599 unpackHObj t = text "rts_get" <> text (showFFIType t)
601 showStgType :: Type -> SDoc
602 showStgType t = text "Hs" <> text (showFFIType t)
604 showFFIType :: Type -> String
605 showFFIType t = getOccString (getName tc)
607 tc = case tcSplitTyConApp_maybe (repType t) of
609 Nothing -> pprPanic "showFFIType" (ppr t)
611 insertRetAddr :: CCallConv -> [(SDoc, SDoc, Type, MachRep)]
612 -> [(SDoc, SDoc, Type, MachRep)]
613 #if !defined(x86_64_TARGET_ARCH)
614 insertRetAddr CCallConv args = ret_addr_arg : args
615 insertRetAddr _ args = args
617 -- On x86_64 we insert the return address after the 6th
618 -- integer argument, because this is the point at which we
619 -- need to flush a register argument to the stack (See rts/Adjustor.c for
621 insertRetAddr CCallConv args = go 0 args
622 where go :: Int -> [(SDoc, SDoc, Type, MachRep)]
623 -> [(SDoc, SDoc, Type, MachRep)]
624 go 6 args = ret_addr_arg : args
625 go n (arg@(_,_,_,rep):args)
626 | I64 <- rep = arg : go (n+1) args
627 | otherwise = arg : go n args
629 insertRetAddr _ args = args
632 ret_addr_arg :: (SDoc, SDoc, Type, MachRep)
633 ret_addr_arg = (text "original_return_addr", text "void*", undefined,
634 typeMachRep addrPrimTy)
636 -- This function returns the primitive type associated with the boxed
637 -- type argument to a foreign export (eg. Int ==> Int#).
638 getPrimTyOf :: Type -> Type
640 | isBoolTy rep_ty = intPrimTy
641 -- Except for Bool, the types we are interested in have a single constructor
642 -- with a single primitive-typed argument (see TcType.legalFEArgTyCon).
644 case splitProductType_maybe rep_ty of
645 Just (_, _, data_con, [prim_ty]) ->
646 ASSERT(dataConSourceArity data_con == 1)
647 ASSERT2(isUnLiftedType prim_ty, ppr prim_ty)
649 _other -> pprPanic "DsForeign.getPrimTyOf" (ppr ty)
653 -- represent a primitive type as a Char, for building a string that
654 -- described the foreign function type. The types are size-dependent,
655 -- e.g. 'W' is a signed 32-bit integer.
656 primTyDescChar :: Type -> Char
658 | ty `coreEqType` unitTy = 'v'
660 = case typePrimRep (getPrimTyOf ty) of
661 IntRep -> signed_word
662 WordRep -> unsigned_word
668 _ -> pprPanic "primTyDescChar" (ppr ty)
670 (signed_word, unsigned_word)
671 | wORD_SIZE == 4 = ('W','w')
672 | wORD_SIZE == 8 = ('L','l')
673 | otherwise = panic "primTyDescChar"