iface/BinIface.hs

    {-# LANGUAGE BinaryLiterals, CPP, ScopedTypeVariables #-}

    --
    --  (c) The University of Glasgow 2002-2006
    --

    {-# OPTIONS_GHC -O #-}
    -- We always optimise this, otherwise performance of a non-optimised
    -- compiler is severely affected

    -- | Binary interface file support.
    module BinIface (
            writeBinIface,
            readBinIface,
            getSymtabName,
            getDictFastString,
            CheckHiWay(..),
            TraceBinIFaceReading(..)
        ) where

    #include "HsVersions.h"

    import TcRnMonad
    import PrelInfo   ( isKnownKeyName, lookupKnownKeyName )
    import IfaceEnv
    import HscTypes
    import Module
    import Name
    import DynFlags
    import UniqFM
    import UniqSupply
    import Panic
    import Binary
    import SrcLoc
    import ErrUtils
    import FastMutInt
    import Unique
    import Outputable
    import NameCache
    import Platform
    import FastString
    import Constants
    import Util

    import Data.Bits
    import Data.Char
    import Data.List
    import Data.Word
    import Data.Array
    import Data.IORef
    import Control.Monad

    -- ---------------------------------------------------------------------------
    -- Reading and writing binary interface files
    --

    data CheckHiWay = CheckHiWay | IgnoreHiWay
        deriving Eq

    data TraceBinIFaceReading = TraceBinIFaceReading | QuietBinIFaceReading
        deriving Eq

    -- | Read an interface file
    readBinIface :: CheckHiWay -> TraceBinIFaceReading -> FilePath
                 -> TcRnIf a b ModIface
    readBinIface checkHiWay traceBinIFaceReading hi_path = do
        ncu <- mkNameCacheUpdater
        dflags <- getDynFlags
        liftIO $ readBinIface_ dflags checkHiWay traceBinIFaceReading hi_path ncu

    readBinIface_ :: DynFlags -> CheckHiWay -> TraceBinIFaceReading -> FilePath
                  -> NameCacheUpdater
                  -> IO ModIface
    readBinIface_ dflags checkHiWay traceBinIFaceReading hi_path ncu = do
        let printer :: SDoc -> IO ()
            printer = case traceBinIFaceReading of
                          TraceBinIFaceReading -> \sd ->
                              putLogMsg dflags
                                        NoReason
                                        SevOutput
                                        noSrcSpan
                                        (defaultDumpStyle dflags)
                                        sd
                          QuietBinIFaceReading -> \_ -> return ()
            wantedGot :: Outputable a => String -> a -> a -> IO ()
            wantedGot what wanted got =
                printer (text what <> text ": " <>
                         vcat [text "Wanted " <> ppr wanted <> text ",",
                               text "got    " <> ppr got])

            errorOnMismatch :: (Eq a, Show a) => String -> a -> a -> IO ()
            errorOnMismatch what wanted got =
                -- This will be caught by readIface which will emit an error
                -- msg containing the iface module name.
                when (wanted /= got) $ throwGhcExceptionIO $ ProgramError
                             (what ++ " (wanted " ++ show wanted
                                   ++ ", got "    ++ show got ++ ")")
        bh <- Binary.readBinMem hi_path

        -- Read the magic number to check that this really is a GHC .hi file
        -- (This magic number does not change when we change
        --  GHC interface file format)
        magic <- get bh
        wantedGot "Magic" (binaryInterfaceMagic dflags) magic
        errorOnMismatch "magic number mismatch: old/corrupt interface file?"
            (binaryInterfaceMagic dflags) magic

        -- Note [dummy iface field]
        -- read a dummy 32/64 bit value.  This field used to hold the
        -- dictionary pointer in old interface file formats, but now
        -- the dictionary pointer is after the version (where it
        -- should be).  Also, the serialisation of value of type "Bin
        -- a" used to depend on the word size of the machine, now they
        -- are always 32 bits.
        if wORD_SIZE dflags == 4
            then do _ <- Binary.get bh :: IO Word32; return ()
            else do _ <- Binary.get bh :: IO Word64; return ()

        -- Check the interface file version and ways.
        check_ver  <- get bh
        let our_ver = show hiVersion
        wantedGot "Version" our_ver check_ver
        errorOnMismatch "mismatched interface file versions" our_ver check_ver

        check_way <- get bh
        let way_descr = getWayDescr dflags
        wantedGot "Way" way_descr check_way
        when (checkHiWay == CheckHiWay) $
            errorOnMismatch "mismatched interface file ways" way_descr check_way

        -- Read the dictionary
        -- The next word in the file is a pointer to where the dictionary is
        -- (probably at the end of the file)
        dict_p <- Binary.get bh
        data_p <- tellBin bh          -- Remember where we are now
        seekBin bh dict_p
        dict   <- getDictionary bh
        seekBin bh data_p             -- Back to where we were before

        -- Initialise the user-data field of bh
        bh <- do
            bh <- return $ setUserData bh $ newReadState (error "getSymtabName")
                                                         (getDictFastString dict)
            symtab_p <- Binary.get bh     -- Get the symtab ptr
            data_p <- tellBin bh          -- Remember where we are now
            seekBin bh symtab_p
            symtab <- getSymbolTable bh ncu
            seekBin bh data_p             -- Back to where we were before

            -- It is only now that we know how to get a Name
            return $ setUserData bh $ newReadState (getSymtabName ncu dict symtab)
                                                   (getDictFastString dict)

        -- Read the interface file
        get bh

    -- | Write an interface file
    writeBinIface :: DynFlags -> FilePath -> ModIface -> IO ()
    writeBinIface dflags hi_path mod_iface = do
        bh <- openBinMem initBinMemSize
        put_ bh (binaryInterfaceMagic dflags)

       -- dummy 32/64-bit field before the version/way for
       -- compatibility with older interface file formats.
       -- See Note [dummy iface field] above.
        if wORD_SIZE dflags == 4
            then Binary.put_ bh (0 :: Word32)
            else Binary.put_ bh (0 :: Word64)

        -- The version and way descriptor go next
        put_ bh (show hiVersion)
        let way_descr = getWayDescr dflags
        put_  bh way_descr

        -- Remember where the dictionary pointer will go
        dict_p_p <- tellBin bh
        -- Placeholder for ptr to dictionary
        put_ bh dict_p_p

        -- Remember where the symbol table pointer will go
        symtab_p_p <- tellBin bh
        put_ bh symtab_p_p

        -- Make some intial state
        symtab_next <- newFastMutInt
        writeFastMutInt symtab_next 0
        symtab_map <- newIORef emptyUFM
        let bin_symtab = BinSymbolTable {
                             bin_symtab_next = symtab_next,
                             bin_symtab_map  = symtab_map }
        dict_next_ref <- newFastMutInt
        writeFastMutInt dict_next_ref 0
        dict_map_ref <- newIORef emptyUFM
        let bin_dict = BinDictionary {
                           bin_dict_next = dict_next_ref,
                           bin_dict_map  = dict_map_ref }

        -- Put the main thing,
        bh <- return $ setUserData bh $ newWriteState (putName bin_dict bin_symtab)
                                                      (putName bin_dict bin_symtab)
                                                      (putFastString bin_dict)
        put_ bh mod_iface

        -- Write the symtab pointer at the front of the file
        symtab_p <- tellBin bh        -- This is where the symtab will start
        putAt bh symtab_p_p symtab_p  -- Fill in the placeholder
        seekBin bh symtab_p           -- Seek back to the end of the file

        -- Write the symbol table itself
        symtab_next <- readFastMutInt symtab_next
        symtab_map  <- readIORef symtab_map
        putSymbolTable bh symtab_next symtab_map
        debugTraceMsg dflags 3 (text "writeBinIface:" <+> int symtab_next
                                    <+> text "Names")

        -- NB. write the dictionary after the symbol table, because
        -- writing the symbol table may create more dictionary entries.

        -- Write the dictionary pointer at the fornt of the file
        dict_p <- tellBin bh          -- This is where the dictionary will start
        putAt bh dict_p_p dict_p      -- Fill in the placeholder
        seekBin bh dict_p             -- Seek back to the end of the file

        -- Write the dictionary itself
        dict_next <- readFastMutInt dict_next_ref
        dict_map  <- readIORef dict_map_ref
        putDictionary bh dict_next dict_map
        debugTraceMsg dflags 3 (text "writeBinIface:" <+> int dict_next
                                    <+> text "dict entries")

        -- And send the result to the file
        writeBinMem bh hi_path

    -- | Initial ram buffer to allocate for writing interface files
    initBinMemSize :: Int
    initBinMemSize = 1024 * 1024

    binaryInterfaceMagic :: DynFlags -> Word32
    binaryInterfaceMagic dflags
     | target32Bit (targetPlatform dflags) = 0x1face
     | otherwise                           = 0x1face64

    -- -----------------------------------------------------------------------------
    -- The symbol table
    --

    putSymbolTable :: BinHandle -> Int -> UniqFM (Int,Name) -> IO ()
    putSymbolTable bh next_off symtab = do
        put_ bh next_off
        let names = elems (array (0,next_off-1) (nonDetEltsUFM symtab))
          -- It's OK to use nonDetEltsUFM here because the elements have
          -- indices that array uses to create order
        mapM_ (\n -> serialiseName bh n symtab) names

    getSymbolTable :: BinHandle -> NameCacheUpdater -> IO SymbolTable
    getSymbolTable bh ncu = do
        sz <- get bh
        od_names <- sequence (replicate sz (get bh))
        updateNameCache ncu $ \namecache ->
            let arr = listArray (0,sz-1) names
                (namecache', names) =
                    mapAccumR (fromOnDiskName arr) namecache od_names
            in (namecache', arr)

    type OnDiskName = (UnitId, ModuleName, OccName)

    fromOnDiskName :: Array Int Name -> NameCache -> OnDiskName -> (NameCache, Name)
    fromOnDiskName _ nc (pid, mod_name, occ) =
        let mod   = mkModule pid mod_name
            cache = nsNames nc
        in case lookupOrigNameCache cache  mod occ of
               Just name -> (nc, name)
               Nothing   ->
                   let (uniq, us) = takeUniqFromSupply (nsUniqs nc)
                       name       = mkExternalName uniq mod occ noSrcSpan
                       new_cache  = extendNameCache cache mod occ name
                   in ( nc{ nsUniqs = us, nsNames = new_cache }, name )

    serialiseName :: BinHandle -> Name -> UniqFM (Int,Name) -> IO ()
    serialiseName bh name _ = do
        let mod = ASSERT2( isExternalName name, ppr name ) nameModule name
        put_ bh (moduleUnitId mod, moduleName mod, nameOccName name)

    -- Note [Symbol table representation of names]
    -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    --
    -- An occurrence of a name in an interface file is serialized as a single 32-bit
    -- word. The format of this word is:
    --  00xxxxxx xxxxxxxx xxxxxxxx xxxxxxxx
    --   A normal name. x is an index into the symbol table
    --  10xxxxxx xxyyyyyy yyyyyyyy yyyyyyyy
    --   A known-key name. x is the Unique's Char, y is the int part. We assume that
    --   all known-key uniques fit in this space. This is asserted by
    --   PrelInfo.knownKeyNamesOkay.
    --
    -- During serialization we check for known-key things using isKnownKeyName.
    -- During deserialization we use lookupKnownKeyName to get from the unique back
    -- to its corresponding Name.

    -- See Note [Symbol table representation of names]
    putName :: BinDictionary -> BinSymbolTable -> BinHandle -> Name -> IO ()
    putName _dict BinSymbolTable{
                   bin_symtab_map = symtab_map_ref,
                   bin_symtab_next = symtab_next }
            bh name
      | isKnownKeyName name
      , let (c, u) = unpkUnique (nameUnique name) -- INVARIANT: (ord c) fits in 8 bits
      = -- ASSERT(u < 2^(22 :: Int))
        put_ bh (0x80000000
                 .|. (fromIntegral (ord c) `shiftL` 22)
                 .|. (fromIntegral u :: Word32))

      | otherwise
      = do symtab_map <- readIORef symtab_map_ref
           case lookupUFM symtab_map name of
             Just (off,_) -> put_ bh (fromIntegral off :: Word32)
             Nothing -> do
                off <- readFastMutInt symtab_next
                -- MASSERT(off < 2^(30 :: Int))
                writeFastMutInt symtab_next (off+1)
                writeIORef symtab_map_ref
                    $! addToUFM symtab_map name (off,name)
                put_ bh (fromIntegral off :: Word32)

    -- See Note [Symbol table representation of names]
    getSymtabName :: NameCacheUpdater
                  -> Dictionary -> SymbolTable
                  -> BinHandle -> IO Name
    getSymtabName _ncu _dict symtab bh = do
        i :: Word32 <- get bh
        case i .&. 0xC0000000 of
          0x00000000 -> return $! symtab ! fromIntegral i

          0x80000000 ->
            let
              tag = chr (fromIntegral ((i .&. 0x3FC00000) `shiftR` 22))
              ix  = fromIntegral i .&. 0x003FFFFF
              u   = mkUnique tag ix
            in
              return $! case lookupKnownKeyName u of
                          Nothing -> pprPanic "getSymtabName:unknown known-key unique"
                                              (ppr i $$ ppr (unpkUnique u))
                          Just n  -> n

          _ -> pprPanic "getSymtabName:unknown name tag" (ppr i)

    data BinSymbolTable = BinSymbolTable {
            bin_symtab_next :: !FastMutInt, -- The next index to use
            bin_symtab_map  :: !(IORef (UniqFM (Int,Name)))
                                    -- indexed by Name
      }

    putFastString :: BinDictionary -> BinHandle -> FastString -> IO ()
    putFastString dict bh fs = allocateFastString dict fs >>= put_ bh

    allocateFastString :: BinDictionary -> FastString -> IO Word32
    allocateFastString BinDictionary { bin_dict_next = j_r,
                                       bin_dict_map  = out_r} f = do
        out <- readIORef out_r
        let uniq = getUnique f
        case lookupUFM out uniq of
            Just (j, _)  -> return (fromIntegral j :: Word32)
            Nothing -> do
               j <- readFastMutInt j_r
               writeFastMutInt j_r (j + 1)
               writeIORef out_r $! addToUFM out uniq (j, f)
               return (fromIntegral j :: Word32)

    getDictFastString :: Dictionary -> BinHandle -> IO FastString
    getDictFastString dict bh = do
        j <- get bh
        return $! (dict ! fromIntegral (j :: Word32))

    data BinDictionary = BinDictionary {
            bin_dict_next :: !FastMutInt, -- The next index to use
            bin_dict_map  :: !(IORef (UniqFM (Int,FastString)))
                                    -- indexed by FastString
      }

    getWayDescr :: DynFlags -> String
    getWayDescr dflags
      | platformUnregisterised (targetPlatform dflags) = 'u':tag
      | otherwise                                      =     tag
      where tag = buildTag dflags
            -- if this is an unregisterised build, make sure our interfaces
            -- can't be used by a registerised build.