+++ /dev/null
-%
-% (c) The GRASP/AQUA Project, Glasgow University, 1993-1998
-%
-\section[StgLint]{A ``lint'' pass to check for Stg correctness}
-
-\begin{code}
-module StgLint ( lintStgBindings ) where
-
-#include "HsVersions.h"
-
-import StgSyn
-
-import Bag ( Bag, emptyBag, isEmptyBag, snocBag, bagToList )
-import Id ( Id, idType, isLocalId )
-import VarSet
-import DataCon ( DataCon, dataConInstArgTys, dataConRepType )
-import CoreSyn ( AltCon(..) )
-import PrimOp ( primOpType )
-import Literal ( literalType )
-import Maybes ( catMaybes )
-import Name ( getSrcLoc )
-import ErrUtils ( Message, mkLocMessage )
-import Type ( mkFunTys, splitFunTys, splitTyConApp_maybe,
- isUnLiftedType, isTyVarTy, dropForAlls, Type
- )
-import TyCon ( isAlgTyCon, isNewTyCon, tyConDataCons )
-import Util ( zipEqual, equalLength )
-import SrcLoc ( srcLocSpan )
-import Outputable
-
-infixr 9 `thenL`, `thenL_`, `thenMaybeL`
-\end{code}
-
-Checks for
- (a) *some* type errors
- (b) locally-defined variables used but not defined
-
-
-Note: unless -dverbose-stg is on, display of lint errors will result
-in "panic: bOGUS_LVs".
-
-WARNING:
-~~~~~~~~
-
-This module has suffered bit-rot; it is likely to yield lint errors
-for Stg code that is currently perfectly acceptable for code
-generation. Solution: don't use it! (KSW 2000-05).
-
-
-%************************************************************************
-%* *
-\subsection{``lint'' for various constructs}
-%* *
-%************************************************************************
-
-@lintStgBindings@ is the top-level interface function.
-
-\begin{code}
-lintStgBindings :: String -> [StgBinding] -> [StgBinding]
-
-lintStgBindings whodunnit binds
- = {-# SCC "StgLint" #-}
- case (initL (lint_binds binds)) of
- Nothing -> binds
- Just msg -> pprPanic "" (vcat [
- ptext SLIT("*** Stg Lint ErrMsgs: in") <+> text whodunnit <+> ptext SLIT("***"),
- msg,
- ptext SLIT("*** Offending Program ***"),
- pprStgBindings binds,
- ptext SLIT("*** End of Offense ***")])
- where
- lint_binds :: [StgBinding] -> LintM ()
-
- lint_binds [] = returnL ()
- lint_binds (bind:binds)
- = lintStgBinds bind `thenL` \ binders ->
- addInScopeVars binders (
- lint_binds binds
- )
-\end{code}
-
-
-\begin{code}
-lintStgArg :: StgArg -> LintM (Maybe Type)
-lintStgArg (StgLitArg lit) = returnL (Just (literalType lit))
-lintStgArg (StgVarArg v) = lintStgVar v
-
-lintStgVar v = checkInScope v `thenL_`
- returnL (Just (idType v))
-\end{code}
-
-\begin{code}
-lintStgBinds :: StgBinding -> LintM [Id] -- Returns the binders
-lintStgBinds (StgNonRec binder rhs)
- = lint_binds_help (binder,rhs) `thenL_`
- returnL [binder]
-
-lintStgBinds (StgRec pairs)
- = addInScopeVars binders (
- mapL lint_binds_help pairs `thenL_`
- returnL binders
- )
- where
- binders = [b | (b,_) <- pairs]
-
-lint_binds_help (binder, rhs)
- = addLoc (RhsOf binder) (
- -- Check the rhs
- lintStgRhs rhs `thenL` \ maybe_rhs_ty ->
-
- -- Check binder doesn't have unlifted type
- checkL (not (isUnLiftedType binder_ty))
- (mkUnLiftedTyMsg binder rhs) `thenL_`
-
- -- Check match to RHS type
- (case maybe_rhs_ty of
- Nothing -> returnL ()
- Just rhs_ty -> checkTys binder_ty
- rhs_ty
- (mkRhsMsg binder rhs_ty)
- ) `thenL_`
-
- returnL ()
- )
- where
- binder_ty = idType binder
-\end{code}
-
-\begin{code}
-lintStgRhs :: StgRhs -> LintM (Maybe Type)
-
-lintStgRhs (StgRhsClosure _ _ _ _ _ [] expr)
- = lintStgExpr expr
-
-lintStgRhs (StgRhsClosure _ _ _ _ _ binders expr)
- = addLoc (LambdaBodyOf binders) (
- addInScopeVars binders (
- lintStgExpr expr `thenMaybeL` \ body_ty ->
- returnL (Just (mkFunTys (map idType binders) body_ty))
- ))
-
-lintStgRhs (StgRhsCon _ con args)
- = mapMaybeL lintStgArg args `thenL` \ maybe_arg_tys ->
- case maybe_arg_tys of
- Nothing -> returnL Nothing
- Just arg_tys -> checkFunApp con_ty arg_tys (mkRhsConMsg con_ty arg_tys)
- where
- con_ty = dataConRepType con
-\end{code}
-
-\begin{code}
-lintStgExpr :: StgExpr -> LintM (Maybe Type) -- Nothing if error found
-
-lintStgExpr (StgLit l) = returnL (Just (literalType l))
-
-lintStgExpr e@(StgApp fun args)
- = lintStgVar fun `thenMaybeL` \ fun_ty ->
- mapMaybeL lintStgArg args `thenL` \ maybe_arg_tys ->
- case maybe_arg_tys of
- Nothing -> returnL Nothing
- Just arg_tys -> checkFunApp fun_ty arg_tys (mkFunAppMsg fun_ty arg_tys e)
-
-lintStgExpr e@(StgConApp con args)
- = mapMaybeL lintStgArg args `thenL` \ maybe_arg_tys ->
- case maybe_arg_tys of
- Nothing -> returnL Nothing
- Just arg_tys -> checkFunApp con_ty arg_tys (mkFunAppMsg con_ty arg_tys e)
- where
- con_ty = dataConRepType con
-
-lintStgExpr e@(StgOpApp (StgFCallOp _ _) args res_ty)
- = -- We don't have enough type information to check
- -- the application; ToDo
- mapMaybeL lintStgArg args `thenL` \ maybe_arg_tys ->
- returnL (Just res_ty)
-
-lintStgExpr e@(StgOpApp (StgPrimOp op) args _)
- = mapMaybeL lintStgArg args `thenL` \ maybe_arg_tys ->
- case maybe_arg_tys of
- Nothing -> returnL Nothing
- Just arg_tys -> checkFunApp op_ty arg_tys (mkFunAppMsg op_ty arg_tys e)
- where
- op_ty = primOpType op
-
-lintStgExpr (StgLam _ bndrs _)
- = addErrL (ptext SLIT("Unexpected StgLam") <+> ppr bndrs) `thenL_`
- returnL Nothing
-
-lintStgExpr (StgLet binds body)
- = lintStgBinds binds `thenL` \ binders ->
- addLoc (BodyOfLetRec binders) (
- addInScopeVars binders (
- lintStgExpr body
- ))
-
-lintStgExpr (StgLetNoEscape _ _ binds body)
- = lintStgBinds binds `thenL` \ binders ->
- addLoc (BodyOfLetRec binders) (
- addInScopeVars binders (
- lintStgExpr body
- ))
-
-lintStgExpr (StgSCC _ expr) = lintStgExpr expr
-
-lintStgExpr e@(StgCase scrut _ _ bndr _ alts_type alts)
- = lintStgExpr scrut `thenMaybeL` \ _ ->
-
- (case alts_type of
- AlgAlt tc -> check_bndr tc
- PrimAlt tc -> check_bndr tc
- UbxTupAlt tc -> check_bndr tc
- PolyAlt -> returnL ()
- ) `thenL_`
-
- (trace (showSDoc (ppr e)) $
- -- we only allow case of tail-call or primop.
- (case scrut of
- StgApp _ _ -> returnL ()
- StgConApp _ _ -> returnL ()
- StgOpApp _ _ _ -> returnL ()
- other -> addErrL (mkCaseOfCaseMsg e)) `thenL_`
-
- addInScopeVars [bndr] (lintStgAlts alts scrut_ty)
- )
- where
- scrut_ty = idType bndr
- bad_bndr = mkDefltMsg bndr
- check_bndr tc = case splitTyConApp_maybe scrut_ty of
- Just (bndr_tc, _) -> checkL (tc == bndr_tc) bad_bndr
- Nothing -> addErrL bad_bndr
-
-
-lintStgAlts :: [StgAlt]
- -> Type -- Type of scrutinee
- -> LintM (Maybe Type) -- Type of alternatives
-
-lintStgAlts alts scrut_ty
- = mapL (lintAlt scrut_ty) alts `thenL` \ maybe_result_tys ->
-
- -- Check the result types
- case catMaybes (maybe_result_tys) of
- [] -> returnL Nothing
-
- (first_ty:tys) -> mapL check tys `thenL_`
- returnL (Just first_ty)
- where
- check ty = checkTys first_ty ty (mkCaseAltMsg alts)
-
-lintAlt scrut_ty (DEFAULT, _, _, rhs)
- = lintStgExpr rhs
-
-lintAlt scrut_ty (LitAlt lit, _, _, rhs)
- = checkTys (literalType lit) scrut_ty (mkAltMsg1 scrut_ty) `thenL_`
- lintStgExpr rhs
-
-lintAlt scrut_ty (DataAlt con, args, _, rhs)
- = (case splitTyConApp_maybe scrut_ty of
- Just (tycon, tys_applied) | isAlgTyCon tycon &&
- not (isNewTyCon tycon) ->
- let
- cons = tyConDataCons tycon
- arg_tys = dataConInstArgTys con tys_applied
- -- This almost certainly does not work for existential constructors
- in
- checkL (con `elem` cons) (mkAlgAltMsg2 scrut_ty con) `thenL_`
- checkL (equalLength arg_tys args) (mkAlgAltMsg3 con args)
- `thenL_`
- mapL check (zipEqual "lintAlgAlt:stg" arg_tys args) `thenL_`
- returnL ()
- other ->
- addErrL (mkAltMsg1 scrut_ty)
- ) `thenL_`
- addInScopeVars args (
- lintStgExpr rhs
- )
- where
- check (ty, arg) = checkTys ty (idType arg) (mkAlgAltMsg4 ty arg)
-
- -- elem: yes, the elem-list here can sometimes be long-ish,
- -- but as it's use-once, probably not worth doing anything different
- -- We give it its own copy, so it isn't overloaded.
- elem _ [] = False
- elem x (y:ys) = x==y || elem x ys
-\end{code}
-
-
-%************************************************************************
-%* *
-\subsection[lint-monad]{The Lint monad}
-%* *
-%************************************************************************
-
-\begin{code}
-type LintM a = [LintLocInfo] -- Locations
- -> IdSet -- Local vars in scope
- -> Bag Message -- Error messages so far
- -> (a, Bag Message) -- Result and error messages (if any)
-
-data LintLocInfo
- = RhsOf Id -- The variable bound
- | LambdaBodyOf [Id] -- The lambda-binder
- | BodyOfLetRec [Id] -- One of the binders
-
-dumpLoc (RhsOf v) =
- (srcLocSpan (getSrcLoc v), ptext SLIT(" [RHS of ") <> pp_binders [v] <> char ']' )
-dumpLoc (LambdaBodyOf bs) =
- (srcLocSpan (getSrcLoc (head bs)), ptext SLIT(" [in body of lambda with binders ") <> pp_binders bs <> char ']' )
-
-dumpLoc (BodyOfLetRec bs) =
- (srcLocSpan (getSrcLoc (head bs)), ptext SLIT(" [in body of letrec with binders ") <> pp_binders bs <> char ']' )
-
-
-pp_binders :: [Id] -> SDoc
-pp_binders bs
- = sep (punctuate comma (map pp_binder bs))
- where
- pp_binder b
- = hsep [ppr b, dcolon, ppr (idType b)]
-\end{code}
-
-\begin{code}
-initL :: LintM a -> Maybe Message
-initL m
- = case (m [] emptyVarSet emptyBag) of { (_, errs) ->
- if isEmptyBag errs then
- Nothing
- else
- Just (vcat (punctuate (text "") (bagToList errs)))
- }
-
-returnL :: a -> LintM a
-returnL r loc scope errs = (r, errs)
-
-thenL :: LintM a -> (a -> LintM b) -> LintM b
-thenL m k loc scope errs
- = case m loc scope errs of
- (r, errs') -> k r loc scope errs'
-
-thenL_ :: LintM a -> LintM b -> LintM b
-thenL_ m k loc scope errs
- = case m loc scope errs of
- (_, errs') -> k loc scope errs'
-
-thenMaybeL :: LintM (Maybe a) -> (a -> LintM (Maybe b)) -> LintM (Maybe b)
-thenMaybeL m k loc scope errs
- = case m loc scope errs of
- (Nothing, errs2) -> (Nothing, errs2)
- (Just r, errs2) -> k r loc scope errs2
-
-mapL :: (a -> LintM b) -> [a] -> LintM [b]
-mapL f [] = returnL []
-mapL f (x:xs)
- = f x `thenL` \ r ->
- mapL f xs `thenL` \ rs ->
- returnL (r:rs)
-
-mapMaybeL :: (a -> LintM (Maybe b)) -> [a] -> LintM (Maybe [b])
- -- Returns Nothing if anything fails
-mapMaybeL f [] = returnL (Just [])
-mapMaybeL f (x:xs)
- = f x `thenMaybeL` \ r ->
- mapMaybeL f xs `thenMaybeL` \ rs ->
- returnL (Just (r:rs))
-\end{code}
-
-\begin{code}
-checkL :: Bool -> Message -> LintM ()
-checkL True msg loc scope errs = ((), errs)
-checkL False msg loc scope errs = ((), addErr errs msg loc)
-
-addErrL :: Message -> LintM ()
-addErrL msg loc scope errs = ((), addErr errs msg loc)
-
-addErr :: Bag Message -> Message -> [LintLocInfo] -> Bag Message
-
-addErr errs_so_far msg locs
- = errs_so_far `snocBag` mk_msg locs
- where
- mk_msg (loc:_) = let (l,hdr) = dumpLoc loc
- in mkLocMessage l (hdr $$ msg)
- mk_msg [] = msg
-
-addLoc :: LintLocInfo -> LintM a -> LintM a
-addLoc extra_loc m loc scope errs
- = m (extra_loc:loc) scope errs
-
-addInScopeVars :: [Id] -> LintM a -> LintM a
-addInScopeVars ids m loc scope errs
- = -- We check if these "new" ids are already
- -- in scope, i.e., we have *shadowing* going on.
- -- For now, it's just a "trace"; we may make
- -- a real error out of it...
- let
- new_set = mkVarSet ids
- in
--- After adding -fliberate-case, Simon decided he likes shadowed
--- names after all. WDP 94/07
--- (if isEmptyVarSet shadowed
--- then id
--- else pprTrace "Shadowed vars:" (ppr (varSetElems shadowed))) $
- m loc (scope `unionVarSet` new_set) errs
-\end{code}
-
-Checking function applications: we only check that the type has the
-right *number* of arrows, we don't actually compare the types. This
-is because we can't expect the types to be equal - the type
-applications and type lambdas that we use to calculate accurate types
-have long since disappeared.
-
-\begin{code}
-checkFunApp :: Type -- The function type
- -> [Type] -- The arg type(s)
- -> Message -- Error messgae
- -> LintM (Maybe Type) -- The result type
-
-checkFunApp fun_ty arg_tys msg loc scope errs
- = cfa res_ty expected_arg_tys arg_tys
- where
- (expected_arg_tys, res_ty) = splitFunTys (dropForAlls fun_ty)
-
- cfa res_ty expected [] -- Args have run out; that's fine
- = (Just (mkFunTys expected res_ty), errs)
-
- cfa res_ty [] arg_tys -- Expected arg tys ran out first;
- -- first see if res_ty is a tyvar template;
- -- otherwise, maybe res_ty is a
- -- dictionary type which is actually a function?
- | isTyVarTy res_ty
- = (Just res_ty, errs)
- | otherwise
- = case splitFunTys res_ty of
- ([], _) -> (Nothing, addErr errs msg loc) -- Too many args
- (new_expected, new_res) -> cfa new_res new_expected arg_tys
-
- cfa res_ty (expected_arg_ty:expected_arg_tys) (arg_ty:arg_tys)
- = cfa res_ty expected_arg_tys arg_tys
-\end{code}
-
-\begin{code}
-checkInScope :: Id -> LintM ()
-checkInScope id loc scope errs
- = if isLocalId id && not (id `elemVarSet` scope) then
- ((), addErr errs (hsep [ppr id, ptext SLIT("is out of scope")]) loc)
- else
- ((), errs)
-
-checkTys :: Type -> Type -> Message -> LintM ()
-checkTys ty1 ty2 msg loc scope errs
- = -- if (ty1 == ty2) then
- ((), errs)
- -- else ((), addErr errs msg loc)
-\end{code}
-
-\begin{code}
-mkCaseAltMsg :: [StgAlt] -> Message
-mkCaseAltMsg alts
- = ($$) (text "In some case alternatives, type of alternatives not all same:")
- (empty) -- LATER: ppr alts
-
-mkDefltMsg :: Id -> Message
-mkDefltMsg bndr
- = ($$) (ptext SLIT("Binder of a case expression doesn't match type of scrutinee:"))
- (panic "mkDefltMsg")
-
-mkFunAppMsg :: Type -> [Type] -> StgExpr -> Message
-mkFunAppMsg fun_ty arg_tys expr
- = vcat [text "In a function application, function type doesn't match arg types:",
- hang (ptext SLIT("Function type:")) 4 (ppr fun_ty),
- hang (ptext SLIT("Arg types:")) 4 (vcat (map (ppr) arg_tys)),
- hang (ptext SLIT("Expression:")) 4 (ppr expr)]
-
-mkRhsConMsg :: Type -> [Type] -> Message
-mkRhsConMsg fun_ty arg_tys
- = vcat [text "In a RHS constructor application, con type doesn't match arg types:",
- hang (ptext SLIT("Constructor type:")) 4 (ppr fun_ty),
- hang (ptext SLIT("Arg types:")) 4 (vcat (map (ppr) arg_tys))]
-
-mkAltMsg1 :: Type -> Message
-mkAltMsg1 ty
- = ($$) (text "In a case expression, type of scrutinee does not match patterns")
- (ppr ty)
-
-mkAlgAltMsg2 :: Type -> DataCon -> Message
-mkAlgAltMsg2 ty con
- = vcat [
- text "In some algebraic case alternative, constructor is not a constructor of scrutinee type:",
- ppr ty,
- ppr con
- ]
-
-mkAlgAltMsg3 :: DataCon -> [Id] -> Message
-mkAlgAltMsg3 con alts
- = vcat [
- text "In some algebraic case alternative, number of arguments doesn't match constructor:",
- ppr con,
- ppr alts
- ]
-
-mkAlgAltMsg4 :: Type -> Id -> Message
-mkAlgAltMsg4 ty arg
- = vcat [
- text "In some algebraic case alternative, type of argument doesn't match data constructor:",
- ppr ty,
- ppr arg
- ]
-
-mkCaseOfCaseMsg :: StgExpr -> Message
-mkCaseOfCaseMsg e
- = text "Case of non-tail-call:" $$ ppr e
-
-mkRhsMsg :: Id -> Type -> Message
-mkRhsMsg binder ty
- = vcat [hsep [ptext SLIT("The type of this binder doesn't match the type of its RHS:"),
- ppr binder],
- hsep [ptext SLIT("Binder's type:"), ppr (idType binder)],
- hsep [ptext SLIT("Rhs type:"), ppr ty]
- ]
-
-mkUnLiftedTyMsg binder rhs
- = (ptext SLIT("Let(rec) binder") <+> quotes (ppr binder) <+>
- ptext SLIT("has unlifted type") <+> quotes (ppr (idType binder)))
- $$
- (ptext SLIT("RHS:") <+> ppr rhs)
-\end{code}
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