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[Git][ghc/ghc][wip/fendor/drop-preloadclosure-from-unitstate] Drop `preloadClosure` from `UnitState`
by Hannes Siebenhandl (＠fendor) 28 May '26

28 May '26

Hannes Siebenhandl pushed to branch wip/fendor/drop-preloadclosure-from-unitstate at Glasgow Haskell Compiler / GHC Commits: d07b7c61 by fendor at 2026-05-28T10:32:23+02:00 Drop `preloadClosure` from `UnitState` It is always hard-coded to the same value. Backpack Unit instantiation isn't using it any more. Allows us to simplify the API and get rid of `improveUnit`. - - - - - 7 changed files: - + changelog.d/T27308 - compiler/GHC/Driver/Backpack.hs - compiler/GHC/Iface/Load.hs - compiler/GHC/Iface/Recomp.hs - compiler/GHC/Unit.hs - compiler/GHC/Unit/State.hs - compiler/GHC/Unit/Types.hs Changes: ===================================== changelog.d/T27308 ===================================== @@ -0,0 +1,10 @@ +section: compiler +synopsis: Drop `preloadClosure` from `UnitState` +issues: #27308 +mrs: !16108 + +description: { + Drop `preloadClosure` from `UnitState` as it is always set to the empty set. + This allows to simplify the `UnitState` and related functions. +} + ===================================== compiler/GHC/Driver/Backpack.hs ===================================== @@ -241,7 +241,6 @@ withBkpSession cid insts deps session_type do_this = do -- Synthesize the flags , packageFlags = packageFlags dflags ++ map (\(uid0, rn) -> let uid = unwireUnit unit_state - $ improveUnit unit_state $ renameHoleUnit unit_state (listToUFM insts) uid0 in ExposePackage (showSDoc dflags @@ -310,19 +309,16 @@ buildUnit session cid insts lunit = do -- The compilation dependencies are just the appropriately filled -- in unit IDs which must be compiled before we can compile. let hsubst = listToUFM insts - deps0 = map (renameHoleUnit (hsc_units hsc_env) hsubst) raw_deps + deps = map (renameHoleUnit (hsc_units hsc_env) hsubst) raw_deps -- Build dependencies OR make sure they make sense. BUT NOTE, -- we can only check the ones that are fully filled; the rest -- we have to defer until we've typechecked our local signature. -- TODO: work this into GHC.Driver.Make!! - forM_ (zip [1..] deps0) $ \(i, dep) -> + forM_ (zip [1..] deps) $ \(i, dep) -> case session of TcSession -> return () - _ -> compileInclude (length deps0) (i, dep) - - -- IMPROVE IT - let deps = map (improveUnit (hsc_units hsc_env)) deps0 + _ -> compileInclude (length deps) (i, dep) mb_old_eps <- case session of TcSession -> fmap Just getEpsGhc ===================================== compiler/GHC/Iface/Load.hs ===================================== @@ -914,13 +914,13 @@ findAndReadIface hsc_env doc_str mod wanted_mod hi_boot_file = do && not (isOneShot (ghcMode dflags)) then return (Failed (HomeModError mod loc)) else do - r <- read_file hooks logger name_cache unit_state dflags wanted_mod (ml_hi_file loc) + r <- read_file hooks logger name_cache dflags wanted_mod (ml_hi_file loc) case r of Failed err -> return (Failed $ BadIfaceFile err) Succeeded (iface,_fp) -> do - r2 <- load_dynamic_too_maybe hooks logger name_cache unit_state + r2 <- load_dynamic_too_maybe hooks logger name_cache (setDynamicNow dflags) wanted_mod iface loc case r2 of @@ -936,20 +936,20 @@ findAndReadIface hsc_env doc_str mod wanted_mod hi_boot_file = do err -- | Check if we need to try the dynamic interface for -dynamic-too -load_dynamic_too_maybe :: Hooks -> Logger -> NameCache -> UnitState -> DynFlags +load_dynamic_too_maybe :: Hooks -> Logger -> NameCache -> DynFlags -> Module -> ModIface -> ModLocation -> IO (MaybeErr MissingInterfaceError ()) -load_dynamic_too_maybe hooks logger name_cache unit_state dflags wanted_mod iface loc +load_dynamic_too_maybe hooks logger name_cache dflags wanted_mod iface loc -- Indefinite interfaces are ALWAYS non-dynamic. | not (moduleIsDefinite (mi_module iface)) = return (Succeeded ()) - | gopt Opt_BuildDynamicToo dflags = load_dynamic_too hooks logger name_cache unit_state dflags wanted_mod iface loc + | gopt Opt_BuildDynamicToo dflags = load_dynamic_too hooks logger name_cache dflags wanted_mod iface loc | otherwise = return (Succeeded ()) -load_dynamic_too :: Hooks -> Logger -> NameCache -> UnitState -> DynFlags +load_dynamic_too :: Hooks -> Logger -> NameCache -> DynFlags -> Module -> ModIface -> ModLocation -> IO (MaybeErr MissingInterfaceError ()) -load_dynamic_too hooks logger name_cache unit_state dflags wanted_mod iface loc = do - read_file hooks logger name_cache unit_state dflags wanted_mod (ml_dyn_hi_file loc) >>= \case +load_dynamic_too hooks logger name_cache dflags wanted_mod iface loc = do + read_file hooks logger name_cache dflags wanted_mod (ml_dyn_hi_file loc) >>= \case Succeeded (dynIface, _) | mi_mod_hash iface == mi_mod_hash dynIface -> return (Succeeded ()) @@ -963,10 +963,10 @@ load_dynamic_too hooks logger name_cache unit_state dflags wanted_mod iface loc -read_file :: Hooks -> Logger -> NameCache -> UnitState -> DynFlags +read_file :: Hooks -> Logger -> NameCache -> DynFlags -> Module -> FilePath -> IO (MaybeErr ReadInterfaceError (ModIface, FilePath)) -read_file hooks logger name_cache unit_state dflags wanted_mod file_path = do +read_file hooks logger name_cache dflags wanted_mod file_path = do -- Figure out what is recorded in mi_module. If this is -- a fully definite interface, it'll match exactly, but @@ -975,7 +975,7 @@ read_file hooks logger name_cache unit_state dflags wanted_mod file_path = do case getModuleInstantiation wanted_mod of (_, Nothing) -> wanted_mod (_, Just indef_mod) -> - instModuleToModule unit_state + instModuleToModule (uninstantiateInstantiatedModule indef_mod) read_result <- readIface hooks logger dflags name_cache wanted_mod' file_path case read_result of ===================================== compiler/GHC/Iface/Recomp.hs ===================================== @@ -620,7 +620,7 @@ checkMergedSignatures hsc_env mod_summary self_recomp = do new_merged = case lookupUniqMap (requirementContext unit_state) (ms_mod_name mod_summary) of Nothing -> [] - Just r -> sort $ map (instModuleToModule unit_state) r + Just r -> sort $ map instModuleToModule r if old_merged == new_merged then up_to_date logger (text "signatures to merge in unchanged" $$ ppr new_merged) else return $ needsRecompileBecause SigsMergeChanged ===================================== compiler/GHC/Unit.hs ===================================== @@ -314,32 +314,6 @@ field in the SDocContext to pretty-print. (i.e. GHC doesn't correctly call `pprWithUnitState` before pretty-printing a UnitId), that's what will be shown to the user so it's no big deal. - -Note [VirtUnit to RealUnit improvement] -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -Over the course of instantiating VirtUnits on the fly while typechecking an -indefinite library, we may end up with a fully instantiated VirtUnit. I.e. -one that could be compiled and installed in the database. During -type-checking we generate a virtual UnitId for it, say "abc". - -Now the question is: do we have a matching installed unit in the database? -Suppose we have one with UnitId "xyz" (provided by Cabal so we don't know how -to generate it). The trouble is that if both units end up being used in the -same type-checking session, their names won't match (e.g. "abc:M.X" vs -"xyz:M.X"). - -As we want them to match we just replace the virtual unit with the installed -one: for some reason this is called "improvement". - -There is one last niggle: improvement based on the unit database means -that we might end up developing on a unit that is not transitively -depended upon by the units the user specified directly via command line -flags. This could lead to strange and difficult to understand bugs if those -instantiations are out of date. The solution is to only improve a -unit id if the new unit id is part of the 'preloadClosure'; i.e., the -closure of all the units which were explicitly specified. - Note [Representation of module/name variables] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ In our ICFP'16, we use <A> to represent module holes, and {A.T} to represent ===================================== compiler/GHC/Unit/State.hs ===================================== @@ -7,7 +7,6 @@ module GHC.Unit.State ( -- * Reading the package config, and processing cmdline args UnitState(..), - PreloadUnitClosure, UnitDatabase (..), UnitErr (..), emptyUnitState, @@ -29,7 +28,6 @@ module GHC.Unit.State ( lookupPackageName, resolvePackageImport, - improveUnit, searchPackageId, listVisibleModuleNames, lookupModuleInAllUnits, @@ -89,7 +87,6 @@ import GHC.Unit.Home import GHC.Types.Unique.FM import GHC.Types.Unique.DFM -import GHC.Types.Unique.Set import GHC.Types.Unique.DSet import GHC.Types.Unique.Map import GHC.Types.Unique @@ -267,8 +264,6 @@ originEmpty :: ModuleOrigin -> Bool originEmpty (ModOrigin Nothing [] [] False) = True originEmpty _ = False -type PreloadUnitClosure = UniqSet UnitId - -- | 'UniqFM' map from 'Unit' to a 'UnitVisibility'. type VisibilityMap = UniqMap Unit UnitVisibility @@ -431,13 +426,6 @@ data UnitState = UnitState { -- may have the 'exposed' flag be 'False'.) unitInfoMap :: UnitInfoMap, - -- | The set of transitively reachable units according - -- to the explicitly provided command line arguments. - -- A fully instantiated VirtUnit may only be replaced by a RealUnit from - -- this set. - -- See Note [VirtUnit to RealUnit improvement] - preloadClosure :: PreloadUnitClosure, - -- | A mapping of 'PackageName' to 'UnitId'. If several units have the same -- package name (e.g. different instantiations), then we return one of them... -- This is used when users refer to packages in Backpack includes. @@ -490,7 +478,6 @@ data UnitState = UnitState { emptyUnitState :: UnitState emptyUnitState = UnitState { unitInfoMap = emptyUniqMap, - preloadClosure = emptyUniqSet, packageNameMap = emptyUFM, wireMap = emptyUniqMap, unwireMap = emptyUniqMap, @@ -516,7 +503,7 @@ type UnitInfoMap = UniqMap UnitId UnitInfo -- | Find the unit we know about with the given unit, if any lookupUnit :: UnitState -> Unit -> Maybe UnitInfo -lookupUnit pkgs = lookupUnit' (allowVirtualUnits pkgs) (unitInfoMap pkgs) (preloadClosure pkgs) +lookupUnit pkgs = lookupUnit' (allowVirtualUnits pkgs) (unitInfoMap pkgs) -- | A more specialized interface, which doesn't require a 'UnitState' (so it -- can be used while we're initializing 'DynFlags') @@ -524,16 +511,15 @@ lookupUnit pkgs = lookupUnit' (allowVirtualUnits pkgs) (unitInfoMap pkgs) (prelo -- Parameters: -- * a boolean specifying whether or not to look for on-the-fly renamed interfaces -- * a 'UnitInfoMap' --- * a 'PreloadUnitClosure' -lookupUnit' :: Bool -> UnitInfoMap -> PreloadUnitClosure -> Unit -> Maybe UnitInfo -lookupUnit' allowOnTheFlyInst pkg_map closure u = case u of +lookupUnit' :: Bool -> UnitInfoMap -> Unit -> Maybe UnitInfo +lookupUnit' allowOnTheFlyInst pkg_map u = case u of HoleUnit -> error "Hole unit" RealUnit i -> lookupUniqMap pkg_map (unDefinite i) VirtUnit i | allowOnTheFlyInst -> -- lookup UnitInfo of the indefinite unit to be instantiated and -- instantiate it on-the-fly - fmap (renameUnitInfo pkg_map closure (instUnitInsts i)) + fmap (renameUnitInfo pkg_map (instUnitInsts i)) (lookupUniqMap pkg_map (instUnitInstanceOf i)) | otherwise @@ -907,7 +893,6 @@ applyTrustFlag prec_map unusable pkgs flag = applyPackageFlag :: UnitPrecedenceMap -> UnitInfoMap - -> PreloadUnitClosure -> UnusableUnits -> Bool -- if False, if you expose a package, it implicitly hides -- any previously exposed packages with the same name @@ -916,10 +901,10 @@ applyPackageFlag -> PackageFlag -- flag to apply -> MaybeErr UnitErr VisibilityMap -- Now exposed -applyPackageFlag prec_map pkg_map closure unusable no_hide_others pkgs vm flag = +applyPackageFlag prec_map pkg_map unusable no_hide_others pkgs vm flag = case flag of ExposePackage _ arg (ModRenaming b rns) -> - case findPackages prec_map pkg_map closure arg pkgs unusable of + case findPackages prec_map pkg_map arg pkgs unusable of Left ps -> Failed (PackageFlagErr flag ps) Right (p:_) -> Succeeded vm' where @@ -983,7 +968,7 @@ applyPackageFlag prec_map pkg_map closure unusable no_hide_others pkgs vm flag = _ -> panic "applyPackageFlag" HidePackage str -> - case findPackages prec_map pkg_map closure (PackageArg str) pkgs unusable of + case findPackages prec_map pkg_map (PackageArg str) pkgs unusable of Left ps -> Failed (PackageFlagErr flag ps) Right ps -> Succeeded $ foldl' delFromUniqMap vm (map mkUnit ps) @@ -992,12 +977,11 @@ applyPackageFlag prec_map pkg_map closure unusable no_hide_others pkgs vm flag = -- if the 'UnitArg' has a renaming associated with it. findPackages :: UnitPrecedenceMap -> UnitInfoMap - -> PreloadUnitClosure -> PackageArg -> [UnitInfo] -> UnusableUnits -> Either [(UnitInfo, UnusableUnitReason)] [UnitInfo] -findPackages prec_map pkg_map closure arg pkgs unusable +findPackages prec_map pkg_map arg pkgs unusable = let ps = mapMaybe (finder arg) pkgs in if null ps then Left (mapMaybe (\(x,y) -> finder arg x >>= \x' -> return (x',y)) @@ -1015,7 +999,7 @@ findPackages prec_map pkg_map closure arg pkgs unusable -> Just p VirtUnit inst | instUnitInstanceOf inst == unitId p - -> Just (renameUnitInfo pkg_map closure (instUnitInsts inst) p) + -> Just (renameUnitInfo pkg_map (instUnitInsts inst) p) _ -> Nothing selectPackages :: UnitPrecedenceMap -> PackageArg -> [UnitInfo] @@ -1030,10 +1014,10 @@ selectPackages prec_map arg pkgs unusable else Right (sortByPreference prec_map ps, rest) -- | Rename a 'UnitInfo' according to some module instantiation. -renameUnitInfo :: UnitInfoMap -> PreloadUnitClosure -> [(ModuleName, Module)] -> UnitInfo -> UnitInfo -renameUnitInfo pkg_map closure insts conf = +renameUnitInfo :: UnitInfoMap -> [(ModuleName, Module)] -> UnitInfo -> UnitInfo +renameUnitInfo pkg_map insts conf = let hsubst = listToUFM insts - smod = renameHoleModule' pkg_map closure hsubst + smod = renameHoleModule' pkg_map hsubst new_insts = map (\(k,v) -> (k,smod v)) (unitInstantiations conf) in conf { unitInstantiations = new_insts, @@ -1631,7 +1615,7 @@ mkUnitState logger cfg = do -- user tries to enable an unusable package, we should let them know. -- vis_map2 <- mayThrowUnitErr - $ foldM (applyPackageFlag prec_map prelim_pkg_db emptyUniqSet unusable + $ foldM (applyPackageFlag prec_map prelim_pkg_db unusable (unitConfigHideAll cfg) pkgs1) vis_map1 other_flags @@ -1660,7 +1644,7 @@ mkUnitState logger cfg = do | otherwise = vis_map2 plugin_vis_map2 <- mayThrowUnitErr - $ foldM (applyPackageFlag prec_map prelim_pkg_db emptyUniqSet unusable + $ foldM (applyPackageFlag prec_map prelim_pkg_db unusable hide_plugin_pkgs pkgs1) plugin_vis_map1 (reverse (unitConfigFlagsPlugins cfg)) @@ -1712,7 +1696,7 @@ mkUnitState logger cfg = do $ closeUnitDeps pkg_db $ zip (map toUnitId preload3) (repeat Nothing) - let mod_map1 = mkModuleNameProvidersMap logger cfg pkg_db emptyUniqSet vis_map + let mod_map1 = mkModuleNameProvidersMap logger cfg pkg_db vis_map mod_map2 = mkUnusableModuleNameProvidersMap unusable mod_map = mod_map2 `plusUniqMap` mod_map1 @@ -1722,9 +1706,8 @@ mkUnitState logger cfg = do , explicitUnits = explicit_pkgs , homeUnitDepends = home_unit_deps , unitInfoMap = pkg_db - , preloadClosure = emptyUniqSet , moduleNameProvidersMap = mod_map - , pluginModuleNameProvidersMap = mkModuleNameProvidersMap logger cfg pkg_db emptyUniqSet plugin_vis_map + , pluginModuleNameProvidersMap = mkModuleNameProvidersMap logger cfg pkg_db plugin_vis_map , packageNameMap = pkgname_map , wireMap = wired_map , unwireMap = listToUniqMap [ (v,k) | (k,v) <- nonDetUniqMapToList wired_map ] @@ -1764,10 +1747,9 @@ mkModuleNameProvidersMap :: Logger -> UnitConfig -> UnitInfoMap - -> PreloadUnitClosure -> VisibilityMap -> ModuleNameProvidersMap -mkModuleNameProvidersMap logger cfg pkg_map closure vis_map = +mkModuleNameProvidersMap logger cfg pkg_map vis_map = -- What should we fold on? Both situations are awkward: -- -- * Folding on the visibility map means that we won't create @@ -1839,7 +1821,7 @@ mkModuleNameProvidersMap logger cfg pkg_map closure vis_map = hiddens = [(m, mkModMap pk m ModHidden) | m <- hidden_mods] pk = mkUnit pkg - unit_lookup uid = lookupUnit' (unitConfigAllowVirtual cfg) pkg_map closure uid + unit_lookup uid = lookupUnit' (unitConfigAllowVirtual cfg) pkg_map uid `orElse` pprPanic "unit_lookup" (ppr uid) exposed_mods = unitExposedModules pkg @@ -2190,44 +2172,16 @@ fsPackageName info = fs where PackageName fs = unitPackageName info - --- | Given a fully instantiated 'InstantiatedUnit', improve it into a --- 'RealUnit' if we can find it in the package database. -improveUnit :: UnitState -> Unit -> Unit -improveUnit state u = improveUnit' (unitInfoMap state) (preloadClosure state) u - --- | Given a fully instantiated 'InstantiatedUnit', improve it into a --- 'RealUnit' if we can find it in the package database. -improveUnit' :: UnitInfoMap -> PreloadUnitClosure -> Unit -> Unit -improveUnit' _ _ uid@(RealUnit _) = uid -- short circuit -improveUnit' pkg_map closure uid = - -- Do NOT lookup indefinite ones, they won't be useful! - case lookupUnit' False pkg_map closure uid of - Nothing -> uid - Just pkg -> - -- Do NOT improve if the indefinite unit id is not - -- part of the closure unique set. See - -- Note [VirtUnit to RealUnit improvement] - if unitId pkg `elementOfUniqSet` closure - then mkUnit pkg - else uid - --- | Check the database to see if we already have an installed unit that --- corresponds to the given 'InstantiatedUnit'. --- --- Return a `UnitId` which either wraps the `InstantiatedUnit` unchanged or --- references a matching installed unit. --- --- See Note [VirtUnit to RealUnit improvement] -instUnitToUnit :: UnitState -> InstantiatedUnit -> Unit -instUnitToUnit state iuid = +-- | Return a `UnitId` which either wraps the `InstantiatedUnit` unchanged. +instUnitToUnit :: InstantiatedUnit -> Unit +instUnitToUnit iuid = -- NB: suppose that we want to compare the instantiated -- unit p[H=impl:H] against p+abcd (where p+abcd -- happens to be the existing, installed version of -- p[H=impl:H]. If we *only* wrap in p[H=impl:H] -- VirtUnit, they won't compare equal; only -- after improvement will the equality hold. - improveUnit state $ VirtUnit iuid + VirtUnit iuid -- | Substitution on module variables, mapping module names to module @@ -2239,30 +2193,30 @@ type ShHoleSubst = ModuleNameEnv Module -- @p[A=\<A>]:B@ maps to @p[A=q():A]:B@ with @A=q():A@; -- similarly, @\<A>@ maps to @q():A@. renameHoleModule :: UnitState -> ShHoleSubst -> Module -> Module -renameHoleModule state = renameHoleModule' (unitInfoMap state) (preloadClosure state) +renameHoleModule state = renameHoleModule' (unitInfoMap state) -- | Substitutes holes in a 'Unit', suitable for renaming when -- an include occurs; see Note [Representation of module/name variables]. -- -- @p[A=\<A>]@ maps to @p[A=\<B>]@ with @A=\<B>@. renameHoleUnit :: UnitState -> ShHoleSubst -> Unit -> Unit -renameHoleUnit state = renameHoleUnit' (unitInfoMap state) (preloadClosure state) +renameHoleUnit state = renameHoleUnit' (unitInfoMap state) --- | Like 'renameHoleModule', but requires only 'ClosureUnitInfoMap' +-- | Like 'renameHoleModule', but requires only 'UnitInfoMap' -- so it can be used by "GHC.Unit.State". -renameHoleModule' :: UnitInfoMap -> PreloadUnitClosure -> ShHoleSubst -> Module -> Module -renameHoleModule' pkg_map closure env m +renameHoleModule' :: UnitInfoMap -> ShHoleSubst -> Module -> Module +renameHoleModule' pkg_map env m | not (isHoleModule m) = - let uid = renameHoleUnit' pkg_map closure env (moduleUnit m) + let uid = renameHoleUnit' pkg_map env (moduleUnit m) in mkModule uid (moduleName m) | Just m' <- lookupUFM env (moduleName m) = m' -- NB m = <Blah>, that's what's in scope. | otherwise = m --- | Like 'renameHoleUnit, but requires only 'ClosureUnitInfoMap' +-- | Like 'renameHoleUnit', but requires only 'UnitInfoMap' -- so it can be used by "GHC.Unit.State". -renameHoleUnit' :: UnitInfoMap -> PreloadUnitClosure -> ShHoleSubst -> Unit -> Unit -renameHoleUnit' pkg_map closure env uid = +renameHoleUnit' :: UnitInfoMap -> ShHoleSubst -> Unit -> Unit +renameHoleUnit' pkg_map env uid = case uid of (VirtUnit InstantiatedUnit{ instUnitInstanceOf = cid @@ -2270,20 +2224,15 @@ renameHoleUnit' pkg_map closure env uid = , instUnitHoles = fh }) -> if isNullUFM (intersectUFM_C const (udfmToUfm (getUniqDSet fh)) env) then uid - -- Functorially apply the substitution to the instantiation, - -- then check the 'ClosureUnitInfoMap' to see if there is - -- a compiled version of this 'InstantiatedUnit' we can improve to. - -- See Note [VirtUnit to RealUnit improvement] - else improveUnit' pkg_map closure $ - mkVirtUnit cid - (map (\(k,v) -> (k, renameHoleModule' pkg_map closure env v)) insts) + else mkVirtUnit cid + (map (\(k,v) -> (k, renameHoleModule' pkg_map env v)) insts) _ -> uid -- | Injects an 'InstantiatedModule' to 'Module' (see also -- 'instUnitToUnit'. -instModuleToModule :: UnitState -> InstantiatedModule -> Module -instModuleToModule pkgstate (Module iuid mod_name) = - mkModule (instUnitToUnit pkgstate iuid) mod_name +instModuleToModule :: InstantiatedModule -> Module +instModuleToModule (Module iuid mod_name) = + mkModule (instUnitToUnit iuid) mod_name -- | Print unit-ids with UnitInfo found in the given UnitState pprWithUnitState :: UnitState -> SDoc -> SDoc ===================================== compiler/GHC/Unit/Types.hs ===================================== @@ -250,9 +250,7 @@ data GenUnit uid -- -- This unit may be indefinite or not (i.e. with remaining holes or not). If it -- is definite, we don't know if it has already been compiled and installed in a --- database. Nevertheless, we have a mechanism called "improvement" to try to --- match a fully instantiated unit with existing compiled and installed units: --- see Note [VirtUnit to RealUnit improvement]. +-- database. -- -- An indefinite unit identifier pretty-prints to something like -- @p[H=<H>,A=aimpl:A>]@ (@p@ is the 'UnitId', and the View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/d07b7c61362f2c19a2f6475496b645e… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/d07b7c61362f2c19a2f6475496b645e… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/supersven/libDir-setting] 2 commits: Add optional config setting for LibDir (#19174)
by Sven Tennie (＠supersven) 28 May '26

28 May '26

Sven Tennie pushed to branch wip/supersven/libDir-setting at Glasgow Haskell Compiler / GHC Commits: 8548be69 by Sven Tennie at 2026-05-28T10:10:47+02:00 Add optional config setting for LibDir (#19174) Previously, the `libDir` was derived from `topDir`. This won't work for inplace stage2 cross-compilers where binaries and libraries are in different stage dirs (`_build/stage1/` for executables and `_build/stage2` for libraries). `LibDir` is set in the inplace `settings` files. For bindists, we generate a new `settings` file with no `LibDir` entry. GHC then defaults to use `topDir` as `libDir` again. This keeps the bindist relocatable. If `LibDir` is a relative path, it is interpreted relatively to `topDir`. The global package db is part of the `lib/` folder. If we want to point for inplace cross-compilers to the succeeding stage's folder, this is done by setting `LibDir`. Thus, the global package db must be found relative to `libDir`` (which may default to `topDir` or be set by `LibDir`). The complexity of settings becomes scary. So, add a test to ensure `LibDir` works as expected. - - - - - 197c5135 by Sven Tennie at 2026-05-28T10:18:25+02:00 Add Haddock to FileSettings Helping to understand the fields' meanings without deeper analyses. - - - - - 12 changed files: - + changelog.d/libdir-setting - compiler/GHC/Driver/Config/Interpreter.hs - compiler/GHC/Driver/DynFlags.hs - compiler/GHC/Driver/Session.hs - compiler/GHC/Settings.hs - compiler/GHC/Settings/IO.hs - hadrian/src/Rules/BinaryDist.hs - hadrian/src/Rules/Generate.hs - libraries/ghc-boot/GHC/Settings/Utils.hs - + testsuite/tests/ghc-api/settings/LibDir.hs - + testsuite/tests/ghc-api/settings/LibDir.stdout - + testsuite/tests/ghc-api/settings/all.T Changes: ===================================== changelog.d/libdir-setting ===================================== @@ -0,0 +1,15 @@ +section: packaging +synopsis: Added a new optional configuration setting for `LibDir` to support inplace + stage2 cross-compilers where binaries and libraries are in different stage + directories. +issues: #19174 +mrs: !15716 + +description: { + Previously, the `libDir` was always derived from `topDir`, which won't work + for inplace stage2 cross-compilers where executables are in `_build/stage1/` + and libraries are in `_build/stage2/`. Now, `LibDir` can be set, but is by + default derived from `topDir`. This facilitates the mentioned behaviour + while keeping the binary distribution code relocatable. This is a refactoring + step that does not change actual behaviour. +} ===================================== compiler/GHC/Driver/Config/Interpreter.hs ===================================== @@ -17,8 +17,8 @@ import System.Directory initInterpOpts :: DynFlags -> IO InterpOpts initInterpOpts dflags = do - wasm_dyld <- makeAbsolute $ topDir dflags </> "dyld.mjs" - js_interp <- makeAbsolute $ topDir dflags </> "ghc-interp.js" + wasm_dyld <- makeAbsolute $ libDir dflags </> "dyld.mjs" + js_interp <- makeAbsolute $ libDir dflags </> "ghc-interp.js" pure $ InterpOpts { interpExternal = gopt Opt_ExternalInterpreter dflags , interpProg = pgm_i dflags ===================================== compiler/GHC/Driver/DynFlags.hs ===================================== @@ -61,7 +61,7 @@ module GHC.Driver.DynFlags ( -- ** System tool settings and locations programName, projectVersion, - ghcUsagePath, ghciUsagePath, topDir, toolDir, + ghcUsagePath, ghciUsagePath, topDir, libDir, toolDir, versionedAppDir, versionedFilePath, extraGccViaCFlags, globalPackageDatabasePath, @@ -1516,6 +1516,8 @@ ghciUsagePath :: DynFlags -> FilePath ghciUsagePath dflags = fileSettings_ghciUsagePath $ fileSettings dflags topDir :: DynFlags -> FilePath topDir dflags = fileSettings_topDir $ fileSettings dflags +libDir :: DynFlags -> FilePath +libDir dflags = fileSettings_libDir $ fileSettings dflags toolDir :: DynFlags -> Maybe FilePath toolDir dflags = fileSettings_toolDir $ fileSettings dflags extraGccViaCFlags :: DynFlags -> [String] ===================================== compiler/GHC/Driver/Session.hs ===================================== @@ -3551,9 +3551,9 @@ compilerInfo dflags ("Project name", cProjectName) -- Next come the settings, so anything else can be overridden -- in the settings file (as "lookup" uses the first match for the - -- key) + -- key). We filter out LibDir from rawSettings to avoid duplication. : map (fmap expandDirectories) - (rawSettings dflags) + (filter ((/= "LibDir") . fst) (rawSettings dflags)) ++ [("C compiler command", queryCmd $ ccProgram . tgtCCompiler), ("C compiler flags", queryFlags $ ccProgram . tgtCCompiler), @@ -3656,7 +3656,7 @@ compilerInfo dflags -- Whether or not GHC was compiled using -prof ("GHC Profiled", showBool hostIsProfiled), ("Debug on", showBool debugIsOn), - ("LibDir", topDir dflags), + ("LibDir", libDir dflags), -- This is always an absolute path, unlike "Relative Global Package DB" which is -- in the settings file. ("Global Package DB", globalPackageDatabasePath dflags) ===================================== compiler/GHC/Settings.hs ===================================== @@ -179,11 +179,24 @@ data ToolSettings = ToolSettings -- | Paths to various files and directories used by GHC, including those that -- provide more settings. data FileSettings = FileSettings - { fileSettings_ghcUsagePath :: FilePath -- ditto - , fileSettings_ghciUsagePath :: FilePath -- ditto - , fileSettings_toolDir :: Maybe FilePath -- ditto - , fileSettings_topDir :: FilePath -- ditto + { fileSettings_ghcUsagePath :: FilePath + -- ^ Path to @ghc-usage.txt@, displayed by @ghc --help@ + , fileSettings_ghciUsagePath :: FilePath + -- ^ Path to @ghci-usage.txt@, displayed by @ghci --help@ + , fileSettings_toolDir :: Maybe FilePath + -- ^ Directory containing the mingw toolchain (Windows only); + -- see Note [tooldir: How GHC finds mingw on Windows] in `GHC.SysTools.BaseDir` + , fileSettings_topDir :: FilePath + -- ^ GHC's top directory: the root from which GHC locates its support files + -- (e.g. settings). + -- See Note [topdir: How GHC finds its files] in `GHC.SysTools.BaseDir` , fileSettings_globalPackageDatabase :: FilePath + -- ^ Path to the global package database, relative to `libDir` + , fileSettings_libDir :: FilePath + -- ^ Directory containing GHC's library packages and the global package + -- database. Defaults to 'fileSettings_topDir' but can differ in inplace + -- builds used for cross-compilation testing (the "stage2 cross-compiler" + -- scenario). } ===================================== compiler/GHC/Settings/IO.hs ===================================== @@ -28,6 +28,7 @@ import GHC.Toolchain.Program import GHC.Toolchain import GHC.Data.Maybe import Data.Bifunctor (Bifunctor(second)) +import Data.Either (fromRight) data SettingsError = SettingsError_MissingData String @@ -117,12 +118,6 @@ initSettings top_dir = do then ["-fwrapv", "-fno-builtin"] else [] - -- The package database is either a relative path to the location of the settings file - -- OR an absolute path. - -- In case the path is absolute then top_dir </> abs_path == abs_path - -- the path is relative then top_dir </> rel_path == top_dir </> rel_path - globalpkgdb_path <- installed <$> getSetting "Relative Global Package DB" - let ghc_usage_msg_path = installed "ghc-usage.txt" ghci_usage_msg_path = installed "ghci-usage.txt" @@ -148,6 +143,19 @@ initSettings top_dir = do baseUnitId <- getSetting_raw "base unit-id" + -- LibDir is optional. If not set, derive it from topDir. This allows + -- bindists to work without explicitly setting LibDir, but gives us the + -- option to override it for inplace test compilers (the "stage2 + -- cross-compiler" scenario). If LibDir is a relative path, it is + -- interpreted relative to topDir. + let lib_dir = installed $ fromRight "." $ + getRawFilePathSetting top_dir settingsFile mySettings "LibDir" + + -- The package database is either a relative path to lib_dir OR an absolute path. + -- In case the path is absolute then lib_dir </> abs_path == abs_path + -- the path is relative then lib_dir </> rel_path == lib_dir </> rel_path + globalpkgdb_path <- (lib_dir </>) <$> getSetting "Relative Global Package DB" + return $ Settings { sGhcNameVersion = GhcNameVersion { ghcNameVersion_programName = "ghc" @@ -159,6 +167,7 @@ initSettings top_dir = do , fileSettings_ghciUsagePath = ghci_usage_msg_path , fileSettings_toolDir = mtool_dir , fileSettings_topDir = top_dir + , fileSettings_libDir = lib_dir , fileSettings_globalPackageDatabase = globalpkgdb_path } ===================================== hadrian/src/Rules/BinaryDist.hs ===================================== @@ -14,6 +14,7 @@ import qualified System.Directory.Extra as IO import Data.Either import qualified Data.Set as Set import Oracles.Flavour +import Rules.Generate (generateSettings) {- Note [Binary distributions] @@ -218,6 +219,17 @@ bindistRules = do IO.createFileLink version_prog versioned_runhaskell_path copyDirectory (ghcBuildDir -/- "lib") bindistFilesDir + + -- Regenerate settings file without LibDir. For bindists, LibDir should + -- be derived from topdir at runtime such that the GHC binary is + -- relocatable. The package DB is always at "package.conf.d" relative to + -- the lib dir, matching the known bindist layout. + let bindistSettings = bindistFilesDir -/- "lib" -/- "settings" + bindistContext = vanillaContext Stage1 compiler + bindistSettingsContent <- interpretInContext bindistContext $ + generateSettings bindistSettings False "package.conf.d" + writeFile' bindistSettings bindistSettingsContent + copyDirectory (rtsIncludeDir) bindistFilesDir when windowsHost $ createGhcii (bindistFilesDir -/- "bin") ===================================== hadrian/src/Rules/Generate.hs ===================================== @@ -1,7 +1,7 @@ module Rules.Generate ( isGeneratedCmmFile, compilerDependencies, generatePackageCode, generateRules, copyRules, generatedDependencies, - templateRules + templateRules, generateSettings ) where import Development.Shake.FilePath @@ -256,8 +256,21 @@ generateRules = do forM_ allStages $ \stage -> do let prefix = root -/- stageString stage -/- "lib" - go gen file = generate file (semiEmptyTarget (succStage stage)) gen - (prefix -/- "settings") %> \out -> go (generateSettings out) out + -- Stage0 compiler builds Stage1, Stage1 -> Stage2, etc. + buildStage = succStage stage + go gen file = generate file (semiEmptyTarget buildStage) gen + (prefix -/- "settings") %> \out -> do + let get_pkg_db stg = packageDbPath (PackageDbLoc stg Final) + pkgDb <- case buildStage of + Stage0 {} -> error "Unable to generate settings for stage0. This should never be reached." + Stage1 -> get_pkg_db Stage1 + Stage2 -> get_pkg_db Stage1 + Stage3 -> get_pkg_db Stage2 + -- addTrailingPathSeparator needed: makeRelativeNoSysLink uses + -- splitPath where "lib" and "lib/" are distinct components. + let lib_topDir = addTrailingPathSeparator prefix + relPkgDb = makeRelativeNoSysLink lib_topDir pkgDb + go (generateSettings out True relPkgDb) out (prefix -/- "targets" -/- "default.target") %> \out -> go (show <$> expr getTargetTarget) out where @@ -460,19 +473,17 @@ ghcWrapper stage = do return $ unwords $ map show $ [ ghcPath ] ++ [ "$@" ] -generateSettings :: FilePath -> Expr String -generateSettings settingsFile = do +-- | Generate settings file, optionally including @LibDir@. +-- +-- @rel_pkg_db@: package DB path relative to the lib dir (e.g. +-- "package.conf.d"). Callers supply the correct relative path. For bindists +-- the layout is known statically; for in-tree builds callers compute it. For +-- bindists, we omit @LibDir@ so it defaults to @topDir@ at runtime. +generateSettings :: FilePath -> Bool -> FilePath -> Expr String +generateSettings settingsFile includeLibDir rel_pkg_db = do ctx <- getContext stage <- getStage - package_db_path <- expr $ do - let get_pkg_db stg = packageDbPath (PackageDbLoc stg Final) - case stage of - Stage0 {} -> error "Unable to generate settings for stage0" - Stage1 -> get_pkg_db Stage1 - Stage2 -> get_pkg_db Stage1 - Stage3 -> get_pkg_db Stage2 - -- The unit-id of the base package which is always linked against (#25382) base_unit_id <- expr $ do case stage of @@ -481,15 +492,24 @@ generateSettings settingsFile = do Stage2 -> pkgUnitId Stage1 base Stage3 -> pkgUnitId Stage2 base - let rel_pkg_db = makeRelativeNoSysLink (dropFileName settingsFile) package_db_path + let -- E.g. the Stage2 compiler lives in _build/stage1 + -- So, we need to decrement the stage to get the correct directory + stage_dir_stage = predStage stage + + -- addTrailingPathSeparator is needed because makeRelativeNoSysLink uses + -- splitPath internally, where "lib" and "lib/" are distinct components. + lib_topDir :: FilePath <- expr $ addTrailingPathSeparator <$> stageLibPath stage_dir_stage + let rel_lib_topDir = makeRelativeNoSysLink (dropFileName settingsFile) lib_topDir settings <- traverse sequence $ - [ ("unlit command", ("$topdir/../bin/" <>) <$> expr (programName (ctx { Context.package = unlit }))) - , ("Use interpreter", expr $ yesNo <$> ghcWithInterpreter (predStage stage)) - , ("RTS ways", escapeArgs . map show . Set.toList <$> getRtsWays) - , ("Relative Global Package DB", pure rel_pkg_db) - , ("base unit-id", pure base_unit_id) - ] + [ ("unlit command", ("$topdir/../bin/" <>) <$> expr (programName (ctx { Context.package = unlit }))) + , ("Use interpreter", expr $ yesNo <$> ghcWithInterpreter (predStage stage)) + , ("RTS ways", escapeArgs . map show . Set.toList <$> getRtsWays) + , ("Relative Global Package DB", pure rel_pkg_db) + , ("base unit-id", pure base_unit_id) + ] + ++ ([("LibDir", pure rel_lib_topDir) | includeLibDir]) + let showTuple (k, v) = "(" ++ show k ++ ", " ++ show v ++ ")" pure $ case settings of [] -> "[]" ===================================== libraries/ghc-boot/GHC/Settings/Utils.hs ===================================== @@ -3,6 +3,7 @@ module GHC.Settings.Utils where import Prelude -- See Note [Why do we import Prelude here?] import Data.Char (isSpace) +import Data.Either (fromRight) import Data.Map (Map) import qualified Data.Map as Map @@ -45,7 +46,10 @@ getTargetArchOS target = tgtArchOs target getGlobalPackageDb :: FilePath -> RawSettings -> Either String FilePath getGlobalPackageDb settingsFile settings = do rel_db <- getRawSetting settingsFile settings "Relative Global Package DB" - return (dropFileName settingsFile </> rel_db) + let top_dir = dropFileName settingsFile + lib_dir = (top_dir </>) $ fromRight "." $ + getRawFilePathSetting top_dir settingsFile settings "LibDir" + return (lib_dir </> rel_db) -------------------------------------------------------------------------------- -- lib/settings ===================================== testsuite/tests/ghc-api/settings/LibDir.hs ===================================== @@ -0,0 +1,130 @@ +module Main where + +import Control.Monad (when) +import Control.Monad.IO.Class (liftIO) +import Data.List (intercalate) +import GHC +import GHC.Driver.DynFlags +import GHC.Driver.Env (hsc_dflags) +import GHC.Settings +import System.Directory +import System.Environment +import System.Exit (ExitCode (ExitFailure), exitWith) +import System.FilePath +import System.IO (hPutStrLn, stderr) +import System.Process (readProcess) +import Unsafe.Coerce (unsafeCoerce) + +-- Verify that a LibDir setting in the settings file is respected: +-- 1. fileSettings_libDir and fileSettings_globalPackageDatabase reflect the +-- configured LibDir path (not topDir) +-- 2. GHC can still compile with a LibDir that differs from topDir +-- 3. --print-libdir and --print-global-package-db output the correct paths +-- +-- We create a symlink to the real lib dir so that the package DB remains +-- findable, but use a separate topDir so that topDir ≠ libDir, proving +-- the LibDir setting is actually used. +-- +-- Tested for both relative and absolute LibDir values. +main :: IO () +main = do + libdir : ghcBin : _ <- getArgs + + (rawSettingOpts, rawTargetOpts, realLibDir) <- runGhc (Just libdir) $ do + dflags <- hsc_dflags <$> getSession + pure (rawSettings dflags, rawTarget dflags, fileSettings_libDir (fileSettings dflags)) + + tmpDir <- getTemporaryDirectory + let topDir = tmpDir </> "T19174_top" + symlinkLib = tmpDir </> "T19174_lib" + -- Remove stale dirs from prior runs; createDirectoryLink fails if path exists. + removePathForcibly topDir + removePathForcibly symlinkLib + createDirectoryIfMissing True (topDir </> "targets") + createDirectoryLink realLibDir symlinkLib + + let testWithLibDir libDirValue = do + writeTopDirFiles topDir rawSettingOpts rawTargetOpts libDirValue + runGhc (Just topDir) $ do + assertSettings topDir symlinkLib + compileAndRunTestExpr + assertGhcFlags ghcBin topDir symlinkLib + + testWithLibDir (".." </> takeFileName symlinkLib) + testWithLibDir symlinkLib + + putStrLn "OK" + +writeTopDirFiles :: + (Show a) => + FilePath -> + [(String, String)] -> + a -> + String -> + IO () +writeTopDirFiles topDir rawSettingOpts rawTargetOpts libDirValue = do + let settings = filter ((/= "LibDir") . fst) rawSettingOpts ++ [("LibDir", libDirValue)] + writeFile (topDir </> "settings") $ + "[" ++ intercalate "\n," (map show settings) ++ "]" + writeFile (topDir </> "targets" </> "default.target") $ + show rawTargetOpts + +assertSettings :: FilePath -> FilePath -> Ghc () +assertSettings topDir expectedLib = do + dflags <- hsc_dflags <$> getSession + let fs = fileSettings dflags + actualLib = fileSettings_libDir fs + actualPkgDb = fileSettings_globalPackageDatabase fs + normActualLib <- liftIO $ canonicalizePath actualLib + normExpected <- liftIO $ canonicalizePath expectedLib + normTopDir <- liftIO $ canonicalizePath topDir + normActualPkgDb <- liftIO $ canonicalizePath actualPkgDb + normExpectedPkgDb <- liftIO $ canonicalizePath (expectedLib </> "package.conf.d") + liftIO $ do + when (normActualLib /= normExpected) $ + die + [ "FAIL: libDir should be " ++ normExpected, + " got " ++ normActualLib + ] + when (normActualLib == normTopDir) $ + die ["FAIL: libDir equals topDir — LibDir setting was ignored"] + when (normActualPkgDb /= normExpectedPkgDb) $ + die + [ "FAIL: globalPackageDB should be " ++ normExpectedPkgDb, + " got " ++ normActualPkgDb + ] + +assertGhcFlags :: FilePath -> FilePath -> FilePath -> IO () +assertGhcFlags ghcBin topDir expectedLib = do + normExpectedLib <- canonicalizePath expectedLib + normExpectedPkgDb <- canonicalizePath (expectedLib </> "package.conf.d") + + printedLibDir <- trim <$> readProcess ghcBin ["-B" ++ topDir, "--print-libdir"] "" + normPrintedLib <- canonicalizePath printedLibDir + when (normPrintedLib /= normExpectedLib) $ + die + [ "FAIL: --print-libdir should be " ++ normExpectedLib, + " got " ++ normPrintedLib + ] + + printedPkgDb <- trim <$> readProcess ghcBin ["-B" ++ topDir, "--print-global-package-db"] "" + normPrintedPkgDb <- canonicalizePath printedPkgDb + when (normPrintedPkgDb /= normExpectedPkgDb) $ + die + [ "FAIL: --print-global-package-db should be " ++ normExpectedPkgDb, + " got " ++ normPrintedPkgDb + ] + +compileAndRunTestExpr :: Ghc () +compileAndRunTestExpr = do + dflags <- getSessionDynFlags + _ <- setSessionDynFlags dflags + setContext [IIDecl (simpleImportDecl (mkModuleName "Prelude"))] + result <- compileExpr "length [1,2,3 :: Int]" + liftIO $ print (unsafeCoerce result :: Int) + +trim :: String -> String +trim = reverse . dropWhile (== '\n') . reverse + +die :: [String] -> IO () +die msgs = mapM_ (hPutStrLn stderr) msgs >> exitWith (ExitFailure 1) ===================================== testsuite/tests/ghc-api/settings/LibDir.stdout ===================================== @@ -0,0 +1,3 @@ +3 +3 +OK ===================================== testsuite/tests/ghc-api/settings/all.T ===================================== @@ -0,0 +1,12 @@ +test('LibDir', + [ extra_run_opts('"' + config.libdir + '" "' + config.compiler + '"') + , req_interp + # createDirectoryLink uses CreateSymbolicLink on Windows (requires developer + # mode or admin); also GHC searches for mingw relative to topDir, which our + # artificial topDir doesn't provide. + , when(opsys('mingw32'), skip) + # TODO: wasm CI image lacks permission to create symlinks in temp dir (`/tmp`). + , when(arch('wasm32'), skip) + ] + , compile_and_run + , ['-package ghc -package directory -package filepath']) View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/f99d858cc211ca2d6577d8bf6a53e7… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/f99d858cc211ca2d6577d8bf6a53e7… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc] Deleted branch wip/fix-hpc-bytecode-modname
by Cheng Shao (＠TerrorJack) 28 May '26

28 May '26

Cheng Shao deleted branch wip/fix-hpc-bytecode-modname at Glasgow Haskell Compiler / GHC -- You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/supersven/libDir-setting] Update docs
by Sven Tennie (＠supersven) 28 May '26

28 May '26

Sven Tennie pushed to branch wip/supersven/libDir-setting at Glasgow Haskell Compiler / GHC Commits: f99d858c by Sven Tennie at 2026-05-28T07:31:13+00:00 Update docs - - - - - 1 changed file: - compiler/GHC/Settings.hs Changes: ===================================== compiler/GHC/Settings.hs ===================================== @@ -191,7 +191,7 @@ data FileSettings = FileSettings -- (e.g. settings). -- See Note [topdir: How GHC finds its files] in `GHC.SysTools.BaseDir` , fileSettings_globalPackageDatabase :: FilePath - -- ^ Path to the global package database + -- ^ Path to the global package database, relative to `libDir` , fileSettings_libDir :: FilePath -- ^ Directory containing GHC's library packages and the global package -- database. Defaults to 'fileSettings_topDir' but can differ in inplace View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/f99d858cc211ca2d6577d8bf6a53e7b… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/f99d858cc211ca2d6577d8bf6a53e7b… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/marge_bot_batch_merge_job] 4 commits: Fixes for black holes
by Marge Bot (＠marge-bot) 28 May '26

28 May '26

Marge Bot pushed to branch wip/marge_bot_batch_merge_job at Glasgow Haskell Compiler / GHC Commits: 99cb9c39 by Luite Stegeman at 2026-05-28T03:10:49-04:00 Fixes for black holes - suspend duplicate work for eager black holes - detect eager black holes in checkBlockingQueues - don't overwrite existing black holes even if they're not in an eager blackhole frame - don't deadlock on self when thunk is already blackholed Fixes #26936 - - - - - 80264eb1 by Wolfgang Jeltsch at 2026-05-28T03:10:49-04:00 Allow `downsweep` to use nodes of an existing module graph To this end, `downsweep` has not been able to use the nodes of a module graph obtained from a previous downsweeping round. In some GHC API applications, downsweeping is performed somewhat incrementally and therefore could profit from reusing such existing results. This contribution makes this possible. Resolves #27054. Co-authored-by: Matthew Pickering <matthewtpickering(a)gmail.com> - - - - - bfea8114 by Simon Jakobi at 2026-05-28T03:10:51-04:00 compiler: use nubOrd from containers Address #27103 by replacing GHC.Utils.Misc.ordNub[On] with Data.Containers.ListUtils.nubOrd[On]. Note that nubOrd suffers from a small inefficiency, a fix for which will be included in the next containers release: https://github.com/haskell/containers/issues/1202 - - - - - 179e22a9 by Simon Jakobi at 2026-05-28T03:10:52-04:00 Add regression test for T11226 Closes #11226. - - - - - 35 changed files: - + changelog.d/fix-blackhole-handling - + changelog.d/module-graph-reuse-in-downsweep - compiler/GHC/CmmToAsm/BlockLayout.hs - compiler/GHC/Driver/Backpack.hs - compiler/GHC/Driver/Downsweep.hs - compiler/GHC/Driver/Make.hs - compiler/GHC/Driver/Session/Units.hs - compiler/GHC/HsToCore/Usage.hs - compiler/GHC/Linker/Unit.hs - compiler/GHC/Rename/Pat.hs - compiler/GHC/Unit/Info.hs - compiler/GHC/Unit/State.hs - compiler/GHC/Utils/Misc.hs - ghc/GHCi/UI.hs - rts/Messages.c - rts/ThreadPaused.c - rts/Threads.c - rts/Updates.h - rts/include/rts/storage/ClosureMacros.h - + testsuite/tests/ghc-api/downsweep/IncrementalDownsweep.hs - + testsuite/tests/ghc-api/downsweep/IncrementalDownsweep.modules/A.hs - + testsuite/tests/ghc-api/downsweep/IncrementalDownsweep.modules/B.hs - + testsuite/tests/ghc-api/downsweep/IncrementalDownsweep.modules/C.hs - + testsuite/tests/ghc-api/downsweep/IncrementalDownsweep.modules/D.hs - + testsuite/tests/ghc-api/downsweep/IncrementalDownsweep.modules/X.hs - + testsuite/tests/ghc-api/downsweep/IncrementalDownsweep.modules/Y.hs - + testsuite/tests/ghc-api/downsweep/IncrementalDownsweep.modules/Z.hs - + testsuite/tests/ghc-api/downsweep/IncrementalDownsweep.stdout - testsuite/tests/ghc-api/downsweep/OldModLocation.hs - testsuite/tests/ghc-api/downsweep/PartialDownsweep.hs - testsuite/tests/ghc-api/downsweep/all.T - testsuite/tests/ghc-api/fixed-nodes/InterfaceModuleGraph.hs - + testsuite/tests/perf/should_run/T11226.hs - + testsuite/tests/perf/should_run/T11226.stdout - testsuite/tests/perf/should_run/all.T The diff was not included because it is too large. View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/9ba3e13a1e8a3f90c1ca0897058641… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/9ba3e13a1e8a3f90c1ca0897058641… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/marge_bot_batch_merge_job] 6 commits: Trim the continuation in mkDupableContWithDmds
by Marge Bot (＠marge-bot) 28 May '26

28 May '26

Marge Bot pushed to branch wip/marge_bot_batch_merge_job at Glasgow Haskell Compiler / GHC Commits: 4a645683 by Simon Peyton Jones at 2026-05-27T21:41:59-04:00 Trim the continuation in mkDupableContWithDmds When there are no remaining argument demands, it means the application is bottoming. In this case, we can trim the continuation to avoid the panic that was observed in #27261. See Note [Trimming the continuation for bottoming functions] in GHC.Core.Opt.Simplify.Iteration. - - - - - 8ab506ff by Cheng Shao at 2026-05-27T21:42:47-04:00 ghci: fix module name string lifetime in hs_hpc_module invocation This patch makes hpcAddModule pass a properly malloced module name string to hs_hpc_module, instead of using useAsCString which causes use-after-free of module name string. Fixes #27297. Co-authored-by: Codex <codex(a)openai.com> - - - - - b0233814 by sheaf at 2026-05-27T21:43:31-04:00 Relax acceptance threshold for T10421 As seen in #27289, the 1% acceptance threshold for this text was overly narrow, resulting in spurious test failures. This commit widens the acceptance threshold to 2%. Fixes #27289. - - - - - d83f887f by Wolfgang Jeltsch at 2026-05-27T22:17:21-04:00 Allow `downsweep` to use nodes of an existing module graph To this end, `downsweep` has not been able to use the nodes of a module graph obtained from a previous downsweeping round. In some GHC API applications, downsweeping is performed somewhat incrementally and therefore could profit from reusing such existing results. This contribution makes this possible. Resolves #27054. Co-authored-by: Matthew Pickering <matthewtpickering(a)gmail.com> - - - - - 0264f626 by Simon Jakobi at 2026-05-27T22:17:22-04:00 compiler: use nubOrd from containers Address #27103 by replacing GHC.Utils.Misc.ordNub[On] with Data.Containers.ListUtils.nubOrd[On]. Note that nubOrd suffers from a small inefficiency, a fix for which will be included in the next containers release: https://github.com/haskell/containers/issues/1202 - - - - - 9ba3e13a by Simon Jakobi at 2026-05-27T22:17:23-04:00 Add regression test for T11226 Closes #11226. - - - - - 40 changed files: - + changelog.d/T27261 - + changelog.d/module-graph-reuse-in-downsweep - compiler/GHC/CmmToAsm/BlockLayout.hs - compiler/GHC/Core/Opt/Simplify/Iteration.hs - compiler/GHC/Core/Opt/Simplify/Utils.hs - compiler/GHC/Driver/Backpack.hs - compiler/GHC/Driver/Downsweep.hs - compiler/GHC/Driver/Make.hs - compiler/GHC/Driver/Session/Units.hs - compiler/GHC/HsToCore/Usage.hs - compiler/GHC/Linker/Unit.hs - compiler/GHC/Rename/Pat.hs - compiler/GHC/Unit/Info.hs - compiler/GHC/Unit/State.hs - compiler/GHC/Utils/Misc.hs - ghc/GHCi/UI.hs - + libraries/ghc-boot/GHC/Data/ShortByteString.hs - libraries/ghc-boot/ghc-boot.cabal.in - libraries/ghci/GHCi/Coverage.hs - libraries/ghci/GHCi/Run.hs - + testsuite/tests/ghc-api/downsweep/IncrementalDownsweep.hs - + testsuite/tests/ghc-api/downsweep/IncrementalDownsweep.modules/A.hs - + testsuite/tests/ghc-api/downsweep/IncrementalDownsweep.modules/B.hs - + testsuite/tests/ghc-api/downsweep/IncrementalDownsweep.modules/C.hs - + testsuite/tests/ghc-api/downsweep/IncrementalDownsweep.modules/D.hs - + testsuite/tests/ghc-api/downsweep/IncrementalDownsweep.modules/X.hs - + testsuite/tests/ghc-api/downsweep/IncrementalDownsweep.modules/Y.hs - + testsuite/tests/ghc-api/downsweep/IncrementalDownsweep.modules/Z.hs - + testsuite/tests/ghc-api/downsweep/IncrementalDownsweep.stdout - testsuite/tests/ghc-api/downsweep/OldModLocation.hs - testsuite/tests/ghc-api/downsweep/PartialDownsweep.hs - testsuite/tests/ghc-api/downsweep/all.T - testsuite/tests/ghc-api/fixed-nodes/InterfaceModuleGraph.hs - testsuite/tests/perf/compiler/all.T - + testsuite/tests/perf/should_run/T11226.hs - + testsuite/tests/perf/should_run/T11226.stdout - testsuite/tests/perf/should_run/all.T - + testsuite/tests/simplCore/should_compile/T27261.hs - + testsuite/tests/simplCore/should_compile/T27261_aux.hs - testsuite/tests/simplCore/should_compile/all.T The diff was not included because it is too large. View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/f716714b9cc801ec40b946f1164db0… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/f716714b9cc801ec40b946f1164db0… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][master] Relax acceptance threshold for T10421
by Marge Bot (＠marge-bot) 28 May '26

28 May '26

Marge Bot pushed to branch master at Glasgow Haskell Compiler / GHC Commits: b0233814 by sheaf at 2026-05-27T21:43:31-04:00 Relax acceptance threshold for T10421 As seen in #27289, the 1% acceptance threshold for this text was overly narrow, resulting in spurious test failures. This commit widens the acceptance threshold to 2%. Fixes #27289. - - - - - 1 changed file: - testsuite/tests/perf/compiler/all.T Changes: ===================================== testsuite/tests/perf/compiler/all.T ===================================== @@ -678,7 +678,7 @@ test ('T18140', ['-v0 -O']) test('T10421', [ only_ways(['normal']), - collect_compiler_runtime(1) + collect_compiler_runtime(2) # 1% tolerance was too small (#27289) ], multimod_compile, ['T10421', '-v0 -O']) View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/b0233814d63c2802a521dfc7dae08b1… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/b0233814d63c2802a521dfc7dae08b1… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][master] ghci: fix module name string lifetime in hs_hpc_module invocation
by Marge Bot (＠marge-bot) 28 May '26

28 May '26

Marge Bot pushed to branch master at Glasgow Haskell Compiler / GHC Commits: 8ab506ff by Cheng Shao at 2026-05-27T21:42:47-04:00 ghci: fix module name string lifetime in hs_hpc_module invocation This patch makes hpcAddModule pass a properly malloced module name string to hs_hpc_module, instead of using useAsCString which causes use-after-free of module name string. Fixes #27297. Co-authored-by: Codex <codex(a)openai.com> - - - - - 4 changed files: - + libraries/ghc-boot/GHC/Data/ShortByteString.hs - libraries/ghc-boot/ghc-boot.cabal.in - libraries/ghci/GHCi/Coverage.hs - libraries/ghci/GHCi/Run.hs Changes: ===================================== libraries/ghc-boot/GHC/Data/ShortByteString.hs ===================================== @@ -0,0 +1,17 @@ +module GHC.Data.ShortByteString + ( newCStringFromSBS + ) where + +import Prelude + +import qualified Data.ByteString.Short as SBS +import Foreign +import Foreign.C + +newCStringFromSBS :: SBS.ShortByteString -> IO CString +newCStringFromSBS sbs = + SBS.useAsCStringLen sbs $ \(src, len) -> do + dst <- mallocBytes (len + 1) + copyBytes dst src len + pokeByteOff dst len (0 :: Word8) + pure dst ===================================== libraries/ghc-boot/ghc-boot.cabal.in ===================================== @@ -51,6 +51,7 @@ Library exposed-modules: GHC.BaseDir + GHC.Data.ShortByteString GHC.Data.ShortText GHC.Data.SizedSeq GHC.Data.SmallArray ===================================== libraries/ghci/GHCi/Coverage.hs ===================================== @@ -9,9 +9,9 @@ import Prelude -- See note [Why do we import Prelude here?] import Control.Exception import Data.ByteString.Short (ShortByteString) -import qualified Data.ByteString.Short as SBS import Data.Word import Foreign +import GHC.Data.ShortByteString import GHC.Foreign (CString) import GHC.Utils.Encoding.UTF8 (utf8DecodeShortByteString) import GHCi.ObjLink (lookupSymbol) @@ -31,17 +31,19 @@ hpcAddModule :: -- ^ Name of the ticks array found in the c-stub. IO () hpcAddModule modlName ticks hash tickboxes = do - SBS.useAsCString modlName $ \modlNameLiteral -> do - -- we need to find the reference to the ticks array. - lookupSymbol tickboxes >>= \ case - Nothing -> do - -- the symbol is not found, this is a bug! - throwIO $ ErrorCall $ "hpcAddModule: failed to find symbol " <> utf8DecodeShortByteString tickboxes - Just tickBoxRef -> do - -- Calling 'hs_hpc_module' multiple times is safe, it will add the module only once. - hpc_register_module modlNameLiteral (fromIntegral ticks) (fromIntegral hash) (castPtr tickBoxRef) - -- calling 'hpc_startup' multiple times is safe, it will only be initialised once. - hpc_startup + -- we need to find the reference to the ticks array. + lookupSymbol tickboxes >>= \ case + Nothing -> do + -- the symbol is not found, this is a bug! + throwIO $ ErrorCall $ "hpcAddModule: failed to find symbol " <> utf8DecodeShortByteString tickboxes + Just tickBoxRef -> do + -- hs_hpc_module stores the module name pointer in the RTS hash table + -- until exitHpc, so pass a malloced C string. + modlNameLiteral <- newCStringFromSBS modlName + -- Calling 'hs_hpc_module' multiple times is safe, it will add the module only once. + hpc_register_module modlNameLiteral (fromIntegral ticks) (fromIntegral hash) (castPtr tickBoxRef) + -- calling 'hpc_startup' multiple times is safe, it will only be initialised once. + hpc_startup foreign import ccall unsafe "hs_hpc_module" hpc_register_module :: CString -> Word32 -> Word32 -> Ptr Word64 -> IO () ===================================== libraries/ghci/GHCi/Run.hs ===================================== @@ -37,6 +37,9 @@ import Control.Monad import Data.ByteString (ByteString) import qualified Data.ByteString.Short.Internal as BS import qualified Data.ByteString.Unsafe as B +#if defined(PROFILING) +import GHC.Data.ShortByteString +#endif import GHC.Exts import qualified GHC.Exts.Heap as Heap import GHC.Stack @@ -447,13 +450,6 @@ mkCostCentres mod ccs = do c_srcspan <- newCStringFromSBS srcspan toRemotePtr <$> c_mkCostCentre c_name c_module c_srcspan - newCStringFromSBS sbs = do - let len = BS.length sbs - buf <- mallocBytes $ len + 1 - BS.copyToPtr sbs 0 buf (fromIntegral len) - pokeByteOff buf len (0 :: Word8) - pure buf - foreign import ccall unsafe "mkCostCentre" c_mkCostCentre :: Ptr CChar -> Ptr CChar -> Ptr CChar -> IO (Ptr CostCentre) #else View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/8ab506ff3219560b20e1d9040e79337… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/8ab506ff3219560b20e1d9040e79337… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][master] Trim the continuation in mkDupableContWithDmds
by Marge Bot (＠marge-bot) 28 May '26

28 May '26

Marge Bot pushed to branch master at Glasgow Haskell Compiler / GHC Commits: 4a645683 by Simon Peyton Jones at 2026-05-27T21:41:59-04:00 Trim the continuation in mkDupableContWithDmds When there are no remaining argument demands, it means the application is bottoming. In this case, we can trim the continuation to avoid the panic that was observed in #27261. See Note [Trimming the continuation for bottoming functions] in GHC.Core.Opt.Simplify.Iteration. - - - - - 6 changed files: - + changelog.d/T27261 - compiler/GHC/Core/Opt/Simplify/Iteration.hs - compiler/GHC/Core/Opt/Simplify/Utils.hs - + testsuite/tests/simplCore/should_compile/T27261.hs - + testsuite/tests/simplCore/should_compile/T27261_aux.hs - testsuite/tests/simplCore/should_compile/all.T Changes: ===================================== changelog.d/T27261 ===================================== @@ -0,0 +1,10 @@ +section: compiler +issues: #27261 +mrs: !16084 +synopsis: + Avoid a crash in ``mkDupableContWithDmds`` when given empty demands +description: + The case of an empty list of remaining argument demands is now explicitly + handled by trimming the simplifier continuation, to avoid a compiler crash + of the form ``Non-exhaustive patterns in dmd : cont_dmds`` or ``expectNonEmpty`` + in ``mkDupableContWithDmds``. ===================================== compiler/GHC/Core/Opt/Simplify/Iteration.hs ===================================== @@ -62,6 +62,7 @@ import GHC.Types.Var ( isTyCoVar ) import GHC.Builtin.Types.Prim( realWorldStatePrimTy ) import GHC.Builtin.Names( runRWKey, seqHashKey ) +import qualified GHC.Data.List.Infinite as Inf import GHC.Data.Maybe ( isNothing, orElse, mapMaybe ) import GHC.Data.FastString import GHC.Unit.Module ( moduleName ) @@ -2444,24 +2445,9 @@ rebuildCall env arg_info _cont ---------- Bottoming applications -------------- rebuildCall env (ArgInfo { ai_fun = fun, ai_args = rev_args, ai_dmds = [] }) cont - -- When we run out of strictness args, it means - -- that the call is definitely bottom; see GHC.Core.Opt.Simplify.Utils.mkArgInfo - -- Then we want to discard the entire strict continuation. E.g. - -- * case (error "hello") of { ... } - -- * (error "Hello") arg - -- * f (error "Hello") where f is strict - -- etc - -- Then, especially in the first of these cases, we'd like to discard - -- the continuation, leaving just the bottoming expression. But the - -- type might not be right, so we may have to add a coerce. - | not (contIsTrivial cont) -- Only do this if there is a non-trivial - -- continuation to discard, else we do it - -- again and again! - = seqType cont_ty `seq` -- See Note [Avoiding space leaks in OutType] - return (emptyFloats env, castBottomExpr res cont_ty) - where - res = argInfoExpr fun rev_args - cont_ty = contResultType cont + -- When we run out of demands, it means that the call is definitely bottom. + -- See (TC2) in Note [Trimming the continuation for bottoming functions] + = rebuild env (argInfoExpr fun rev_args) (mkBottomCont cont) ---------- Simplify type applications -------------- rebuildCall env info (ApplyToTy { sc_arg_ty = arg_ty, sc_hole_ty = hole_ty, sc_cont = cont }) @@ -4045,6 +4031,41 @@ When we have then we can just duplicate those alts because the A and C cases will disappear immediately. This is more direct than creating join points and inlining them away. See #4930. + +Note [Trimming the continuation for bottoming functions] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +Suppose + f :: Int -> Int -> Int + f x = error "urk" + + foo = f 3 4 + +f's demand signature say "after one arg I return bottom". We can drop +the remaining arguments, thus + + foo = case f 3 of {} + +This trimming can also be done with other continuations: + * case (error "hello") of { ... } + * f (error "Hello") where f is strict + etc + +We implement the trimming in three parts: + +(TC1) In `mkArgInfo`, for a bottoming function, we make a list of `RemainingArgDmds` + with a finite list of elements (in the example above, just one). + + For comparison, note that, for non-bottoming functions, the `RemainingArgDmds` + always finishes with an infinite list of `topDmd`. + +(TC2) In `rebuildCall`, when we run out of `RemainingArgDmds` we discard the + remaining continuation. + + After discarding the continuation, the types might not match, in which case + we leave behind a (case <hole> of {}) wrapper. See the call to `mkBottomCont`. + +(TC3) In `mkDupableContWithDmds`, we similarly discard the continuation when + we run out of `RemainingArgDmds`. -} -------------------- @@ -4079,10 +4100,10 @@ mkDupableCont env cont = mkDupableContWithDmds (zapSubstEnv env) (repeat topDmd) cont mkDupableContWithDmds - :: SimplEnvIS -> [Demand] -- Demands on arguments; always infinite + :: SimplEnvIS -> RemainingArgDmds -> SimplCont -> SimplM ( SimplFloats, SimplCont) -mkDupableContWithDmds env _ cont +mkDupableContWithDmds env remaining_dmds cont -- Check the invariant | assertPpr (checkSimplEnvIS env) (pprBadSimplEnvIS env) False = pprPanic "mkDupableContWithDmds" empty @@ -4090,6 +4111,13 @@ mkDupableContWithDmds env _ cont | contIsDupable cont = return (emptyFloats env, cont) + -- No more demands => function is definitely bottom + -- => simply trim the continuation + -- c.f. the null-demands case in `rebuildCall` + -- See (TC3) in Note [Trimming the continuation for bottoming functions] + | null remaining_dmds + = return (emptyFloats env, mkBottomCont cont) + mkDupableContWithDmds _ _ (Stop {}) = panic "mkDupableCont" -- Handled by previous eqn mkDupableContWithDmds env dmds (CastIt { sc_co = co, sc_opt = opt, sc_cont = cont }) @@ -4134,7 +4162,8 @@ mkDupableContWithDmds env _ , thumbsUpPlanA cont = -- Use Plan A of Note [Duplicating StrictArg] -- pprTrace "Using plan A" (ppr (ai_fun fun) $$ text "args" <+> ppr (ai_args fun) $$ text "cont" <+> ppr cont) $ - do { let _ :| dmds = expectNonEmpty $ ai_dmds fun + do { let _ :| dmds = expectNonEmpty (ai_dmds fun) -- See Invariant of StrictArg; + -- ai_dmds is never empty ; (floats1, cont') <- mkDupableContWithDmds env dmds cont -- Use the demands from the function to add the right -- demand info on any bindings we make for further args @@ -4180,7 +4209,10 @@ mkDupableContWithDmds env dmds -- let a = ...arg... -- in [...hole...] a -- NB: sc_dup /= OkToDup; that is caught earlier by contIsDupable - do { let dmd:|cont_dmds = expectNonEmpty dmds + do { let dmd:|cont_dmds = + -- We took care to handle an empty demand list at the start, + -- ensuring this call to 'expectNonEmpty' does not panic (#27261). + expectNonEmpty dmds ; (floats1, cont') <- mkDupableContWithDmds env cont_dmds cont ; let env' = env `setInScopeFromF` floats1 ; arg' <- simplArg env' Nothing hole_ty se arg arg_mco @@ -4251,7 +4283,7 @@ mkDupableStrictBind env arg_bndr join_rhs res_ty ; let arg_info = ArgInfo { ai_fun = join_bndr , ai_rules = [], ai_args = [] , ai_encl = False, ai_dmds = repeat topDmd - , ai_discs = repeat 0 } + , ai_discs = Inf.repeat 0 } ; return ( addJoinFloats (emptyFloats env) $ unitJoinFloat $ NonRec join_bndr $ ===================================== compiler/GHC/Core/Opt/Simplify/Utils.hs ===================================== @@ -25,13 +25,13 @@ module GHC.Core.Opt.Simplify.Utils ( StaticEnv(..), isSimplified, contIsStop, contIsDupable, contResultType, contHoleType, contHoleScaling, - contIsTrivial, contArgs, contIsRhs, + contIsTrivial, contArgs, contIsRhs, mkBottomCont, hasArgs, countArgs, contOutArgs, dropContArgs, mkBoringStop, mkRhsStop, mkLazyArgStop, interestingCallContext, -- ArgInfo - ArgInfo(..), ArgSpec(..), mkArgInfo, + ArgInfo(..), ArgSpec(..), RemainingArgDmds, mkArgInfo, addValArgTo, addTyArgTo, argInfoExpr, argSpecArg, pushOutArgs, pushArgSpecs, @@ -54,8 +54,10 @@ import GHC.Core.Opt.Stats ( Tick(..) ) import qualified GHC.Core.Subst import GHC.Core.Ppr import GHC.Core.TyCo.Ppr ( pprParendType ) +import GHC.Core.TyCo.Compare ( eqTypeIgnoringMultiplicity ) import GHC.Core.FVs import GHC.Core.Utils +import GHC.Core.Make( mkWildValBinder ) import GHC.Core.Opt.Arity import GHC.Core.Unfold import GHC.Core.Unfold.Make @@ -75,6 +77,8 @@ import GHC.Types.Var.Set import GHC.Types.Basic import GHC.Types.Name.Env +import GHC.Data.List.Infinite ( Infinite(..) ) +import qualified GHC.Data.List.Infinite as Inf import GHC.Data.OrdList ( isNilOL ) import GHC.Data.FastString ( fsLit ) @@ -205,10 +209,10 @@ data SimplCont | StrictArg -- (StrictArg (f e1 ..en) K)[e] = K[ f e1 .. en e ] { sc_dup :: DupFlag - , sc_fun :: ArgInfo -- Specifies f, e1..en, Whether f has rules, etc + , sc_fun :: ArgInfo -- Specifies f, e1..en, whether f has rules, etc -- plus demands and discount flags for *this* arg -- and further args - -- So ai_dmds and ai_discs are never empty + -- Invariant: ai_dmds and ai_discs are never empty , sc_fun_ty :: OutType -- Type of the function (f e1 .. en), -- presumably (arg_ty -> res_ty) -- where res_ty is expected by sc_cont @@ -348,32 +352,41 @@ doesn't matter because we'll never compute them all. data ArgInfo = ArgInfo { - ai_fun :: OutId, -- The function - ai_args :: [ArgSpec], -- ...applied to these args (which are in *reverse* order) + ai_fun :: OutId, -- ^ The function + ai_args :: [ArgSpec], -- ^ ...applied to these args (which are in *reverse* order) -- NB: all these argumennts are already simplified - ai_rules :: [CoreRule], -- Rules for this function - ai_encl :: Bool, -- Flag saying whether this function - -- or an enclosing one has rules (recursively) - -- True => be keener to inline in all args + ai_rules :: [CoreRule], -- ^ Rules for this function + ai_encl :: Bool, + -- ^ Flag saying whether this function or an enclosing one has rules + -- (recursively) + -- + -- @True@ means: be keener to inline in all args - ai_dmds :: [Demand], -- Demands on remaining value arguments (beyond ai_args) - -- Usually infinite, but if it is finite it guarantees - -- that the function diverges after being given - -- that number of args + ai_dmds :: RemainingArgDmds, + -- ^ Demands on remaining value arguments (beyond 'ai_args') - ai_discs :: [Int] -- Discounts for remaining value arguments (beyond ai_args) - -- non-zero => be keener to inline - -- Always infinite + ai_discs :: Infinite Int + -- ^ Discounts for remaining value arguments (beyond 'ai_args') + -- + -- A non-zero value means: be keener to inline } -data ArgSpec - = ValArg { as_dmd :: Demand -- Demand placed on this argument - , as_arg :: OutExpr -- Apply to this (coercion or value); c.f. ApplyToVal - , as_hole_ty :: OutType } -- Type of the function (presumably t1 -> t2) +-- | 'RemainingArgDmds' gives the demands on any remaining value arguments. +-- +-- It is usually infinite (with 'topDmd's in the tail), but if it is finite it +-- guarantees that the function diverges after being applied to that number +-- of arguments. +type RemainingArgDmds = [Demand] - | TyArg { as_arg_ty :: OutType -- Apply to this type; c.f. ApplyToTy - , as_hole_ty :: OutType } -- Type of the function (presumably forall a. blah) +data ArgSpec + -- | A value argument + = ValArg { as_dmd :: Demand -- ^ Demand placed on this argument + , as_arg :: OutExpr -- ^ Apply to this (coercion or value); c.f. 'ApplyToVal' + , as_hole_ty :: OutType } -- ^ Type of the function (presumably @t1 -> t2@ for 'ValArg' or @forall a. blah@ for 'TyArg') + -- | A type argument + | TyArg { as_arg_ty :: OutType -- ^ Apply to this type; c.f. 'ApplyToTy' + , as_hole_ty :: OutType } -- ^ Type of the function (presumably @t1 -> t2@ for 'ValArg' or @forall a. blah@ for 'TyArg') instance Outputable ArgInfo where ppr (ArgInfo { ai_fun = fun, ai_args = args, ai_dmds = dmds, ai_rules = rules }) @@ -389,7 +402,7 @@ instance Outputable ArgSpec where addValArgTo :: ArgInfo -> OutExpr -> OutType -> ArgInfo addValArgTo ai arg hole_ty - | ArgInfo { ai_dmds = dmd:dmds, ai_discs = _:discs } <- ai + | ArgInfo { ai_dmds = dmd:dmds, ai_discs = Inf _ discs } <- ai -- Pop the top demand and and discounts off , let arg_spec = ValArg { as_arg = arg, as_hole_ty = hole_ty, as_dmd = dmd } = ai { ai_args = arg_spec : ai_args ai @@ -492,12 +505,23 @@ contIsDupable (TickIt _ k) = contIsDupable k contIsTrivial :: SimplCont -> Bool contIsTrivial (Stop {}) = True contIsTrivial (ApplyToTy { sc_cont = k }) = contIsTrivial k --- This one doesn't look right. A value application is not trivial --- contIsTrivial (ApplyToVal { sc_arg = Coercion _, sc_cont = k }) = contIsTrivial k contIsTrivial (CastIt { sc_cont = k }) = contIsTrivial k contIsTrivial _ = False ------------------- +contStop :: SimplCont -> SimplCont +-- ^ Get the 'Stop' at the tail of the continuation +-- +-- Always returns a continuation of form @(Stop ...)@. +contStop stop@(Stop {}) = stop +contStop (CastIt { sc_cont = k }) = contStop k +contStop (StrictBind { sc_cont = k }) = contStop k +contStop (StrictArg { sc_cont = k }) = contStop k +contStop (Select { sc_cont = k }) = contStop k +contStop (ApplyToTy { sc_cont = k }) = contStop k +contStop (ApplyToVal { sc_cont = k }) = contStop k +contStop (TickIt _ k) = contStop k + contResultType :: SimplCont -> OutType contResultType (Stop ty _ _) = ty contResultType (CastIt { sc_cont = k }) = contResultType k @@ -651,6 +675,35 @@ contEvalContext bndrs cont = go cont -- Perhaps reconstruct the demand on the scrutinee by looking at field -- and case binder dmds, see addCaseBndrDmd. No priority right now. +------------------- +mkBottomCont ::SimplCont -> SimplCont +-- ^ Given a continuation `cont`, return a `cont` /of the same type/, +-- looking like @(case \<hole\> of {})@. +-- +-- This is used when we are going to fill in the @<hole>@ with bottom. +-- See (TC2,3) in Note [Trimming the continuation for bottoming functions] +-- +-- Don't bother to trim, making a @case <hole> of {}@, if we have only +-- an essentially-trivial continuation; e.g. @(<hole> \@ty |> co)@. +mkBottomCont cont = go cont + where + go k@(Stop {}) = k + go (TickIt t k') = TickIt t (go k') + go k@(CastIt { sc_cont = k' }) = k { sc_cont = go k' } + go k@(ApplyToTy { sc_cont = k' }) = k { sc_cont = go k' } + go k@(Select { sc_alts = [], sc_cont = Stop {} }) = k -- Optimisation only + go k | Stop res_ty _ _ <- stop_cont + , hole_ty `eqTypeIgnoringMultiplicity` res_ty + = stop_cont + | otherwise + = Select { sc_alts = [] + , sc_bndr = mkWildValBinder OneTy hole_ty + , sc_env = Simplified OkDup + , sc_cont = stop_cont } + where + hole_ty = contHoleType k + stop_cont = contStop k + ------------------- mkArgInfo :: SimplEnv -> Id -> [CoreRule] -> SimplCont -> ArgInfo mkArgInfo env fun rules_for_fun cont @@ -672,16 +725,17 @@ mkArgInfo env fun rules_for_fun cont fun_has_rules = not (null rules_for_fun) - vanilla_discounts, arg_discounts :: [Int] - vanilla_discounts = repeat 0 + vanilla_discounts, arg_discounts :: Infinite Int + vanilla_discounts = Inf.repeat 0 arg_discounts = case idUnfolding fun of CoreUnfolding {uf_guidance = UnfIfGoodArgs {ug_args = discounts}} - -> discounts ++ vanilla_discounts + -> discounts Inf.++ vanilla_discounts _ -> vanilla_discounts - vanilla_dmds, arg_dmds :: [Demand] + vanilla_dmds :: RemainingArgDmds vanilla_dmds = repeat topDmd + arg_dmds :: RemainingArgDmds arg_dmds | not (seInline env) = vanilla_dmds -- See Note [Do not expose strictness if sm_inline=False] @@ -689,26 +743,22 @@ mkArgInfo env fun rules_for_fun cont = -- add_type_str fun_ty $ case splitDmdSig (idDmdSig fun) of (demands, result_info) - | not (demands `lengthExceeds` n_val_args) - -> -- Enough args, use the strictness given. - -- For bottoming functions we used to pretend that the arg - -- is lazy, so that we don't treat the arg as an - -- interesting context. This avoids substituting - -- top-level bindings for (say) strings into - -- calls to error. But now we are more careful about - -- inlining lone variables, so its ok - -- (see GHC.Core.Op.Simplify.Utils.analyseCont) - if isDeadEndDiv result_info then - demands -- Finite => result is bottom - else - demands ++ vanilla_dmds + | not (demands `lengthExceeds` n_val_args) + -> remaining_dmds -- Enough args, use the strictness given. | otherwise -> warnPprTrace True "More demands than arity" (ppr fun <+> ppr (idArity fun) <+> ppr n_val_args <+> ppr demands) $ vanilla_dmds -- Not enough args, or no strictness - add_type_strictness :: Type -> [Demand] -> [Demand] - -- If the function arg types are strict, record that in the 'strictness bits' + where + remaining_dmds :: RemainingArgDmds + -- isDeadEndDiv: if remaining_dmds is finite, result is bottom + -- See (TC1) in Note [Trimming the continuation for bottoming functions] + remaining_dmds | isDeadEndDiv result_info = demands + | otherwise = demands ++ vanilla_dmds + + add_type_strictness :: Type -> RemainingArgDmds -> RemainingArgDmds + -- If the function arg /types/ are strict, record that in the RemainingArgDmds -- No need to instantiate because unboxed types (which dominate the strict -- types) can't instantiate type variables. -- add_type_strictness is done repeatedly (for each call); @@ -915,16 +965,16 @@ the incentive to disappear when we inline `f`! lazyArgContext :: ArgInfo -> CallCtxt -- Use this for lazy arguments lazyArgContext (ArgInfo { ai_encl = encl_rules, ai_discs = discs }) - | encl_rules = RuleArgCtxt - | disc:_ <- discs, disc > 0 = DiscArgCtxt -- Be keener here - | otherwise = BoringCtxt -- Nothing interesting + | encl_rules = RuleArgCtxt + | Inf disc _ <- discs, disc > 0 = DiscArgCtxt -- Be keener here + | otherwise = BoringCtxt -- Nothing interesting strictArgContext :: ArgInfo -> CallCtxt strictArgContext (ArgInfo { ai_encl = encl_rules, ai_discs = discs }) -- Use this for strict arguments - | encl_rules = RuleArgCtxt - | disc:_ <- discs, disc > 0 = DiscArgCtxt -- Be keener here - | otherwise = RhsCtxt NonRecursive + | encl_rules = RuleArgCtxt + | Inf disc _ <- discs, disc > 0 = DiscArgCtxt -- Be keener here + | otherwise = RhsCtxt NonRecursive -- Why RhsCtxt? if we see f (g x), and f is strict, we -- want to be a bit more eager to inline g, because it may -- expose an eval (on x perhaps) that can be eliminated or ===================================== testsuite/tests/simplCore/should_compile/T27261.hs ===================================== @@ -0,0 +1,17 @@ +{-# OPTIONS_GHC -fno-full-laziness #-} + +module T27261 (foo) where + +import T27261_aux (myError) + +foo :: [String] -> (() -> Int) -> Int +foo cs = + \ k -> ( case bar of + Just str -> let cs2 = case cs of { [] -> cs; _ -> "stack entry" : cs } + in myError cs2 str + Nothing -> \ c -> c () ) + ( \ _ -> k () ) + +bar :: Maybe String +bar = Nothing +{-# NOINLINE bar #-} ===================================== testsuite/tests/simplCore/should_compile/T27261_aux.hs ===================================== @@ -0,0 +1,7 @@ +{-# LANGUAGE BangPatterns #-} + +module T27261_aux (myError) where + +myError :: [String] -> String -> a +myError !_ _ = undefined +{-# NOINLINE myError #-} ===================================== testsuite/tests/simplCore/should_compile/all.T ===================================== @@ -601,3 +601,4 @@ test('T25718a', normal, compile, ['-O -ddump-simpl -dsuppress-uniques -dsuppress test('T25718b', normal, compile, ['-O -ddump-simpl -dsuppress-uniques -dsuppress-all -dno-typeable-binds']) test('T25718c', normal, compile, ['-O -ddump-simpl -dsuppress-uniques -dsuppress-all -dno-typeable-binds']) test('T19166', normal, compile, ['-O -ddump-simpl -dsuppress-uniques -dsuppress-all -dno-typeable-binds']) +test('T27261', [extra_files(['T27261_aux.hs'])], multimod_compile, ['T27261', '-v0 -O']) View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/4a645683ee0bd4421a88cd6ec49b40c… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/4a645683ee0bd4421a88cd6ec49b40c… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/az/ghc-10.1-exactprint-update-wip] Added an intro section
by Simon Peyton Jones (＠simonpj) 28 May '26

28 May '26

Simon Peyton Jones pushed to branch wip/az/ghc-10.1-exactprint-update-wip at Glasgow Haskell Compiler / GHC Commits: 2d4151e9 by Simon Peyton Jones at 2026-05-28T00:10:26+01:00 Added an intro section - - - - - 1 changed file: - ExactPrint.md Changes: ===================================== ExactPrint.md ===================================== @@ -13,6 +13,67 @@ information directly into every AST node to allow the tree to be reprinted _exac original source, byte-for-byte (modulo tab expansion). When a tool modifies the AST it adjusts only the annotations it needs to change; all surrounding nodes reprint themselves unchanged. +## Background: the syntax tree + +The AST of the source program is represented using the data types defined in `Language.Haskell.Syntax.*`. +This data type uses the "Trees That Grow (TTG)" plan; +see [Implementing trees that grow](https://gitlab.haskell.org/ghc/ghc/-/wikis/implementing-trees-that-gr… + +For example, in (GHC-independent) `Language.Haskell.Syntax.Expr`: +``` +data HsExpr p + = ... many constructors including ... + | HsLet (XLet p) + (HsLocalBinds p) + (LHsExpr p) + +type family XLet p +type LHsExpr p = XRec p (HsExpr p) + +``` +Note that +* The `(XLet p)` field is the *extension field* of the `HsLet` data constructor, + where `XLet` is a type family. +* Almost every node is wrapped in an `XRec`, another type family. That makes it easy + for clients to attach arbitrary information to each node. + +GHC specialises this data a type in `GHC.Hs.*`, as follows: +``` +data Pass = Parsed | Renamed | Typechecked + +data GhcPass (c :: Pass) where + GhcPs :: GhcPass 'Parsed + GhcRn :: GhcPass 'Renamed + GhcTc :: GhcPass 'Typechecked + +type family XRec p a = r | r -> a +type instance XRec (GhcPass p) t = XRecGhc t + +-- (XRecGhc tree) wraps `tree` in a GHC-specific, +-- but pass-independent, source location +type XRecGhc t = GenLocated (Anno t) t + +data GenLocated l e = L l e +type family Anno t +``` +So, via `XRec`, every node `e :: t` in the GHC-specific version of HsSyn is wrapped in +a `L ann e`, where `ann :: Anno t` is the annotation on the node. + +Notice that there are two places we can hang information: +* (EXT) **Constructor-specific punctuation**: the extension field of each data constructor + can contain information that is specific to that constructor. Example: the location + of the keywords `let` and `in` for the `HsLet` construct. + +* (XREC) **Entire-node information**: the `Anno t` field that wraps almost every node in the + syntax tree can contain information that is needed for *every* node. Classic example: + the `SrcSpan` of the node. + +**NOTE**: currently there is information in (XREC) that more properly belongs in (EXT). +A refactoring project is under way to put this right. + + +## File layout + The subsystem lives primarily in `utils/check-exact/` and is exposed through three main layers: | Layer | Key operation | Purpose | View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/2d4151e92b1cce8fcb7140619d008ac… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/2d4151e92b1cce8fcb7140619d008ac… You're receiving this email because of your account on gitlab.haskell.org.

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