{-# LANGUAGE BangPatterns #-} {-# LANGUAGE DeriveTraversable #-} {-# LANGUAGE NamedFieldPuns #-} {-# LANGUAGE NondecreasingIndentation #-} {-# LANGUAGE ScopedTypeVariables #-} {-# OPTIONS_GHC -Wno-incomplete-uni-patterns #-} {-# LANGUAGE FlexibleContexts #-} {-# LANGUAGE GADTs #-} {-# LANGUAGE MultiParamTypeClasses #-} {-# LANGUAGE FlexibleInstances #-} {-# LANGUAGE RankNTypes #-} {-# LANGUAGE DerivingStrategies #-} {-# LANGUAGE GeneralisedNewtypeDeriving #-} {-# LANGUAGE TupleSections #-} {-# LANGUAGE ApplicativeDo #-} {-# LANGUAGE MultiWayIf #-} {-# LANGUAGE RecordWildCards #-} -- ----------------------------------------------------------------------------- -- -- (c) The University of Glasgow, 2011 -- -- This module implements multi-module compilation, and is used -- by --make and GHCi. -- -- ----------------------------------------------------------------------------- module GHC.Driver.Make ( depanal, depanalE, depanalPartial, checkHomeUnitsClosed, load, loadWithCache, load', LoadHowMuch(..), ModIfaceCache(..), noIfaceCache, newIfaceCache, instantiationNodes, downsweep, topSortModuleGraph, ms_home_srcimps, ms_home_imps, summariseModule, SummariseResult(..), summariseFile, hscSourceToIsBoot, findExtraSigImports, implicitRequirementsShallow, noModError, cyclicModuleErr, SummaryNode, IsBootInterface(..), mkNodeKey, ModNodeKey, ModNodeKeyWithUid(..), ModNodeMap(..), emptyModNodeMap, modNodeMapElems, modNodeMapLookup, modNodeMapInsert, modNodeMapSingleton, modNodeMapUnionWith ) where import GHC.Prelude import GHC.Platform import GHC.Tc.Utils.Backpack import GHC.Tc.Utils.Monad ( initIfaceCheck ) import GHC.Runtime.Interpreter import qualified GHC.Linker.Loader as Linker import GHC.Linker.Types import GHC.Platform.Ways import GHC.Driver.Config.Finder (initFinderOpts) import GHC.Driver.Config.Parser (initParserOpts) import GHC.Driver.Config.Diagnostic import GHC.Driver.Phases import GHC.Driver.Pipeline import GHC.Driver.Session import GHC.Driver.Backend import GHC.Driver.Monad import GHC.Driver.Env import GHC.Driver.Errors import GHC.Driver.Errors.Types import GHC.Driver.Main import GHC.Parser.Header import GHC.Iface.Load ( cannotFindModule ) import GHC.IfaceToCore ( typecheckIface ) import GHC.Iface.Recomp ( RecompileRequired(..), CompileReason(..) ) import GHC.Data.Bag ( listToBag ) import GHC.Data.Graph.Directed import GHC.Data.FastString import GHC.Data.Maybe ( expectJust ) import GHC.Data.StringBuffer import qualified GHC.LanguageExtensions as LangExt import GHC.Utils.Exception ( throwIO, SomeAsyncException ) import GHC.Utils.Outputable import GHC.Utils.Panic import GHC.Utils.Panic.Plain import GHC.Utils.Misc import GHC.Utils.Error import GHC.Utils.Logger import GHC.Utils.Fingerprint import GHC.Utils.TmpFs import GHC.Types.Basic import GHC.Types.Error import GHC.Types.Target import GHC.Types.SourceFile import GHC.Types.SourceError import GHC.Types.SrcLoc import GHC.Types.Unique.FM import GHC.Types.PkgQual import GHC.Unit import GHC.Unit.Env import GHC.Unit.Finder import GHC.Unit.Module.ModSummary import GHC.Unit.Module.ModIface import GHC.Unit.Module.Graph import GHC.Unit.Home.ModInfo import GHC.Unit.Module.ModDetails import Data.Either ( rights, partitionEithers, lefts ) import qualified Data.Map as Map import qualified Data.Set as Set import Control.Concurrent ( newQSem, waitQSem, signalQSem, ThreadId, killThread, forkIOWithUnmask ) import qualified GHC.Conc as CC import Control.Concurrent.MVar import Control.Monad import Control.Monad.Trans.Except ( ExceptT(..), runExceptT, throwE ) import qualified Control.Monad.Catch as MC import Data.IORef import Data.Maybe import Data.Time import Data.Bifunctor (first) import System.Directory import System.FilePath import System.IO ( fixIO ) import GHC.Conc ( getNumProcessors, getNumCapabilities, setNumCapabilities ) import Control.Monad.IO.Class import Control.Monad.Trans.Reader import GHC.Driver.Pipeline.LogQueue import qualified Data.Map.Strict as M import GHC.Types.TypeEnv import Control.Monad.Trans.State.Lazy import Control.Monad.Trans.Class import GHC.Driver.Env.KnotVars import Control.Concurrent.STM import Control.Monad.Trans.Maybe import GHC.Runtime.Loader import GHC.Rename.Names import GHC.Utils.Constants -- ----------------------------------------------------------------------------- -- Loading the program -- | Perform a dependency analysis starting from the current targets -- and update the session with the new module graph. -- -- Dependency analysis entails parsing the @import@ directives and may -- therefore require running certain preprocessors. -- -- Note that each 'ModSummary' in the module graph caches its 'DynFlags'. -- These 'DynFlags' are determined by the /current/ session 'DynFlags' and the -- @OPTIONS@ and @LANGUAGE@ pragmas of the parsed module. Thus if you want -- changes to the 'DynFlags' to take effect you need to call this function -- again. -- In case of errors, just throw them. -- depanal :: GhcMonad m => [ModuleName] -- ^ excluded modules -> Bool -- ^ allow duplicate roots -> m ModuleGraph depanal excluded_mods allow_dup_roots = do (errs, mod_graph) <- depanalE excluded_mods allow_dup_roots if isEmptyMessages errs then pure mod_graph else throwErrors (fmap GhcDriverMessage errs) -- | Perform dependency analysis like in 'depanal'. -- In case of errors, the errors and an empty module graph are returned. depanalE :: GhcMonad m => -- New for #17459 [ModuleName] -- ^ excluded modules -> Bool -- ^ allow duplicate roots -> m (DriverMessages, ModuleGraph) depanalE excluded_mods allow_dup_roots = do hsc_env <- getSession (errs, mod_graph) <- depanalPartial excluded_mods allow_dup_roots if isEmptyMessages errs then do hsc_env <- getSession let one_unit_messages get_mod_errs k hue = do errs <- get_mod_errs unknown_module_err <- warnUnknownModules (hscSetActiveUnitId k hsc_env) (homeUnitEnv_dflags hue) mod_graph let unused_home_mod_err = warnMissingHomeModules (homeUnitEnv_dflags hue) (hsc_targets hsc_env) mod_graph unused_pkg_err = warnUnusedPackages (homeUnitEnv_units hue) (homeUnitEnv_dflags hue) mod_graph return $ errs `unionMessages` unused_home_mod_err `unionMessages` unused_pkg_err `unionMessages` unknown_module_err all_errs <- liftIO $ unitEnv_foldWithKey one_unit_messages (return emptyMessages) (hsc_HUG hsc_env) logDiagnostics (GhcDriverMessage <$> all_errs) setSession hsc_env { hsc_mod_graph = mod_graph } pure (emptyMessages, mod_graph) else do -- We don't have a complete module dependency graph, -- The graph may be disconnected and is unusable. setSession hsc_env { hsc_mod_graph = emptyMG } pure (errs, emptyMG) -- | Perform dependency analysis like 'depanal' but return a partial module -- graph even in the face of problems with some modules. -- -- Modules which have parse errors in the module header, failing -- preprocessors or other issues preventing them from being summarised will -- simply be absent from the returned module graph. -- -- Unlike 'depanal' this function will not update 'hsc_mod_graph' with the -- new module graph. depanalPartial :: GhcMonad m => [ModuleName] -- ^ excluded modules -> Bool -- ^ allow duplicate roots -> m (DriverMessages, ModuleGraph) -- ^ possibly empty 'Bag' of errors and a module graph. depanalPartial excluded_mods allow_dup_roots = do hsc_env <- getSession let targets = hsc_targets hsc_env old_graph = hsc_mod_graph hsc_env logger = hsc_logger hsc_env withTiming logger (text "Chasing dependencies") (const ()) $ do liftIO $ debugTraceMsg logger 2 (hcat [ text "Chasing modules from: ", hcat (punctuate comma (map pprTarget targets))]) -- Home package modules may have been moved or deleted, and new -- source files may have appeared in the home package that shadow -- external package modules, so we have to discard the existing -- cached finder data. liftIO $ flushFinderCaches (hsc_FC hsc_env) (hsc_unit_env hsc_env) (errs, graph_nodes) <- liftIO $ downsweep hsc_env (mgModSummaries old_graph) excluded_mods allow_dup_roots let mod_graph = mkModuleGraph graph_nodes return (unionManyMessages errs, mod_graph) -- | Collect the instantiations of dependencies to create 'InstantiationNode' work graph nodes. -- These are used to represent the type checking that is done after -- all the free holes (sigs in current package) relevant to that instantiation -- are compiled. This is necessary to catch some instantiation errors. -- -- In the future, perhaps more of the work of instantiation could be moved here, -- instead of shoved in with the module compilation nodes. That could simplify -- backpack, and maybe hs-boot too. instantiationNodes :: UnitId -> UnitState -> [ModuleGraphNode] instantiationNodes uid unit_state = InstantiationNode uid <$> iuids_to_check where iuids_to_check :: [InstantiatedUnit] iuids_to_check = nubSort $ concatMap (goUnitId . fst) (explicitUnits unit_state) where goUnitId uid = [ recur | VirtUnit indef <- [uid] , inst <- instUnitInsts indef , recur <- (indef :) $ goUnitId $ moduleUnit $ snd inst ] -- The linking plan for each module. If we need to do linking for a home unit -- then this function returns a graph node which depends on all the modules in the home unit. -- At the moment nothing can depend on these LinkNodes. linkNodes :: [ModuleGraphNode] -> UnitId -> HomeUnitEnv -> Maybe (Either (Messages DriverMessage) ModuleGraphNode) linkNodes summaries uid hue = let dflags = homeUnitEnv_dflags hue ofile = outputFile_ dflags unit_nodes :: [NodeKey] unit_nodes = map mkNodeKey (filter ((== uid) . moduleGraphNodeUnitId) summaries) -- Issue a warning for the confusing case where the user -- said '-o foo' but we're not going to do any linking. -- We attempt linking if either (a) one of the modules is -- called Main, or (b) the user said -no-hs-main, indicating -- that main() is going to come from somewhere else. -- no_hs_main = gopt Opt_NoHsMain dflags main_sum = any (== NodeKey_Module (ModNodeKeyWithUid (GWIB (mainModuleNameIs dflags) NotBoot) uid)) unit_nodes do_linking = main_sum || no_hs_main || ghcLink dflags == LinkDynLib || ghcLink dflags == LinkStaticLib in if | ghcLink dflags == LinkBinary && isJust ofile && not do_linking -> Just (Left $ singleMessage $ mkPlainErrorMsgEnvelope noSrcSpan (DriverRedirectedNoMain $ mainModuleNameIs dflags)) -- This should be an error, not a warning (#10895). | ghcLink dflags /= NoLink, do_linking -> Just (Right (LinkNode unit_nodes uid)) | otherwise -> Nothing -- Note [Missing home modules] -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -- Sometimes user doesn't want GHC to pick up modules, not explicitly listed -- in a command line. For example, cabal may want to enable this warning -- when building a library, so that GHC warns user about modules, not listed -- neither in `exposed-modules`, nor in `other-modules`. -- -- Here "home module" means a module, that doesn't come from an other package. -- -- For example, if GHC is invoked with modules "A" and "B" as targets, -- but "A" imports some other module "C", then GHC will issue a warning -- about module "C" not being listed in a command line. -- -- The warning in enabled by `-Wmissing-home-modules`. See #13129 warnMissingHomeModules :: DynFlags -> [Target] -> ModuleGraph -> DriverMessages warnMissingHomeModules dflags targets mod_graph = if null missing then emptyMessages else warn where diag_opts = initDiagOpts dflags is_known_module mod = any (is_my_target mod) targets -- We need to be careful to handle the case where (possibly -- path-qualified) filenames (aka 'TargetFile') rather than module -- names are being passed on the GHC command-line. -- -- For instance, `ghc --make src-exe/Main.hs` and -- `ghc --make -isrc-exe Main` are supposed to be equivalent. -- Note also that we can't always infer the associated module name -- directly from the filename argument. See #13727. is_my_target mod target = let tuid = targetUnitId target in case targetId target of TargetModule name -> moduleName (ms_mod mod) == name && tuid == ms_unitid mod TargetFile target_file _ | Just mod_file <- ml_hs_file (ms_location mod) -> target_file == mod_file || -- Don't warn on B.hs-boot if B.hs is specified (#16551) addBootSuffix target_file == mod_file || -- We can get a file target even if a module name was -- originally specified in a command line because it can -- be converted in guessTarget (by appending .hs/.lhs). -- So let's convert it back and compare with module name mkModuleName (fst $ splitExtension target_file) == moduleName (ms_mod mod) _ -> False missing = map (moduleName . ms_mod) $ filter (not . is_known_module) $ (filter (\ms -> ms_unitid ms == homeUnitId_ dflags) (mgModSummaries mod_graph)) warn = singleMessage $ mkPlainMsgEnvelope diag_opts noSrcSpan $ DriverMissingHomeModules missing (checkBuildingCabalPackage dflags) -- Check that any modules we want to reexport or hide are actually in the package. warnUnknownModules :: HscEnv -> DynFlags -> ModuleGraph -> IO DriverMessages warnUnknownModules hsc_env dflags mod_graph = do reexported_warns <- filterM check_reexport (Set.toList reexported_mods) return $ final_msgs hidden_warns reexported_warns where diag_opts = initDiagOpts dflags unit_mods = Set.fromList (map ms_mod_name (filter (\ms -> ms_unitid ms == homeUnitId_ dflags) (mgModSummaries mod_graph))) reexported_mods = reexportedModules dflags hidden_mods = hiddenModules dflags hidden_warns = hidden_mods `Set.difference` unit_mods lookupModule mn = findImportedModule hsc_env mn NoPkgQual check_reexport mn = do fr <- lookupModule mn case fr of Found _ m -> return (moduleUnitId m == homeUnitId_ dflags) _ -> return True warn flag mod = singleMessage $ mkPlainMsgEnvelope diag_opts noSrcSpan $ flag mod final_msgs hidden_warns reexported_warns = unionManyMessages $ [warn DriverUnknownHiddenModules (Set.toList hidden_warns) | not (Set.null hidden_warns)] ++ [warn DriverUnknownReexportedModules reexported_warns | not (null reexported_warns)] -- | Describes which modules of the module graph need to be loaded. data LoadHowMuch = LoadAllTargets -- ^ Load all targets and its dependencies. | LoadUpTo HomeUnitModule -- ^ Load only the given module and its dependencies. | LoadDependenciesOf HomeUnitModule -- ^ Load only the dependencies of the given module, but not the module -- itself. {- Note [Caching HomeModInfo] ~~~~~~~~~~~~~~~~~~~~~~~~~~ API clients who call `load` like to cache the HomeModInfo in memory between calls to this function. In the old days, this cache was a simple MVar which stored a HomePackageTable. This was insufficient, as the interface files for boot modules were not recorded in the cache. In the less old days, the cache was returned at the end of load, and supplied at the start of load, however, this was not sufficient because it didn't account for the possibility of exceptions such as SIGINT (#20780). So now, in the current day, we have this ModIfaceCache abstraction which can incrementally be updated during the process of upsweep. This allows us to store interface files for boot modules in an exception-safe way. When the final version of an interface file is completed then it is placed into the cache. The contents of the cache is retrieved, and the cache cleared, by iface_clearCache. Note that because we only store the ModIface and Linkable in the ModIfaceCache, hydration and rehydration is totally irrelevant, and we just store the CachedIface as soon as it is completed. -} -- Abstract interface to a cache of HomeModInfo -- See Note [Caching HomeModInfo] data ModIfaceCache = ModIfaceCache { iface_clearCache :: IO [CachedIface] , iface_addToCache :: CachedIface -> IO () } addHmiToCache :: ModIfaceCache -> HomeModInfo -> IO () addHmiToCache c (HomeModInfo i _ l) = iface_addToCache c (CachedIface i l) data CachedIface = CachedIface { cached_modiface :: !ModIface , cached_linkable :: !(Maybe Linkable) } noIfaceCache :: Maybe ModIfaceCache noIfaceCache = Nothing newIfaceCache :: IO ModIfaceCache newIfaceCache = do ioref <- newIORef [] return $ ModIfaceCache { iface_clearCache = atomicModifyIORef' ioref (\c -> ([], c)) , iface_addToCache = \hmi -> atomicModifyIORef' ioref (\c -> (hmi:c, ())) } -- | Try to load the program. See 'LoadHowMuch' for the different modes. -- -- This function implements the core of GHC's @--make@ mode. It preprocesses, -- compiles and loads the specified modules, avoiding re-compilation wherever -- possible. Depending on the backend (see 'DynFlags.backend' field) compiling -- and loading may result in files being created on disk. -- -- Calls the 'defaultWarnErrLogger' after each compiling each module, whether -- successful or not. -- -- If errors are encountered during dependency analysis, the module `depanalE` -- returns together with the errors an empty ModuleGraph. -- After processing this empty ModuleGraph, the errors of depanalE are thrown. -- All other errors are reported using the 'defaultWarnErrLogger'. load :: GhcMonad f => LoadHowMuch -> f SuccessFlag load how_much = loadWithCache noIfaceCache how_much mkBatchMsg :: HscEnv -> Messager mkBatchMsg hsc_env = if length (hsc_all_home_unit_ids hsc_env) > 1 -- This also displays what unit each module is from. then batchMultiMsg else batchMsg loadWithCache :: GhcMonad m => Maybe ModIfaceCache -> LoadHowMuch -> m SuccessFlag loadWithCache cache how_much = do (errs, mod_graph) <- depanalE [] False -- #17459 msg <- mkBatchMsg <$> getSession success <- load' cache how_much (Just msg) mod_graph if isEmptyMessages errs then pure success else throwErrors (fmap GhcDriverMessage errs) -- Note [Unused packages] -- ~~~~~~~~~~~~~~~~~~~~~~ -- Cabal passes `--package-id` flag for each direct dependency. But GHC -- loads them lazily, so when compilation is done, we have a list of all -- actually loaded packages. All the packages, specified on command line, -- but never loaded, are probably unused dependencies. warnUnusedPackages :: UnitState -> DynFlags -> ModuleGraph -> DriverMessages warnUnusedPackages us dflags mod_graph = let diag_opts = initDiagOpts dflags -- Only need non-source imports here because SOURCE imports are always HPT loadedPackages = concat $ mapMaybe (\(fs, mn) -> lookupModulePackage us (unLoc mn) fs) $ concatMap ms_imps ( filter (\ms -> homeUnitId_ dflags == ms_unitid ms) (mgModSummaries mod_graph)) used_args = Set.fromList $ map unitId loadedPackages resolve (u,mflag) = do -- The units which we depend on via the command line explicitly flag <- mflag -- Which we can find the UnitInfo for (should be all of them) ui <- lookupUnit us u -- Which are not explicitly used guard (Set.notMember (unitId ui) used_args) return (unitId ui, unitPackageName ui, unitPackageVersion ui, flag) unusedArgs = mapMaybe resolve (explicitUnits us) warn = singleMessage $ mkPlainMsgEnvelope diag_opts noSrcSpan (DriverUnusedPackages unusedArgs) in if null unusedArgs then emptyMessages else warn -- | A ModuleGraphNode which also has a hs-boot file, and the list of nodes on any -- path from module to its boot file. data ModuleGraphNodeWithBootFile = ModuleGraphNodeWithBootFile ModuleGraphNode [ModuleGraphNode] instance Outputable ModuleGraphNodeWithBootFile where ppr (ModuleGraphNodeWithBootFile mgn deps) = text "ModeGraphNodeWithBootFile: " <+> ppr mgn $$ ppr deps getNode :: ModuleGraphNodeWithBootFile -> ModuleGraphNode getNode (ModuleGraphNodeWithBootFile mgn _) = mgn data BuildPlan = SingleModule ModuleGraphNode -- A simple, single module all alone but *might* have an hs-boot file which isn't part of a cycle | ResolvedCycle [Either ModuleGraphNode ModuleGraphNodeWithBootFile] -- A resolved cycle, linearised by hs-boot files | UnresolvedCycle [ModuleGraphNode] -- An actual cycle, which wasn't resolved by hs-boot files instance Outputable BuildPlan where ppr (SingleModule mgn) = text "SingleModule" <> parens (ppr mgn) ppr (ResolvedCycle mgn) = text "ResolvedCycle:" <+> ppr mgn ppr (UnresolvedCycle mgn) = text "UnresolvedCycle:" <+> ppr mgn -- Just used for an assertion countMods :: BuildPlan -> Int countMods (SingleModule _) = 1 countMods (ResolvedCycle ns) = length ns countMods (UnresolvedCycle ns) = length ns -- See Note [Upsweep] for a high-level description. createBuildPlan :: ModuleGraph -> Maybe HomeUnitModule -> [BuildPlan] createBuildPlan mod_graph maybe_top_mod = let -- Step 1: Compute SCCs without .hi-boot files, to find the cycles cycle_mod_graph = topSortModuleGraph True mod_graph maybe_top_mod -- Step 2: Reanalyse loops, with relevant boot modules, to solve the cycles. build_plan :: [BuildPlan] build_plan -- Fast path, if there are no boot modules just do a normal toposort | isEmptyModuleEnv boot_modules = collapseAcyclic $ topSortModuleGraph False mod_graph maybe_top_mod | otherwise = toBuildPlan cycle_mod_graph [] toBuildPlan :: [SCC ModuleGraphNode] -> [ModuleGraphNode] -> [BuildPlan] toBuildPlan [] mgn = collapseAcyclic (topSortWithBoot mgn) toBuildPlan ((AcyclicSCC node):sccs) mgn = toBuildPlan sccs (node:mgn) -- Interesting case toBuildPlan ((CyclicSCC nodes):sccs) mgn = let acyclic = collapseAcyclic (topSortWithBoot mgn) -- Now perform another toposort but just with these nodes and relevant hs-boot files. -- The result should be acyclic, if it's not, then there's an unresolved cycle in the graph. mresolved_cycle = collapseSCC (topSortWithBoot nodes) in acyclic ++ [maybe (UnresolvedCycle nodes) ResolvedCycle mresolved_cycle] ++ toBuildPlan sccs [] (mg, lookup_node) = moduleGraphNodes False (mgModSummaries' mod_graph) trans_deps_map = allReachable mg (mkNodeKey . node_payload) -- Compute the intermediate modules between a file and its hs-boot file. -- See Step 2a in Note [Upsweep] boot_path mn uid = map (summaryNodeSummary . expectJust "toNode" . lookup_node) $ Set.toList $ -- Don't include the boot module itself Set.delete (NodeKey_Module (key IsBoot)) $ -- Keep intermediate dependencies: as per Step 2a in Note [Upsweep], these are -- the transitive dependencies of the non-boot file which transitively depend -- on the boot file. Set.filter (\nk -> nodeKeyUnitId nk == uid -- Cheap test && (NodeKey_Module (key IsBoot)) `Set.member` expectJust "dep_on_boot" (M.lookup nk trans_deps_map)) $ expectJust "not_boot_dep" (M.lookup (NodeKey_Module (key NotBoot)) trans_deps_map) where key ib = ModNodeKeyWithUid (GWIB mn ib) uid -- An environment mapping a module to its hs-boot file and all nodes on the path between the two, if one exists boot_modules = mkModuleEnv [ (ms_mod ms, (m, boot_path (ms_mod_name ms) (ms_unitid ms))) | m@(ModuleNode _ ms) <- (mgModSummaries' mod_graph), isBootSummary ms == IsBoot] select_boot_modules :: [ModuleGraphNode] -> [ModuleGraphNode] select_boot_modules = mapMaybe (fmap fst . get_boot_module) get_boot_module :: (ModuleGraphNode -> Maybe (ModuleGraphNode, [ModuleGraphNode])) get_boot_module m = case m of ModuleNode _ ms | HsSrcFile <- ms_hsc_src ms -> lookupModuleEnv boot_modules (ms_mod ms); _ -> Nothing -- Any cycles should be resolved now collapseSCC :: [SCC ModuleGraphNode] -> Maybe [(Either ModuleGraphNode ModuleGraphNodeWithBootFile)] -- Must be at least two nodes, as we were in a cycle collapseSCC [AcyclicSCC node1, AcyclicSCC node2] = Just [toNodeWithBoot node1, toNodeWithBoot node2] collapseSCC (AcyclicSCC node : nodes) = (toNodeWithBoot node :) <$> collapseSCC nodes -- Cyclic collapseSCC _ = Nothing toNodeWithBoot :: (ModuleGraphNode -> Either ModuleGraphNode ModuleGraphNodeWithBootFile) toNodeWithBoot mn = case get_boot_module mn of -- The node doesn't have a boot file Nothing -> Left mn -- The node does have a boot file Just path -> Right (ModuleGraphNodeWithBootFile mn (snd path)) -- The toposort and accumulation of acyclic modules is solely to pick-up -- hs-boot files which are **not** part of cycles. collapseAcyclic :: [SCC ModuleGraphNode] -> [BuildPlan] collapseAcyclic (AcyclicSCC node : nodes) = SingleModule node : collapseAcyclic nodes collapseAcyclic (CyclicSCC cy_nodes : nodes) = (UnresolvedCycle cy_nodes) : collapseAcyclic nodes collapseAcyclic [] = [] topSortWithBoot nodes = topSortModules False (select_boot_modules nodes ++ nodes) Nothing in assertPpr (sum (map countMods build_plan) == length (mgModSummaries' mod_graph)) (vcat [text "Build plan missing nodes:", (text "PLAN:" <+> ppr (sum (map countMods build_plan))), (text "GRAPH:" <+> ppr (length (mgModSummaries' mod_graph )))]) build_plan -- | Generalized version of 'load' which also supports a custom -- 'Messager' (for reporting progress) and 'ModuleGraph' (generally -- produced by calling 'depanal'. load' :: GhcMonad m => Maybe ModIfaceCache -> LoadHowMuch -> Maybe Messager -> ModuleGraph -> m SuccessFlag load' mhmi_cache how_much mHscMessage mod_graph = do modifySession $ \hsc_env -> hsc_env { hsc_mod_graph = mod_graph } guessOutputFile hsc_env <- getSession let dflags = hsc_dflags hsc_env let logger = hsc_logger hsc_env let interp = hscInterp hsc_env -- The "bad" boot modules are the ones for which we have -- B.hs-boot in the module graph, but no B.hs -- The downsweep should have ensured this does not happen -- (see msDeps) let all_home_mods = Set.fromList [ Module (ms_unitid s) (ms_mod_name s) | s <- mgModSummaries mod_graph, isBootSummary s == NotBoot] -- TODO: Figure out what the correct form of this assert is. It's violated -- when you have HsBootMerge nodes in the graph: then you'll have hs-boot -- files without corresponding hs files. -- bad_boot_mods = [s | s <- mod_graph, isBootSummary s, -- not (ms_mod_name s `elem` all_home_mods)] -- assert (null bad_boot_mods ) return () -- check that the module given in HowMuch actually exists, otherwise -- topSortModuleGraph will bomb later. let checkHowMuch (LoadUpTo m) = checkMod m checkHowMuch (LoadDependenciesOf m) = checkMod m checkHowMuch _ = id checkMod m and_then | m `Set.member` all_home_mods = and_then | otherwise = do liftIO $ errorMsg logger (text "no such module:" <+> quotes (ppr (moduleUnit m) <> colon <> ppr (moduleName m))) return Failed checkHowMuch how_much $ do -- mg2_with_srcimps drops the hi-boot nodes, returning a -- graph with cycles. It is just used for warning about unecessary source imports. let mg2_with_srcimps :: [SCC ModuleGraphNode] mg2_with_srcimps = topSortModuleGraph True mod_graph Nothing -- If we can determine that any of the {-# SOURCE #-} imports -- are definitely unnecessary, then emit a warning. warnUnnecessarySourceImports (filterToposortToModules mg2_with_srcimps) let maybe_top_mod = case how_much of LoadUpTo m -> Just m LoadDependenciesOf m -> Just m _ -> Nothing build_plan = createBuildPlan mod_graph maybe_top_mod cache <- liftIO $ maybe (return []) iface_clearCache mhmi_cache let -- prune the HPT so everything is not retained when doing an -- upsweep. !pruned_cache = pruneCache cache (flattenSCCs (filterToposortToModules mg2_with_srcimps)) -- before we unload anything, make sure we don't leave an old -- interactive context around pointing to dead bindings. Also, -- write an empty HPT to allow the old HPT to be GC'd. let pruneHomeUnitEnv hme = hme { homeUnitEnv_hpt = emptyHomePackageTable } setSession $ discardIC $ hscUpdateHUG (unitEnv_map pruneHomeUnitEnv) hsc_env -- Unload everything liftIO $ unload interp hsc_env liftIO $ debugTraceMsg logger 2 (hang (text "Ready for upsweep") 2 (ppr build_plan)) n_jobs <- case parMakeCount (hsc_dflags hsc_env) of Nothing -> liftIO getNumProcessors Just n -> return n setSession $ hscUpdateHUG (unitEnv_map pruneHomeUnitEnv) hsc_env (upsweep_ok, hsc_env1) <- withDeferredDiagnostics $ do hsc_env <- getSession liftIO $ upsweep n_jobs hsc_env mhmi_cache mHscMessage (toCache pruned_cache) build_plan setSession hsc_env1 case upsweep_ok of Failed -> loadFinish upsweep_ok Succeeded -> do liftIO $ debugTraceMsg logger 2 (text "Upsweep completely successful.") -- Clean up after ourselves liftIO $ cleanCurrentModuleTempFilesMaybe logger (hsc_tmpfs hsc_env1) dflags loadFinish upsweep_ok -- | Finish up after a load. loadFinish :: GhcMonad m => SuccessFlag -> m SuccessFlag -- Empty the interactive context and set the module context to the topmost -- newly loaded module, or the Prelude if none were loaded. loadFinish all_ok = do modifySession discardIC return all_ok -- | If there is no -o option, guess the name of target executable -- by using top-level source file name as a base. guessOutputFile :: GhcMonad m => m () guessOutputFile = modifySession $ \env -> -- Force mod_graph to avoid leaking env let !mod_graph = hsc_mod_graph env new_home_graph = flip unitEnv_map (hsc_HUG env) $ \hue -> let dflags = homeUnitEnv_dflags hue platform = targetPlatform dflags mainModuleSrcPath :: Maybe String mainModuleSrcPath = do ms <- mgLookupModule mod_graph (mainModIs hue) ml_hs_file (ms_location ms) name = fmap dropExtension mainModuleSrcPath -- MP: This exception is quite sensitive to being forced, if you -- force it here then the error message is different because it gets -- caught by a different error handler than the test (T9930fail) expects. -- Putting an exception into DynFlags is probably not a great design but -- I'll write this comment rather than more eagerly force the exception. name_exe = do -- we must add the .exe extension unconditionally here, otherwise -- when name has an extension of its own, the .exe extension will -- not be added by GHC.Driver.Pipeline.exeFileName. See #2248 !name' <- if platformOS platform == OSMinGW32 then fmap (<.> "exe") name else name mainModuleSrcPath' <- mainModuleSrcPath -- #9930: don't clobber input files (unless they ask for it) if name' == mainModuleSrcPath' then throwGhcException . UsageError $ "default output name would overwrite the input file; " ++ "must specify -o explicitly" else Just name' in case outputFile_ dflags of Just _ -> hue Nothing -> hue {homeUnitEnv_dflags = dflags { outputFile_ = name_exe } } in env { hsc_unit_env = (hsc_unit_env env) { ue_home_unit_graph = new_home_graph } } -- ----------------------------------------------------------------------------- -- -- | Prune the HomePackageTable -- -- Before doing an upsweep, we can throw away: -- -- - all ModDetails, all linked code -- - all unlinked code that is out of date with respect to -- the source file -- -- This is VERY IMPORTANT otherwise we'll end up requiring 2x the -- space at the end of the upsweep, because the topmost ModDetails of the -- old HPT holds on to the entire type environment from the previous -- compilation. -- Note [GHC Heap Invariants] pruneCache :: [CachedIface] -> [ModSummary] -> [HomeModInfo] pruneCache hpt summ = strictMap prune hpt where prune (CachedIface { cached_modiface = iface , cached_linkable = linkable }) = HomeModInfo iface emptyModDetails linkable' where modl = moduleName (mi_module iface) linkable' | Just ms <- lookupUFM ms_map modl , mi_src_hash iface /= ms_hs_hash ms = Nothing | otherwise = linkable ms_map = listToUFM [(ms_mod_name ms, ms) | ms <- summ] -- --------------------------------------------------------------------------- -- -- | Unloading unload :: Interp -> HscEnv -> IO () unload interp hsc_env = case ghcLink (hsc_dflags hsc_env) of LinkInMemory -> Linker.unload interp hsc_env [] _other -> return () {- Parallel Upsweep The parallel upsweep attempts to concurrently compile the modules in the compilation graph using multiple Haskell threads. The Algorithm * The list of `MakeAction`s are created by `interpretBuildPlan`. A `MakeAction` is a pair of an `IO a` action and a `MVar a`, where to place the result. The list is sorted topologically, so can be executed in order without fear of blocking. * runPipelines takes this list and eventually passes it to runLoop which executes each action and places the result into the right MVar. * The amount of parrelism is controlled by a semaphore. This is just used around the module compilation step, so that only the right number of modules are compiled at the same time which reduces overal memory usage and allocations. * Each proper node has a LogQueue, which dictates where to send it's output. * The LogQueue is placed into the LogQueueQueue when the action starts and a worker thread processes the LogQueueQueue printing logs for each module in a stable order. * The result variable for an action producing `a` is of type `Maybe a`, therefore it is still filled on a failure. If a module fails to compile, the failure is propagated through the whole module graph and any modules which didn't depend on the failure can still be compiled. This behaviour also makes the code quite a bit cleaner. -} {- Note [--make mode] ~~~~~~~~~~~~~~~~~ There are two main parts to `--make` mode. 1. `downsweep`: Starts from the top of the module graph and computes dependencies. 2. `upsweep`: Starts from the bottom of the module graph and compiles modules. The result of the downsweep is a 'ModuleGraph', which is then passed to 'upsweep' which computers how to build this ModuleGraph. Note [Upsweep] ~~~~~~~~~~~~~~ Upsweep takes a 'ModuleGraph' as input, computes a build plan and then executes the plan in order to compile the project. The first step is computing the build plan from a 'ModuleGraph'. The output of this step is a `[BuildPlan]`, which is a topologically sorted plan for how to build all the modules. ``` data BuildPlan = SingleModule ModuleGraphNode -- A simple, single module all alone but *might* have an hs-boot file which isn't part of a cycle | ResolvedCycle [Either ModuleGraphNode ModuleGraphNodeWithBoot] -- A resolved cycle, linearised by hs-boot files | UnresolvedCycle [ModuleGraphNode] -- An actual cycle, which wasn't resolved by hs-boot files ``` The plan is computed in two steps: Step 1: Topologically sort the module graph without hs-boot files. This returns a [SCC ModuleGraphNode] which contains cycles. Step 2: For each cycle, topologically sort the modules in the cycle *with* the relevant hs-boot files. This should result in an acyclic build plan if the hs-boot files are sufficient to resolve the cycle. Step 2a: For each module in the cycle, if the module has a boot file then compute the modules on the path between it and the hs-boot file. These are the intermediate modules which: (1) are (transitive) dependencies of the non-boot module, and (2) have the boot module as a (transitive) dependency. In particular, all such intermediate modules must appear in the same unit as the module under consideration, as module cycles cannot cross unit boundaries. This information is stored in ModuleGraphNodeWithBoot. The `[BuildPlan]` is then interpreted by the `interpretBuildPlan` function. * SingleModule nodes are compiled normally by either the upsweep_inst or upsweep_mod functions. * ResolvedCycles need to compiled "together" so that modules outside the cycle are presented with a consistent knot-tied version of modules at the end. - When the ModuleGraphNodeWithBoot nodes are compiled then suitable rehydration is performed both before and after the module in question is compiled. See Note [Hydrating Modules] for more information. * UnresolvedCycles are indicative of a proper cycle, unresolved by hs-boot files and are reported as an error to the user. The main trickiness of `interpretBuildPlan` is deciding which version of a dependency is visible from each module. For modules which are not in a cycle, there is just one version of a module, so that is always used. For modules in a cycle, there are two versions of 'HomeModInfo'. 1. Internal to loop: The version created whilst compiling the loop by upsweep_mod. 2. External to loop: The knot-tied version created by typecheckLoop. Whilst compiling a module inside the loop, we need to use the (1). For a module which is outside of the loop which depends on something from in the loop, the (2) version is used. As the plan is interpreted, which version of a HomeModInfo is visible is updated by updating a map held in a state monad. So after a loop has finished being compiled, the visible module is the one created by typecheckLoop and the internal version is not used again. This plan also ensures the most important invariant to do with module loops: > If you depend on anything within a module loop, before you can use the dependency, the whole loop has to finish compiling. The end result of `interpretBuildPlan` is a `[MakeAction]`, which are pairs of `IO a` actions and a `MVar (Maybe a)`, somewhere to put the result of running the action. This list is topologically sorted, so can be run in order to compute the whole graph. As well as this `interpretBuildPlan` also outputs an `IO [Maybe (Maybe HomeModInfo)]` which can be queried at the end to get the result of all modules at the end, with their proper visibility. For example, if any module in a loop fails then all modules in that loop will report as failed because the visible node at the end will be the result of checking these modules together. -} -- | Simple wrapper around MVar which allows a functor instance. data ResultVar b = forall a . ResultVar (a -> b) (MVar (Maybe a)) instance Functor ResultVar where fmap f (ResultVar g var) = ResultVar (f . g) var mkResultVar :: MVar (Maybe a) -> ResultVar a mkResultVar = ResultVar id -- | Block until the result is ready. waitResult :: ResultVar a -> MaybeT IO a waitResult (ResultVar f var) = MaybeT (fmap f <$> readMVar var) data BuildLoopState = BuildLoopState { buildDep :: M.Map NodeKey (SDoc, ResultVar (Maybe HomeModInfo)) -- The current way to build a specific TNodeKey, without cycles this just points to -- the appropiate result of compiling a module but with -- cycles there can be additional indirection and can point to the result of typechecking a loop , nNODE :: Int , hug_var :: MVar HomeUnitGraph -- A global variable which is incrementally updated with the result -- of compiling modules. } nodeId :: BuildM Int nodeId = do n <- gets nNODE modify (\m -> m { nNODE = n + 1 }) return n setModulePipeline :: NodeKey -> SDoc -> ResultVar (Maybe HomeModInfo) -> BuildM () setModulePipeline mgn doc wrapped_pipeline = do modify (\m -> m { buildDep = M.insert mgn (doc, wrapped_pipeline) (buildDep m) }) getBuildMap :: BuildM (M.Map NodeKey (SDoc, ResultVar (Maybe HomeModInfo))) getBuildMap = gets buildDep type BuildM a = StateT BuildLoopState IO a -- | Abstraction over the operations of a semaphore which allows usage with the -- -j1 case data AbstractSem = AbstractSem { acquireSem :: IO () , releaseSem :: IO () } withAbstractSem :: AbstractSem -> IO b -> IO b withAbstractSem sem = MC.bracket_ (acquireSem sem) (releaseSem sem) -- | Environment used when compiling a module data MakeEnv = MakeEnv { hsc_env :: !HscEnv -- The basic HscEnv which will be augmented for each module , compile_sem :: !AbstractSem -- Modify the environment for module k, with the supplied logger modification function. -- For -j1, this wrapper doesn't do anything -- For -jn, the wrapper initialised a log queue and then modifies the logger to pipe its output -- into the log queue. , withLogger :: forall a . Int -> ((Logger -> Logger) -> IO a) -> IO a , env_messager :: !(Maybe Messager) } type RunMakeM a = ReaderT MakeEnv (MaybeT IO) a -- | Given the build plan, creates a graph which indicates where each NodeKey should -- get its direct dependencies from. This might not be the corresponding build action -- if the module participates in a loop. This step also labels each node with a number for the output. -- See Note [Upsweep] for a high-level description. interpretBuildPlan :: HomeUnitGraph -> Maybe ModIfaceCache -> M.Map ModNodeKeyWithUid HomeModInfo -> [BuildPlan] -> IO ( Maybe [ModuleGraphNode] -- Is there an unresolved cycle , [MakeAction] -- Actions we need to run in order to build everything , IO [Maybe (Maybe HomeModInfo)]) -- An action to query to get all the built modules at the end. interpretBuildPlan hug mhmi_cache old_hpt plan = do hug_var <- newMVar hug ((mcycle, plans), build_map) <- runStateT (buildLoop plan) (BuildLoopState M.empty 1 hug_var) let wait = collect_results (buildDep build_map) return (mcycle, plans, wait) where collect_results build_map = sequence (map (\(_doc, res_var) -> collect_result res_var) (M.elems build_map)) where collect_result res_var = runMaybeT (waitResult res_var) n_mods = sum (map countMods plan) buildLoop :: [BuildPlan] -> BuildM (Maybe [ModuleGraphNode], [MakeAction]) -- Build the abstract pipeline which we can execute -- Building finished buildLoop [] = return (Nothing, []) buildLoop (plan:plans) = case plan of -- If there was no cycle, then typecheckLoop is not necessary SingleModule m -> do (one_plan, _) <- buildSingleModule Nothing m (cycle, all_plans) <- buildLoop plans return (cycle, one_plan : all_plans) -- For a resolved cycle, depend on everything in the loop, then update -- the cache to point to this node rather than directly to the module build -- nodes ResolvedCycle ms -> do pipes <- buildModuleLoop ms (cycle, graph) <- buildLoop plans return (cycle, pipes ++ graph) -- Can't continue past this point as the cycle is unresolved. UnresolvedCycle ns -> return (Just ns, []) buildSingleModule :: Maybe [ModuleGraphNode] -- Modules we need to rehydrate before compiling this module -> ModuleGraphNode -- The node we are compiling -> BuildM (MakeAction, ResultVar (Maybe HomeModInfo)) buildSingleModule rehydrate_nodes mod = do mod_idx <- nodeId home_mod_map <- getBuildMap hug_var <- gets hug_var -- 1. Get the transitive dependencies of this module, by looking up in the dependency map let direct_deps = nodeDependencies False mod doc_build_deps = map (expectJust "dep_map" . flip M.lookup home_mod_map) direct_deps build_deps = map snd doc_build_deps -- 2. Set the default way to build this node, not in a loop here let build_action = withCurrentUnit (moduleGraphNodeUnitId mod) $ case mod of InstantiationNode uid iu -> const Nothing <$> executeInstantiationNode mod_idx n_mods (wait_deps_hug hug_var build_deps) uid iu ModuleNode _build_deps ms -> do let !old_hmi = M.lookup (msKey ms) old_hpt rehydrate_mods = mapMaybe moduleGraphNodeModule <$> rehydrate_nodes hmi <- executeCompileNode mod_idx n_mods old_hmi (wait_deps_hug hug_var build_deps) rehydrate_mods ms -- Write the HMI to an external cache (if one exists) -- See Note [Caching HomeModInfo] liftIO $ forM mhmi_cache $ \hmi_cache -> addHmiToCache hmi_cache hmi -- This global MVar is incrementally modified in order to avoid having to -- recreate the HPT before compiling each module which leads to a quadratic amount of work. hsc_env <- asks hsc_env hmi' <- liftIO $ modifyMVar hug_var (\hug -> do let new_hpt = addHomeModInfoToHug hmi hug new_hsc = setHUG new_hpt hsc_env maybeRehydrateAfter hmi new_hsc rehydrate_mods ) return (Just hmi') LinkNode _nks uid -> do executeLinkNode (wait_deps_hug hug_var build_deps) (mod_idx, n_mods) uid direct_deps return Nothing res_var <- liftIO newEmptyMVar let result_var = mkResultVar res_var setModulePipeline (mkNodeKey mod) (text "N") result_var return $ (MakeAction build_action res_var, result_var) buildOneLoopyModule :: ModuleGraphNodeWithBootFile -> BuildM (MakeAction, (ResultVar (Maybe HomeModInfo))) buildOneLoopyModule (ModuleGraphNodeWithBootFile mn deps) = buildSingleModule (Just deps) mn buildModuleLoop :: [Either ModuleGraphNode ModuleGraphNodeWithBootFile] -> BuildM [MakeAction] buildModuleLoop ms = do (build_modules, wait_modules) <- mapAndUnzipM (either (buildSingleModule Nothing) buildOneLoopyModule) ms res_var <- liftIO newEmptyMVar let loop_action = wait_deps wait_modules let fanout i = Just . (!! i) <$> mkResultVar res_var -- From outside the module loop, anyone must wait for the loop to finish and then -- use the result of the rehydrated iface. This makes sure that things not in the -- module loop will see the updated interfaces for all the identifiers in the loop. let update_module_pipeline (m, i) = setModulePipeline (NodeKey_Module m) (text "T") (fanout i) let ms_i = zip (mapMaybe (fmap msKey . moduleGraphNodeModSum . either id getNode) ms) [0..] mapM update_module_pipeline ms_i return $ build_modules ++ [MakeAction loop_action res_var] withCurrentUnit :: UnitId -> RunMakeM a -> RunMakeM a withCurrentUnit uid = do local (\env -> env { hsc_env = hscSetActiveUnitId uid (hsc_env env)}) upsweep :: Int -- ^ The number of workers we wish to run in parallel -> HscEnv -- ^ The base HscEnv, which is augmented for each module -> Maybe ModIfaceCache -- ^ A cache to incrementally write final interface files to -> Maybe Messager -> M.Map ModNodeKeyWithUid HomeModInfo -> [BuildPlan] -> IO (SuccessFlag, HscEnv) upsweep n_jobs hsc_env hmi_cache mHscMessage old_hpt build_plan = do (cycle, pipelines, collect_result) <- interpretBuildPlan (hsc_HUG hsc_env) hmi_cache old_hpt build_plan runPipelines n_jobs hsc_env mHscMessage pipelines res <- collect_result let completed = [m | Just (Just m) <- res] let hsc_env' = addDepsToHscEnv completed hsc_env -- Handle any cycle in the original compilation graph and return the result -- of the upsweep. case cycle of Just mss -> do let logger = hsc_logger hsc_env liftIO $ fatalErrorMsg logger (cyclicModuleErr mss) return (Failed, hsc_env) Nothing -> do let success_flag = successIf (all isJust res) return (success_flag, hsc_env') toCache :: [HomeModInfo] -> M.Map (ModNodeKeyWithUid) HomeModInfo toCache hmis = M.fromList ([(miKey $ hm_iface hmi, hmi) | hmi <- hmis]) miKey :: ModIface -> ModNodeKeyWithUid miKey hmi = ModNodeKeyWithUid (mi_mnwib hmi) ((toUnitId $ moduleUnit (mi_module hmi))) upsweep_inst :: HscEnv -> Maybe Messager -> Int -- index of module -> Int -- total number of modules -> UnitId -> InstantiatedUnit -> IO () upsweep_inst hsc_env mHscMessage mod_index nmods uid iuid = do case mHscMessage of Just hscMessage -> hscMessage hsc_env (mod_index, nmods) (NeedsRecompile MustCompile) (InstantiationNode uid iuid) Nothing -> return () runHsc hsc_env $ ioMsgMaybe $ hoistTcRnMessage $ tcRnCheckUnit hsc_env $ VirtUnit iuid pure () -- | Compile a single module. Always produce a Linkable for it if -- successful. If no compilation happened, return the old Linkable. upsweep_mod :: HscEnv -> Maybe Messager -> Maybe HomeModInfo -> ModSummary -> Int -- index of module -> Int -- total number of modules -> IO HomeModInfo upsweep_mod hsc_env mHscMessage old_hmi summary mod_index nmods = do hmi <- compileOne' mHscMessage hsc_env summary mod_index nmods (hm_iface <$> old_hmi) (old_hmi >>= hm_linkable) -- MP: This is a bit janky, because before you add the entries you have to extend the HPT with the module -- you just compiled. Another option, would be delay adding anything until after upsweep has finished, but I -- am unsure if this is sound (wrt running TH splices for example). -- This function only does anything if the linkable produced is a BCO, which only happens with the -- bytecode backend, no need to guard against the backend type additionally. addSptEntries (hscUpdateHPT (\hpt -> addToHpt hpt (ms_mod_name summary) hmi) hsc_env) (hm_linkable hmi) return hmi -- | Add the entries from a BCO linkable to the SPT table, see -- See Note [Grand plan for static forms] in GHC.Iface.Tidy.StaticPtrTable. addSptEntries :: HscEnv -> Maybe Linkable -> IO () addSptEntries hsc_env mlinkable = hscAddSptEntries hsc_env [ spt | Just linkable <- [mlinkable] , unlinked <- linkableUnlinked linkable , BCOs _ spts <- pure unlinked , spt <- spts ] {- Note [-fno-code mode] ~~~~~~~~~~~~~~~~~~~~~~~~ GHC offers the flag -fno-code for the purpose of parsing and typechecking a program without generating object files. This is intended to be used by tooling and IDEs to provide quick feedback on any parser or type errors as cheaply as possible. When GHC is invoked with -fno-code no object files or linked output will be generated. As many errors and warnings as possible will be generated, as if -fno-code had not been passed. The session DynFlags will have backend == NoBackend. -fwrite-interface ~~~~~~~~~~~~~~~~ Whether interface files are generated in -fno-code mode is controlled by the -fwrite-interface flag. The -fwrite-interface flag is a no-op if -fno-code is not also passed. Recompilation avoidance requires interface files, so passing -fno-code without -fwrite-interface should be avoided. If -fno-code were re-implemented today, -fwrite-interface would be discarded and it would be considered always on; this behaviour is as it is for backwards compatibility. ================================================================ IN SUMMARY: ALWAYS PASS -fno-code AND -fwrite-interface TOGETHER ================================================================ Template Haskell ~~~~~~~~~~~~~~~~ A module using template haskell may invoke an imported function from inside a splice. This will cause the type-checker to attempt to execute that code, which would fail if no object files had been generated. See #8025. To rectify this, during the downsweep we patch the DynFlags in the ModSummary of any home module that is imported by a module that uses template haskell, to generate object code. The flavour of generated object code is chosen by defaultObjectTarget for the target platform. It would likely be faster to generate bytecode, but this is not supported on all platforms(?Please Confirm?), and does not support the entirety of GHC haskell. See #1257. The object files (and interface files if -fwrite-interface is disabled) produced for template haskell are written to temporary files. Note that since template haskell can run arbitrary IO actions, -fno-code mode is no more secure than running without it. Potential TODOS: ~~~~~ * Remove -fwrite-interface and have interface files always written in -fno-code mode * Both .o and .dyn_o files are generated for template haskell, but we only need .dyn_o. Fix it. * In make mode, a message like Compiling A (A.hs, /tmp/ghc_123.o) is shown if downsweep enabled object code generation for A. Perhaps we should show "nothing" or "temporary object file" instead. Note that one can currently use -keep-tmp-files and inspect the generated file with the current behaviour. * Offer a -no-codedir command line option, and write what were temporary object files there. This would speed up recompilation. * Use existing object files (if they are up to date) instead of always generating temporary ones. -} -- Note [When source is considered modified] -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -- A number of functions in GHC.Driver accept a SourceModified argument, which -- is part of how GHC determines whether recompilation may be avoided (see the -- definition of the SourceModified data type for details). -- -- Determining whether or not a source file is considered modified depends not -- only on the source file itself, but also on the output files which compiling -- that module would produce. This is done because GHC supports a number of -- flags which control which output files should be produced, e.g. -fno-code -- -fwrite-interface and -fwrite-ide-file; we must check not only whether the -- source file has been modified since the last compile, but also whether the -- source file has been modified since the last compile which produced all of -- the output files which have been requested. -- -- Specifically, a source file is considered unmodified if it is up-to-date -- relative to all of the output files which have been requested. Whether or -- not an output file is up-to-date depends on what kind of file it is: -- -- * iface (.hi) files are considered up-to-date if (and only if) their -- mi_src_hash field matches the hash of the source file, -- -- * all other output files (.o, .dyn_o, .hie, etc) are considered up-to-date -- if (and only if) their modification times on the filesystem are greater -- than or equal to the modification time of the corresponding .hi file. -- -- Why do we use '>=' rather than '>' for output files other than the .hi file? -- If the filesystem has poor resolution for timestamps (e.g. FAT32 has a -- resolution of 2 seconds), we may often find that the .hi and .o files have -- the same modification time. Using >= is slightly unsafe, but it matches -- make's behaviour. -- -- This strategy allows us to do the minimum work necessary in order to ensure -- that all the files the user cares about are up-to-date; e.g. we should not -- worry about .o files if the user has indicated that they are not interested -- in them via -fno-code. See also #9243. -- -- Note that recompilation avoidance is dependent on .hi files being produced, -- which does not happen if -fno-write-interface -fno-code is passed. That is, -- passing -fno-write-interface -fno-code means that you cannot benefit from -- recompilation avoidance. See also Note [-fno-code mode]. -- -- The correctness of this strategy depends on an assumption that whenever we -- are producing multiple output files, the .hi file is always written first. -- If this assumption is violated, we risk recompiling unnecessarily by -- incorrectly regarding non-.hi files as outdated. -- -- --------------------------------------------------------------------------- -- -- | Topological sort of the module graph topSortModuleGraph :: Bool -- ^ Drop hi-boot nodes? (see below) -> ModuleGraph -> Maybe HomeUnitModule -- ^ Root module name. If @Nothing@, use the full graph. -> [SCC ModuleGraphNode] -- ^ Calculate SCCs of the module graph, possibly dropping the hi-boot nodes -- The resulting list of strongly-connected-components is in topologically -- sorted order, starting with the module(s) at the bottom of the -- dependency graph (ie compile them first) and ending with the ones at -- the top. -- -- Drop hi-boot nodes (first boolean arg)? -- -- - @False@: treat the hi-boot summaries as nodes of the graph, -- so the graph must be acyclic -- -- - @True@: eliminate the hi-boot nodes, and instead pretend -- the a source-import of Foo is an import of Foo -- The resulting graph has no hi-boot nodes, but can be cyclic topSortModuleGraph drop_hs_boot_nodes module_graph mb_root_mod = -- stronglyConnCompG flips the original order, so if we reverse -- the summaries we get a stable topological sort. topSortModules drop_hs_boot_nodes (reverse $ mgModSummaries' module_graph) mb_root_mod topSortModules :: Bool -> [ModuleGraphNode] -> Maybe HomeUnitModule -> [SCC ModuleGraphNode] topSortModules drop_hs_boot_nodes summaries mb_root_mod = map (fmap summaryNodeSummary) $ stronglyConnCompG initial_graph where (graph, lookup_node) = moduleGraphNodes drop_hs_boot_nodes summaries initial_graph = case mb_root_mod of Nothing -> graph Just (Module uid root_mod) -> -- restrict the graph to just those modules reachable from -- the specified module. We do this by building a graph with -- the full set of nodes, and determining the reachable set from -- the specified node. let root | Just node <- lookup_node $ NodeKey_Module $ ModNodeKeyWithUid (GWIB root_mod NotBoot) uid , graph `hasVertexG` node = node | otherwise = throwGhcException (ProgramError "module does not exist") in graphFromEdgedVerticesUniq (seq root (reachableG graph root)) newtype ModNodeMap a = ModNodeMap { unModNodeMap :: Map.Map ModNodeKey a } deriving (Functor, Traversable, Foldable) emptyModNodeMap :: ModNodeMap a emptyModNodeMap = ModNodeMap Map.empty modNodeMapInsert :: ModNodeKey -> a -> ModNodeMap a -> ModNodeMap a modNodeMapInsert k v (ModNodeMap m) = ModNodeMap (Map.insert k v m) modNodeMapElems :: ModNodeMap a -> [a] modNodeMapElems (ModNodeMap m) = Map.elems m modNodeMapLookup :: ModNodeKey -> ModNodeMap a -> Maybe a modNodeMapLookup k (ModNodeMap m) = Map.lookup k m modNodeMapSingleton :: ModNodeKey -> a -> ModNodeMap a modNodeMapSingleton k v = ModNodeMap (M.singleton k v) modNodeMapUnionWith :: (a -> a -> a) -> ModNodeMap a -> ModNodeMap a -> ModNodeMap a modNodeMapUnionWith f (ModNodeMap m) (ModNodeMap n) = ModNodeMap (M.unionWith f m n) -- | If there are {-# SOURCE #-} imports between strongly connected -- components in the topological sort, then those imports can -- definitely be replaced by ordinary non-SOURCE imports: if SOURCE -- were necessary, then the edge would be part of a cycle. warnUnnecessarySourceImports :: GhcMonad m => [SCC ModSummary] -> m () warnUnnecessarySourceImports sccs = do diag_opts <- initDiagOpts <$> getDynFlags when (diag_wopt Opt_WarnUnusedImports diag_opts) $ do let check ms = let mods_in_this_cycle = map ms_mod_name ms in [ warn i | m <- ms, i <- ms_home_srcimps m, unLoc i `notElem` mods_in_this_cycle ] warn :: Located ModuleName -> MsgEnvelope GhcMessage warn (L loc mod) = GhcDriverMessage <$> mkPlainMsgEnvelope diag_opts loc (DriverUnnecessarySourceImports mod) logDiagnostics (mkMessages $ listToBag (concatMap (check . flattenSCC) sccs)) -- This caches the answer to the question, if we are in this unit, what does -- an import of this module mean. type DownsweepCache = M.Map (UnitId, PkgQual, ModuleNameWithIsBoot) [Either DriverMessages ModSummary] ----------------------------------------------------------------------------- -- -- | Downsweep (dependency analysis) -- -- Chase downwards from the specified root set, returning summaries -- for all home modules encountered. Only follow source-import -- links. -- -- We pass in the previous collection of summaries, which is used as a -- cache to avoid recalculating a module summary if the source is -- unchanged. -- -- The returned list of [ModSummary] nodes has one node for each home-package -- module, plus one for any hs-boot files. The imports of these nodes -- are all there, including the imports of non-home-package modules. downsweep :: HscEnv -> [ModSummary] -- ^ Old summaries -> [ModuleName] -- Ignore dependencies on these; treat -- them as if they were package modules -> Bool -- True <=> allow multiple targets to have -- the same module name; this is -- very useful for ghc -M -> IO ([DriverMessages], [ModuleGraphNode]) -- The non-error elements of the returned list all have distinct -- (Modules, IsBoot) identifiers, unless the Bool is true in -- which case there can be repeats downsweep hsc_env old_summaries excl_mods allow_dup_roots = do rootSummaries <- mapM getRootSummary roots let (root_errs, rootSummariesOk) = partitionEithers rootSummaries -- #17549 root_map = mkRootMap rootSummariesOk checkDuplicates root_map (deps, pkg_deps, map0) <- loopSummaries rootSummariesOk (M.empty, Set.empty, root_map) let closure_errs = checkHomeUnitsClosed (hsc_unit_env hsc_env) (hsc_all_home_unit_ids hsc_env) (Set.toList pkg_deps) let unit_env = hsc_unit_env hsc_env let tmpfs = hsc_tmpfs hsc_env let downsweep_errs = lefts $ concat $ M.elems map0 downsweep_nodes = M.elems deps (other_errs, unit_nodes) = partitionEithers $ unitEnv_foldWithKey (\nodes uid hue -> nodes ++ unitModuleNodes downsweep_nodes uid hue) [] (hsc_HUG hsc_env) all_nodes = downsweep_nodes ++ unit_nodes all_errs = all_root_errs ++ downsweep_errs ++ other_errs all_root_errs = closure_errs ++ map snd root_errs -- if we have been passed -fno-code, we enable code generation -- for dependencies of modules that have -XTemplateHaskell, -- otherwise those modules will fail to compile. -- See Note [-fno-code mode] #8025 th_enabled_nodes <- enableCodeGenForTH logger tmpfs unit_env all_nodes if null all_root_errs then return (all_errs, th_enabled_nodes) else pure $ (all_root_errs, []) where -- Dependencies arising on a unit (backpack and module linking deps) unitModuleNodes :: [ModuleGraphNode] -> UnitId -> HomeUnitEnv -> [Either (Messages DriverMessage) ModuleGraphNode] unitModuleNodes summaries uid hue = let instantiation_nodes = instantiationNodes uid (homeUnitEnv_units hue) in map Right instantiation_nodes ++ maybeToList (linkNodes (instantiation_nodes ++ summaries) uid hue) calcDeps ms = -- Add a dependency on the HsBoot file if it exists -- This gets passed to the loopImports function which just ignores it if it -- can't be found. [(ms_unitid ms, NoPkgQual, GWIB (noLoc $ ms_mod_name ms) IsBoot) | NotBoot <- [isBootSummary ms] ] ++ [(ms_unitid ms, b, c) | (b, c) <- msDeps ms ] logger = hsc_logger hsc_env roots = hsc_targets hsc_env -- A cache from file paths to the already summarised modules. -- Reuse these if we can because the most expensive part of downsweep is -- reading the headers. old_summary_map :: M.Map FilePath ModSummary old_summary_map = M.fromList [(msHsFilePath ms, ms) | ms <- old_summaries] getRootSummary :: Target -> IO (Either (UnitId, DriverMessages) ModSummary) getRootSummary Target { targetId = TargetFile file mb_phase , targetContents = maybe_buf , targetUnitId = uid } = do let offset_file = augmentByWorkingDirectory dflags file exists <- liftIO $ doesFileExist offset_file if exists || isJust maybe_buf then first (uid,) <$> summariseFile hsc_env home_unit old_summary_map offset_file mb_phase maybe_buf else return $ Left $ (uid,) $ singleMessage $ mkPlainErrorMsgEnvelope noSrcSpan (DriverFileNotFound offset_file) where dflags = homeUnitEnv_dflags (ue_findHomeUnitEnv uid (hsc_unit_env hsc_env)) home_unit = ue_unitHomeUnit uid (hsc_unit_env hsc_env) getRootSummary Target { targetId = TargetModule modl , targetContents = maybe_buf , targetUnitId = uid } = do maybe_summary <- summariseModule hsc_env home_unit old_summary_map NotBoot (L rootLoc modl) (ThisPkg (homeUnitId home_unit)) maybe_buf excl_mods case maybe_summary of FoundHome s -> return (Right s) FoundHomeWithError err -> return (Left err) _ -> return $ Left $ (uid, moduleNotFoundErr modl) where home_unit = ue_unitHomeUnit uid (hsc_unit_env hsc_env) rootLoc = mkGeneralSrcSpan (fsLit "") -- In a root module, the filename is allowed to diverge from the module -- name, so we have to check that there aren't multiple root files -- defining the same module (otherwise the duplicates will be silently -- ignored, leading to confusing behaviour). checkDuplicates :: DownsweepCache -> IO () checkDuplicates root_map | allow_dup_roots = return () | null dup_roots = return () | otherwise = liftIO $ multiRootsErr (head dup_roots) where dup_roots :: [[ModSummary]] -- Each at least of length 2 dup_roots = filterOut isSingleton $ map rights (M.elems root_map) -- This loops over all the mod summaries in the dependency graph, accumulates the actual dependencies for each module/unit loopSummaries :: [ModSummary] -> (M.Map NodeKey ModuleGraphNode, Set.Set (UnitId, UnitId), DownsweepCache) -> IO ((M.Map NodeKey ModuleGraphNode), Set.Set (UnitId, UnitId), DownsweepCache) loopSummaries [] done = return done loopSummaries (ms:next) (done, pkgs, summarised) | Just {} <- M.lookup k done = loopSummaries next (done, pkgs, summarised) -- Didn't work out what the imports mean yet, now do that. | otherwise = do (final_deps, pkgs1, done', summarised') <- loopImports (calcDeps ms) done summarised -- This has the effect of finding a .hs file if we are looking at the .hs-boot file. (_, _, done'', summarised'') <- loopImports (maybeToList hs_file_for_boot) done' summarised' loopSummaries next (M.insert k (ModuleNode final_deps ms) done'', pkgs1 `Set.union` pkgs, summarised'') where k = NodeKey_Module (msKey ms) hs_file_for_boot | HsBootFile <- ms_hsc_src ms = Just $ ((ms_unitid ms), NoPkgQual, (GWIB (noLoc $ ms_mod_name ms) NotBoot)) | otherwise = Nothing -- This loops over each import in each summary. It is mutually recursive with loopSummaries if we discover -- a new module by doing this. loopImports :: [(UnitId, PkgQual, GenWithIsBoot (Located ModuleName))] -- Work list: process these modules -> M.Map NodeKey ModuleGraphNode -> DownsweepCache -- Visited set; the range is a list because -- the roots can have the same module names -- if allow_dup_roots is True -> IO ([NodeKey], Set.Set (UnitId, UnitId), M.Map NodeKey ModuleGraphNode, DownsweepCache) -- The result is the completed NodeMap loopImports [] done summarised = return ([], Set.empty, done, summarised) loopImports ((home_uid,mb_pkg, gwib) : ss) done summarised | Just summs <- M.lookup cache_key summarised = case summs of [Right ms] -> do let nk = NodeKey_Module (msKey ms) (rest, pkgs, summarised', done') <- loopImports ss done summarised return (nk: rest, pkgs, summarised', done') [Left _err] -> loopImports ss done summarised _errs -> do loopImports ss done summarised | otherwise = do mb_s <- summariseModule hsc_env home_unit old_summary_map is_boot wanted_mod mb_pkg Nothing excl_mods case mb_s of NotThere -> loopImports ss done summarised External uid -> do (other_deps, pkgs, done', summarised') <- loopImports ss done summarised return (other_deps, Set.insert (homeUnitId home_unit, uid) pkgs, done', summarised') FoundInstantiation iud -> do (other_deps, pkgs, done', summarised') <- loopImports ss done summarised return (NodeKey_Unit iud : other_deps, pkgs, done', summarised') FoundHomeWithError (_uid, e) -> loopImports ss done (Map.insert cache_key [(Left e)] summarised) FoundHome s -> do (done', pkgs1, summarised') <- loopSummaries [s] (done, Set.empty, Map.insert cache_key [Right s] summarised) (other_deps, pkgs2, final_done, final_summarised) <- loopImports ss done' summarised' -- MP: This assumes that we can only instantiate non home units, which is probably fair enough for now. return (NodeKey_Module (msKey s) : other_deps, pkgs1 `Set.union` pkgs2, final_done, final_summarised) where cache_key = (home_uid, mb_pkg, unLoc <$> gwib) home_unit = ue_unitHomeUnit home_uid (hsc_unit_env hsc_env) GWIB { gwib_mod = L loc mod, gwib_isBoot = is_boot } = gwib wanted_mod = L loc mod -- This function checks then important property that if both p and q are home units -- then any dependency of p, which transitively depends on q is also a home unit. checkHomeUnitsClosed :: UnitEnv -> Set.Set UnitId -> [(UnitId, UnitId)] -> [DriverMessages] -- Fast path, trivially closed. checkHomeUnitsClosed ue home_id_set home_imp_ids | Set.size home_id_set == 1 = [] | otherwise = let res = foldMap loop home_imp_ids -- Now check whether everything which transitively depends on a home_unit is actually a home_unit -- These units are the ones which we need to load as home packages but failed to do for some reason, -- it's a bug in the tool invoking GHC. bad_unit_ids = Set.difference res home_id_set in if Set.null bad_unit_ids then [] else [singleMessage $ mkPlainErrorMsgEnvelope rootLoc $ DriverHomePackagesNotClosed (Set.toList bad_unit_ids)] where rootLoc = mkGeneralSrcSpan (fsLit "") -- TODO: This could repeat quite a bit of work but I struggled to write this function. -- Which units transitively depend on a home unit loop :: (UnitId, UnitId) -> Set.Set UnitId -- The units which transitively depend on a home unit loop (from_uid, uid) = let us = ue_findHomeUnitEnv from_uid ue in let um = unitInfoMap (homeUnitEnv_units us) in case Map.lookup uid um of Nothing -> pprPanic "uid not found" (ppr uid) Just ui -> let depends = unitDepends ui home_depends = Set.fromList depends `Set.intersection` home_id_set other_depends = Set.fromList depends `Set.difference` home_id_set in -- Case 1: The unit directly depends on a home_id if not (null home_depends) then let res = foldMap (loop . (from_uid,)) other_depends in Set.insert uid res -- Case 2: Check the rest of the dependencies, and then see if any of them depended on else let res = foldMap (loop . (from_uid,)) other_depends in if not (Set.null res) then Set.insert uid res else res -- | Update the every ModSummary that is depended on -- by a module that needs template haskell. We enable codegen to -- the specified target, disable optimization and change the .hi -- and .o file locations to be temporary files. -- See Note [-fno-code mode] enableCodeGenForTH :: Logger -> TmpFs -> UnitEnv -> [ModuleGraphNode] -> IO [ModuleGraphNode] enableCodeGenForTH logger tmpfs unit_env = enableCodeGenWhen logger tmpfs TFL_CurrentModule TFL_GhcSession unit_env -- | Helper used to implement 'enableCodeGenForTH'. -- In particular, this enables -- unoptimized code generation for all modules that meet some -- condition (first parameter), or are dependencies of those -- modules. The second parameter is a condition to check before -- marking modules for code generation. enableCodeGenWhen :: Logger -> TmpFs -> TempFileLifetime -> TempFileLifetime -> UnitEnv -> [ModuleGraphNode] -> IO [ModuleGraphNode] enableCodeGenWhen logger tmpfs staticLife dynLife unit_env mod_graph = mapM enable_code_gen mod_graph where defaultBackendOf ms = platformDefaultBackend (targetPlatform $ ue_unitFlags (ms_unitid ms) unit_env) enable_code_gen :: ModuleGraphNode -> IO ModuleGraphNode enable_code_gen n@(ModuleNode deps ms) | ModSummary { ms_location = ms_location , ms_hsc_src = HsSrcFile , ms_hspp_opts = dflags } <- ms , mkNodeKey n `Set.member` needs_codegen_set = if | nocode_enable ms -> do let new_temp_file suf dynsuf = do tn <- newTempName logger tmpfs (tmpDir dflags) staticLife suf let dyn_tn = tn -<.> dynsuf addFilesToClean tmpfs dynLife [dyn_tn] return (tn, dyn_tn) -- We don't want to create .o or .hi files unless we have been asked -- to by the user. But we need them, so we patch their locations in -- the ModSummary with temporary files. -- ((hi_file, dyn_hi_file), (o_file, dyn_o_file)) <- -- If ``-fwrite-interface` is specified, then the .o and .hi files -- are written into `-odir` and `-hidir` respectively. #16670 if gopt Opt_WriteInterface dflags then return ((ml_hi_file ms_location, ml_dyn_hi_file ms_location) , (ml_obj_file ms_location, ml_dyn_obj_file ms_location)) else (,) <$> (new_temp_file (hiSuf_ dflags) (dynHiSuf_ dflags)) <*> (new_temp_file (objectSuf_ dflags) (dynObjectSuf_ dflags)) let ms' = ms { ms_location = ms_location { ml_hi_file = hi_file , ml_obj_file = o_file , ml_dyn_hi_file = dyn_hi_file , ml_dyn_obj_file = dyn_o_file } , ms_hspp_opts = updOptLevel 0 $ dflags {backend = defaultBackendOf ms} } -- Recursive call to catch the other cases enable_code_gen (ModuleNode deps ms') | dynamic_too_enable ms -> do let ms' = ms { ms_hspp_opts = gopt_set (ms_hspp_opts ms) Opt_BuildDynamicToo } -- Recursive call to catch the other cases enable_code_gen (ModuleNode deps ms') | ext_interp_enable ms -> do let ms' = ms { ms_hspp_opts = gopt_set (ms_hspp_opts ms) Opt_ExternalInterpreter } -- Recursive call to catch the other cases enable_code_gen (ModuleNode deps ms') | otherwise -> return n enable_code_gen ms = return ms nocode_enable ms@(ModSummary { ms_hspp_opts = dflags }) = backend dflags == NoBackend && -- Don't enable codegen for TH on indefinite packages; we -- can't compile anything anyway! See #16219. isHomeUnitDefinite (ue_unitHomeUnit (ms_unitid ms) unit_env) -- #8180 - when using TemplateHaskell, switch on -dynamic-too so -- the linker can correctly load the object files. This isn't necessary -- when using -fexternal-interpreter. dynamic_too_enable ms = hostIsDynamic && internalInterpreter && not isDynWay && not isProfWay && not dyn_too_enabled where lcl_dflags = ms_hspp_opts ms internalInterpreter = not (gopt Opt_ExternalInterpreter lcl_dflags) dyn_too_enabled = (gopt Opt_BuildDynamicToo lcl_dflags) isDynWay = hasWay (ways lcl_dflags) WayDyn isProfWay = hasWay (ways lcl_dflags) WayProf -- #16331 - when no "internal interpreter" is available but we -- need to process some TemplateHaskell or QuasiQuotes, we automatically -- turn on -fexternal-interpreter. ext_interp_enable ms = not ghciSupported && internalInterpreter where lcl_dflags = ms_hspp_opts ms internalInterpreter = not (gopt Opt_ExternalInterpreter lcl_dflags) (mg, lookup_node) = moduleGraphNodes False mod_graph needs_codegen_set = Set.fromList $ map (mkNodeKey . node_payload) $ reachablesG mg (map (expectJust "needs_th" . lookup_node) has_th_set) has_th_set = [ mkNodeKey mn | mn@(ModuleNode _ ms) <- mod_graph , isTemplateHaskellOrQQNonBoot ms ] -- | Populate the Downsweep cache with the root modules. mkRootMap :: [ModSummary] -> DownsweepCache mkRootMap summaries = Map.fromListWith (flip (++)) [ ((ms_unitid s, NoPkgQual, ms_mnwib s), [Right s]) | s <- summaries ] ----------------------------------------------------------------------------- -- Summarising modules -- We have two types of summarisation: -- -- * Summarise a file. This is used for the root module(s) passed to -- cmLoadModules. The file is read, and used to determine the root -- module name. The module name may differ from the filename. -- -- * Summarise a module. We are given a module name, and must provide -- a summary. The finder is used to locate the file in which the module -- resides. summariseFile :: HscEnv -> HomeUnit -> M.Map FilePath ModSummary -- old summaries -> FilePath -- source file name -> Maybe Phase -- start phase -> Maybe (StringBuffer,UTCTime) -> IO (Either DriverMessages ModSummary) summariseFile hsc_env' home_unit old_summaries src_fn mb_phase maybe_buf -- we can use a cached summary if one is available and the -- source file hasn't changed, But we have to look up the summary -- by source file, rather than module name as we do in summarise. | Just old_summary <- M.lookup src_fn old_summaries = do let location = ms_location $ old_summary src_hash <- get_src_hash -- The file exists; we checked in getRootSummary above. -- If it gets removed subsequently, then this -- getFileHash may fail, but that's the right -- behaviour. -- return the cached summary if the source didn't change checkSummaryHash hsc_env (new_summary src_fn) old_summary location src_hash | otherwise = do src_hash <- get_src_hash new_summary src_fn src_hash where -- change the main active unit so all operations happen relative to the given unit hsc_env = hscSetActiveHomeUnit home_unit hsc_env' -- src_fn does not necessarily exist on the filesystem, so we need to -- check what kind of target we are dealing with get_src_hash = case maybe_buf of Just (buf,_) -> return $ fingerprintStringBuffer buf Nothing -> liftIO $ getFileHash src_fn new_summary src_fn src_hash = runExceptT $ do preimps@PreprocessedImports {..} <- getPreprocessedImports hsc_env src_fn mb_phase maybe_buf let fopts = initFinderOpts (hsc_dflags hsc_env) -- Make a ModLocation for this file let location = mkHomeModLocation fopts pi_mod_name src_fn -- Tell the Finder cache where it is, so that subsequent calls -- to findModule will find it, even if it's not on any search path mod <- liftIO $ do let home_unit = hsc_home_unit hsc_env let fc = hsc_FC hsc_env addHomeModuleToFinder fc home_unit pi_mod_name location liftIO $ makeNewModSummary hsc_env $ MakeNewModSummary { nms_src_fn = src_fn , nms_src_hash = src_hash , nms_is_boot = NotBoot , nms_hsc_src = if isHaskellSigFilename src_fn then HsigFile else HsSrcFile , nms_location = location , nms_mod = mod , nms_preimps = preimps } checkSummaryHash :: HscEnv -> (Fingerprint -> IO (Either e ModSummary)) -> ModSummary -> ModLocation -> Fingerprint -> IO (Either e ModSummary) checkSummaryHash hsc_env new_summary old_summary location src_hash | ms_hs_hash old_summary == src_hash && not (gopt Opt_ForceRecomp (hsc_dflags hsc_env)) = do -- update the object-file timestamp obj_timestamp <- modificationTimeIfExists (ml_obj_file location) -- We have to repopulate the Finder's cache for file targets -- because the file might not even be on the regular search path -- and it was likely flushed in depanal. This is not technically -- needed when we're called from sumariseModule but it shouldn't -- hurt. -- Also, only add to finder cache for non-boot modules as the finder cache -- makes sure to add a boot suffix for boot files. _ <- do let fc = hsc_FC hsc_env case ms_hsc_src old_summary of HsSrcFile -> addModuleToFinder fc (ms_mod old_summary) location _ -> return () hi_timestamp <- modificationTimeIfExists (ml_hi_file location) hie_timestamp <- modificationTimeIfExists (ml_hie_file location) return $ Right ( old_summary { ms_obj_date = obj_timestamp , ms_iface_date = hi_timestamp , ms_hie_date = hie_timestamp } ) | otherwise = -- source changed: re-summarise. new_summary src_hash data SummariseResult = FoundInstantiation InstantiatedUnit | FoundHomeWithError (UnitId, DriverMessages) | FoundHome ModSummary | External UnitId | NotThere -- Summarise a module, and pick up source and timestamp. summariseModule :: HscEnv -> HomeUnit -> M.Map FilePath ModSummary -- ^ Map of old summaries -> IsBootInterface -- True <=> a {-# SOURCE #-} import -> Located ModuleName -- Imported module to be summarised -> PkgQual -> Maybe (StringBuffer, UTCTime) -> [ModuleName] -- Modules to exclude -> IO SummariseResult summariseModule hsc_env' home_unit old_summary_map is_boot (L _ wanted_mod) mb_pkg maybe_buf excl_mods | wanted_mod `elem` excl_mods = return NotThere | otherwise = find_it where -- Temporarily change the currently active home unit so all operations -- happen relative to it hsc_env = hscSetActiveHomeUnit home_unit hsc_env' dflags = hsc_dflags hsc_env find_it :: IO SummariseResult find_it = do found <- findImportedModule hsc_env wanted_mod mb_pkg case found of Found location mod | isJust (ml_hs_file location) -> -- Home package just_found location mod | VirtUnit iud <- moduleUnit mod , not (isHomeModule home_unit mod) -> return $ FoundInstantiation iud | otherwise -> return $ External (moduleUnitId mod) _ -> return NotThere -- Not found -- (If it is TRULY not found at all, we'll -- error when we actually try to compile) just_found location mod = do -- Adjust location to point to the hs-boot source file, -- hi file, object file, when is_boot says so let location' = case is_boot of IsBoot -> addBootSuffixLocn location NotBoot -> location src_fn = expectJust "summarise2" (ml_hs_file location') -- Check that it exists -- It might have been deleted since the Finder last found it maybe_h <- fileHashIfExists src_fn case maybe_h of -- This situation can also happen if we have found the .hs file but the -- .hs-boot file doesn't exist. Nothing -> return NotThere Just h -> do fresult <- new_summary_cache_check location' mod src_fn h return $ case fresult of Left err -> FoundHomeWithError (moduleUnitId mod, err) Right ms -> FoundHome ms new_summary_cache_check loc mod src_fn h | Just old_summary <- Map.lookup src_fn old_summary_map = -- check the hash on the source file, and -- return the cached summary if it hasn't changed. If the -- file has changed then need to resummarise. case maybe_buf of Just (buf,_) -> checkSummaryHash hsc_env (new_summary loc mod src_fn) old_summary loc (fingerprintStringBuffer buf) Nothing -> checkSummaryHash hsc_env (new_summary loc mod src_fn) old_summary loc h | otherwise = new_summary loc mod src_fn h new_summary :: ModLocation -> Module -> FilePath -> Fingerprint -> IO (Either DriverMessages ModSummary) new_summary location mod src_fn src_hash = runExceptT $ do preimps@PreprocessedImports {..} -- Remember to set the active unit here, otherwise the wrong include paths are passed to CPP -- See multiHomeUnits_cpp2 test <- getPreprocessedImports (hscSetActiveUnitId (moduleUnitId mod) hsc_env) src_fn Nothing maybe_buf -- NB: Despite the fact that is_boot is a top-level parameter, we -- don't actually know coming into this function what the HscSource -- of the module in question is. This is because we may be processing -- this module because another module in the graph imported it: in this -- case, we know if it's a boot or not because of the {-# SOURCE #-} -- annotation, but we don't know if it's a signature or a regular -- module until we actually look it up on the filesystem. let hsc_src | is_boot == IsBoot = HsBootFile | isHaskellSigFilename src_fn = HsigFile | otherwise = HsSrcFile when (pi_mod_name /= wanted_mod) $ throwE $ singleMessage $ mkPlainErrorMsgEnvelope pi_mod_name_loc $ DriverFileModuleNameMismatch pi_mod_name wanted_mod let instantiations = homeUnitInstantiations home_unit when (hsc_src == HsigFile && isNothing (lookup pi_mod_name instantiations)) $ throwE $ singleMessage $ mkPlainErrorMsgEnvelope pi_mod_name_loc $ DriverUnexpectedSignature pi_mod_name (checkBuildingCabalPackage dflags) instantiations liftIO $ makeNewModSummary hsc_env $ MakeNewModSummary { nms_src_fn = src_fn , nms_src_hash = src_hash , nms_is_boot = is_boot , nms_hsc_src = hsc_src , nms_location = location , nms_mod = mod , nms_preimps = preimps } -- | Convenience named arguments for 'makeNewModSummary' only used to make -- code more readable, not exported. data MakeNewModSummary = MakeNewModSummary { nms_src_fn :: FilePath , nms_src_hash :: Fingerprint , nms_is_boot :: IsBootInterface , nms_hsc_src :: HscSource , nms_location :: ModLocation , nms_mod :: Module , nms_preimps :: PreprocessedImports } makeNewModSummary :: HscEnv -> MakeNewModSummary -> IO ModSummary makeNewModSummary hsc_env MakeNewModSummary{..} = do let PreprocessedImports{..} = nms_preimps obj_timestamp <- modificationTimeIfExists (ml_obj_file nms_location) dyn_obj_timestamp <- modificationTimeIfExists (ml_dyn_obj_file nms_location) hi_timestamp <- modificationTimeIfExists (ml_hi_file nms_location) hie_timestamp <- modificationTimeIfExists (ml_hie_file nms_location) extra_sig_imports <- findExtraSigImports hsc_env nms_hsc_src pi_mod_name (implicit_sigs, _inst_deps) <- implicitRequirementsShallow (hscSetActiveUnitId (moduleUnitId nms_mod) hsc_env) pi_theimps return $ ModSummary { ms_mod = nms_mod , ms_hsc_src = nms_hsc_src , ms_location = nms_location , ms_hspp_file = pi_hspp_fn , ms_hspp_opts = pi_local_dflags , ms_hspp_buf = Just pi_hspp_buf , ms_parsed_mod = Nothing , ms_srcimps = pi_srcimps , ms_ghc_prim_import = pi_ghc_prim_import , ms_textual_imps = ((,) NoPkgQual . noLoc <$> extra_sig_imports) ++ ((,) NoPkgQual . noLoc <$> implicit_sigs) ++ pi_theimps , ms_hs_hash = nms_src_hash , ms_iface_date = hi_timestamp , ms_hie_date = hie_timestamp , ms_obj_date = obj_timestamp , ms_dyn_obj_date = dyn_obj_timestamp } data PreprocessedImports = PreprocessedImports { pi_local_dflags :: DynFlags , pi_srcimps :: [(PkgQual, Located ModuleName)] , pi_theimps :: [(PkgQual, Located ModuleName)] , pi_ghc_prim_import :: Bool , pi_hspp_fn :: FilePath , pi_hspp_buf :: StringBuffer , pi_mod_name_loc :: SrcSpan , pi_mod_name :: ModuleName } -- Preprocess the source file and get its imports -- The pi_local_dflags contains the OPTIONS pragmas getPreprocessedImports :: HscEnv -> FilePath -> Maybe Phase -> Maybe (StringBuffer, UTCTime) -- ^ optional source code buffer and modification time -> ExceptT DriverMessages IO PreprocessedImports getPreprocessedImports hsc_env src_fn mb_phase maybe_buf = do (pi_local_dflags, pi_hspp_fn) <- ExceptT $ preprocess hsc_env src_fn (fst <$> maybe_buf) mb_phase pi_hspp_buf <- liftIO $ hGetStringBuffer pi_hspp_fn (pi_srcimps', pi_theimps', pi_ghc_prim_import, L pi_mod_name_loc pi_mod_name) <- ExceptT $ do let imp_prelude = xopt LangExt.ImplicitPrelude pi_local_dflags popts = initParserOpts pi_local_dflags mimps <- getImports popts imp_prelude pi_hspp_buf pi_hspp_fn src_fn return (first (mkMessages . fmap mkDriverPsHeaderMessage . getMessages) mimps) let rn_pkg_qual = renameRawPkgQual (hsc_unit_env hsc_env) let rn_imps = fmap (\(pk, lmn@(L _ mn)) -> (rn_pkg_qual mn pk, lmn)) let pi_srcimps = rn_imps pi_srcimps' let pi_theimps = rn_imps pi_theimps' return PreprocessedImports {..} ----------------------------------------------------------------------------- -- Error messages ----------------------------------------------------------------------------- -- Defer and group warning, error and fatal messages so they will not get lost -- in the regular output. withDeferredDiagnostics :: GhcMonad m => m a -> m a withDeferredDiagnostics f = do dflags <- getDynFlags if not $ gopt Opt_DeferDiagnostics dflags then f else do warnings <- liftIO $ newIORef [] errors <- liftIO $ newIORef [] fatals <- liftIO $ newIORef [] logger <- getLogger let deferDiagnostics _dflags !msgClass !srcSpan !msg = do let action = logMsg logger msgClass srcSpan msg case msgClass of MCDiagnostic SevWarning _reason -> atomicModifyIORef' warnings $ \i -> (action: i, ()) MCDiagnostic SevError _reason -> atomicModifyIORef' errors $ \i -> (action: i, ()) MCFatal -> atomicModifyIORef' fatals $ \i -> (action: i, ()) _ -> action printDeferredDiagnostics = liftIO $ forM_ [warnings, errors, fatals] $ \ref -> do -- This IORef can leak when the dflags leaks, so let us always -- reset the content. actions <- atomicModifyIORef' ref $ \i -> ([], i) sequence_ $ reverse actions MC.bracket (pushLogHookM (const deferDiagnostics)) (\_ -> popLogHookM >> printDeferredDiagnostics) (\_ -> f) noModError :: HscEnv -> SrcSpan -> ModuleName -> FindResult -> MsgEnvelope GhcMessage -- ToDo: we don't have a proper line number for this error noModError hsc_env loc wanted_mod err = mkPlainErrorMsgEnvelope loc $ GhcDriverMessage $ DriverUnknownMessage $ mkPlainError noHints $ cannotFindModule hsc_env wanted_mod err {- noHsFileErr :: SrcSpan -> String -> DriverMessages noHsFileErr loc path = singleMessage $ mkPlainErrorMsgEnvelope loc (DriverFileNotFound path) -} moduleNotFoundErr :: ModuleName -> DriverMessages moduleNotFoundErr mod = singleMessage $ mkPlainErrorMsgEnvelope noSrcSpan (DriverModuleNotFound mod) multiRootsErr :: [ModSummary] -> IO () multiRootsErr [] = panic "multiRootsErr" multiRootsErr summs@(summ1:_) = throwOneError $ fmap GhcDriverMessage $ mkPlainErrorMsgEnvelope noSrcSpan $ DriverDuplicatedModuleDeclaration mod files where mod = ms_mod summ1 files = map (expectJust "checkDup" . ml_hs_file . ms_location) summs cyclicModuleErr :: [ModuleGraphNode] -> SDoc -- From a strongly connected component we find -- a single cycle to report cyclicModuleErr mss = assert (not (null mss)) $ case findCycle graph of Nothing -> text "Unexpected non-cycle" <+> ppr mss Just path0 -> vcat [ text "Module graph contains a cycle:" , nest 2 (show_path path0)] where graph :: [Node NodeKey ModuleGraphNode] graph = [ DigraphNode { node_payload = ms , node_key = mkNodeKey ms , node_dependencies = nodeDependencies False ms } | ms <- mss ] show_path :: [ModuleGraphNode] -> SDoc show_path [] = panic "show_path" show_path [m] = ppr_node m <+> text "imports itself" show_path (m1:m2:ms) = vcat ( nest 6 (ppr_node m1) : nest 6 (text "imports" <+> ppr_node m2) : go ms ) where go [] = [text "which imports" <+> ppr_node m1] go (m:ms) = (text "which imports" <+> ppr_node m) : go ms ppr_node :: ModuleGraphNode -> SDoc ppr_node (ModuleNode _deps m) = text "module" <+> ppr_ms m ppr_node (InstantiationNode _uid u) = text "instantiated unit" <+> ppr u ppr_node (LinkNode uid _) = pprPanic "LinkNode should not be in a cycle" (ppr uid) ppr_ms :: ModSummary -> SDoc ppr_ms ms = quotes (ppr (moduleName (ms_mod ms))) <+> (parens (text (msHsFilePath ms))) cleanCurrentModuleTempFilesMaybe :: MonadIO m => Logger -> TmpFs -> DynFlags -> m () cleanCurrentModuleTempFilesMaybe logger tmpfs dflags = unless (gopt Opt_KeepTmpFiles dflags) $ liftIO $ cleanCurrentModuleTempFiles logger tmpfs addDepsToHscEnv :: [HomeModInfo] -> HscEnv -> HscEnv addDepsToHscEnv deps hsc_env = hscUpdateHUG (\hug -> foldr addHomeModInfoToHug hug deps) hsc_env setHPT :: HomePackageTable -> HscEnv -> HscEnv setHPT deps hsc_env = hscUpdateHPT (const $ deps) hsc_env setHUG :: HomeUnitGraph -> HscEnv -> HscEnv setHUG deps hsc_env = hscUpdateHUG (const $ deps) hsc_env -- | Wrap an action to catch and handle exceptions. wrapAction :: HscEnv -> IO a -> IO (Maybe a) wrapAction hsc_env k = do let lcl_logger = hsc_logger hsc_env lcl_dynflags = hsc_dflags hsc_env let logg err = printMessages lcl_logger (initDiagOpts lcl_dynflags) (srcErrorMessages err) -- MP: It is a bit strange how prettyPrintGhcErrors handles some errors but then we handle -- SourceError and ThreadKilled differently directly below. TODO: Refactor to use `catches` -- directly. MP should probably use safeTry here to not catch async exceptions but that will regress performance due to -- internally using forkIO. mres <- MC.try $ liftIO $ prettyPrintGhcErrors lcl_logger $ k case mres of Right res -> return $ Just res Left exc -> do case fromException exc of Just (err :: SourceError) -> logg err Nothing -> case fromException exc of -- ThreadKilled in particular needs to actually kill the thread. -- So rethrow that and the other async exceptions Just (err :: SomeAsyncException) -> throwIO err _ -> errorMsg lcl_logger (text (show exc)) return Nothing withParLog :: TVar LogQueueQueue -> Int -> ((Logger -> Logger) -> IO b) -> IO b withParLog lqq_var k cont = do let init_log = do -- Make a new log queue lq <- newLogQueue k -- Add it into the LogQueueQueue atomically $ initLogQueue lqq_var lq return lq finish_log lq = liftIO (finishLogQueue lq) MC.bracket init_log finish_log $ \lq -> cont (pushLogHook (const (parLogAction lq))) withLoggerHsc :: Int -> MakeEnv -> (HscEnv -> IO a) -> IO a withLoggerHsc k MakeEnv{withLogger, hsc_env} cont = do withLogger k $ \modifyLogger -> do let lcl_logger = modifyLogger (hsc_logger hsc_env) hsc_env' = hsc_env { hsc_logger = lcl_logger } -- Run continuation with modified logger cont hsc_env' executeInstantiationNode :: Int -> Int -> RunMakeM HomeUnitGraph -> UnitId -> InstantiatedUnit -> RunMakeM () executeInstantiationNode k n wait_deps uid iu = do -- Wait for the dependencies of this node deps <- wait_deps env <- ask -- Output of the logger is mediated by a central worker to -- avoid output interleaving msg <- asks env_messager lift $ MaybeT $ withLoggerHsc k env $ \hsc_env -> let lcl_hsc_env = setHUG deps hsc_env in wrapAction lcl_hsc_env $ do res <- upsweep_inst lcl_hsc_env msg k n uid iu cleanCurrentModuleTempFilesMaybe (hsc_logger hsc_env) (hsc_tmpfs hsc_env) (hsc_dflags hsc_env) return res executeCompileNode :: Int -> Int -> Maybe HomeModInfo -> RunMakeM HomeUnitGraph -> Maybe [ModuleName] -- List of modules we need to rehydrate before compiling -> ModSummary -> RunMakeM HomeModInfo executeCompileNode k n !old_hmi wait_deps mrehydrate_mods mod = do me@MakeEnv{..} <- ask deps <- wait_deps -- Rehydrate any dependencies if this module had a boot file or is a signature file. lift $ MaybeT (withAbstractSem compile_sem $ withLoggerHsc k me $ \hsc_env -> do hydrated_hsc_env <- liftIO $ maybeRehydrateBefore (setHUG deps hsc_env) mod fixed_mrehydrate_mods let -- Use the cached DynFlags which includes OPTIONS_GHC pragmas lcl_dynflags = ms_hspp_opts mod let lcl_hsc_env = -- Localise the hsc_env to use the cached flags hscSetFlags lcl_dynflags $ hydrated_hsc_env -- Compile the module, locking with a semphore to avoid too many modules -- being compiled at the same time leading to high memory usage. wrapAction lcl_hsc_env $ do res <- upsweep_mod lcl_hsc_env env_messager old_hmi mod k n cleanCurrentModuleTempFilesMaybe (hsc_logger hsc_env) (hsc_tmpfs hsc_env) lcl_dynflags return res) where fixed_mrehydrate_mods = case ms_hsc_src mod of -- MP: It is probably a bit of a misimplementation in backpack that -- compiling a signature requires an knot_var for that unit. -- If you remove this then a lot of backpack tests fail. HsigFile -> Just [] _ -> mrehydrate_mods {- Rehydration, see Note [Rehydrating Modules] -} rehydrate :: HscEnv -- ^ The HPT in this HscEnv needs rehydrating. -> [HomeModInfo] -- ^ These are the modules we want to rehydrate. -> IO HscEnv rehydrate hsc_env hmis = do debugTraceMsg logger 2 $ text "Re-hydrating loop: " new_mods <- fixIO $ \new_mods -> do let new_hpt = addListToHpt old_hpt new_mods let new_hsc_env = hscUpdateHPT (const new_hpt) hsc_env mds <- initIfaceCheck (text "rehydrate") new_hsc_env $ mapM (typecheckIface . hm_iface) hmis let new_mods = [ (mn,hmi{ hm_details = details }) | (hmi,details) <- zip hmis mds , let mn = moduleName (mi_module (hm_iface hmi)) ] return new_mods return $ setHPT (foldl' (\old (mn, hmi) -> addToHpt old mn hmi) old_hpt new_mods) hsc_env where logger = hsc_logger hsc_env to_delete = (map (moduleName . mi_module . hm_iface) hmis) -- Filter out old modules before tying the knot, otherwise we can end -- up with a thunk which keeps reference to the old HomeModInfo. !old_hpt = foldl' delFromHpt (hsc_HPT hsc_env) to_delete -- If needed, then rehydrate the necessary modules with a suitable KnotVars for the -- module currently being compiled. maybeRehydrateBefore :: HscEnv -> ModSummary -> Maybe [ModuleName] -> IO HscEnv maybeRehydrateBefore hsc_env _ Nothing = return hsc_env maybeRehydrateBefore hsc_env mod (Just mns) = do knot_var <- initialise_knot_var hsc_env let hmis = map (expectJust "mr" . lookupHpt (hsc_HPT hsc_env)) mns rehydrate (hsc_env { hsc_type_env_vars = knotVarsFromModuleEnv knot_var }) hmis where initialise_knot_var hsc_env = liftIO $ let mod_name = homeModuleInstantiation (hsc_home_unit_maybe hsc_env) (ms_mod mod) in mkModuleEnv . (:[]) . (mod_name,) <$> newIORef emptyTypeEnv maybeRehydrateAfter :: HomeModInfo -> HscEnv -> Maybe [ModuleName] -> IO (HomeUnitGraph, HomeModInfo) maybeRehydrateAfter hmi new_hsc Nothing = return (hsc_HUG new_hsc, hmi) maybeRehydrateAfter hmi new_hsc (Just mns) = do let new_hpt = hsc_HPT new_hsc hmis = map (expectJust "mrAfter" . lookupHpt new_hpt) mns new_mod_name = moduleName (mi_module (hm_iface hmi)) hsc_env <- rehydrate (new_hsc { hsc_type_env_vars = emptyKnotVars }) (hmi : hmis) return (hsc_HUG hsc_env, expectJust "rehydrate" $ lookupHpt (hsc_HPT hsc_env) new_mod_name) {- Note [Hydrating Modules] ~~~~~~~~~~~~~~~~~~~~~~~~ There are at least 4 different representations of an interface file as described by this diagram. ------------------------------ | On-disk M.hi | ------------------------------ | ^ | Read file | Write file V | ------------------------------- | ByteString | ------------------------------- | ^ | Binary.get | Binary.put V | -------------------------------- | ModIface (an acyclic AST) | -------------------------------- | ^ | hydrate | mkIfaceTc V | --------------------------------- | ModDetails (lots of cycles) | --------------------------------- The last step, converting a ModIface into a ModDetails is known as "hydration". Hydration happens in three different places * When an interface file is initially loaded from disk, it has to be hydrated. * When a module is finished compiling, we hydrate the ModIface in order to generate the version of ModDetails which exists in memory (see Note [ModDetails and --make mode]) * When dealing with boot files and module loops (see Note [Rehydrating Modules]) Note [Rehydrating Modules] ~~~~~~~~~~~~~~~~~~~~~~~~~~~ If a module has a boot file then it is critical to rehydrate the modules on the path between the two (see #20561). Suppose we have ("R" for "recursive"): ``` R.hs-boot: module R where data T g :: T -> T A.hs: module A( f, T, g ) where import {-# SOURCE #-} R data S = MkS T f :: T -> S = ...g... R.hs: module R where import A data T = T1 | T2 S g = ...f... ``` == Why we need to rehydrate A's ModIface before compiling R.hs After compiling A.hs we'll have a TypeEnv in which the Id for `f` has a type type uses the AbstractTyCon T; and a TyCon for `S` that also mentions that same AbstractTyCon. (Abstract because it came from R.hs-boot; we know nothing about it.) When compiling R.hs, we build a TyCon for `T`. But that TyCon mentions `S`, and it currently has an AbstractTyCon for `T` inside it. But we want to build a fully cyclic structure, in which `S` refers to `T` and `T` refers to `S`. Solution: **rehydration**. *Before compiling `R.hs`*, rehydrate all the ModIfaces below it that depend on R.hs-boot. To rehydrate a ModIface, call `typecheckIface` to convert it to a ModDetails. It's just a de-serialisation step, no type inference, just lookups. Now `S` will be bound to a thunk that, when forced, will "see" the final binding for `T`; see [Tying the knot](https://gitlab.haskell.org/ghc/ghc/-/wikis/commentary/compiler/tying-the-knot). But note that this must be done *before* compiling R.hs. == Why we need to rehydrate A's ModIface after compiling R.hs When compiling R.hs, the knot-tying stuff above will ensure that `f`'s unfolding mentions the `LocalId` for `g`. But when we finish R, we carefully ensure that all those `LocalIds` are turned into completed `GlobalIds`, replete with unfoldings etc. Alas, that will not apply to the occurrences of `g` in `f`'s unfolding. And if we leave matters like that, they will stay that way, and *all* subsequent modules that import A will see a crippled unfolding for `f`. Solution: rehydrate both R and A's ModIface together, right after completing R.hs. ~~ Which modules to rehydrate We only need rehydrate modules that are * Below R.hs * Above R.hs-boot There might be many unrelated modules (in the home package) that don't need to be rehydrated. == Modules "above" the loop This dark corner is the subject of #14092. Suppose we add to our example ``` X.hs module X where import A data XT = MkX T fx = ...g... ``` If in `--make` we compile R.hs-boot, then A.hs, then X.hs, we'll get a `ModDetails` for `X` that has an AbstractTyCon for `T` in the the argument type of `MkX`. So: * Either we should delay compiling X until after R has beeen compiled. (This is what we do) * Or we should rehydrate X after compiling R -- because it transitively depends on R.hs-boot. Ticket #20200 has exposed some issues to do with the knot-tying logic in GHC.Make, in `--make` mode. #20200 has lots of issues, many of them now fixed; this particular issue starts [here](https://gitlab.haskell.org/ghc/ghc/-/issues/20200#note_385758). The wiki page [Tying the knot](https://gitlab.haskell.org/ghc/ghc/-/wikis/commentary/compiler/tying-the-knot) is helpful. Also closely related are * #14092 * #14103 -} executeLinkNode :: RunMakeM HomeUnitGraph -> (Int, Int) -> UnitId -> [NodeKey] -> RunMakeM () executeLinkNode wait_deps kn uid deps = do withCurrentUnit uid $ do MakeEnv{..} <- ask hug <- wait_deps let dflags = hsc_dflags hsc_env let hsc_env' = setHUG hug hsc_env msg' = (\messager -> \recomp -> messager hsc_env kn recomp (LinkNode deps uid)) <$> env_messager linkresult <- liftIO $ withAbstractSem compile_sem $ do link (ghcLink dflags) (hsc_logger hsc_env') (hsc_tmpfs hsc_env') (hsc_hooks hsc_env') dflags (hsc_unit_env hsc_env') True -- We already decided to link msg' (hsc_HPT hsc_env') case linkresult of Failed -> fail "Link Failed" Succeeded -> return () -- | Wait for some dependencies to finish and then read from the given MVar. wait_deps_hug :: MVar b -> [ResultVar (Maybe HomeModInfo)] -> ReaderT MakeEnv (MaybeT IO) b wait_deps_hug hug_var deps = do _ <- wait_deps deps liftIO $ readMVar hug_var -- | Wait for dependencies to finish, and then return their results. wait_deps :: [ResultVar (Maybe HomeModInfo)] -> RunMakeM [HomeModInfo] wait_deps [] = return [] wait_deps (x:xs) = do res <- lift $ waitResult x case res of Nothing -> wait_deps xs Just hmi -> (hmi:) <$> wait_deps xs -- Executing the pipelines -- | Start a thread which reads from the LogQueueQueue label_self :: String -> IO () label_self thread_name = do self_tid <- CC.myThreadId CC.labelThread self_tid thread_name runPipelines :: Int -> HscEnv -> Maybe Messager -> [MakeAction] -> IO () -- Don't even initialise plugins if there are no pipelines runPipelines _ _ _ [] = return () runPipelines n_job orig_hsc_env mHscMessager all_pipelines = do liftIO $ label_self "main --make thread" plugins_hsc_env <- initializePlugins orig_hsc_env case n_job of 1 -> runSeqPipelines plugins_hsc_env mHscMessager all_pipelines _n -> runParPipelines n_job plugins_hsc_env mHscMessager all_pipelines runSeqPipelines :: HscEnv -> Maybe Messager -> [MakeAction] -> IO () runSeqPipelines plugin_hsc_env mHscMessager all_pipelines = let env = MakeEnv { hsc_env = plugin_hsc_env , withLogger = \_ k -> k id , compile_sem = AbstractSem (return ()) (return ()) , env_messager = mHscMessager } in runAllPipelines 1 env all_pipelines -- | Build and run a pipeline runParPipelines :: Int -- ^ How many capabilities to use -> HscEnv -- ^ The basic HscEnv which is augmented with specific info for each module -> Maybe Messager -- ^ Optional custom messager to use to report progress -> [MakeAction] -- ^ The build plan for all the module nodes -> IO () runParPipelines n_jobs plugin_hsc_env mHscMessager all_pipelines = do -- A variable which we write to when an error has happened and we have to tell the -- logging thread to gracefully shut down. stopped_var <- newTVarIO False -- The queue of LogQueues which actions are able to write to. When an action starts it -- will add it's LogQueue into this queue. log_queue_queue_var <- newTVarIO newLogQueueQueue -- Thread which coordinates the printing of logs wait_log_thread <- logThread n_jobs (length all_pipelines) (hsc_logger plugin_hsc_env) stopped_var log_queue_queue_var -- Make the logger thread-safe, in case there is some output which isn't sent via the LogQueue. thread_safe_logger <- liftIO $ makeThreadSafe (hsc_logger plugin_hsc_env) let thread_safe_hsc_env = plugin_hsc_env { hsc_logger = thread_safe_logger } let updNumCapabilities = liftIO $ do n_capabilities <- getNumCapabilities n_cpus <- getNumProcessors -- Setting number of capabilities more than -- CPU count usually leads to high userspace -- lock contention. #9221 let n_caps = min n_jobs n_cpus unless (n_capabilities /= 1) $ setNumCapabilities n_caps return n_capabilities let resetNumCapabilities orig_n = do liftIO $ setNumCapabilities orig_n atomically $ writeTVar stopped_var True wait_log_thread compile_sem <- newQSem n_jobs let abstract_sem = AbstractSem (waitQSem compile_sem) (signalQSem compile_sem) -- Reset the number of capabilities once the upsweep ends. let env = MakeEnv { hsc_env = thread_safe_hsc_env , withLogger = withParLog log_queue_queue_var , compile_sem = abstract_sem , env_messager = mHscMessager } MC.bracket updNumCapabilities resetNumCapabilities $ \_ -> runAllPipelines n_jobs env all_pipelines withLocalTmpFS :: RunMakeM a -> RunMakeM a withLocalTmpFS act = do let initialiser = do MakeEnv{..} <- ask lcl_tmpfs <- liftIO $ forkTmpFsFrom (hsc_tmpfs hsc_env) return $ hsc_env { hsc_tmpfs = lcl_tmpfs } finaliser lcl_env = do gbl_env <- ask liftIO $ mergeTmpFsInto (hsc_tmpfs lcl_env) (hsc_tmpfs (hsc_env gbl_env)) -- Add remaining files which weren't cleaned up into local tmp fs for -- clean-up later. -- Clear the logQueue if this node had it's own log queue MC.bracket initialiser finaliser $ \lcl_hsc_env -> local (\env -> env { hsc_env = lcl_hsc_env}) act -- | Run the given actions and then wait for them all to finish. runAllPipelines :: Int -> MakeEnv -> [MakeAction] -> IO () runAllPipelines n_jobs env acts = do let spawn_actions :: IO [ThreadId] spawn_actions = if n_jobs == 1 then (:[]) <$> (forkIOWithUnmask $ \unmask -> void $ runLoop (\io -> io unmask) env acts) else runLoop forkIOWithUnmask env acts kill_actions :: [ThreadId] -> IO () kill_actions tids = mapM_ killThread tids MC.bracket spawn_actions kill_actions $ \_ -> do mapM_ waitMakeAction acts -- | Execute each action in order, limiting the amount of parrelism by the given -- semaphore. runLoop :: (((forall a. IO a -> IO a) -> IO ()) -> IO a) -> MakeEnv -> [MakeAction] -> IO [a] runLoop _ _env [] = return [] runLoop fork_thread env (MakeAction act res_var :acts) = do new_thread <- fork_thread $ \unmask -> (do mres <- (unmask $ run_pipeline (withLocalTmpFS act)) `MC.onException` (putMVar res_var Nothing) -- Defensive: If there's an unhandled exception then still signal the failure. putMVar res_var mres) threads <- runLoop fork_thread env acts return (new_thread : threads) where run_pipeline :: RunMakeM a -> IO (Maybe a) run_pipeline p = runMaybeT (runReaderT p env) data MakeAction = forall a . MakeAction (RunMakeM a) (MVar (Maybe a)) waitMakeAction :: MakeAction -> IO () waitMakeAction (MakeAction _ mvar) = () <$ readMVar mvar {- Note [GHC Heap Invariants] ~~~~~~~~~~~~~~~~~~~~~~~~~~ This note is a general place to explain some of the heap invariants which should hold for a program compiled with --make mode. These invariants are all things which can be checked easily using ghc-debug. 1. No HomeModInfo are reachable via the EPS. Why? Interfaces are lazily loaded into the EPS and the lazy thunk retains a reference to the entire HscEnv, if we are not careful the HscEnv will contain the HomePackageTable at the time the interface was loaded and it will never be released. Where? dontLeakTheHPT in GHC.Iface.Load 2. No KnotVars are live at the end of upsweep (#20491) Why? KnotVars contains an old stale reference to the TypeEnv for modules which participate in a loop. At the end of a loop all the KnotVars references should be removed by the call to typecheckLoop. Where? typecheckLoop in GHC.Driver.Make. 3. Immediately after a reload, no ModDetails are live. Why? During the upsweep all old ModDetails are replaced with a new ModDetails generated from a ModIface. If we don't clear the ModDetails before the reload takes place then memory usage during the reload is twice as much as it should be as we retain a copy of the ModDetails for too long. Where? pruneCache in GHC.Driver.Make 4. No TcGblEnv or TcLclEnv are live after typechecking is completed. Why? By the time we get to simplification all the data structures from typechecking should be eliminated. Where? No one place in the compiler. These leaks can be introduced by not suitable forcing functions which take a TcLclEnv as an argument. -}