Marge Bot pushed to branch master at Glasgow Haskell Compiler / GHC Commits: 4f2a21f7 by Andreas Klebinger at 2026-08-02T22:46:46-04:00 Apply oneShot Monad trick to STG LintM - - - - - 21e4b89d by Andreas Klebinger at 2026-08-02T22:46:46-04:00 stgLint: Use a single reader env for read only arguments. - - - - - 1 changed file: - compiler/GHC/Stg/Lint.hs Changes: ===================================== compiler/GHC/Stg/Lint.hs ===================================== @@ -92,6 +92,7 @@ be ill-typed in Core. But it must still be well-kinded! -} {-# LANGUAGE TypeFamilies #-} +{-# LANGUAGE PatternSynonyms #-} module GHC.Stg.Lint ( lintStgTopBindings ) where @@ -123,6 +124,7 @@ import GHC.Unit.Module ( Module ) import GHC.Data.Bag ( Bag, emptyBag, isEmptyBag, snocBag, bagToList ) import Control.Monad +import GHC.Exts ( oneShot ) import GHC.Core.Multiplicity (scaledThing) import GHC.Settings (Platform) import GHC.Core.TyCon (primRepCompatible, primRepsCompatible) @@ -432,17 +434,40 @@ The Lint monad ************************************************************************ -} -newtype LintM a = LintM - { unLintM :: Module - -> LintFlags - -> DiagOpts -- Diagnostic options - -> StgPprOpts -- Pretty-printing options +data LintReaderEnv = LintReaderEnv + { le_mod :: !Module + , le_flags :: !LintFlags + , le_diag_opts :: !DiagOpts -- Diagnostic options + , le_ppr_opts :: !StgPprOpts -- Pretty-printing options + } + +newtype LintM a = LintM' + { unLintM :: LintReaderEnv -> [LintLocInfo] -- Locations -> IdSet -- Local vars in scope -> Bag SDoc -- Error messages so far -> (a, Bag SDoc) -- Result and error messages (if any) } - deriving (Functor) +instance Functor LintM where + fmap f (LintM m) = + LintM $ \env loc scope errs -> + case m env loc scope errs of + (a, errs') -> (f a, errs') + +-- See Note [The one-shot state monad trick] in GHC.Utils.Monad +{-# COMPLETE LintM #-} +pattern LintM :: (LintReaderEnv + -> [LintLocInfo] + -> IdSet + -> Bag SDoc + -> (a, Bag SDoc)) + -> LintM a +pattern LintM m <- LintM' m + where + LintM m = LintM' $ oneShot (\env -> oneShot + (\loc -> oneShot + (\scope -> oneShot + (\errs -> m env loc scope errs)))) data LintFlags = LintFlags { lf_unarised :: !Bool , lf_platform :: !Platform @@ -473,14 +498,16 @@ pp_binders bs initL :: Platform -> DiagOpts -> Module -> Bool -> StgPprOpts -> IdSet -> LintM a -> Maybe SDoc initL platform diag_opts this_mod unarised opts locals (LintM m) = do - let (_, errs) = m this_mod (LintFlags unarised platform) diag_opts opts [] locals emptyBag + let !flags = LintFlags unarised platform + !env = LintReaderEnv this_mod flags diag_opts opts + (_, errs) = m env [] locals emptyBag if isEmptyBag errs then Nothing else Just (vcat (punctuate blankLine (bagToList errs))) instance Applicative LintM where - pure a = LintM $ \_mod _lf _df _opts _loc _scope errs -> (a, errs) + pure a = LintM $ \_env _loc _scope errs -> (a, errs) (<*>) = ap (*>) = thenL_ @@ -489,14 +516,14 @@ instance Monad LintM where (>>) = (*>) thenL :: LintM a -> (a -> LintM b) -> LintM b -thenL m k = LintM $ \mod lf diag_opts opts loc scope errs - -> case unLintM m mod lf diag_opts opts loc scope errs of - (r, errs') -> unLintM (k r) mod lf diag_opts opts loc scope errs' +thenL m k = LintM $ \env loc scope errs + -> case unLintM m env loc scope errs of + (r, errs') -> unLintM (k r) env loc scope errs' thenL_ :: LintM a -> LintM b -> LintM b -thenL_ m k = LintM $ \mod lf diag_opts opts loc scope errs - -> case unLintM m mod lf diag_opts opts loc scope errs of - (_, errs') -> unLintM k mod lf diag_opts opts loc scope errs' +thenL_ m k = LintM $ \env loc scope errs + -> case unLintM m env loc scope errs of + (_, errs') -> unLintM k env loc scope errs' checkL :: Bool -> SDoc -> LintM () checkL True _ = return () @@ -525,7 +552,8 @@ checkPostUnariseId id id_ty = idType id addErrL :: SDoc -> LintM () -addErrL msg = LintM $ \_mod _lf df _opts loc _scope errs -> ((), addErr df errs msg loc) +addErrL msg = LintM $ \LintReaderEnv{le_diag_opts = df} loc _scope errs + -> ((), addErr df errs msg loc) addErr :: DiagOpts -> Bag SDoc -> SDoc -> [LintLocInfo] -> Bag SDoc addErr diag_opts errs_so_far msg locs @@ -537,23 +565,23 @@ addErr diag_opts errs_so_far msg locs mk_msg [] = msg addLoc :: LintLocInfo -> LintM a -> LintM a -addLoc extra_loc m = LintM $ \mod lf diag_opts opts loc scope errs - -> unLintM m mod lf diag_opts opts (extra_loc:loc) scope errs +addLoc extra_loc m = LintM $ \env loc scope errs + -> unLintM m env (extra_loc:loc) scope errs addInScopeVars :: [Id] -> LintM a -> LintM a -addInScopeVars ids m = LintM $ \mod lf diag_opts opts loc scope errs +addInScopeVars ids m = LintM $ \env loc scope errs -> let new_set = mkVarSet ids - in unLintM m mod lf diag_opts opts loc (scope `unionVarSet` new_set) errs + in unLintM m env loc (scope `unionVarSet` new_set) errs getLintFlags :: LintM LintFlags -getLintFlags = LintM $ \_mod lf _df _opts _loc _scope errs -> (lf, errs) +getLintFlags = LintM $ \LintReaderEnv{le_flags = lf} _loc _scope errs -> (lf, errs) getStgPprOpts :: LintM StgPprOpts -getStgPprOpts = LintM $ \_mod _lf _df opts _loc _scope errs -> (opts, errs) +getStgPprOpts = LintM $ \LintReaderEnv{le_ppr_opts = opts} _loc _scope errs -> (opts, errs) checkInScope :: Id -> LintM () -checkInScope id = LintM $ \mod _lf diag_opts _opts loc scope errs +checkInScope id = LintM $ \LintReaderEnv{le_mod = mod, le_diag_opts = diag_opts} loc scope errs -> if nameIsLocalOrFrom mod (idName id) && not (id `elemVarSet` scope) then ((), addErr diag_opts errs (hsep [ppr id, dcolon, ppr (idType id), text "is out of scope"]) loc) View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/c9a34a0054b95fcd7a9717b8b41a7b6... -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/c9a34a0054b95fcd7a9717b8b41a7b6... 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