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Diffstat (limited to 'compiler/deSugar/DsForeign.lhs')
| -rw-r--r-- | compiler/deSugar/DsForeign.lhs | 646 |
1 files changed, 646 insertions, 0 deletions
diff --git a/compiler/deSugar/DsForeign.lhs b/compiler/deSugar/DsForeign.lhs new file mode 100644 index 0000000000..52956a09ff --- /dev/null +++ b/compiler/deSugar/DsForeign.lhs @@ -0,0 +1,646 @@ +% +% (c) The AQUA Project, Glasgow University, 1998 +% +\section[DsCCall]{Desugaring \tr{foreign} declarations} + +Expanding out @foreign import@ and @foreign export@ declarations. + +\begin{code} +module DsForeign ( dsForeigns ) where + +#include "HsVersions.h" +import TcRnMonad -- temp + +import CoreSyn + +import DsCCall ( dsCCall, mkFCall, boxResult, unboxArg, resultWrapper ) +import DsMonad + +import HsSyn ( ForeignDecl(..), ForeignExport(..), LForeignDecl, + ForeignImport(..), CImportSpec(..) ) +import DataCon ( splitProductType_maybe ) +#ifdef DEBUG +import DataCon ( dataConSourceArity ) +import Type ( isUnLiftedType ) +#endif +import MachOp ( machRepByteWidth, MachRep(..) ) +import SMRep ( argMachRep, typeCgRep ) +import CoreUtils ( exprType, mkInlineMe ) +import Id ( Id, idType, idName, mkSysLocal, setInlinePragma ) +import Literal ( Literal(..), mkStringLit ) +import Module ( moduleFS ) +import Name ( getOccString, NamedThing(..) ) +import Type ( repType, coreEqType ) +import TcType ( Type, mkFunTys, mkForAllTys, mkTyConApp, + mkFunTy, tcSplitTyConApp_maybe, + tcSplitForAllTys, tcSplitFunTys, tcTyConAppArgs, + ) + +import BasicTypes ( Boxity(..) ) +import HscTypes ( ForeignStubs(..) ) +import ForeignCall ( ForeignCall(..), CCallSpec(..), + Safety(..), playSafe, + CExportSpec(..), CLabelString, + CCallConv(..), ccallConvToInt, + ccallConvAttribute + ) +import TysWiredIn ( unitTy, tupleTyCon ) +import TysPrim ( addrPrimTy, mkStablePtrPrimTy, alphaTy ) +import PrelNames ( hasKey, ioTyConKey, stablePtrTyConName, newStablePtrName, bindIOName, + checkDotnetResName ) +import BasicTypes ( Activation( NeverActive ) ) +import SrcLoc ( Located(..), unLoc ) +import Outputable +import Maybe ( fromJust, isNothing ) +import FastString +\end{code} + +Desugaring of @foreign@ declarations is naturally split up into +parts, an @import@ and an @export@ part. A @foreign import@ +declaration +\begin{verbatim} + foreign import cc nm f :: prim_args -> IO prim_res +\end{verbatim} +is the same as +\begin{verbatim} + f :: prim_args -> IO prim_res + f a1 ... an = _ccall_ nm cc a1 ... an +\end{verbatim} +so we reuse the desugaring code in @DsCCall@ to deal with these. + +\begin{code} +type Binding = (Id, CoreExpr) -- No rec/nonrec structure; + -- the occurrence analyser will sort it all out + +dsForeigns :: [LForeignDecl Id] + -> DsM (ForeignStubs, [Binding]) +dsForeigns [] + = returnDs (NoStubs, []) +dsForeigns fos + = foldlDs combine (ForeignStubs empty empty [] [], []) fos + where + combine stubs (L loc decl) = putSrcSpanDs loc (combine1 stubs decl) + + combine1 (ForeignStubs acc_h acc_c acc_hdrs acc_feb, acc_f) + (ForeignImport id _ spec depr) + = traceIf (text "fi start" <+> ppr id) `thenDs` \ _ -> + dsFImport (unLoc id) spec `thenDs` \ (bs, h, c, mbhd) -> + warnDepr depr `thenDs` \ _ -> + traceIf (text "fi end" <+> ppr id) `thenDs` \ _ -> + returnDs (ForeignStubs (h $$ acc_h) + (c $$ acc_c) + (addH mbhd acc_hdrs) + acc_feb, + bs ++ acc_f) + + combine1 (ForeignStubs acc_h acc_c acc_hdrs acc_feb, acc_f) + (ForeignExport (L _ id) _ (CExport (CExportStatic ext_nm cconv)) depr) + = dsFExport id (idType id) + ext_nm cconv False `thenDs` \(h, c, _, _) -> + warnDepr depr `thenDs` \_ -> + returnDs (ForeignStubs (h $$ acc_h) (c $$ acc_c) acc_hdrs (id:acc_feb), + acc_f) + + addH Nothing ls = ls + addH (Just e) ls + | e `elem` ls = ls + | otherwise = e:ls + + warnDepr False = returnDs () + warnDepr True = dsWarn msg + where + msg = ptext SLIT("foreign declaration uses deprecated non-standard syntax") +\end{code} + + +%************************************************************************ +%* * +\subsection{Foreign import} +%* * +%************************************************************************ + +Desugaring foreign imports is just the matter of creating a binding +that on its RHS unboxes its arguments, performs the external call +(using the @CCallOp@ primop), before boxing the result up and returning it. + +However, we create a worker/wrapper pair, thus: + + foreign import f :: Int -> IO Int +==> + f x = IO ( \s -> case x of { I# x# -> + case fw s x# of { (# s1, y# #) -> + (# s1, I# y# #)}}) + + fw s x# = ccall f s x# + +The strictness/CPR analyser won't do this automatically because it doesn't look +inside returned tuples; but inlining this wrapper is a Really Good Idea +because it exposes the boxing to the call site. + +\begin{code} +dsFImport :: Id + -> ForeignImport + -> DsM ([Binding], SDoc, SDoc, Maybe FastString) +dsFImport id (CImport cconv safety header lib spec) + = dsCImport id spec cconv safety no_hdrs `thenDs` \(ids, h, c) -> + returnDs (ids, h, c, if no_hdrs then Nothing else Just header) + where + no_hdrs = nullFS header + + -- FIXME: the `lib' field is needed for .NET ILX generation when invoking + -- routines that are external to the .NET runtime, but GHC doesn't + -- support such calls yet; if `nullFastString lib', the value was not given +dsFImport id (DNImport spec) + = dsFCall id (DNCall spec) True {- No headers -} `thenDs` \(ids, h, c) -> + returnDs (ids, h, c, Nothing) + +dsCImport :: Id + -> CImportSpec + -> CCallConv + -> Safety + -> Bool -- True <=> no headers in the f.i decl + -> DsM ([Binding], SDoc, SDoc) +dsCImport id (CLabel cid) _ _ no_hdrs + = resultWrapper (idType id) `thenDs` \ (resTy, foRhs) -> + ASSERT(fromJust resTy `coreEqType` addrPrimTy) -- typechecker ensures this + let rhs = foRhs (mkLit (MachLabel cid Nothing)) in + returnDs ([(setImpInline no_hdrs id, rhs)], empty, empty) +dsCImport id (CFunction target) cconv safety no_hdrs + = dsFCall id (CCall (CCallSpec target cconv safety)) no_hdrs +dsCImport id CWrapper cconv _ _ + = dsFExportDynamic id cconv + +setImpInline :: Bool -- True <=> No #include headers + -- in the foreign import declaration + -> Id -> Id +-- If there is a #include header in the foreign import +-- we make the worker non-inlinable, because we currently +-- don't keep the #include stuff in the CCallId, and hence +-- it won't be visible in the importing module, which can be +-- fatal. +-- (The #include stuff is just collected from the foreign import +-- decls in a module.) +-- If you want to do cross-module inlining of the c-calls themselves, +-- put the #include stuff in the package spec, not the foreign +-- import decl. +setImpInline True id = id +setImpInline False id = id `setInlinePragma` NeverActive +\end{code} + + +%************************************************************************ +%* * +\subsection{Foreign calls} +%* * +%************************************************************************ + +\begin{code} +dsFCall fn_id fcall no_hdrs + = let + ty = idType fn_id + (tvs, fun_ty) = tcSplitForAllTys ty + (arg_tys, io_res_ty) = tcSplitFunTys fun_ty + -- Must use tcSplit* functions because we want to + -- see that (IO t) in the corner + in + newSysLocalsDs arg_tys `thenDs` \ args -> + mapAndUnzipDs unboxArg (map Var args) `thenDs` \ (val_args, arg_wrappers) -> + + let + work_arg_ids = [v | Var v <- val_args] -- All guaranteed to be vars + + forDotnet = + case fcall of + DNCall{} -> True + _ -> False + + topConDs + | forDotnet = + dsLookupGlobalId checkDotnetResName `thenDs` \ check_id -> + return (Just check_id) + | otherwise = return Nothing + + augmentResultDs + | forDotnet = + newSysLocalDs addrPrimTy `thenDs` \ err_res -> + returnDs (\ (mb_res_ty, resWrap) -> + case mb_res_ty of + Nothing -> (Just (mkTyConApp (tupleTyCon Unboxed 1) + [ addrPrimTy ]), + resWrap) + Just x -> (Just (mkTyConApp (tupleTyCon Unboxed 2) + [ x, addrPrimTy ]), + resWrap)) + | otherwise = returnDs id + in + augmentResultDs `thenDs` \ augment -> + topConDs `thenDs` \ topCon -> + boxResult augment topCon io_res_ty `thenDs` \ (ccall_result_ty, res_wrapper) -> + + newUnique `thenDs` \ ccall_uniq -> + newUnique `thenDs` \ work_uniq -> + let + -- Build the worker + worker_ty = mkForAllTys tvs (mkFunTys (map idType work_arg_ids) ccall_result_ty) + the_ccall_app = mkFCall ccall_uniq fcall val_args ccall_result_ty + work_rhs = mkLams tvs (mkLams work_arg_ids the_ccall_app) + work_id = setImpInline no_hdrs $ -- See comments with setImpInline + mkSysLocal FSLIT("$wccall") work_uniq worker_ty + + -- Build the wrapper + work_app = mkApps (mkVarApps (Var work_id) tvs) val_args + wrapper_body = foldr ($) (res_wrapper work_app) arg_wrappers + wrap_rhs = mkInlineMe (mkLams (tvs ++ args) wrapper_body) + in + returnDs ([(work_id, work_rhs), (fn_id, wrap_rhs)], empty, empty) + +unsafe_call (CCall (CCallSpec _ _ safety)) = playSafe safety +unsafe_call (DNCall _) = False +\end{code} + + +%************************************************************************ +%* * +\subsection{Foreign export} +%* * +%************************************************************************ + +The function that does most of the work for `@foreign export@' declarations. +(see below for the boilerplate code a `@foreign export@' declaration expands + into.) + +For each `@foreign export foo@' in a module M we generate: +\begin{itemize} +\item a C function `@foo@', which calls +\item a Haskell stub `@M.$ffoo@', which calls +\end{itemize} +the user-written Haskell function `@M.foo@'. + +\begin{code} +dsFExport :: Id -- Either the exported Id, + -- or the foreign-export-dynamic constructor + -> Type -- The type of the thing callable from C + -> CLabelString -- The name to export to C land + -> CCallConv + -> Bool -- True => foreign export dynamic + -- so invoke IO action that's hanging off + -- the first argument's stable pointer + -> DsM ( SDoc -- contents of Module_stub.h + , SDoc -- contents of Module_stub.c + , [MachRep] -- primitive arguments expected by stub function + , Int -- size of args to stub function + ) + +dsFExport fn_id ty ext_name cconv isDyn + = + let + (_tvs,sans_foralls) = tcSplitForAllTys ty + (fe_arg_tys', orig_res_ty) = tcSplitFunTys sans_foralls + -- We must use tcSplits here, because we want to see + -- the (IO t) in the corner of the type! + fe_arg_tys | isDyn = tail fe_arg_tys' + | otherwise = fe_arg_tys' + in + -- Look at the result type of the exported function, orig_res_ty + -- If it's IO t, return (t, True) + -- If it's plain t, return (t, False) + (case tcSplitTyConApp_maybe orig_res_ty of + -- We must use tcSplit here so that we see the (IO t) in + -- the type. [IO t is transparent to plain splitTyConApp.] + + Just (ioTyCon, [res_ty]) + -> ASSERT( ioTyCon `hasKey` ioTyConKey ) + -- The function already returns IO t + returnDs (res_ty, True) + + other -> -- The function returns t + returnDs (orig_res_ty, False) + ) + `thenDs` \ (res_ty, -- t + is_IO_res_ty) -> -- Bool + returnDs $ + mkFExportCBits ext_name + (if isDyn then Nothing else Just fn_id) + fe_arg_tys res_ty is_IO_res_ty cconv +\end{code} + +@foreign export dynamic@ lets you dress up Haskell IO actions +of some fixed type behind an externally callable interface (i.e., +as a C function pointer). Useful for callbacks and stuff. + +\begin{verbatim} +foreign export dynamic f :: (Addr -> Int -> IO Int) -> IO Addr + +-- Haskell-visible constructor, which is generated from the above: +-- SUP: No check for NULL from createAdjustor anymore??? + +f :: (Addr -> Int -> IO Int) -> IO Addr +f cback = + bindIO (newStablePtr cback) + (\StablePtr sp# -> IO (\s1# -> + case _ccall_ createAdjustor cconv sp# ``f_helper'' s1# of + (# s2#, a# #) -> (# s2#, A# a# #))) + +foreign export "f_helper" f_helper :: StablePtr (Addr -> Int -> IO Int) -> Addr -> Int -> IO Int +-- `special' foreign export that invokes the closure pointed to by the +-- first argument. +\end{verbatim} + +\begin{code} +dsFExportDynamic :: Id + -> CCallConv + -> DsM ([Binding], SDoc, SDoc) +dsFExportDynamic id cconv + = newSysLocalDs ty `thenDs` \ fe_id -> + getModuleDs `thenDs` \ mod_name -> + let + -- hack: need to get at the name of the C stub we're about to generate. + fe_nm = mkFastString (unpackFS (zEncodeFS (moduleFS mod_name)) ++ "_" ++ toCName fe_id) + in + newSysLocalDs arg_ty `thenDs` \ cback -> + dsLookupGlobalId newStablePtrName `thenDs` \ newStablePtrId -> + dsLookupTyCon stablePtrTyConName `thenDs` \ stable_ptr_tycon -> + let + mk_stbl_ptr_app = mkApps (Var newStablePtrId) [ Type arg_ty, Var cback ] + stable_ptr_ty = mkTyConApp stable_ptr_tycon [arg_ty] + export_ty = mkFunTy stable_ptr_ty arg_ty + in + dsLookupGlobalId bindIOName `thenDs` \ bindIOId -> + newSysLocalDs stable_ptr_ty `thenDs` \ stbl_value -> + dsFExport id export_ty fe_nm cconv True + `thenDs` \ (h_code, c_code, arg_reps, args_size) -> + let + stbl_app cont ret_ty = mkApps (Var bindIOId) + [ Type stable_ptr_ty + , Type ret_ty + , mk_stbl_ptr_app + , cont + ] + {- + The arguments to the external function which will + create a little bit of (template) code on the fly + for allowing the (stable pointed) Haskell closure + to be entered using an external calling convention + (stdcall, ccall). + -} + adj_args = [ mkIntLitInt (ccallConvToInt cconv) + , Var stbl_value + , mkLit (MachLabel fe_nm mb_sz_args) + , mkLit (mkStringLit arg_type_info) + ] + -- name of external entry point providing these services. + -- (probably in the RTS.) + adjustor = FSLIT("createAdjustor") + + arg_type_info = map repCharCode arg_reps + repCharCode F32 = 'f' + repCharCode F64 = 'd' + repCharCode I64 = 'l' + repCharCode _ = 'i' + + -- Determine the number of bytes of arguments to the stub function, + -- so that we can attach the '@N' suffix to its label if it is a + -- stdcall on Windows. + mb_sz_args = case cconv of + StdCallConv -> Just args_size + _ -> Nothing + + in + dsCCall adjustor adj_args PlayRisky io_res_ty `thenDs` \ ccall_adj -> + -- PlayRisky: the adjustor doesn't allocate in the Haskell heap or do a callback + let ccall_adj_ty = exprType ccall_adj + ccall_io_adj = mkLams [stbl_value] $ + Note (Coerce io_res_ty ccall_adj_ty) + ccall_adj + io_app = mkLams tvs $ + mkLams [cback] $ + stbl_app ccall_io_adj res_ty + fed = (id `setInlinePragma` NeverActive, io_app) + -- Never inline the f.e.d. function, because the litlit + -- might not be in scope in other modules. + in + returnDs ([fed], h_code, c_code) + + where + ty = idType id + (tvs,sans_foralls) = tcSplitForAllTys ty + ([arg_ty], io_res_ty) = tcSplitFunTys sans_foralls + [res_ty] = tcTyConAppArgs io_res_ty + -- Must use tcSplit* to see the (IO t), which is a newtype + +toCName :: Id -> String +toCName i = showSDoc (pprCode CStyle (ppr (idName i))) +\end{code} + +%* +% +\subsection{Generating @foreign export@ stubs} +% +%* + +For each @foreign export@ function, a C stub function is generated. +The C stub constructs the application of the exported Haskell function +using the hugs/ghc rts invocation API. + +\begin{code} +mkFExportCBits :: FastString + -> Maybe Id -- Just==static, Nothing==dynamic + -> [Type] + -> Type + -> Bool -- True <=> returns an IO type + -> CCallConv + -> (SDoc, + SDoc, + [MachRep], -- the argument reps + Int -- total size of arguments + ) +mkFExportCBits c_nm maybe_target arg_htys res_hty is_IO_res_ty cc + = (header_bits, c_bits, + [rep | (_,_,_,rep) <- arg_info], -- just the real args + sum [ machRepByteWidth rep | (_,_,_,rep) <- aug_arg_info] -- all the args + ) + where + -- list the arguments to the C function + arg_info :: [(SDoc, -- arg name + SDoc, -- C type + Type, -- Haskell type + MachRep)] -- the MachRep + arg_info = [ (text ('a':show n), showStgType ty, ty, + typeMachRep (getPrimTyOf ty)) + | (ty,n) <- zip arg_htys [1..] ] + + -- add some auxiliary args; the stable ptr in the wrapper case, and + -- a slot for the dummy return address in the wrapper + ccall case + aug_arg_info + | isNothing maybe_target = stable_ptr_arg : insertRetAddr cc arg_info + | otherwise = arg_info + + stable_ptr_arg = + (text "the_stableptr", text "StgStablePtr", undefined, + typeMachRep (mkStablePtrPrimTy alphaTy)) + + -- stuff to do with the return type of the C function + res_hty_is_unit = res_hty `coreEqType` unitTy -- Look through any newtypes + + cResType | res_hty_is_unit = text "void" + | otherwise = showStgType res_hty + + -- Now we can cook up the prototype for the exported function. + pprCconv = case cc of + CCallConv -> empty + StdCallConv -> text (ccallConvAttribute cc) + + header_bits = ptext SLIT("extern") <+> fun_proto <> semi + + fun_proto = cResType <+> pprCconv <+> ftext c_nm <> + parens (hsep (punctuate comma (map (\(nm,ty,_,_) -> ty <+> nm) + aug_arg_info))) + + -- the target which will form the root of what we ask rts_evalIO to run + the_cfun + = case maybe_target of + Nothing -> text "(StgClosure*)deRefStablePtr(the_stableptr)" + Just hs_fn -> char '&' <> ppr hs_fn <> text "_closure" + + cap = text "cap" <> comma + + -- the expression we give to rts_evalIO + expr_to_run + = foldl appArg the_cfun arg_info -- NOT aug_arg_info + where + appArg acc (arg_cname, _, arg_hty, _) + = text "rts_apply" + <> parens (cap <> acc <> comma <> mkHObj arg_hty <> parens (cap <> arg_cname)) + + -- various other bits for inside the fn + declareResult = text "HaskellObj ret;" + declareCResult | res_hty_is_unit = empty + | otherwise = cResType <+> text "cret;" + + assignCResult | res_hty_is_unit = empty + | otherwise = + text "cret=" <> unpackHObj res_hty <> parens (text "ret") <> semi + + -- an extern decl for the fn being called + extern_decl + = case maybe_target of + Nothing -> empty + Just hs_fn -> text "extern StgClosure " <> ppr hs_fn <> text "_closure" <> semi + + + -- Initialise foreign exports by registering a stable pointer from an + -- __attribute__((constructor)) function. + -- The alternative is to do this from stginit functions generated in + -- codeGen/CodeGen.lhs; however, stginit functions have a negative impact + -- on binary sizes and link times because the static linker will think that + -- all modules that are imported directly or indirectly are actually used by + -- the program. + -- (this is bad for big umbrella modules like Graphics.Rendering.OpenGL) + + initialiser + = case maybe_target of + Nothing -> empty + Just hs_fn -> + vcat + [ text "static void stginit_export_" <> ppr hs_fn + <> text "() __attribute__((constructor));" + , text "static void stginit_export_" <> ppr hs_fn <> text "()" + , braces (text "getStablePtr" + <> parens (text "(StgPtr) &" <> ppr hs_fn <> text "_closure") + <> semi) + ] + + -- finally, the whole darn thing + c_bits = + space $$ + extern_decl $$ + fun_proto $$ + vcat + [ lbrace + , text "Capability *cap;" + , declareResult + , declareCResult + , text "cap = rts_lock();" + -- create the application + perform it. + , text "cap=rts_evalIO" <> parens ( + cap <> + text "rts_apply" <> parens ( + cap <> + text "(HaskellObj)" + <> text (if is_IO_res_ty + then "runIO_closure" + else "runNonIO_closure") + <> comma + <> expr_to_run + ) <+> comma + <> text "&ret" + ) <> semi + , text "rts_checkSchedStatus" <> parens (doubleQuotes (ftext c_nm) + <> comma <> text "cap") <> semi + , assignCResult + , text "rts_unlock(cap);" + , if res_hty_is_unit then empty + else text "return cret;" + , rbrace + ] $$ + initialiser + +-- NB. the calculation here isn't strictly speaking correct. +-- We have a primitive Haskell type (eg. Int#, Double#), and +-- we want to know the size, when passed on the C stack, of +-- the associated C type (eg. HsInt, HsDouble). We don't have +-- this information to hand, but we know what GHC's conventions +-- are for passing around the primitive Haskell types, so we +-- use that instead. I hope the two coincide --SDM +typeMachRep ty = argMachRep (typeCgRep ty) + +mkHObj :: Type -> SDoc +mkHObj t = text "rts_mk" <> text (showFFIType t) + +unpackHObj :: Type -> SDoc +unpackHObj t = text "rts_get" <> text (showFFIType t) + +showStgType :: Type -> SDoc +showStgType t = text "Hs" <> text (showFFIType t) + +showFFIType :: Type -> String +showFFIType t = getOccString (getName tc) + where + tc = case tcSplitTyConApp_maybe (repType t) of + Just (tc,_) -> tc + Nothing -> pprPanic "showFFIType" (ppr t) + +#if !defined(x86_64_TARGET_ARCH) +insertRetAddr CCallConv args = ret_addr_arg : args +insertRetAddr _ args = args +#else +-- On x86_64 we insert the return address after the 6th +-- integer argument, because this is the point at which we +-- need to flush a register argument to the stack (See rts/Adjustor.c for +-- details). +insertRetAddr CCallConv args = go 0 args + where go 6 args = ret_addr_arg : args + go n (arg@(_,_,_,rep):args) + | I64 <- rep = arg : go (n+1) args + | otherwise = arg : go n args + go n [] = [] +insertRetAddr _ args = args +#endif + +ret_addr_arg = (text "original_return_addr", text "void*", undefined, + typeMachRep addrPrimTy) + +-- This function returns the primitive type associated with the boxed +-- type argument to a foreign export (eg. Int ==> Int#). It assumes +-- that all the types we are interested in have a single constructor +-- with a single primitive-typed argument, which is true for all of the legal +-- foreign export argument types (see TcType.legalFEArgTyCon). +getPrimTyOf :: Type -> Type +getPrimTyOf ty = + case splitProductType_maybe (repType ty) of + Just (_, _, data_con, [prim_ty]) -> + ASSERT(dataConSourceArity data_con == 1) + ASSERT2(isUnLiftedType prim_ty, ppr prim_ty) + prim_ty + _other -> pprPanic "DsForeign.getPrimTyOf" (ppr ty) +\end{code} |