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Wolfgang Jeltsch pushed to branch wip/jeltsch/smaller-pit at Glasgow Haskell Compiler / GHC

Commits:

969e7ea7

by Wolfgang Jeltsch at 2026-10-12T17:42:15+03:00

Make `IfaceBinHandle` a type synonym family

This brings the handling of `IfaceBinHandle` somewhat in line with how
other phase-dependent data is handled. Note that `mi_hi_bytes_` now
includes the `Strict.Maybe` layer itself, independently of the phase.
This is necessary, because with a type family instead of a GADT
`clear_mi_hi_bytes` cannot determine the phase at runtime anymore and
thus has to set `mi_hi_bytes_` to `Strict.Nothing` for every phase.

3 changed files:

compiler/GHC/Iface/Binary.hs
compiler/GHC/Iface/Make.hs
compiler/GHC/Unit/Module/ModIface.hs

Changes:

compiler/GHC/Iface/Binary.hs

@@ -197,7 +197,7 @@ getIfaceWithExtFields name_cache bh = do
    modIfaceBinData <- freezeBinHandle bh start
    pure $ mod_iface
      & set_mi_ext_fields extFields
 -    & set_mi_hi_bytes (FullIfaceBinHandle $ Strict.Just modIfaceBinData)
 +    & set_mi_hi_bytes (Strict.Just modIfaceBinData)
  -- | This performs a get action after reading the dictionary and symbol
  -- table. It is necessary to run this before trying to deserialise any
@@ -276,10 +276,10 @@ writeBinIface profile traceBinIface compressionLevel hi_path mod_iface = do
  putIfaceWithExtFields :: TraceBinIFace -> CompressionIFace -> WriteBinHandle -> ModIface -> IO ()
  putIfaceWithExtFields traceBinIface compressionLevel bh mod_iface =
    case mi_hi_bytes mod_iface of
 -    FullIfaceBinHandle Strict.Nothing -> do
 +    Strict.Nothing -> do
        forwardPutRel_ bh (\_ -> put_ bh (mi_ext_fields mod_iface)) $ do
          putWithUserData traceBinIface compressionLevel bh mod_iface
 -    FullIfaceBinHandle (Strict.Just binData) -> putFullBinData bh binData
 +    Strict.Just binData -> putFullBinData bh binData
  -- | Put a piece of data with an initialised `UserData` field. This
  -- is necessary if you want to serialise Names or FastStrings.

compiler/GHC/Iface/Make.hs

@@ -77,6 +77,7 @@ import GHC.Iface.Binary
  import GHC.Data.FastString
  import GHC.Data.Maybe
 +import qualified GHC.Data.Strict as Strict
  import GHC.HsToCore.Docs
  import GHC.HsToCore.Usage
@@ -394,7 +395,7 @@ mkIface_ hsc_env
            & set_mi_docs             docs
            & set_mi_abi_hashes       ()
            & set_mi_ext_fields       emptyExtensibleFields
 -          & set_mi_hi_bytes         PartialIfaceBinHandle
 +          & set_mi_hi_bytes         Strict.Nothing
    where
       cmp_rule     = lexicalCompareFS `on` ifRuleName

compiler/GHC/Unit/Module/ModIface.hs

@@ -70,7 +70,7 @@ module GHC.Unit.Module.ModIface
     , set_mi_hash_fn
     , completePartialModIface
     , shrinkModIface
 -   , IfaceBinHandle(..)
 +   , IfaceBinHandle
     , PartialModIface
     , RetainedModIface
     , IfaceAbiHashes (..)
@@ -160,6 +160,7 @@ import GHC.Utils.Binary
  import Control.DeepSeq
  import Control.Exception
 +import Data.Void (Void)
  {- Note [Interface file stages]
@@ -236,15 +237,10 @@ data ModIfacePhase
  -- | In-memory byte array representation of a 'ModIface'.
  --
  -- See Note [Sharing of ModIface] for why we need this.
 -data IfaceBinHandle (phase :: ModIfacePhase) where
 -  -- | A partial 'ModIface' cannot be serialised to disk.
 -  PartialIfaceBinHandle :: IfaceBinHandle 'ModIfaceCore
 -  -- | Optional 'FullBinData' that can be serialised to disk directly.
 -  --
 -  -- See Note [Private fields in ModIface] for when this fields needs to be cleared
 -  -- (e.g., set to 'Nothing').
 -  FullIfaceBinHandle :: !(Strict.Maybe FullBinData) -> IfaceBinHandle 'ModIfaceFinal
 -  RetainedIfaceBinHandle :: IfaceBinHandle 'ModIfaceRetained
 +type family IfaceBinHandle (phase :: ModIfacePhase) where
 +  IfaceBinHandle 'ModIfaceCore     = Void
 +  IfaceBinHandle 'ModIfaceFinal    = FullBinData
 +  IfaceBinHandle 'ModIfaceRetained = Void
  type family IfaceSelfRecompData (phase :: ModIfacePhase) where
    IfaceSelfRecompData 'ModIfaceCore     = Maybe IfaceSelfRecomp
@@ -322,11 +318,22 @@ withSelfRecomp iface nk jk =
  -- fields.
  data ModIface_ (phase :: ModIfacePhase)
    = PrivateModIface {
 -        mi_hi_bytes_ :: !(IfaceBinHandle phase),
 -                -- ^ A serialised in-memory buffer of this 'ModIface'.
 -                -- If this handle is given, we can avoid serialising the 'ModIface'
 -                -- when writing this 'ModIface' to disk, and write this buffer to disk instead.
 -                -- See Note [Sharing of ModIface].
 +        mi_hi_bytes_ :: !(Strict.Maybe (IfaceBinHandle phase)),
 +                -- ^ Optionally an in-memory buffer that contains the
 +                --   serialization of this 'ModIface'. If such a buffer is
 +                --   present, we can avoid serialising the 'ModIface' when
 +                --   writing it to disk and write this buffer instead. See
 +                --   Note [Sharing of ModIface] and
 +                --   Note [Private fields in ModIface].
 +                --
 +                --   Only in the 'ModIfaceFinal' phase, there can be a buffer
 +                --   with the serialization. Both @IfaceBinHandle 'ModIfaceCore@
 +                --   and @IfaceBinHandle 'ModIfaceRetained@ are defined to be
 +                --   'Void', so that the 'mi_hi_bytes' field gets the type
 +                --   @Strict.Maybe Void@. This type is isomorphic to '()', even
 +                --   when taking partially defined values into account, because
 +                --   @Strict.Just undefined@ is @undefined@ and so @Nothing@ and
 +                --   @undefined@ are the only inhabitants of that type.
          mi_iface_hash_  :: Fingerprint, -- A hash of the whole interface
          mi_mod_info_     :: IfaceModInfo,
@@ -718,7 +725,7 @@ instance Binary ModIface where
                   -- We can't populate this field here, as we are
                   -- missing the 'mi_ext_fields_' field, which is
                   -- handled in 'getIfaceWithExtFields'.
 -                 mi_hi_bytes_    = FullIfaceBinHandle Strict.Nothing
 +                 mi_hi_bytes_    = Strict.Nothing
                   })
  instance Binary IfaceModInfo where
@@ -833,7 +840,7 @@ emptyPartialModIface mod
    = PrivateModIface
        { mi_mod_info_    = emptyIfaceModInfo mod,
          mi_iface_hash_  = fingerprint0,
 -        mi_hi_bytes_    = PartialIfaceBinHandle,
 +        mi_hi_bytes_    = Strict.Nothing,
          mi_deps_        = noDependencies,
          mi_public_      = emptyPublicModIface [] [] [] [] [] [] [] (),
          mi_simplified_core_ = Nothing,
@@ -907,7 +914,7 @@ emptyFullModIface :: Module -> ModIface
  emptyFullModIface mod =
      (emptyPartialModIface mod)
        { mi_public_ = emptyPublicModIface [] [] [] [] [] [] [] emptyIfaceBackend
 -      , mi_hi_bytes_ = FullIfaceBinHandle Strict.Nothing
 +      , mi_hi_bytes_ = Strict.Nothing
+       }
@@ -940,7 +947,7 @@ instance ( NFData (IfaceSelfRecompData phase)
           , NFData (IfaceAbiHashesData phase)
           ) => NFData (ModIface_ phase) where
    rnf (PrivateModIface a1 a2 a3 a4 a5 a6 a7 a8 a9 a10)
 -    = (a1 :: IfaceBinHandle phase)
 +    = a1
      `seq` rnf a2
      `seq` rnf a3
      `seq` rnf a4
@@ -1051,7 +1058,7 @@ completePartialModIface :: PartialModIface
  completePartialModIface partial iface_hash decls extra_decls final_exts cache = partial
    { mi_public_ = completePublicModIface decls final_exts cache (mi_public_ partial)
    , mi_simplified_core_ = extra_decls
 -  , mi_hi_bytes_ = FullIfaceBinHandle Strict.Nothing
 +  , mi_hi_bytes_ = Strict.Nothing
    , mi_iface_hash_ = iface_hash
+   }
@@ -1072,7 +1079,7 @@ shrinkModIface :: ModIface -> RetainedModIface
  shrinkModIface PrivateModIface {..}
    = PrivateModIface
+     {
 -      mi_hi_bytes_        = RetainedIfaceBinHandle,
 +      mi_hi_bytes_        = Strict.Nothing,
        mi_public_          = shrinkIfacePublic mi_public_,
        mi_self_recomp_     = (),
        mi_simplified_core_ = (),
@@ -1100,7 +1107,7 @@ set_mi_mod_info val iface = clear_mi_hi_bytes $ iface { mi_mod_info_ = val }
  set_mi_self_recomp :: IfaceSelfRecompData phase -> ModIface_ phase -> ModIface_ phase
  set_mi_self_recomp val iface = clear_mi_hi_bytes $ iface { mi_self_recomp_ = val }
 -set_mi_hi_bytes :: IfaceBinHandle phase -> ModIface_ phase -> ModIface_ phase
 +set_mi_hi_bytes :: Strict.Maybe (IfaceBinHandle phase) -> ModIface_ phase -> ModIface_ phase
  set_mi_hi_bytes val iface = iface { mi_hi_bytes_ = val }
  set_mi_deps :: Dependencies -> ModIface_ phase -> ModIface_ phase
@@ -1203,12 +1210,7 @@ set_mi_mod_info_field f iface = clear_mi_hi_bytes $ iface { mi_mod_info_ = f (mi
  -- | Invalidate any byte array buffer we might have.
  clear_mi_hi_bytes :: ModIface_ phase -> ModIface_ phase
 -clear_mi_hi_bytes iface = iface
 -  { mi_hi_bytes_ = case mi_hi_bytes iface of
 -      PartialIfaceBinHandle  -> PartialIfaceBinHandle
 -      FullIfaceBinHandle _   -> FullIfaceBinHandle Strict.Nothing
 -      RetainedIfaceBinHandle -> RetainedIfaceBinHandle
 -  }
 +clear_mi_hi_bytes iface = iface { mi_hi_bytes_ = Strict.Nothing }
  -- ----------------------------------------------------------------------------
  -- 'ModIface' pattern synonyms to keep breakage low.
@@ -1319,7 +1321,7 @@ pattern ModIface ::
    -> Maybe Docs
    -> IfaceAbiHashesData phase
    -> ExtensibleFieldsData phase
 -  -> IfaceBinHandle phase
 +  -> Strict.Maybe (IfaceBinHandle phase)
    -> IfaceSelfRecompData phase
    -> (OccName -> Maybe Fixity)
    -> (OccName -> Maybe (OccName, Fingerprint))