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Matthew Pickering pushed to branch wip/refactorLoadDecls at Glasgow Haskell Compiler / GHC

Commits:

d80c5d1f

by Matthew Pickering at 2025-09-29T16:00:27+01:00

loader: Unify loadDecls and loadModuleLinkables functions

These two functions nearly did the same thing. I have refactored them so
that `loadDecls` now calls `loadModuleLinkables`.

Fixes #26459

2 changed files:

compiler/GHC/Driver/Main.hs
compiler/GHC/Linker/Loader.hs

Changes:

compiler/GHC/Driver/Main.hs

@@ -2793,10 +2793,12 @@ hscCompileCoreExpr' hsc_env srcspan ds_expr = do
        {- load it -}
        bco_time <- getCurrentTime
 -      (fv_hvs, mods_needed, units_needed) <- loadDecls interp hsc_env srcspan $
 +      (mods_needed, units_needed) <- loadDecls interp hsc_env srcspan $
          Linkable bco_time this_mod $ NE.singleton $ BCOs bcos
 +      -- Get the foreign reference to the name we should have just loaded.
 +      mhvs <- lookupFromLoadedEnv interp (idName binding_id)
        {- Get the HValue for the root -}
 -      return (expectJust $ lookup (idName binding_id) fv_hvs, mods_needed, units_needed)
 +      return (expectJust mhvs, mods_needed, units_needed)

compiler/GHC/Linker/Loader.hs

@@ -27,6 +27,7 @@ module GHC.Linker.Loader
     , withExtendedLoadedEnv
     , extendLoadedEnv
     , deleteFromLoadedEnv
 +   , lookupFromLoadedEnv
     -- * Internals
     , allocateBreakArrays
     , rmDupLinkables
@@ -212,6 +213,15 @@ deleteFromLoadedEnv interp to_remove =
      return $ modifyClosureEnv pls $ \ce ->
        delListFromNameEnv ce to_remove
 +-- | Have we already loaded a name into the interpreter?
 +lookupFromLoadedEnv :: Interp -> Name -> IO (Maybe ForeignHValue)
 +lookupFromLoadedEnv interp name = do
 +  mstate <- getLoaderState interp
 +  return $ do
 +    pls <- mstate
 +    res <- lookupNameEnv (closure_env (linker_env pls)) name
 +    return (snd res)
++
  -- | Load the module containing the given Name and get its associated 'HValue'.
  --
  -- Throws a 'ProgramError' if loading fails or the name cannot be found.
@@ -257,7 +267,7 @@ loadDependencies interp hsc_env pls span needed_mods = do
     -- Link the packages and modules required
     pls1 <- loadPackages' interp hsc_env (ldUnits deps) pls
 -   (pls2, succ) <- loadModuleLinkables interp hsc_env pls1 (ldNeededLinkables deps)
 +   (pls2, succ) <- loadExternalModuleLinkables interp hsc_env pls1 (ldNeededLinkables deps)
     let this_pkgs_loaded = udfmRestrictKeys all_pkgs_loaded $ getUniqDSet trans_pkgs_needed
         all_pkgs_loaded = pkgs_loaded pls2
         trans_pkgs_needed = unionManyUniqDSets (this_pkgs_needed : [ loaded_pkg_trans_deps pkg
@@ -683,41 +693,23 @@ get_reachable_nodes hsc_env mods
    ********************************************************************* -}
 -loadDecls :: Interp -> HscEnv -> SrcSpan -> Linkable -> IO ([(Name, ForeignHValue)], [Linkable], PkgsLoaded)
 +-- | Load the dependencies of a linkable, and then load the linkable itself.
 +loadDecls :: Interp -> HscEnv -> SrcSpan -> Linkable -> IO ([Linkable], PkgsLoaded)
  loadDecls interp hsc_env span linkable = do
      -- Initialise the linker (if it's not been done already)
      initLoaderState interp hsc_env
      -- Take lock for the actual work.
      modifyLoaderState interp $ \pls0 -> do
 -      -- Link the foreign objects first; BCOs in linkable are ignored here.
 -      (pls1, objs_ok) <- loadObjects interp hsc_env pls0 [linkable]
 -      when (failed objs_ok) $ throwGhcExceptionIO $ ProgramError "loadDecls: failed to load foreign objects"
+-
        -- Link the packages and modules required
 -      (pls, ok, links_needed, units_needed) <- loadDependencies interp hsc_env pls1 span needed_mods
 +      (pls, ok, links_needed, units_needed) <- loadDependencies interp hsc_env pls0 span needed_mods
        if failed ok
 -        then throwGhcExceptionIO (ProgramError "")
 +        then throwGhcExceptionIO (ProgramError "could not load dependencies for decls")
          else do
 -          -- Link the expression itself
 -          let le  = linker_env pls
 -          let lb  = linked_breaks pls
 -          le2_itbl_env <- linkITbls interp (itbl_env le) (concat $ map bc_itbls cbcs)
 -          le2_addr_env <- foldlM (\env cbc -> allocateTopStrings interp (bc_strs cbc) env) (addr_env le) cbcs
 -          le2_breakarray_env <- allocateBreakArrays interp (breakarray_env lb) (catMaybes $ map bc_breaks cbcs)
 -          le2_ccs_env        <- allocateCCS         interp (ccs_env lb)        (catMaybes $ map bc_breaks cbcs)
 -          let le2 = le { itbl_env = le2_itbl_env
 -                       , addr_env = le2_addr_env }
 -          let lb2 = lb { breakarray_env = le2_breakarray_env
 -                       , ccs_env = le2_ccs_env }
+-
 -          -- Link the necessary packages and linkables
 -          new_bindings <- linkSomeBCOs interp (pkgs_loaded pls) le2 lb2 cbcs
 -          nms_fhvs <- makeForeignNamedHValueRefs interp new_bindings
 -          let ce2  = extendClosureEnv (closure_env le2) nms_fhvs
 -              !pls2 = pls { linker_env = le2 { closure_env = ce2 }
 -                          , linked_breaks = lb2 }
 -          return (pls2, (nms_fhvs, links_needed, units_needed))
 +          (pls2, ok2) <- loadInternalModuleLinkables interp hsc_env pls [linkable]
 +          when (failed ok2) $
 +            throwGhcExceptionIO (ProgramError "could not load linkable for decls")
 +          return (pls2, (links_needed, units_needed))
    where
      cbcs = linkableBCOs linkable
@@ -759,8 +751,29 @@ loadModule interp hsc_env mod = do
    ********************************************************************* -}
 -loadModuleLinkables :: Interp -> HscEnv -> LoaderState -> [Linkable] -> IO (LoaderState, SuccessFlag)
 -loadModuleLinkables interp hsc_env pls linkables
 +-- | Which closures from a Linkable to add to the 'ClosureEnv' in the 'LoaderState'
 +data KeepModuleLinkableDefinitions = KeepAllDefinitions -- ^ Keep all definitions
 +                                   | KeepExternalDefinitions -- ^ Only keep external definitions
++
 +-- | Interpret a 'KeepModuleLinkableDefinitions' specification to a predictate on 'Name'
 +keepDefinitions :: KeepModuleLinkableDefinitions -> (Name -> Bool)
 +keepDefinitions KeepAllDefinitions = const True
 +keepDefinitions KeepExternalDefinitions = isExternalName
++
 +-- | Load a linkable from a module, and only add externally visible names to the
 +-- environment.
 +loadExternalModuleLinkables :: Interp -> HscEnv -> LoaderState -> [Linkable] -> IO (LoaderState, SuccessFlag)
 +loadExternalModuleLinkables interp hsc_env pls linkables =
 +  loadModuleLinkables interp hsc_env pls KeepExternalDefinitions linkables
++
 +-- | Load a linkable from a module, and add all the names from the linkable into the
 +-- closure environment.
 +loadInternalModuleLinkables :: Interp -> HscEnv -> LoaderState -> [Linkable] -> IO (LoaderState, SuccessFlag)
 +loadInternalModuleLinkables interp hsc_env pls linkables  =
 +  loadModuleLinkables interp hsc_env pls KeepAllDefinitions linkables
++
 +loadModuleLinkables :: Interp -> HscEnv -> LoaderState -> KeepModuleLinkableDefinitions -> [Linkable] -> IO (LoaderState, SuccessFlag)
 +loadModuleLinkables interp hsc_env pls keep_spec linkables
    = mask_ $ do  -- don't want to be interrupted by ^C in here
          debugTraceMsg (hsc_logger hsc_env) 3 $
@@ -775,7 +788,7 @@ loadModuleLinkables interp hsc_env pls linkables
          if failed ok_flag then
                  return (pls1, Failed)
            else do
 -                pls2 <- dynLinkBCOs interp pls1 bcos
 +                pls2 <- dynLinkBCOs interp pls1 keep_spec bcos
                  return (pls2, Succeeded)
    where
      (objs, bcos) = partitionLinkables linkables
@@ -918,8 +931,8 @@ rmDupLinkables already ls
    ********************************************************************* -}
 -dynLinkBCOs :: Interp -> LoaderState -> [Linkable] -> IO LoaderState
 -dynLinkBCOs interp pls bcos = do
 +dynLinkBCOs :: Interp -> LoaderState -> KeepModuleLinkableDefinitions -> [Linkable] -> IO LoaderState
 +dynLinkBCOs interp pls keep_spec bcos = do
          let (bcos_loaded', new_bcos) = rmDupLinkables (bcos_loaded pls) bcos
              pls1                     = pls { bcos_loaded = bcos_loaded' }
@@ -943,7 +956,7 @@ dynLinkBCOs interp pls bcos = do
          names_and_refs <- linkSomeBCOs interp (pkgs_loaded pls) le2 lb2 cbcs
          -- We only want to add the external ones to the ClosureEnv
 -        let (to_add, to_drop) = partition (isExternalName.fst) names_and_refs
 +        let (to_add, to_drop) = partition (keepDefinitions keep_spec . fst) names_and_refs
          -- Immediately release any HValueRefs we're not going to add
          freeHValueRefs interp (map snd to_drop)