--- /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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