{-# LANGUAGE CPP #-} -- | Handy functions for creating much Core syntax module MkCore ( -- * Constructing normal syntax mkCoreLet, mkCoreLets, mkCoreApp, mkCoreApps, mkCoreConApps, mkCoreLams, mkWildCase, mkIfThenElse, mkWildValBinder, mkWildEvBinder, sortQuantVars, castBottomExpr, -- * Constructing boxed literals mkWordExpr, mkWordExprWord, mkIntExpr, mkIntExprInt, mkIntegerExpr, mkNaturalExpr, mkFloatExpr, mkDoubleExpr, mkCharExpr, mkStringExpr, mkStringExprFS, mkStringExprFSWith, -- * Floats FloatBind(..), wrapFloat, -- * Constructing small tuples mkCoreVarTup, mkCoreVarTupTy, mkCoreTup, mkCoreUbxTup, mkCoreTupBoxity, unitExpr, -- * Constructing big tuples mkBigCoreVarTup, mkBigCoreVarTup1, mkBigCoreVarTupTy, mkBigCoreTupTy, mkBigCoreTup, -- * Deconstructing small tuples mkSmallTupleSelector, mkSmallTupleCase, -- * Deconstructing big tuples mkTupleSelector, mkTupleSelector1, mkTupleCase, -- * Constructing list expressions mkNilExpr, mkConsExpr, mkListExpr, mkFoldrExpr, mkBuildExpr, -- * Constructing Maybe expressions mkNothingExpr, mkJustExpr, -- * Error Ids mkRuntimeErrorApp, mkImpossibleExpr, errorIds, rEC_CON_ERROR_ID, iRREFUT_PAT_ERROR_ID, rUNTIME_ERROR_ID, nON_EXHAUSTIVE_GUARDS_ERROR_ID, nO_METHOD_BINDING_ERROR_ID, pAT_ERROR_ID, rEC_SEL_ERROR_ID, aBSENT_ERROR_ID, tYPE_ERROR_ID, ) where #include "HsVersions.h" import Id import Var ( EvVar, setTyVarUnique ) import CoreSyn import CoreUtils ( exprType, needsCaseBinding, bindNonRec ) import Literal import HscTypes import TysWiredIn import PrelNames import HsUtils ( mkChunkified, chunkify ) import TcType ( mkSpecSigmaTy ) import Type import Coercion ( isCoVar ) import TysPrim import DataCon ( DataCon, dataConWorkId ) import IdInfo ( vanillaIdInfo, setStrictnessInfo, setArityInfo ) import Demand import Name hiding ( varName ) import Outputable import FastString import UniqSupply import BasicTypes import Util import DynFlags import Data.List import Data.Char ( ord ) infixl 4 `mkCoreApp`, `mkCoreApps` {- ************************************************************************ * * \subsection{Basic CoreSyn construction} * * ************************************************************************ -} sortQuantVars :: [Var] -> [Var] -- Sort the variables, putting type and covars first, in scoped order, -- and then other Ids -- It is a deterministic sort, meaining it doesn't look at the values of -- Uniques. For explanation why it's important See Note [Unique Determinism] -- in Unique. sortQuantVars vs = sorted_tcvs ++ ids where (tcvs, ids) = partition (isTyVar <||> isCoVar) vs sorted_tcvs = toposortTyVars tcvs -- | Bind a binding group over an expression, using a @let@ or @case@ as -- appropriate (see "CoreSyn#let_app_invariant") mkCoreLet :: CoreBind -> CoreExpr -> CoreExpr mkCoreLet (NonRec bndr rhs) body -- See Note [CoreSyn let/app invariant] | needsCaseBinding (idType bndr) rhs , not (isJoinId bndr) = Case rhs bndr (exprType body) [(DEFAULT,[],body)] mkCoreLet bind body = Let bind body -- | Bind a list of binding groups over an expression. The leftmost binding -- group becomes the outermost group in the resulting expression mkCoreLets :: [CoreBind] -> CoreExpr -> CoreExpr mkCoreLets binds body = foldr mkCoreLet body binds -- | Construct an expression which represents the application of one expression -- to the other mkCoreApp :: SDoc -> CoreExpr -> CoreExpr -> CoreExpr -- Respects the let/app invariant by building a case expression where necessary -- See CoreSyn Note [CoreSyn let/app invariant] mkCoreApp _ fun (Type ty) = App fun (Type ty) mkCoreApp _ fun (Coercion co) = App fun (Coercion co) mkCoreApp d fun arg = ASSERT2( isFunTy fun_ty, ppr fun $$ ppr arg $$ d ) mk_val_app fun arg arg_ty res_ty where fun_ty = exprType fun (arg_ty, res_ty) = splitFunTy fun_ty -- | Construct an expression which represents the application of a number of -- expressions to another. The leftmost expression in the list is applied first -- Respects the let/app invariant by building a case expression where necessary -- See CoreSyn Note [CoreSyn let/app invariant] mkCoreApps :: CoreExpr -> [CoreExpr] -> CoreExpr -- Slightly more efficient version of (foldl mkCoreApp) mkCoreApps orig_fun orig_args = go orig_fun (exprType orig_fun) orig_args where go fun _ [] = fun go fun fun_ty (Type ty : args) = go (App fun (Type ty)) (piResultTy fun_ty ty) args go fun fun_ty (arg : args) = ASSERT2( isFunTy fun_ty, ppr fun_ty $$ ppr orig_fun $$ ppr orig_args ) go (mk_val_app fun arg arg_ty res_ty) res_ty args where (arg_ty, res_ty) = splitFunTy fun_ty -- | Construct an expression which represents the application of a number of -- expressions to that of a data constructor expression. The leftmost expression -- in the list is applied first mkCoreConApps :: DataCon -> [CoreExpr] -> CoreExpr mkCoreConApps con args = mkCoreApps (Var (dataConWorkId con)) args mk_val_app :: CoreExpr -> CoreExpr -> Type -> Type -> CoreExpr -- Build an application (e1 e2), -- or a strict binding (case e2 of x -> e1 x) -- using the latter when necessary to respect the let/app invariant -- See Note [CoreSyn let/app invariant] mk_val_app fun arg arg_ty res_ty | not (needsCaseBinding arg_ty arg) = App fun arg -- The vastly common case | otherwise = Case arg arg_id res_ty [(DEFAULT,[],App fun (Var arg_id))] where arg_id = mkWildValBinder arg_ty -- Lots of shadowing, but it doesn't matter, -- because 'fun ' should not have a free wild-id -- -- This is Dangerous. But this is the only place we play this -- game, mk_val_app returns an expression that does not have -- have a free wild-id. So the only thing that can go wrong -- is if you take apart this case expression, and pass a -- fragment of it as the fun part of a 'mk_val_app'. ----------- mkWildEvBinder :: PredType -> EvVar mkWildEvBinder pred = mkWildValBinder pred -- | Make a /wildcard binder/. This is typically used when you need a binder -- that you expect to use only at a *binding* site. Do not use it at -- occurrence sites because it has a single, fixed unique, and it's very -- easy to get into difficulties with shadowing. That's why it is used so little. -- See Note [WildCard binders] in SimplEnv mkWildValBinder :: Type -> Id mkWildValBinder ty = mkLocalIdOrCoVar wildCardName ty mkWildCase :: CoreExpr -> Type -> Type -> [CoreAlt] -> CoreExpr -- Make a case expression whose case binder is unused -- The alts should not have any occurrences of WildId mkWildCase scrut scrut_ty res_ty alts = Case scrut (mkWildValBinder scrut_ty) res_ty alts mkIfThenElse :: CoreExpr -> CoreExpr -> CoreExpr -> CoreExpr mkIfThenElse guard then_expr else_expr -- Not going to be refining, so okay to take the type of the "then" clause = mkWildCase guard boolTy (exprType then_expr) [ (DataAlt falseDataCon, [], else_expr), -- Increasing order of tag! (DataAlt trueDataCon, [], then_expr) ] castBottomExpr :: CoreExpr -> Type -> CoreExpr -- (castBottomExpr e ty), assuming that 'e' diverges, -- return an expression of type 'ty' -- See Note [Empty case alternatives] in CoreSyn castBottomExpr e res_ty | e_ty `eqType` res_ty = e | otherwise = Case e (mkWildValBinder e_ty) res_ty [] where e_ty = exprType e {- The functions from this point don't really do anything cleverer than their counterparts in CoreSyn, but they are here for consistency -} -- | Create a lambda where the given expression has a number of variables -- bound over it. The leftmost binder is that bound by the outermost -- lambda in the result mkCoreLams :: [CoreBndr] -> CoreExpr -> CoreExpr mkCoreLams = mkLams {- ************************************************************************ * * \subsection{Making literals} * * ************************************************************************ -} -- | Create a 'CoreExpr' which will evaluate to the given @Int@ mkIntExpr :: DynFlags -> Integer -> CoreExpr -- Result = I# i :: Int mkIntExpr dflags i = mkCoreConApps intDataCon [mkIntLit dflags i] -- | Create a 'CoreExpr' which will evaluate to the given @Int@ mkIntExprInt :: DynFlags -> Int -> CoreExpr -- Result = I# i :: Int mkIntExprInt dflags i = mkCoreConApps intDataCon [mkIntLitInt dflags i] -- | Create a 'CoreExpr' which will evaluate to the a @Word@ with the given value mkWordExpr :: DynFlags -> Integer -> CoreExpr mkWordExpr dflags w = mkCoreConApps wordDataCon [mkWordLit dflags w] -- | Create a 'CoreExpr' which will evaluate to the given @Word@ mkWordExprWord :: DynFlags -> Word -> CoreExpr mkWordExprWord dflags w = mkCoreConApps wordDataCon [mkWordLitWord dflags w] -- | Create a 'CoreExpr' which will evaluate to the given @Integer@ mkIntegerExpr :: MonadThings m => Integer -> m CoreExpr -- Result :: Integer mkIntegerExpr i = do t <- lookupTyCon integerTyConName return (Lit (mkLitInteger i (mkTyConTy t))) -- | Create a 'CoreExpr' which will evaluate to the given @Natural@ -- -- TODO: should we add LitNatural to Core? mkNaturalExpr :: MonadThings m => Integer -> m CoreExpr -- Result :: Natural mkNaturalExpr i = do iExpr <- mkIntegerExpr i fiExpr <- lookupId naturalFromIntegerName return (mkCoreApps (Var fiExpr) [iExpr]) -- | Create a 'CoreExpr' which will evaluate to the given @Float@ mkFloatExpr :: Float -> CoreExpr mkFloatExpr f = mkCoreConApps floatDataCon [mkFloatLitFloat f] -- | Create a 'CoreExpr' which will evaluate to the given @Double@ mkDoubleExpr :: Double -> CoreExpr mkDoubleExpr d = mkCoreConApps doubleDataCon [mkDoubleLitDouble d] -- | Create a 'CoreExpr' which will evaluate to the given @Char@ mkCharExpr :: Char -> CoreExpr -- Result = C# c :: Int mkCharExpr c = mkCoreConApps charDataCon [mkCharLit c] -- | Create a 'CoreExpr' which will evaluate to the given @String@ mkStringExpr :: MonadThings m => String -> m CoreExpr -- Result :: String -- | Create a 'CoreExpr' which will evaluate to a string morally equivalent to the given @FastString@ mkStringExprFS :: MonadThings m => FastString -> m CoreExpr -- Result :: String mkStringExpr str = mkStringExprFS (mkFastString str) mkStringExprFS = mkStringExprFSWith lookupId mkStringExprFSWith :: Monad m => (Name -> m Id) -> FastString -> m CoreExpr mkStringExprFSWith lookupM str | nullFS str = return (mkNilExpr charTy) | all safeChar chars = do unpack_id <- lookupM unpackCStringName return (App (Var unpack_id) lit) | otherwise = do unpack_utf8_id <- lookupM unpackCStringUtf8Name return (App (Var unpack_utf8_id) lit) where chars = unpackFS str safeChar c = ord c >= 1 && ord c <= 0x7F lit = Lit (MachStr (fastStringToByteString str)) {- ************************************************************************ * * \subsection{Tuple constructors} * * ************************************************************************ -} {- Creating tuples and their types for Core expressions @mkBigCoreVarTup@ builds a tuple; the inverse to @mkTupleSelector@. * If it has only one element, it is the identity function. * If there are more elements than a big tuple can have, it nests the tuples. Note [Flattening one-tuples] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ This family of functions creates a tuple of variables/expressions/types. mkCoreTup [e1,e2,e3] = (e1,e2,e3) What if there is just one variable/expression/type in the argument? We could do one of two things: * Flatten it out, so that mkCoreTup [e1] = e1 * Built a one-tuple (see Note [One-tuples] in TysWiredIn) mkCoreTup1 [e1] = Unit e1 We use a suffix "1" to indicate this. Usually we want the former, but occasionally the latter. -} -- | Build a small tuple holding the specified variables -- One-tuples are flattened; see Note [Flattening one-tuples] mkCoreVarTup :: [Id] -> CoreExpr mkCoreVarTup ids = mkCoreTup (map Var ids) -- | Build the type of a small tuple that holds the specified variables -- One-tuples are flattened; see Note [Flattening one-tuples] mkCoreVarTupTy :: [Id] -> Type mkCoreVarTupTy ids = mkBoxedTupleTy (map idType ids) -- | Build a small tuple holding the specified expressions -- One-tuples are flattened; see Note [Flattening one-tuples] mkCoreTup :: [CoreExpr] -> CoreExpr mkCoreTup [] = Var unitDataConId mkCoreTup [c] = c mkCoreTup cs = mkCoreConApps (tupleDataCon Boxed (length cs)) (map (Type . exprType) cs ++ cs) -- | Build a small unboxed tuple holding the specified expressions, -- with the given types. The types must be the types of the expressions. -- Do not include the RuntimeRep specifiers; this function calculates them -- for you. -- Does /not/ flatten one-tuples; see Note [Flattening one-tuples] mkCoreUbxTup :: [Type] -> [CoreExpr] -> CoreExpr mkCoreUbxTup tys exps = ASSERT( tys `equalLength` exps) mkCoreConApps (tupleDataCon Unboxed (length tys)) (map (Type . getRuntimeRep "mkCoreUbxTup") tys ++ map Type tys ++ exps) -- | Make a core tuple of the given boxity mkCoreTupBoxity :: Boxity -> [CoreExpr] -> CoreExpr mkCoreTupBoxity Boxed exps = mkCoreTup exps mkCoreTupBoxity Unboxed exps = mkCoreUbxTup (map exprType exps) exps -- | Build a big tuple holding the specified variables -- One-tuples are flattened; see Note [Flattening one-tuples] mkBigCoreVarTup :: [Id] -> CoreExpr mkBigCoreVarTup ids = mkBigCoreTup (map Var ids) mkBigCoreVarTup1 :: [Id] -> CoreExpr -- Same as mkBigCoreVarTup, but one-tuples are NOT flattened -- see Note [Flattening one-tuples] mkBigCoreVarTup1 [id] = mkCoreConApps (tupleDataCon Boxed 1) [Type (idType id), Var id] mkBigCoreVarTup1 ids = mkBigCoreTup (map Var ids) -- | Build the type of a big tuple that holds the specified variables -- One-tuples are flattened; see Note [Flattening one-tuples] mkBigCoreVarTupTy :: [Id] -> Type mkBigCoreVarTupTy ids = mkBigCoreTupTy (map idType ids) -- | Build a big tuple holding the specified expressions -- One-tuples are flattened; see Note [Flattening one-tuples] mkBigCoreTup :: [CoreExpr] -> CoreExpr mkBigCoreTup = mkChunkified mkCoreTup -- | Build the type of a big tuple that holds the specified type of thing -- One-tuples are flattened; see Note [Flattening one-tuples] mkBigCoreTupTy :: [Type] -> Type mkBigCoreTupTy = mkChunkified mkBoxedTupleTy -- | The unit expression unitExpr :: CoreExpr unitExpr = Var unitDataConId {- ************************************************************************ * * \subsection{Tuple destructors} * * ************************************************************************ -} -- | Builds a selector which scrutises the given -- expression and extracts the one name from the list given. -- If you want the no-shadowing rule to apply, the caller -- is responsible for making sure that none of these names -- are in scope. -- -- If there is just one 'Id' in the tuple, then the selector is -- just the identity. -- -- If necessary, we pattern match on a \"big\" tuple. mkTupleSelector, mkTupleSelector1 :: [Id] -- ^ The 'Id's to pattern match the tuple against -> Id -- ^ The 'Id' to select -> Id -- ^ A variable of the same type as the scrutinee -> CoreExpr -- ^ Scrutinee -> CoreExpr -- ^ Selector expression -- mkTupleSelector [a,b,c,d] b v e -- = case e of v { -- (p,q) -> case p of p { -- (a,b) -> b }} -- We use 'tpl' vars for the p,q, since shadowing does not matter. -- -- In fact, it's more convenient to generate it innermost first, getting -- -- case (case e of v -- (p,q) -> p) of p -- (a,b) -> b mkTupleSelector vars the_var scrut_var scrut = mk_tup_sel (chunkify vars) the_var where mk_tup_sel [vars] the_var = mkSmallTupleSelector vars the_var scrut_var scrut mk_tup_sel vars_s the_var = mkSmallTupleSelector group the_var tpl_v $ mk_tup_sel (chunkify tpl_vs) tpl_v where tpl_tys = [mkBoxedTupleTy (map idType gp) | gp <- vars_s] tpl_vs = mkTemplateLocals tpl_tys [(tpl_v, group)] = [(tpl,gp) | (tpl,gp) <- zipEqual "mkTupleSelector" tpl_vs vars_s, the_var `elem` gp ] -- ^ 'mkTupleSelector1' is like 'mkTupleSelector' -- but one-tuples are NOT flattened (see Note [Flattening one-tuples]) mkTupleSelector1 vars the_var scrut_var scrut | [_] <- vars = mkSmallTupleSelector1 vars the_var scrut_var scrut | otherwise = mkTupleSelector vars the_var scrut_var scrut -- | Like 'mkTupleSelector' but for tuples that are guaranteed -- never to be \"big\". -- -- > mkSmallTupleSelector [x] x v e = [| e |] -- > mkSmallTupleSelector [x,y,z] x v e = [| case e of v { (x,y,z) -> x } |] mkSmallTupleSelector, mkSmallTupleSelector1 :: [Id] -- The tuple args -> Id -- The selected one -> Id -- A variable of the same type as the scrutinee -> CoreExpr -- Scrutinee -> CoreExpr mkSmallTupleSelector [var] should_be_the_same_var _ scrut = ASSERT(var == should_be_the_same_var) scrut -- Special case for 1-tuples mkSmallTupleSelector vars the_var scrut_var scrut = mkSmallTupleSelector1 vars the_var scrut_var scrut -- ^ 'mkSmallTupleSelector1' is like 'mkSmallTupleSelector' -- but one-tuples are NOT flattened (see Note [Flattening one-tuples]) mkSmallTupleSelector1 vars the_var scrut_var scrut = ASSERT( notNull vars ) Case scrut scrut_var (idType the_var) [(DataAlt (tupleDataCon Boxed (length vars)), vars, Var the_var)] -- | A generalization of 'mkTupleSelector', allowing the body -- of the case to be an arbitrary expression. -- -- To avoid shadowing, we use uniques to invent new variables. -- -- If necessary we pattern match on a \"big\" tuple. mkTupleCase :: UniqSupply -- ^ For inventing names of intermediate variables -> [Id] -- ^ The tuple identifiers to pattern match on -> CoreExpr -- ^ Body of the case -> Id -- ^ A variable of the same type as the scrutinee -> CoreExpr -- ^ Scrutinee -> CoreExpr -- ToDo: eliminate cases where none of the variables are needed. -- -- mkTupleCase uniqs [a,b,c,d] body v e -- = case e of v { (p,q) -> -- case p of p { (a,b) -> -- case q of q { (c,d) -> -- body }}} mkTupleCase uniqs vars body scrut_var scrut = mk_tuple_case uniqs (chunkify vars) body where -- This is the case where don't need any nesting mk_tuple_case _ [vars] body = mkSmallTupleCase vars body scrut_var scrut -- This is the case where we must make nest tuples at least once mk_tuple_case us vars_s body = let (us', vars', body') = foldr one_tuple_case (us, [], body) vars_s in mk_tuple_case us' (chunkify vars') body' one_tuple_case chunk_vars (us, vs, body) = let (uniq, us') = takeUniqFromSupply us scrut_var = mkSysLocal (fsLit "ds") uniq (mkBoxedTupleTy (map idType chunk_vars)) body' = mkSmallTupleCase chunk_vars body scrut_var (Var scrut_var) in (us', scrut_var:vs, body') -- | As 'mkTupleCase', but for a tuple that is small enough to be guaranteed -- not to need nesting. mkSmallTupleCase :: [Id] -- ^ The tuple args -> CoreExpr -- ^ Body of the case -> Id -- ^ A variable of the same type as the scrutinee -> CoreExpr -- ^ Scrutinee -> CoreExpr mkSmallTupleCase [var] body _scrut_var scrut = bindNonRec var scrut body mkSmallTupleCase vars body scrut_var scrut -- One branch no refinement? = Case scrut scrut_var (exprType body) [(DataAlt (tupleDataCon Boxed (length vars)), vars, body)] {- ************************************************************************ * * Floats * * ************************************************************************ -} data FloatBind = FloatLet CoreBind | FloatCase CoreExpr Id AltCon [Var] -- case e of y { C ys -> ... } -- See Note [Floating cases] in SetLevels instance Outputable FloatBind where ppr (FloatLet b) = text "LET" <+> ppr b ppr (FloatCase e b c bs) = hang (text "CASE" <+> ppr e <+> ptext (sLit "of") <+> ppr b) 2 (ppr c <+> ppr bs) wrapFloat :: FloatBind -> CoreExpr -> CoreExpr wrapFloat (FloatLet defns) body = Let defns body wrapFloat (FloatCase e b con bs) body = Case e b (exprType body) [(con, bs, body)] {- ************************************************************************ * * \subsection{Common list manipulation expressions} * * ************************************************************************ Call the constructor Ids when building explicit lists, so that they interact well with rules. -} -- | Makes a list @[]@ for lists of the specified type mkNilExpr :: Type -> CoreExpr mkNilExpr ty = mkCoreConApps nilDataCon [Type ty] -- | Makes a list @(:)@ for lists of the specified type mkConsExpr :: Type -> CoreExpr -> CoreExpr -> CoreExpr mkConsExpr ty hd tl = mkCoreConApps consDataCon [Type ty, hd, tl] -- | Make a list containing the given expressions, where the list has the given type mkListExpr :: Type -> [CoreExpr] -> CoreExpr mkListExpr ty xs = foldr (mkConsExpr ty) (mkNilExpr ty) xs -- | Make a fully applied 'foldr' expression mkFoldrExpr :: MonadThings m => Type -- ^ Element type of the list -> Type -- ^ Fold result type -> CoreExpr -- ^ "Cons" function expression for the fold -> CoreExpr -- ^ "Nil" expression for the fold -> CoreExpr -- ^ List expression being folded acress -> m CoreExpr mkFoldrExpr elt_ty result_ty c n list = do foldr_id <- lookupId foldrName return (Var foldr_id `App` Type elt_ty `App` Type result_ty `App` c `App` n `App` list) -- | Make a 'build' expression applied to a locally-bound worker function mkBuildExpr :: (MonadThings m, MonadUnique m) => Type -- ^ Type of list elements to be built -> ((Id, Type) -> (Id, Type) -> m CoreExpr) -- ^ Function that, given information about the 'Id's -- of the binders for the build worker function, returns -- the body of that worker -> m CoreExpr mkBuildExpr elt_ty mk_build_inside = do [n_tyvar] <- newTyVars [alphaTyVar] let n_ty = mkTyVarTy n_tyvar c_ty = mkFunTys [elt_ty, n_ty] n_ty [c, n] <- sequence [mkSysLocalM (fsLit "c") c_ty, mkSysLocalM (fsLit "n") n_ty] build_inside <- mk_build_inside (c, c_ty) (n, n_ty) build_id <- lookupId buildName return $ Var build_id `App` Type elt_ty `App` mkLams [n_tyvar, c, n] build_inside where newTyVars tyvar_tmpls = do uniqs <- getUniquesM return (zipWith setTyVarUnique tyvar_tmpls uniqs) {- ************************************************************************ * * Manipulating Maybe data type * * ************************************************************************ -} -- | Makes a Nothing for the specified type mkNothingExpr :: Type -> CoreExpr mkNothingExpr ty = mkConApp nothingDataCon [Type ty] -- | Makes a Just from a value of the specified type mkJustExpr :: Type -> CoreExpr -> CoreExpr mkJustExpr ty val = mkConApp justDataCon [Type ty, val] {- ************************************************************************ * * Error expressions * * ************************************************************************ -} mkRuntimeErrorApp :: Id -- Should be of type (forall a. Addr# -> a) -- where Addr# points to a UTF8 encoded string -> Type -- The type to instantiate 'a' -> String -- The string to print -> CoreExpr mkRuntimeErrorApp err_id res_ty err_msg = mkApps (Var err_id) [ Type (getRuntimeRep "mkRuntimeErrorApp" res_ty) , Type res_ty, err_string ] where err_string = Lit (mkMachString err_msg) mkImpossibleExpr :: Type -> CoreExpr mkImpossibleExpr res_ty = mkRuntimeErrorApp rUNTIME_ERROR_ID res_ty "Impossible case alternative" {- ************************************************************************ * * Error Ids * * ************************************************************************ GHC randomly injects these into the code. @patError@ is just a version of @error@ for pattern-matching failures. It knows various ``codes'' which expand to longer strings---this saves space! @absentErr@ is a thing we put in for ``absent'' arguments. They jolly well shouldn't be yanked on, but if one is, then you will get a friendly message from @absentErr@ (rather than a totally random crash). @parError@ is a special version of @error@ which the compiler does not know to be a bottoming Id. It is used in the @_par_@ and @_seq_@ templates, but we don't ever expect to generate code for it. -} errorIds :: [Id] errorIds = [ rUNTIME_ERROR_ID, iRREFUT_PAT_ERROR_ID, nON_EXHAUSTIVE_GUARDS_ERROR_ID, nO_METHOD_BINDING_ERROR_ID, pAT_ERROR_ID, rEC_CON_ERROR_ID, rEC_SEL_ERROR_ID, aBSENT_ERROR_ID, tYPE_ERROR_ID -- Used with Opt_DeferTypeErrors, see #10284 ] recSelErrorName, runtimeErrorName, absentErrorName :: Name irrefutPatErrorName, recConErrorName, patErrorName :: Name nonExhaustiveGuardsErrorName, noMethodBindingErrorName :: Name typeErrorName :: Name recSelErrorName = err_nm "recSelError" recSelErrorIdKey rEC_SEL_ERROR_ID absentErrorName = err_nm "absentError" absentErrorIdKey aBSENT_ERROR_ID runtimeErrorName = err_nm "runtimeError" runtimeErrorIdKey rUNTIME_ERROR_ID irrefutPatErrorName = err_nm "irrefutPatError" irrefutPatErrorIdKey iRREFUT_PAT_ERROR_ID recConErrorName = err_nm "recConError" recConErrorIdKey rEC_CON_ERROR_ID patErrorName = err_nm "patError" patErrorIdKey pAT_ERROR_ID typeErrorName = err_nm "typeError" typeErrorIdKey tYPE_ERROR_ID noMethodBindingErrorName = err_nm "noMethodBindingError" noMethodBindingErrorIdKey nO_METHOD_BINDING_ERROR_ID nonExhaustiveGuardsErrorName = err_nm "nonExhaustiveGuardsError" nonExhaustiveGuardsErrorIdKey nON_EXHAUSTIVE_GUARDS_ERROR_ID err_nm :: String -> Unique -> Id -> Name err_nm str uniq id = mkWiredInIdName cONTROL_EXCEPTION_BASE (fsLit str) uniq id rEC_SEL_ERROR_ID, rUNTIME_ERROR_ID, iRREFUT_PAT_ERROR_ID, rEC_CON_ERROR_ID :: Id pAT_ERROR_ID, nO_METHOD_BINDING_ERROR_ID, nON_EXHAUSTIVE_GUARDS_ERROR_ID :: Id tYPE_ERROR_ID, aBSENT_ERROR_ID :: Id rEC_SEL_ERROR_ID = mkRuntimeErrorId recSelErrorName rUNTIME_ERROR_ID = mkRuntimeErrorId runtimeErrorName iRREFUT_PAT_ERROR_ID = mkRuntimeErrorId irrefutPatErrorName rEC_CON_ERROR_ID = mkRuntimeErrorId recConErrorName pAT_ERROR_ID = mkRuntimeErrorId patErrorName nO_METHOD_BINDING_ERROR_ID = mkRuntimeErrorId noMethodBindingErrorName nON_EXHAUSTIVE_GUARDS_ERROR_ID = mkRuntimeErrorId nonExhaustiveGuardsErrorName aBSENT_ERROR_ID = mkRuntimeErrorId absentErrorName tYPE_ERROR_ID = mkRuntimeErrorId typeErrorName mkRuntimeErrorId :: Name -> Id -- Error function -- with type: forall (r:RuntimeRep) (a:TYPE r). Addr# -> a -- with arity: 1 -- which diverges after being given one argument -- The Addr# is expected to be the address of -- a UTF8-encoded error string mkRuntimeErrorId name = mkVanillaGlobalWithInfo name runtime_err_ty bottoming_info where bottoming_info = vanillaIdInfo `setStrictnessInfo` strict_sig `setArityInfo` 1 -- Make arity and strictness agree -- Do *not* mark them as NoCafRefs, because they can indeed have -- CAF refs. For example, pAT_ERROR_ID calls GHC.Err.untangle, -- which has some CAFs -- In due course we may arrange that these error-y things are -- regarded by the GC as permanently live, in which case we -- can give them NoCaf info. As it is, any function that calls -- any pc_bottoming_Id will itself have CafRefs, which bloats -- SRTs. strict_sig = mkClosedStrictSig [evalDmd] exnRes -- exnRes: these throw an exception, not just diverge -- forall (rr :: RuntimeRep) (a :: rr). Addr# -> a -- See Note [Error and friends have an "open-tyvar" forall] runtime_err_ty = mkSpecSigmaTy [runtimeRep1TyVar, openAlphaTyVar] [] (mkFunTy addrPrimTy openAlphaTy) {- Note [Error and friends have an "open-tyvar" forall] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 'error' and 'undefined' have types error :: forall (v :: RuntimeRep) (a :: TYPE v). String -> a undefined :: forall (v :: RuntimeRep) (a :: TYPE v). a Notice the runtime-representation polymorphism. This ensures that "error" can be instantiated at unboxed as well as boxed types. This is OK because it never returns, so the return type is irrelevant. -}