path: root/compiler/main/DriverPipeline.hs

{-# OPTIONS -fno-cse #-}
-- -fno-cse is needed for GLOBAL_VAR's to behave properly

-----------------------------------------------------------------------------
--
-- GHC Driver
--
-- (c) The University of Glasgow 2005
--
-----------------------------------------------------------------------------

module DriverPipeline (
        -- Run a series of compilation steps in a pipeline, for a
        -- collection of source files.
   oneShot, compileFile,

        -- Interfaces for the batch-mode driver
   linkBinary,

        -- Interfaces for the compilation manager (interpreted/batch-mode)
   preprocess,
   compile, compile',
   link,

  ) where

#include "HsVersions.h"

import Packages
import HeaderInfo
import DriverPhases
import SysTools
import HscMain
import Finder
import HscTypes
import Outputable
import Module
import UniqFM           ( eltsUFM )
import ErrUtils
import DynFlags
import StaticFlags      ( v_Ld_inputs, opt_PIC, opt_Static, WayName(..) )
import Config
import Panic
import Util
import StringBuffer     ( hGetStringBuffer )
import BasicTypes       ( SuccessFlag(..) )
import Maybes           ( expectJust )
import ParserCoreUtils  ( getCoreModuleName )
import SrcLoc
import FastString
import LlvmCodeGen      ( llvmFixupAsm )
import MonadUtils

-- import Data.Either
import Exception
import Data.IORef       ( readIORef )
-- import GHC.Exts              ( Int(..) )
import System.Directory
import System.FilePath
import System.IO
import Control.Monad
import Data.List        ( isSuffixOf )
import Data.Maybe
import System.Environment

-- ---------------------------------------------------------------------------
-- Pre-process

-- | Just preprocess a file, put the result in a temp. file (used by the
-- compilation manager during the summary phase).
--
-- We return the augmented DynFlags, because they contain the result
-- of slurping in the OPTIONS pragmas

preprocess :: HscEnv
           -> (FilePath, Maybe Phase) -- ^ filename and starting phase
           -> IO (DynFlags, FilePath)
preprocess hsc_env (filename, mb_phase) =
  ASSERT2(isJust mb_phase || isHaskellSrcFilename filename, text filename)
  runPipeline anyHsc hsc_env (filename, mb_phase)
        Nothing Temporary Nothing{-no ModLocation-}

-- ---------------------------------------------------------------------------

-- | Compile
--
-- Compile a single module, under the control of the compilation manager.
--
-- This is the interface between the compilation manager and the
-- compiler proper (hsc), where we deal with tedious details like
-- reading the OPTIONS pragma from the source file, converting the
-- C or assembly that GHC produces into an object file, and compiling
-- FFI stub files.
--
-- NB.  No old interface can also mean that the source has changed.

compile :: HscEnv
        -> ModSummary      -- ^ summary for module being compiled
        -> Int             -- ^ module N ...
        -> Int             -- ^ ... of M
        -> Maybe ModIface  -- ^ old interface, if we have one
        -> Maybe Linkable  -- ^ old linkable, if we have one
        -> IO HomeModInfo   -- ^ the complete HomeModInfo, if successful

compile = compile' (hscCompileNothing, hscCompileInteractive, hscCompileBatch)

compile' :: 
           (Compiler (HscStatus, ModIface, ModDetails),
            Compiler (InteractiveStatus, ModIface, ModDetails),
            Compiler (HscStatus, ModIface, ModDetails))
        -> HscEnv
        -> ModSummary      -- ^ summary for module being compiled
        -> Int             -- ^ module N ...
        -> Int             -- ^ ... of M
        -> Maybe ModIface  -- ^ old interface, if we have one
        -> Maybe Linkable  -- ^ old linkable, if we have one
        -> IO HomeModInfo   -- ^ the complete HomeModInfo, if successful

compile' (nothingCompiler, interactiveCompiler, batchCompiler)
        hsc_env0 summary mod_index nmods mb_old_iface maybe_old_linkable
 = do
   let dflags0     = ms_hspp_opts summary
       this_mod    = ms_mod summary
       src_flavour = ms_hsc_src summary
       location    = ms_location summary
       input_fn    = expectJust "compile:hs" (ml_hs_file location)
       input_fnpp  = ms_hspp_file summary

   debugTraceMsg dflags0 2 (text "compile: input file" <+> text input_fnpp)

   let basename = dropExtension input_fn

  -- We add the directory in which the .hs files resides) to the import path.
  -- This is needed when we try to compile the .hc file later, if it
  -- imports a _stub.h file that we created here.
   let current_dir = case takeDirectory basename of
                     "" -> "." -- XXX Hack
                     d -> d
       old_paths   = includePaths dflags0
       dflags      = dflags0 { includePaths = current_dir : old_paths }
       hsc_env     = hsc_env0 {hsc_dflags = dflags}

   -- Figure out what lang we're generating
   let hsc_lang = hscMaybeAdjustTarget dflags StopLn src_flavour (hscTarget dflags)
   -- ... and what the next phase should be
   let next_phase = hscNextPhase dflags src_flavour hsc_lang
   -- ... and what file to generate the output into
   output_fn <- getOutputFilename next_phase
                        Temporary basename dflags next_phase (Just location)

   let dflags' = dflags { hscTarget = hsc_lang,
                                hscOutName = output_fn,
                                extCoreName = basename ++ ".hcr" }
   let hsc_env' = hsc_env { hsc_dflags = dflags' }

   -- -fforce-recomp should also work with --make
   let force_recomp = dopt Opt_ForceRecomp dflags
       source_unchanged = isJust maybe_old_linkable && not force_recomp
       object_filename = ml_obj_file location

   let getStubLinkable False = return []
       getStubLinkable True
           = do stub_o <- compileStub hsc_env' this_mod location
                return [ DotO stub_o ]

       handleBatch HscNoRecomp
           = ASSERT (isJust maybe_old_linkable)
             return maybe_old_linkable

       handleBatch (HscRecomp hasStub _)
           | isHsBoot src_flavour
               = do when (isObjectTarget hsc_lang) $ -- interpreted reaches here too
                       liftIO $ SysTools.touch dflags' "Touching object file"
                                   object_filename
                    return maybe_old_linkable

           | otherwise
               = do stub_unlinked <- getStubLinkable hasStub
                    (hs_unlinked, unlinked_time) <-
                        case hsc_lang of
                          HscNothing
                            -> return ([], ms_hs_date summary)
                          -- We're in --make mode: finish the compilation pipeline.
                          _other
                            -> do _ <- runPipeline StopLn hsc_env' (output_fn,Nothing)
                                              (Just basename)
                                              Persistent
                                              (Just location)
                                  -- The object filename comes from the ModLocation
                                  o_time <- getModificationTime object_filename
                                  return ([DotO object_filename], o_time)
                    let linkable = LM unlinked_time this_mod
                                   (hs_unlinked ++ stub_unlinked)
                    return (Just linkable)

       handleInterpreted HscNoRecomp
           = ASSERT (isJust maybe_old_linkable)
             return maybe_old_linkable
       handleInterpreted (HscRecomp _hasStub Nothing)
           = ASSERT (isHsBoot src_flavour)
             return maybe_old_linkable
       handleInterpreted (HscRecomp hasStub (Just (comp_bc, modBreaks)))
           = do stub_unlinked <- getStubLinkable hasStub
                let hs_unlinked = [BCOs comp_bc modBreaks]
                    unlinked_time = ms_hs_date summary
                  -- Why do we use the timestamp of the source file here,
                  -- rather than the current time?  This works better in
                  -- the case where the local clock is out of sync
                  -- with the filesystem's clock.  It's just as accurate:
                  -- if the source is modified, then the linkable will
                  -- be out of date.
                let linkable = LM unlinked_time this_mod
                               (hs_unlinked ++ stub_unlinked)
                return (Just linkable)

   let -- runCompiler :: Compiler result -> (result -> Maybe Linkable)
       --            -> m HomeModInfo
       runCompiler compiler handle
           = do (result, iface, details)
                    <- compiler hsc_env' summary source_unchanged mb_old_iface
                                (Just (mod_index, nmods))
                linkable <- handle result
                return (HomeModInfo{ hm_details  = details,
                                     hm_iface    = iface,
                                     hm_linkable = linkable })
   -- run the compiler
   case hsc_lang of
      HscInterpreted -> runCompiler interactiveCompiler handleInterpreted
      HscNothing     -> runCompiler nothingCompiler     handleBatch
      _other         -> runCompiler batchCompiler       handleBatch

-----------------------------------------------------------------------------
-- stub .h and .c files (for foreign export support)

-- The _stub.c file is derived from the haskell source file, possibly taking
-- into account the -stubdir option.
--
-- Consequently, we derive the _stub.o filename from the haskell object
-- filename.
--
-- This isn't necessarily the same as the object filename we
-- would get if we just compiled the _stub.c file using the pipeline.
-- For example:
--
--    ghc src/A.hs -odir obj
--
-- results in obj/A.o, and src/A_stub.c.  If we compile src/A_stub.c with
-- -odir obj, we would get obj/src/A_stub.o, which is wrong; we want
-- obj/A_stub.o.

compileStub :: HscEnv -> Module -> ModLocation -> IO FilePath
compileStub hsc_env mod location = do
        -- compile the _stub.c file w/ gcc
        let (stub_c,_,stub_o) = mkStubPaths (hsc_dflags hsc_env)
                                   (moduleName mod) location

        _ <- runPipeline StopLn hsc_env (stub_c,Nothing)  Nothing
                (SpecificFile stub_o) Nothing{-no ModLocation-}

        return stub_o


-- ---------------------------------------------------------------------------
-- Link

link :: GhcLink                 -- interactive or batch
     -> DynFlags                -- dynamic flags
     -> Bool                    -- attempt linking in batch mode?
     -> HomePackageTable        -- what to link
     -> IO SuccessFlag

-- For the moment, in the batch linker, we don't bother to tell doLink
-- which packages to link -- it just tries all that are available.
-- batch_attempt_linking should only be *looked at* in batch mode.  It
-- should only be True if the upsweep was successful and someone
-- exports main, i.e., we have good reason to believe that linking
-- will succeed.

#ifdef GHCI
link LinkInMemory _ _ _
    = do -- Not Linking...(demand linker will do the job)
         return Succeeded
#endif

link NoLink _ _ _
   = return Succeeded

link LinkBinary dflags batch_attempt_linking hpt
   = link' dflags batch_attempt_linking hpt

link LinkDynLib dflags batch_attempt_linking hpt
   = link' dflags batch_attempt_linking hpt

#ifndef GHCI
-- warning suppression
link other _ _ _ = panicBadLink other
#endif

panicBadLink :: GhcLink -> a
panicBadLink other = panic ("link: GHC not built to link this way: " ++
                            show other)

link' :: DynFlags                -- dynamic flags
      -> Bool                    -- attempt linking in batch mode?
      -> HomePackageTable        -- what to link
      -> IO SuccessFlag

link' dflags batch_attempt_linking hpt
   | batch_attempt_linking
   = do
        let
            home_mod_infos = eltsUFM hpt

            -- the packages we depend on
            pkg_deps  = concatMap (dep_pkgs . mi_deps . hm_iface) home_mod_infos

            -- the linkables to link
            linkables = map (expectJust "link".hm_linkable) home_mod_infos

        debugTraceMsg dflags 3 (text "link: linkables are ..." $$ vcat (map ppr linkables))

        -- check for the -no-link flag
        if isNoLink (ghcLink dflags)
          then do debugTraceMsg dflags 3 (text "link(batch): linking omitted (-c flag given).")
                  return Succeeded
          else do

        let getOfiles (LM _ _ us) = map nameOfObject (filter isObject us)
            obj_files = concatMap getOfiles linkables

            exe_file = exeFileName dflags

        linking_needed <- linkingNeeded dflags linkables pkg_deps

        if not (dopt Opt_ForceRecomp dflags) && not linking_needed
           then do debugTraceMsg dflags 2 (text exe_file <+> ptext (sLit "is up to date, linking not required."))
                   return Succeeded
           else do

        debugTraceMsg dflags 1 (ptext (sLit "Linking") <+> text exe_file
                                 <+> text "...")

        -- Don't showPass in Batch mode; doLink will do that for us.
        let link = case ghcLink dflags of
                LinkBinary  -> linkBinary
                LinkDynLib  -> linkDynLib
                other       -> panicBadLink other
        link dflags obj_files pkg_deps

        debugTraceMsg dflags 3 (text "link: done")

        -- linkBinary only returns if it succeeds
        return Succeeded

   | otherwise
   = do debugTraceMsg dflags 3 (text "link(batch): upsweep (partially) failed OR" $$
                                text "   Main.main not exported; not linking.")
        return Succeeded


linkingNeeded :: DynFlags -> [Linkable] -> [PackageId] -> IO Bool
linkingNeeded dflags linkables pkg_deps = do
        -- if the modification time on the executable is later than the
        -- modification times on all of the objects and libraries, then omit
        -- linking (unless the -fforce-recomp flag was given).
  let exe_file = exeFileName dflags
  e_exe_time <- tryIO $ getModificationTime exe_file
  case e_exe_time of
    Left _  -> return True
    Right t -> do
        -- first check object files and extra_ld_inputs
        extra_ld_inputs <- readIORef v_Ld_inputs
        e_extra_times <- mapM (tryIO . getModificationTime) extra_ld_inputs
        let (errs,extra_times) = splitEithers e_extra_times
        let obj_times =  map linkableTime linkables ++ extra_times
        if not (null errs) || any (t <) obj_times
            then return True
            else do

        -- next, check libraries. XXX this only checks Haskell libraries,
        -- not extra_libraries or -l things from the command line.
        let pkg_map = pkgIdMap (pkgState dflags)
            pkg_hslibs  = [ (libraryDirs c, lib)
                          | Just c <- map (lookupPackage pkg_map) pkg_deps,
                            lib <- packageHsLibs dflags c ]

        pkg_libfiles <- mapM (uncurry findHSLib) pkg_hslibs
        if any isNothing pkg_libfiles then return True else do
        e_lib_times <- mapM (tryIO . getModificationTime)
                          (catMaybes pkg_libfiles)
        let (lib_errs,lib_times) = splitEithers e_lib_times
        if not (null lib_errs) || any (t <) lib_times
           then return True
           else return False

findHSLib :: [String] -> String -> IO (Maybe FilePath)
findHSLib dirs lib = do
  let batch_lib_file = "lib" ++ lib <.> "a"
  found <- filterM doesFileExist (map (</> batch_lib_file) dirs)
  case found of
    [] -> return Nothing
    (x:_) -> return (Just x)

-- -----------------------------------------------------------------------------
-- Compile files in one-shot mode.

oneShot :: HscEnv -> Phase -> [(String, Maybe Phase)] -> IO ()
oneShot hsc_env stop_phase srcs = do
  o_files <- mapM (compileFile hsc_env stop_phase) srcs
  doLink (hsc_dflags hsc_env) stop_phase o_files

compileFile :: HscEnv -> Phase -> (FilePath, Maybe Phase) -> IO FilePath
compileFile hsc_env stop_phase (src, mb_phase) = do
   exists <- doesFileExist src
   when (not exists) $
        ghcError (CmdLineError ("does not exist: " ++ src))

   let
        dflags = hsc_dflags hsc_env
        split     = dopt Opt_SplitObjs dflags
        mb_o_file = outputFile dflags
        ghc_link  = ghcLink dflags      -- Set by -c or -no-link

        -- When linking, the -o argument refers to the linker's output.
        -- otherwise, we use it as the name for the pipeline's output.
        output
         | StopLn <- stop_phase, not (isNoLink ghc_link) = Persistent
                -- -o foo applies to linker
         | Just o_file <- mb_o_file = SpecificFile o_file
                -- -o foo applies to the file we are compiling now
         | otherwise = Persistent

        stop_phase' = case stop_phase of
                        As | split -> SplitAs
                        _          -> stop_phase

   ( _, out_file) <- runPipeline stop_phase' hsc_env
                            (src, mb_phase) Nothing output
                            Nothing{-no ModLocation-}
   return out_file


doLink :: DynFlags -> Phase -> [FilePath] -> IO ()
doLink dflags stop_phase o_files
  | not (isStopLn stop_phase)
  = return ()           -- We stopped before the linking phase

  | otherwise
  = case ghcLink dflags of
        NoLink     -> return ()
        LinkBinary -> linkBinary dflags o_files []
        LinkDynLib -> linkDynLib dflags o_files []
        other      -> panicBadLink other


-- ---------------------------------------------------------------------------

data PipelineOutput
  = Temporary
        -- ^ Output should be to a temporary file: we're going to
        -- run more compilation steps on this output later.
  | Persistent
        -- ^ We want a persistent file, i.e. a file in the current directory
        -- derived from the input filename, but with the appropriate extension.
        -- eg. in "ghc -c Foo.hs" the output goes into ./Foo.o.
  | SpecificFile FilePath
        -- ^ The output must go into the specified file.

-- | Run a compilation pipeline, consisting of multiple phases.
--
-- This is the interface to the compilation pipeline, which runs
-- a series of compilation steps on a single source file, specifying
-- at which stage to stop.
--
-- The DynFlags can be modified by phases in the pipeline (eg. by
-- OPTIONS_GHC pragmas), and the changes affect later phases in the
-- pipeline.
runPipeline
  :: Phase                      -- ^ When to stop
  -> HscEnv                     -- ^ Compilation environment
  -> (FilePath,Maybe Phase)     -- ^ Input filename (and maybe -x suffix)
  -> Maybe FilePath             -- ^ original basename (if different from ^^^)
  -> PipelineOutput             -- ^ Output filename
  -> Maybe ModLocation          -- ^ A ModLocation, if this is a Haskell module
  -> IO (DynFlags, FilePath)     -- ^ (final flags, output filename)

runPipeline stop_phase hsc_env0 (input_fn, mb_phase) mb_basename output maybe_loc
  = do
  let dflags0 = hsc_dflags hsc_env0
      (input_basename, suffix) = splitExtension input_fn
      suffix' = drop 1 suffix -- strip off the .
      basename | Just b <- mb_basename = b
               | otherwise             = input_basename

      -- Decide where dump files should go based on the pipeline output
      dflags = dflags0 { dumpPrefix = Just (basename ++ ".") }
      hsc_env = hsc_env0 {hsc_dflags = dflags}

        -- If we were given a -x flag, then use that phase to start from
      start_phase = fromMaybe (startPhase suffix') mb_phase

  -- We want to catch cases of "you can't get there from here" before
  -- we start the pipeline, because otherwise it will just run off the
  -- end.
  --
  -- There is a partial ordering on phases, where A < B iff A occurs
  -- before B in a normal compilation pipeline.

  when (not (start_phase `happensBefore` stop_phase)) $
        ghcError (UsageError
                    ("cannot compile this file to desired target: "
                       ++ input_fn))

  -- this is a function which will be used to calculate output file names
  -- as we go along (we partially apply it to some of its inputs here)
  let get_output_fn = getOutputFilename stop_phase output basename

  -- Execute the pipeline...
  (dflags', output_fn, maybe_loc) <-
        pipeLoop hsc_env start_phase stop_phase input_fn
                 basename suffix' get_output_fn maybe_loc

  -- Sometimes, a compilation phase doesn't actually generate any output
  -- (eg. the CPP phase when -fcpp is not turned on).  If we end on this
  -- stage, but we wanted to keep the output, then we have to explicitly
  -- copy the file, remembering to prepend a {-# LINE #-} pragma so that
  -- further compilation stages can tell what the original filename was.
  case output of
    Temporary ->
        return (dflags', output_fn)
    _other -> 
        do final_fn <- get_output_fn dflags' stop_phase maybe_loc
           when (final_fn /= output_fn) $ do
              let msg = ("Copying `" ++ output_fn ++"' to `" ++ final_fn ++ "'")
                  line_prag = Just ("{-# LINE 1 \"" ++ input_fn ++ "\" #-}\n")
              copyWithHeader dflags msg line_prag output_fn final_fn
           return (dflags', final_fn)



pipeLoop :: HscEnv -> Phase -> Phase
         -> FilePath  -> String -> Suffix
         -> (DynFlags -> Phase -> Maybe ModLocation -> IO FilePath)
         -> Maybe ModLocation
         -> IO (DynFlags, FilePath, Maybe ModLocation)

pipeLoop hsc_env phase stop_phase
         input_fn orig_basename orig_suff
         orig_get_output_fn maybe_loc

  | phase `eqPhase` stop_phase            -- All done
  = return (hsc_dflags hsc_env, input_fn, maybe_loc)

  | not (phase `happensBefore` stop_phase)
        -- Something has gone wrong.  We'll try to cover all the cases when
        -- this could happen, so if we reach here it is a panic.
        -- eg. it might happen if the -C flag is used on a source file that
        -- has {-# OPTIONS -fasm #-}.
  = panic ("pipeLoop: at phase " ++ show phase ++
           " but I wanted to stop at phase " ++ show stop_phase)

  | otherwise
  = do debugTraceMsg (hsc_dflags hsc_env) 4
                         (ptext (sLit "Running phase") <+> ppr phase)
       (next_phase, dflags', maybe_loc, output_fn)
          <- runPhase phase stop_phase hsc_env orig_basename
                      orig_suff input_fn orig_get_output_fn maybe_loc
       let hsc_env' = hsc_env {hsc_dflags = dflags'}
       pipeLoop hsc_env' next_phase stop_phase output_fn
                orig_basename orig_suff orig_get_output_fn maybe_loc

getOutputFilename
  :: Phase -> PipelineOutput -> String
  -> DynFlags -> Phase{-next phase-} -> Maybe ModLocation -> IO FilePath
getOutputFilename stop_phase output basename
 = func
 where
        func dflags next_phase maybe_location
           | is_last_phase, Persistent <- output     = persistent_fn
           | is_last_phase, SpecificFile f <- output = return f
           | keep_this_output                        = persistent_fn
           | otherwise                               = newTempName dflags suffix
           where
                hcsuf      = hcSuf dflags
                odir       = objectDir dflags
                osuf       = objectSuf dflags
                keep_hc    = dopt Opt_KeepHcFiles dflags
                keep_raw_s = dopt Opt_KeepRawSFiles dflags
                keep_s     = dopt Opt_KeepSFiles dflags
                keep_bc    = dopt Opt_KeepLlvmFiles dflags

                myPhaseInputExt HCc    = hcsuf
                myPhaseInputExt StopLn = osuf
                myPhaseInputExt other  = phaseInputExt other

                is_last_phase = next_phase `eqPhase` stop_phase

                -- sometimes, we keep output from intermediate stages
                keep_this_output =
                     case next_phase of
                             StopLn               -> True
                             Mangle  | keep_raw_s -> True
                             As      | keep_s     -> True
                             LlvmOpt | keep_bc    -> True
                             HCc     | keep_hc    -> True
                             _other               -> False

                suffix = myPhaseInputExt next_phase

                -- persistent object files get put in odir
                persistent_fn
                   | StopLn <- next_phase = return odir_persistent
                   | otherwise            = return persistent

                persistent = basename <.> suffix

                odir_persistent
                   | Just loc <- maybe_location = ml_obj_file loc
                   | Just d <- odir = d </> persistent
                   | otherwise      = persistent


-- -----------------------------------------------------------------------------
-- | Each phase in the pipeline returns the next phase to execute, and the
-- name of the file in which the output was placed.
--
-- We must do things dynamically this way, because we often don't know
-- what the rest of the phases will be until part-way through the
-- compilation: for example, an {-# OPTIONS -fasm #-} at the beginning
-- of a source file can change the latter stages of the pipeline from
-- taking the via-C route to using the native code generator.
--
runPhase :: Phase       -- ^ Do this phase first
         -> Phase       -- ^ Stop just before this phase
         -> HscEnv
         -> String      -- ^ basename of original input source
         -> String      -- ^ its extension
         -> FilePath    -- ^ name of file which contains the input to this phase.
         -> (DynFlags -> Phase -> Maybe ModLocation -> IO FilePath)
                        -- ^ how to calculate the output filename
         -> Maybe ModLocation           -- ^ the ModLocation, if we have one
         -> IO (Phase,                   -- next phase
                DynFlags,                -- new dynamic flags
                Maybe ModLocation,       -- the ModLocation, if we have one
                FilePath)                -- output filename

        -- Invariant: the output filename always contains the output
        -- Interesting case: Hsc when there is no recompilation to do
        --                   Then the output filename is still a .o file

-------------------------------------------------------------------------------
-- Unlit phase

runPhase (Unlit sf) _stop hsc_env _basename _suff input_fn get_output_fn maybe_loc
  = do
       let dflags = hsc_dflags hsc_env
       output_fn <- get_output_fn dflags (Cpp sf) maybe_loc

       let unlit_flags = getOpts dflags opt_L
           flags = map SysTools.Option unlit_flags ++
                   [ -- The -h option passes the file name for unlit to
                     -- put in a #line directive
                     SysTools.Option     "-h"
                     -- cpp interprets \b etc as escape sequences,
                     -- so we use / for filenames in pragmas
                   , SysTools.Option $ reslash Forwards $ normalise input_fn
                   , SysTools.FileOption "" input_fn
                   , SysTools.FileOption "" output_fn
                   ]

       SysTools.runUnlit dflags flags

       return (Cpp sf, dflags, maybe_loc, output_fn)

-------------------------------------------------------------------------------
-- Cpp phase : (a) gets OPTIONS out of file
--             (b) runs cpp if necessary

runPhase (Cpp sf) _stop hsc_env _basename _suff input_fn get_output_fn maybe_loc
  = do let dflags0 = hsc_dflags hsc_env
       src_opts <- getOptionsFromFile dflags0 input_fn
       (dflags1, unhandled_flags, warns)
           <- parseDynamicNoPackageFlags dflags0 src_opts
       checkProcessArgsResult unhandled_flags

       if not (xopt Opt_Cpp dflags1) then do
           -- we have to be careful to emit warnings only once.
           unless (dopt Opt_Pp dflags1) $ handleFlagWarnings dflags1 warns

           -- no need to preprocess CPP, just pass input file along
           -- to the next phase of the pipeline.
           return (HsPp sf, dflags1, maybe_loc, input_fn)
        else do
            output_fn <- get_output_fn dflags1 (HsPp sf) maybe_loc
            doCpp dflags1 True{-raw-} False{-no CC opts-} input_fn output_fn
            -- re-read the pragmas now that we've preprocessed the file
            -- See #2464,#3457
            src_opts <- getOptionsFromFile dflags0 output_fn
            (dflags2, unhandled_flags, warns)
                <- parseDynamicNoPackageFlags dflags0 src_opts
            unless (dopt Opt_Pp dflags2) $ handleFlagWarnings dflags2 warns
            -- the HsPp pass below will emit warnings
            checkProcessArgsResult unhandled_flags

            return (HsPp sf, dflags2, maybe_loc, output_fn)

-------------------------------------------------------------------------------
-- HsPp phase

runPhase (HsPp sf) _stop hsc_env basename suff input_fn get_output_fn maybe_loc
  = do let dflags = hsc_dflags hsc_env
       if not (dopt Opt_Pp dflags) then
           -- no need to preprocess, just pass input file along
           -- to the next phase of the pipeline.
          return (Hsc sf, dflags, maybe_loc, input_fn)
        else do
            let hspp_opts = getOpts dflags opt_F
            let orig_fn = basename <.> suff
            output_fn <- get_output_fn dflags (Hsc sf) maybe_loc
            SysTools.runPp dflags
                           ( [ SysTools.Option     orig_fn
                             , SysTools.Option     input_fn
                             , SysTools.FileOption "" output_fn
                             ] ++
                             map SysTools.Option hspp_opts
                           )

            -- re-read pragmas now that we've parsed the file (see #3674)
            src_opts <- getOptionsFromFile dflags output_fn
            (dflags1, unhandled_flags, warns)
                <- parseDynamicNoPackageFlags dflags src_opts
            handleFlagWarnings dflags1 warns
            checkProcessArgsResult unhandled_flags

            return (Hsc sf, dflags1, maybe_loc, output_fn)

-----------------------------------------------------------------------------
-- Hsc phase

-- Compilation of a single module, in "legacy" mode (_not_ under
-- the direction of the compilation manager).
runPhase (Hsc src_flavour) stop hsc_env basename suff input_fn get_output_fn _maybe_loc
 = do   -- normal Hsc mode, not mkdependHS
        let dflags0 = hsc_dflags hsc_env

  -- we add the current directory (i.e. the directory in which
  -- the .hs files resides) to the include path, since this is
  -- what gcc does, and it's probably what you want.
        let current_dir = case takeDirectory basename of
                      "" -> "." -- XXX Hack
                      d -> d

            paths = includePaths dflags0
            dflags = dflags0 { includePaths = current_dir : paths }

  -- gather the imports and module name
        (hspp_buf,mod_name,imps,src_imps) <-
            case src_flavour of
                ExtCoreFile -> do  -- no explicit imports in ExtCore input.
                    m <- getCoreModuleName input_fn
                    return (Nothing, mkModuleName m, [], [])

                _           -> do
                    buf <- hGetStringBuffer input_fn
                    (src_imps,imps,L _ mod_name) <- getImports dflags buf input_fn (basename <.> suff)
                    return (Just buf, mod_name, imps, src_imps)

  -- Build a ModLocation to pass to hscMain.
  -- The source filename is rather irrelevant by now, but it's used
  -- by hscMain for messages.  hscMain also needs
  -- the .hi and .o filenames, and this is as good a way
  -- as any to generate them, and better than most. (e.g. takes
  -- into accout the -osuf flags)
        location1 <- mkHomeModLocation2 dflags mod_name basename suff

  -- Boot-ify it if necessary
        let location2 | isHsBoot src_flavour = addBootSuffixLocn location1
                      | otherwise            = location1


  -- Take -ohi into account if present
  -- This can't be done in mkHomeModuleLocation because
  -- it only applies to the module being compiles
        let ohi = outputHi dflags
            location3 | Just fn <- ohi = location2{ ml_hi_file = fn }
                      | otherwise      = location2

  -- Take -o into account if present
  -- Very like -ohi, but we must *only* do this if we aren't linking
  -- (If we're linking then the -o applies to the linked thing, not to
  -- the object file for one module.)
  -- Note the nasty duplication with the same computation in compileFile above
        let expl_o_file = outputFile dflags
            location4 | Just ofile <- expl_o_file
                      , isNoLink (ghcLink dflags)
                      = location3 { ml_obj_file = ofile }
                      | otherwise = location3

            o_file = ml_obj_file location4      -- The real object file


  -- Figure out if the source has changed, for recompilation avoidance.
  --
  -- Setting source_unchanged to True means that M.o seems
  -- to be up to date wrt M.hs; so no need to recompile unless imports have
  -- changed (which the compiler itself figures out).
  -- Setting source_unchanged to False tells the compiler that M.o is out of
  -- date wrt M.hs (or M.o doesn't exist) so we must recompile regardless.
        src_timestamp <- getModificationTime (basename <.> suff)

        let force_recomp = dopt Opt_ForceRecomp dflags
            hsc_lang = hscMaybeAdjustTarget dflags stop src_flavour (hscTarget dflags)
        source_unchanged <-
          if force_recomp || not (isStopLn stop)
                -- Set source_unchanged to False unconditionally if
                --      (a) recompilation checker is off, or
                --      (b) we aren't going all the way to .o file (e.g. ghc -S)
             then return False
                -- Otherwise look at file modification dates
             else do o_file_exists <- doesFileExist o_file
                     if not o_file_exists
                        then return False       -- Need to recompile
                        else do t2 <- getModificationTime o_file
                                if t2 > src_timestamp
                                  then return True
                                  else return False

  -- get the DynFlags
        let next_phase = hscNextPhase dflags src_flavour hsc_lang
        output_fn  <- get_output_fn dflags next_phase (Just location4)

        let dflags' = dflags { hscTarget = hsc_lang,
                               hscOutName = output_fn,
                               extCoreName = basename ++ ".hcr" }

        let hsc_env' = hsc_env {hsc_dflags = dflags'}

  -- Tell the finder cache about this module
        mod <- addHomeModuleToFinder hsc_env' mod_name location4

  -- Make the ModSummary to hand to hscMain
        let
            mod_summary = ModSummary {  ms_mod       = mod,
                                        ms_hsc_src   = src_flavour,
                                        ms_hspp_file = input_fn,
                                        ms_hspp_opts = dflags,
                                        ms_hspp_buf  = hspp_buf,
                                        ms_location  = location4,
                                        ms_hs_date   = src_timestamp,
                                        ms_obj_date  = Nothing,
                                        ms_imps      = imps,
                                        ms_srcimps   = src_imps }

  -- run the compiler!
        result <- hscCompileOneShot hsc_env'
                          mod_summary source_unchanged
                          Nothing       -- No iface
                          Nothing       -- No "module i of n" progress info

        case result of
          HscNoRecomp
              -> do SysTools.touch dflags' "Touching object file" o_file
                    -- The .o file must have a later modification date
                    -- than the source file (else we wouldn't be in HscNoRecomp)
                    -- but we touch it anyway, to keep 'make' happy (we think).
                    return (StopLn, dflags', Just location4, o_file)
          (HscRecomp hasStub _)
              -> do when hasStub $
                         do stub_o <- compileStub hsc_env' mod location4
                            liftIO $ consIORef v_Ld_inputs stub_o
                    -- In the case of hs-boot files, generate a dummy .o-boot
                    -- stamp file for the benefit of Make
                    when (isHsBoot src_flavour) $
                      SysTools.touch dflags' "Touching object file" o_file
                    return (next_phase, dflags', Just location4, output_fn)

-----------------------------------------------------------------------------
-- Cmm phase

runPhase CmmCpp _stop hsc_env _basename _suff input_fn get_output_fn maybe_loc
  = do
       let dflags = hsc_dflags hsc_env
       output_fn <- get_output_fn dflags Cmm maybe_loc
       doCpp dflags False{-not raw-} True{-include CC opts-} input_fn output_fn
       return (Cmm, dflags, maybe_loc, output_fn)

runPhase Cmm stop hsc_env basename _ input_fn get_output_fn maybe_loc
  = do
        let dflags = hsc_dflags hsc_env
        let hsc_lang = hscMaybeAdjustTarget dflags stop HsSrcFile (hscTarget dflags)
        let next_phase = hscNextPhase dflags HsSrcFile hsc_lang
        output_fn <- get_output_fn dflags next_phase maybe_loc

        let dflags' = dflags { hscTarget = hsc_lang,
                               hscOutName = output_fn,
                               extCoreName = basename ++ ".hcr" }
        let hsc_env' = hsc_env {hsc_dflags = dflags'}

        hscCompileCmmFile hsc_env' input_fn

        -- XXX: catch errors above and convert them into ghcError?  Original
        -- code was:
        --
        --when (not ok) $ ghcError (PhaseFailed "cmm" (ExitFailure 1))

        return (next_phase, dflags, maybe_loc, output_fn)

-----------------------------------------------------------------------------
-- Cc phase

-- we don't support preprocessing .c files (with -E) now.  Doing so introduces
-- way too many hacks, and I can't say I've ever used it anyway.

runPhase cc_phase _stop hsc_env _basename _suff input_fn get_output_fn maybe_loc
   | cc_phase `eqPhase` Cc || cc_phase `eqPhase` Ccpp || cc_phase `eqPhase` HCc
   = do let dflags = hsc_dflags hsc_env
        let cc_opts = getOpts dflags opt_c
            hcc = cc_phase `eqPhase` HCc

        let cmdline_include_paths = includePaths dflags

        -- HC files have the dependent packages stamped into them
        pkgs <- if hcc then getHCFilePackages input_fn else return []

        -- add package include paths even if we're just compiling .c
        -- files; this is the Value Add(TM) that using ghc instead of
        -- gcc gives you :)
        pkg_include_dirs <- getPackageIncludePath dflags pkgs
        let include_paths = foldr (\ x xs -> "-I" : x : xs) []
                              (cmdline_include_paths ++ pkg_include_dirs)

        let (md_c_flags, md_regd_c_flags) = machdepCCOpts dflags
        gcc_extra_viac_flags <- getExtraViaCOpts dflags
        let pic_c_flags = picCCOpts dflags

        let verb = getVerbFlag dflags

        -- cc-options are not passed when compiling .hc files.  Our
        -- hc code doesn't not #include any header files anyway, so these
        -- options aren't necessary.
        pkg_extra_cc_opts <-
          if cc_phase `eqPhase` HCc
             then return []
             else getPackageExtraCcOpts dflags pkgs

#ifdef darwin_TARGET_OS
        pkg_framework_paths <- getPackageFrameworkPath dflags pkgs
        let cmdline_framework_paths = frameworkPaths dflags
        let framework_paths = map ("-F"++)
                        (cmdline_framework_paths ++ pkg_framework_paths)
#endif

        let split_objs = dopt Opt_SplitObjs dflags
            split_opt | hcc && split_objs = [ "-DUSE_SPLIT_MARKERS" ]
                      | otherwise         = [ ]

        let cc_opt | optLevel dflags >= 2 = "-O2"
                   | otherwise            = "-O"

        -- Decide next phase

        let mangle = dopt Opt_DoAsmMangling dflags
            next_phase
                | hcc && mangle     = Mangle
                | otherwise         = As
        output_fn <- get_output_fn dflags next_phase maybe_loc

        let
          more_hcc_opts =
#if i386_TARGET_ARCH
                -- on x86 the floating point regs have greater precision
                -- than a double, which leads to unpredictable results.
                -- By default, we turn this off with -ffloat-store unless
                -- the user specified -fexcess-precision.
                (if dopt Opt_ExcessPrecision dflags
                        then []
                        else [ "-ffloat-store" ]) ++
#endif

                -- gcc's -fstrict-aliasing allows two accesses to memory
                -- to be considered non-aliasing if they have different types.
                -- This interacts badly with the C code we generate, which is
                -- very weakly typed, being derived from C--.
                ["-fno-strict-aliasing"]

        SysTools.runCc dflags (
                -- force the C compiler to interpret this file as C when
                -- compiling .hc files, by adding the -x c option.
                -- Also useful for plain .c files, just in case GHC saw a
                -- -x c option.
                        [ SysTools.Option "-x", if cc_phase `eqPhase` Ccpp
                                                then SysTools.Option "c++"
                                                else SysTools.Option "c"] ++
                        [ SysTools.FileOption "" input_fn
                        , SysTools.Option "-o"
                        , SysTools.FileOption "" output_fn
                        ]
                       ++ map SysTools.Option (
                          md_c_flags
                       ++ pic_c_flags

#if    defined(mingw32_TARGET_OS)
                -- Stub files generated for foreign exports references the runIO_closure
                -- and runNonIO_closure symbols, which are defined in the base package.
                -- These symbols are imported into the stub.c file via RtsAPI.h, and the
                -- way we do the import depends on whether we're currently compiling
                -- the base package or not.
                       ++ (if thisPackage dflags == basePackageId
                                then [ "-DCOMPILING_BASE_PACKAGE" ]
                                else [])
#endif

#ifdef sparc_TARGET_ARCH
        -- We only support SparcV9 and better because V8 lacks an atomic CAS
        -- instruction. Note that the user can still override this
        -- (e.g., -mcpu=ultrasparc) as GCC picks the "best" -mcpu flag
        -- regardless of the ordering.
        --
        -- This is a temporary hack.
                       ++ ["-mcpu=v9"]
#endif
                       ++ (if hcc && mangle
                             then md_regd_c_flags
                             else [])
                       ++ (if hcc
                             then if mangle
                                     then gcc_extra_viac_flags
                                     else filter (=="-fwrapv")
                                                gcc_extra_viac_flags
                                -- still want -fwrapv even for unreg'd
                             else [])
                       ++ (if hcc
                             then more_hcc_opts
                             else [])
                       ++ [ verb, "-S", "-Wimplicit", cc_opt ]
                       ++ [ "-D__GLASGOW_HASKELL__="++cProjectVersionInt ]
#ifdef darwin_TARGET_OS
                       ++ framework_paths
#endif
                       ++ cc_opts
                       ++ split_opt
                       ++ include_paths
                       ++ pkg_extra_cc_opts
                       ))

        return (next_phase, dflags, maybe_loc, output_fn)

        -- ToDo: postprocess the output from gcc

-----------------------------------------------------------------------------
-- Mangle phase

runPhase Mangle _stop hsc_env _basename _suff input_fn get_output_fn maybe_loc
   = do let dflags = hsc_dflags hsc_env
        let mangler_opts = getOpts dflags opt_m

#if i386_TARGET_ARCH
        machdep_opts <- return [ show (stolen_x86_regs dflags) ]
#else
        machdep_opts <- return []
#endif

        let split = dopt Opt_SplitObjs dflags
            next_phase
                | split = SplitMangle
                | otherwise = As
        output_fn <- get_output_fn dflags next_phase maybe_loc

        SysTools.runMangle dflags (map SysTools.Option mangler_opts
                          ++ [ SysTools.FileOption "" input_fn
                             , SysTools.FileOption "" output_fn
                             ]
                          ++ map SysTools.Option machdep_opts)

        return (next_phase, dflags, maybe_loc, output_fn)

-----------------------------------------------------------------------------
-- Splitting phase

runPhase SplitMangle _stop hsc_env _basename _suff input_fn _get_output_fn maybe_loc
  = do  -- tmp_pfx is the prefix used for the split .s files
        -- We also use it as the file to contain the no. of split .s files (sigh)
        let dflags = hsc_dflags hsc_env
        split_s_prefix <- SysTools.newTempName dflags "split"
        let n_files_fn = split_s_prefix

        SysTools.runSplit dflags
                          [ SysTools.FileOption "" input_fn
                          , SysTools.FileOption "" split_s_prefix
                          , SysTools.FileOption "" n_files_fn
                          ]

        -- Save the number of split files for future references
        s <- readFile n_files_fn
        let n_files = read s :: Int
            dflags' = dflags { splitInfo = Just (split_s_prefix, n_files) }

        -- Remember to delete all these files
        addFilesToClean dflags' [ split_s_prefix ++ "__" ++ show n ++ ".s"
                                | n <- [1..n_files]]

        return (SplitAs, dflags', maybe_loc, "**splitmangle**")
          -- we don't use the filename

-----------------------------------------------------------------------------
-- As phase

runPhase As _stop hsc_env _basename _suff input_fn get_output_fn maybe_loc
  = do  let dflags = hsc_dflags hsc_env
        let as_opts =  getOpts dflags opt_a
        let cmdline_include_paths = includePaths dflags

        output_fn <- get_output_fn dflags StopLn maybe_loc

        -- we create directories for the object file, because it
        -- might be a hierarchical module.
        createDirectoryHierarchy (takeDirectory output_fn)

        let (md_c_flags, _) = machdepCCOpts dflags
        SysTools.runAs dflags
                       (map SysTools.Option as_opts
                       ++ [ SysTools.Option ("-I" ++ p) | p <- cmdline_include_paths ]
#ifdef sparc_TARGET_ARCH
        -- We only support SparcV9 and better because V8 lacks an atomic CAS
        -- instruction so we have to make sure that the assembler accepts the
        -- instruction set. Note that the user can still override this
        -- (e.g., -mcpu=ultrasparc). GCC picks the "best" -mcpu flag
        -- regardless of the ordering.
        --
        -- This is a temporary hack.
                       ++ [ SysTools.Option "-mcpu=v9" ]
#endif
                       ++ [ SysTools.Option "-c"
                          , SysTools.FileOption "" input_fn
                          , SysTools.Option "-o"
                          , SysTools.FileOption "" output_fn
                          ]
                       ++ map SysTools.Option md_c_flags)

        return (StopLn, dflags, maybe_loc, output_fn)


runPhase SplitAs _stop hsc_env _basename _suff _input_fn get_output_fn maybe_loc
  = do
        let dflags = hsc_dflags hsc_env
        output_fn <- get_output_fn dflags StopLn maybe_loc

        let base_o = dropExtension output_fn
            osuf = objectSuf dflags
            split_odir  = base_o ++ "_" ++ osuf ++ "_split"

        createDirectoryHierarchy split_odir

        -- remove M_split/ *.o, because we're going to archive M_split/ *.o
        -- later and we don't want to pick up any old objects.
        fs <- getDirectoryContents split_odir
        mapM_ removeFile $ map (split_odir </>) $ filter (osuf `isSuffixOf`) fs

        let as_opts = getOpts dflags opt_a

        let (split_s_prefix, n) = case splitInfo dflags of
                                  Nothing -> panic "No split info"
                                  Just x -> x

        let split_s   n = split_s_prefix ++ "__" ++ show n <.> "s"
            split_obj n = split_odir </>
                          takeFileName base_o ++ "__" ++ show n <.> osuf

        let (md_c_flags, _) = machdepCCOpts dflags
        let assemble_file n
              = SysTools.runAs dflags
                         (map SysTools.Option as_opts ++
#ifdef sparc_TARGET_ARCH
        -- We only support SparcV9 and better because V8 lacks an atomic CAS
        -- instruction so we have to make sure that the assembler accepts the
        -- instruction set. Note that the user can still override this
        -- (e.g., -mcpu=ultrasparc). GCC picks the "best" -mcpu flag
        -- regardless of the ordering.
        --
        -- This is a temporary hack.
                          [ SysTools.Option "-mcpu=v9" ] ++
#endif
                          [ SysTools.Option "-c"
                          , SysTools.Option "-o"
                          , SysTools.FileOption "" (split_obj n)
                          , SysTools.FileOption "" (split_s n)
                          ]
                       ++ map SysTools.Option md_c_flags)

        mapM_ assemble_file [1..n]

        -- join them into a single .o file
        joinObjectFiles dflags (map split_obj [1..n]) output_fn

        return (StopLn, dflags, maybe_loc, output_fn)

-----------------------------------------------------------------------------
-- LlvmOpt phase

runPhase LlvmOpt _stop hsc_env _basename _suff input_fn get_output_fn maybe_loc
  = do
    let dflags  = hsc_dflags hsc_env
    let lo_opts = getOpts dflags opt_lo
    let opt_lvl = max 0 (min 2 $ optLevel dflags)
    -- don't specify anything if user has specified commands. We do this for
    -- opt but not llc since opt is very specifically for optimisation passes
    -- only, so if the user is passing us extra options we assume they know
    -- what they are doing and don't get in the way.
    let optFlag = if null lo_opts
                     then [SysTools.Option (llvmOpts !! opt_lvl)]
                     else []

    output_fn <- get_output_fn dflags LlvmLlc maybe_loc

    SysTools.runLlvmOpt dflags
               ([ SysTools.FileOption "" input_fn,
                    SysTools.Option "-o",
                    SysTools.FileOption "" output_fn]
                ++ optFlag
                ++ map SysTools.Option lo_opts)

    return (LlvmLlc, dflags, maybe_loc, output_fn)
  where 
        -- we always (unless -optlo specified) run Opt since we rely on it to
        -- fix up some pretty big deficiencies in the code we generate
        llvmOpts = ["-mem2reg", "-O1", "-O2"]


-----------------------------------------------------------------------------
-- LlvmLlc phase

runPhase LlvmLlc _stop hsc_env _basename _suff input_fn get_output_fn maybe_loc
  = do
    let dflags  = hsc_dflags hsc_env
    let lc_opts = getOpts dflags opt_lc
    let opt_lvl = max 0 (min 2 $ optLevel dflags)
#if darwin_TARGET_OS
    let nphase = LlvmMangle
#else
    let nphase = As
#endif
    let rmodel | opt_PIC        = "pic"
               | not opt_Static = "dynamic-no-pic"
               | otherwise      = "static"

    output_fn <- get_output_fn dflags nphase maybe_loc

    SysTools.runLlvmLlc dflags
                ([ SysTools.Option (llvmOpts !! opt_lvl),
                    SysTools.Option $ "-relocation-model=" ++ rmodel,
                    SysTools.FileOption "" input_fn,
                    SysTools.Option "-o", SysTools.FileOption "" output_fn]
                ++ map SysTools.Option lc_opts)

    return (nphase, dflags, maybe_loc, output_fn)
  where
#if darwin_TARGET_OS
        llvmOpts = ["-O1", "-O2", "-O2"]
#else
        llvmOpts = ["-O1", "-O2", "-O3"]
#endif


-----------------------------------------------------------------------------
-- LlvmMangle phase

runPhase LlvmMangle _stop hsc_env _basename _suff input_fn get_output_fn maybe_loc
  = do
    let dflags = hsc_dflags hsc_env
    output_fn <- get_output_fn dflags As maybe_loc
    llvmFixupAsm input_fn output_fn
    return (As, dflags, maybe_loc, output_fn)


-- warning suppression
runPhase other _stop _dflags _basename _suff _input_fn _get_output_fn _maybe_loc =
   panic ("runPhase: don't know how to run phase " ++ show other)
-----------------------------------------------------------------------------
-- MoveBinary sort-of-phase
-- After having produced a binary, move it somewhere else and generate a
-- wrapper script calling the binary. Currently, we need this only in
-- a parallel way (i.e. in GUM), because PVM expects the binary in a
-- central directory.
-- This is called from linkBinary below, after linking. I haven't made it
-- a separate phase to minimise interfering with other modules, and
-- we don't need the generality of a phase (MoveBinary is always
-- done after linking and makes only sense in a parallel setup)   -- HWL

runPhase_MoveBinary :: DynFlags -> FilePath -> IO Bool
runPhase_MoveBinary dflags input_fn
    | WayPar `elem` (wayNames dflags) && not opt_Static =
        panic ("Don't know how to combine PVM wrapper and dynamic wrapper")
    | WayPar `elem` (wayNames dflags) = do
        let sysMan = pgm_sysman dflags
        pvm_root <- getEnv "PVM_ROOT"
        pvm_arch <- getEnv "PVM_ARCH"
        let
           pvm_executable_base = "=" ++ input_fn
           pvm_executable = pvm_root ++ "/bin/" ++ pvm_arch ++ "/" ++ pvm_executable_base
        -- nuke old binary; maybe use configur'ed names for cp and rm?
        _ <- tryIO (removeFile pvm_executable)
        -- move the newly created binary into PVM land
        copy dflags "copying PVM executable" input_fn pvm_executable
        -- generate a wrapper script for running a parallel prg under PVM
        writeFile input_fn (mk_pvm_wrapper_script pvm_executable pvm_executable_base sysMan)
        return True
    | otherwise = return True

mkExtraCObj :: DynFlags -> [String] -> IO FilePath
mkExtraCObj dflags xs
 = do cFile <- newTempName dflags "c"
      oFile <- newTempName dflags "o"
      writeFile cFile $ unlines xs
      let rtsDetails = getPackageDetails (pkgState dflags) rtsPackageId
          (md_c_flags, _) = machdepCCOpts dflags
      SysTools.runCc dflags
                     ([Option        "-c",
                       FileOption "" cFile,
                       Option        "-o",
                       FileOption "" oFile] ++
                      map (FileOption "-I") (includeDirs rtsDetails) ++
                      map Option md_c_flags)
      return oFile

mkRtsOptionsLevelObj :: DynFlags -> IO [FilePath]
mkRtsOptionsLevelObj dflags
 = do let mkRtsEnabledObj val
              = do fn <- mkExtraCObj dflags
                             ["#include \"Rts.h\"",
                              "#include \"RtsOpts.h\"",
                              "const rtsOptsEnabledEnum rtsOptsEnabled = "
                                  ++ val ++ ";"]
                   return [fn]
      case rtsOptsEnabled dflags of
          RtsOptsNone     -> mkRtsEnabledObj "rtsOptsNone"
          RtsOptsSafeOnly -> return [] -- The default
          RtsOptsAll      -> mkRtsEnabledObj "rtsOptsAll"

-- generates a Perl skript starting a parallel prg under PVM
mk_pvm_wrapper_script :: String -> String -> String -> String
mk_pvm_wrapper_script pvm_executable pvm_executable_base sysMan = unlines $
 [
  "eval 'exec perl -S $0 ${1+\"$@\"}'",
  "  if $running_under_some_shell;",
  "# =!=!=!=!=!=!=!=!=!=!=!",
  "# This script is automatically generated: DO NOT EDIT!!!",
  "# Generated by Glasgow Haskell Compiler",
  "# ngoqvam choHbogh vaj' vIHoHnISbej !!!!",
  "#",
  "$pvm_executable      = '" ++ pvm_executable ++ "';",
  "$pvm_executable_base = '" ++ pvm_executable_base ++ "';",
  "$SysMan = '" ++ sysMan ++ "';",
  "",
  {- ToDo: add the magical shortcuts again iff we actually use them -- HWL
  "# first, some magical shortcuts to run "commands" on the binary",
  "# (which is hidden)",
  "if ($#ARGV == 1 && $ARGV[0] eq '+RTS' && $ARGV[1] =~ /^--((size|file|strip|rm|nm).*)/ ) {",
  "    local($cmd) = $1;",
  "    system("$cmd $pvm_executable");",
  "    exit(0); # all done",
  "}", -}
  "",
  "# Now, run the real binary; process the args first",
  "$ENV{'PE'} = $pvm_executable_base;", --  ++ pvm_executable_base,
  "$debug = '';",
  "$nprocessors = 0; # the default: as many PEs as machines in PVM config",
  "@nonPVM_args = ();",
  "$in_RTS_args = 0;",
  "",
  "args: while ($a = shift(@ARGV)) {",
  "    if ( $a eq '+RTS' ) {",
  "        $in_RTS_args = 1;",
  "    } elsif ( $a eq '-RTS' ) {",
  "        $in_RTS_args = 0;",
  "    }",
  "    if ( $a eq '-d' && $in_RTS_args ) {",
  "        $debug = '-';",
  "    } elsif ( $a =~ /^-qN(\\d+)/ && $in_RTS_args ) {",
  "        $nprocessors = $1;",
  "    } elsif ( $a =~ /^-qp(\\d+)/ && $in_RTS_args ) {",
  "        $nprocessors = $1;",
  "    } else {",
  "        push(@nonPVM_args, $a);",
  "    }",
  "}",
  "",
  "local($return_val) = 0;",
  "# Start the parallel execution by calling SysMan",
  "system(\"$SysMan $debug $pvm_executable $nprocessors @nonPVM_args\");",
  "$return_val = $?;",
  "# ToDo: fix race condition moving files and flushing them!!",
  "system(\"cp $ENV{'HOME'}/$pvm_executable_base.???.gr .\") if -f \"$ENV{'HOME'}/$pvm_executable_base.002.gr\";",
  "exit($return_val);"
 ]

-----------------------------------------------------------------------------
-- Look for the /* GHC_PACKAGES ... */ comment at the top of a .hc file

getHCFilePackages :: FilePath -> IO [PackageId]
getHCFilePackages filename =
  Exception.bracket (openFile filename ReadMode) hClose $ \h -> do
    l <- hGetLine h
    case l of
      '/':'*':' ':'G':'H':'C':'_':'P':'A':'C':'K':'A':'G':'E':'S':rest ->
          return (map stringToPackageId (words rest))
      _other ->
          return []

-----------------------------------------------------------------------------
-- Static linking, of .o files

-- The list of packages passed to link is the list of packages on
-- which this program depends, as discovered by the compilation
-- manager.  It is combined with the list of packages that the user
-- specifies on the command line with -package flags.
--
-- In one-shot linking mode, we can't discover the package
-- dependencies (because we haven't actually done any compilation or
-- read any interface files), so the user must explicitly specify all
-- the packages.

linkBinary :: DynFlags -> [FilePath] -> [PackageId] -> IO ()
linkBinary dflags o_files dep_packages = do
    let verb = getVerbFlag dflags
        output_fn = exeFileName dflags

    -- get the full list of packages to link with, by combining the
    -- explicit packages with the auto packages and all of their
    -- dependencies, and eliminating duplicates.

    pkg_lib_paths <- getPackageLibraryPath dflags dep_packages
    let pkg_lib_path_opts = concat (map get_pkg_lib_path_opts pkg_lib_paths)
#ifdef elf_OBJ_FORMAT
        get_pkg_lib_path_opts l | (dynLibLoader dflags)==SystemDependent && not opt_Static = ["-L" ++ l, "-Wl,-rpath", "-Wl," ++ l]
                                | otherwise = ["-L" ++ l]
#else
        get_pkg_lib_path_opts l = ["-L" ++ l]
#endif

    let lib_paths = libraryPaths dflags
    let lib_path_opts = map ("-L"++) lib_paths

    -- The C "main" function is not in the rts but in a separate static
    -- library libHSrtsmain.a that sits next to the rts lib files. Assuming
    -- we're using a Haskell main function then we need to link it in.
    let no_hs_main = dopt Opt_NoHsMain dflags
    let main_lib | no_hs_main = []
                 | otherwise  = [ "-lHSrtsmain" ]
    rtsEnabledObj <- mkRtsOptionsLevelObj dflags
    rtsOptsObj <- case rtsOpts dflags of
                  Just opts ->
                      do fn <- mkExtraCObj dflags
                                 -- We assume that the Haskell "show" does
                                 -- the right thing here
                                 ["char *ghc_rts_opts = " ++ show opts ++ ";"]
                         return [fn]
                  Nothing -> return []

    pkg_link_opts <- getPackageLinkOpts dflags dep_packages

#ifdef darwin_TARGET_OS
    pkg_framework_paths <- getPackageFrameworkPath dflags dep_packages
    let pkg_framework_path_opts = map ("-F"++) pkg_framework_paths

    let framework_paths = frameworkPaths dflags
        framework_path_opts = map ("-F"++) framework_paths

    pkg_frameworks <- getPackageFrameworks dflags dep_packages
    let pkg_framework_opts = concat [ ["-framework", fw] | fw <- pkg_frameworks ]

    let frameworks = cmdlineFrameworks dflags
        framework_opts = concat [ ["-framework", fw] | fw <- reverse frameworks ]
         -- reverse because they're added in reverse order from the cmd line
#endif
        -- probably _stub.o files
    extra_ld_inputs <- readIORef v_Ld_inputs

        -- opts from -optl-<blah> (including -l<blah> options)
    let extra_ld_opts = getOpts dflags opt_l

    let ways = wayNames dflags

    -- Here are some libs that need to be linked at the *end* of
    -- the command line, because they contain symbols that are referred to
    -- by the RTS.  We can't therefore use the ordinary way opts for these.
    let
        debug_opts | WayDebug `elem` ways = [
#if defined(HAVE_LIBBFD)
                        "-lbfd", "-liberty"
#endif
                         ]
                   | otherwise            = []

    let
        thread_opts | WayThreaded `elem` ways = [
#if !defined(mingw32_TARGET_OS) && !defined(freebsd_TARGET_OS) && !defined(openbsd_TARGET_OS) && !defined(haiku_TARGET_OS)
                        "-lpthread"
#endif
#if defined(osf3_TARGET_OS)
                        , "-lexc"
#endif
                        ]
                    | otherwise               = []

    rc_objs <- maybeCreateManifest dflags output_fn

    let (md_c_flags, _) = machdepCCOpts dflags
    SysTools.runLink dflags (
                       [ SysTools.Option verb
                       , SysTools.Option "-o"
                       , SysTools.FileOption "" output_fn
                       ]
                      ++ map SysTools.Option (
                         md_c_flags

#ifdef mingw32_TARGET_OS
                      -- Permit the linker to auto link _symbol to _imp_symbol.
                      -- This lets us link against DLLs without needing an "import library".
                      ++ ["-Wl,--enable-auto-import"]
#endif
                      ++ o_files
                      ++ extra_ld_inputs
                      ++ lib_path_opts
                      ++ extra_ld_opts
                      ++ rc_objs
#ifdef darwin_TARGET_OS
                      ++ framework_path_opts
                      ++ framework_opts
#endif
                      ++ pkg_lib_path_opts
                      ++ main_lib
                      ++ rtsEnabledObj
                      ++ rtsOptsObj
                      ++ pkg_link_opts
#ifdef darwin_TARGET_OS
                      ++ pkg_framework_path_opts
                      ++ pkg_framework_opts
#endif
                      ++ debug_opts
                      ++ thread_opts
                    ))

    -- parallel only: move binary to another dir -- HWL
    success <- runPhase_MoveBinary dflags output_fn
    if success then return ()
               else ghcError (InstallationError ("cannot move binary"))


exeFileName :: DynFlags -> FilePath
exeFileName dflags
  | Just s <- outputFile dflags =
#if defined(mingw32_HOST_OS)
      if null (takeExtension s)
        then s <.> "exe"
        else s
#else
      s
#endif
  | otherwise =
#if defined(mingw32_HOST_OS)
        "main.exe"
#else
        "a.out"
#endif

maybeCreateManifest
   :: DynFlags
   -> FilePath                          -- filename of executable
   -> IO [FilePath]                     -- extra objects to embed, maybe
#ifndef mingw32_TARGET_OS
maybeCreateManifest _ _ = do
  return []
#else
maybeCreateManifest dflags exe_filename = do
  if not (dopt Opt_GenManifest dflags) then return [] else do

  let manifest_filename = exe_filename <.> "manifest"

  writeFile manifest_filename $
      "<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"yes\"?>\n"++
      "  <assembly xmlns=\"urn:schemas-microsoft-com:asm.v1\" manifestVersion=\"1.0\">\n"++
      "  <assemblyIdentity version=\"1.0.0.0\"\n"++
      "     processorArchitecture=\"X86\"\n"++
      "     name=\"" ++ dropExtension exe_filename ++ "\"\n"++
      "     type=\"win32\"/>\n\n"++
      "  <trustInfo xmlns=\"urn:schemas-microsoft-com:asm.v3\">\n"++
      "    <security>\n"++
      "      <requestedPrivileges>\n"++
      "        <requestedExecutionLevel level=\"asInvoker\" uiAccess=\"false\"/>\n"++
      "        </requestedPrivileges>\n"++
      "       </security>\n"++
      "  </trustInfo>\n"++
      "</assembly>\n"

  -- Windows will find the manifest file if it is named foo.exe.manifest.
  -- However, for extra robustness, and so that we can move the binary around,
  -- we can embed the manifest in the binary itself using windres:
  if not (dopt Opt_EmbedManifest dflags) then return [] else do

  rc_filename <- newTempName dflags "rc"
  rc_obj_filename <- newTempName dflags (objectSuf dflags)

  writeFile rc_filename $
      "1 24 MOVEABLE PURE " ++ show manifest_filename ++ "\n"
        -- magic numbers :-)
        -- show is a bit hackish above, but we need to escape the
        -- backslashes in the path.

  let wr_opts = getOpts dflags opt_windres
  runWindres dflags $ map SysTools.Option $
        ["--input="++rc_filename,
         "--output="++rc_obj_filename,
         "--output-format=coff"]
        ++ wr_opts
        -- no FileOptions here: windres doesn't like seeing
        -- backslashes, apparently

  removeFile manifest_filename

  return [rc_obj_filename]
#endif


linkDynLib :: DynFlags -> [String] -> [PackageId] -> IO ()
linkDynLib dflags o_files dep_packages = do
    let verb = getVerbFlag dflags
    let o_file = outputFile dflags

    pkgs <- getPreloadPackagesAnd dflags dep_packages

    let pkg_lib_paths = collectLibraryPaths pkgs
    let pkg_lib_path_opts = concatMap get_pkg_lib_path_opts pkg_lib_paths
#ifdef elf_OBJ_FORMAT
        get_pkg_lib_path_opts l | (dynLibLoader dflags)==SystemDependent && not opt_Static = ["-L" ++ l, "-Wl,-rpath", "-Wl," ++ l]
                                | otherwise = ["-L" ++ l]
#else
        get_pkg_lib_path_opts l = ["-L" ++ l]
#endif

    let lib_paths = libraryPaths dflags
    let lib_path_opts = map ("-L"++) lib_paths

    -- We don't want to link our dynamic libs against the RTS package,
    -- because the RTS lib comes in several flavours and we want to be
    -- able to pick the flavour when a binary is linked.
    -- On Windows we need to link the RTS import lib as Windows does
    -- not allow undefined symbols.
    -- The RTS library path is still added to the library search path
    -- above in case the RTS is being explicitly linked in (see #3807).
#if !defined(mingw32_HOST_OS)
    let pkgs_no_rts = filter ((/= rtsPackageId) . packageConfigId) pkgs
#else
    let pkgs_no_rts = pkgs
#endif
    let pkg_link_opts = collectLinkOpts dflags pkgs_no_rts

        -- probably _stub.o files
    extra_ld_inputs <- readIORef v_Ld_inputs

    let (md_c_flags, _) = machdepCCOpts dflags
    let extra_ld_opts = getOpts dflags opt_l

    rtsEnabledObj <- mkRtsOptionsLevelObj dflags

#if defined(mingw32_HOST_OS)
    -----------------------------------------------------------------------------
    -- Making a DLL
    -----------------------------------------------------------------------------
    let output_fn = case o_file of { Just s -> s; Nothing -> "HSdll.dll"; }

    SysTools.runLink dflags
         ([ SysTools.Option verb
          , SysTools.Option "-o"
          , SysTools.FileOption "" output_fn
          , SysTools.Option "-shared"
          ] ++
          [ SysTools.FileOption "-Wl,--out-implib=" (output_fn ++ ".a")
          | dopt Opt_SharedImplib dflags
          ]
         ++ map (SysTools.FileOption "") o_files
         ++ map SysTools.Option (
            md_c_flags

         -- Permit the linker to auto link _symbol to _imp_symbol
         -- This lets us link against DLLs without needing an "import library"
         ++ ["-Wl,--enable-auto-import"]

         ++ extra_ld_inputs
         ++ lib_path_opts
         ++ extra_ld_opts
         ++ pkg_lib_path_opts
         ++ rtsEnabledObj
         ++ pkg_link_opts
        ))
#elif defined(darwin_TARGET_OS)
    -----------------------------------------------------------------------------
    -- Making a darwin dylib
    -----------------------------------------------------------------------------
    -- About the options used for Darwin:
    -- -dynamiclib
    --   Apple's way of saying -shared
    -- -undefined dynamic_lookup:
    --   Without these options, we'd have to specify the correct dependencies
    --   for each of the dylibs. Note that we could (and should) do without this
    --   for all libraries except the RTS; all we need to do is to pass the
    --   correct HSfoo_dyn.dylib files to the link command.
    --   This feature requires Mac OS X 10.3 or later; there is a similar feature,
    --   -flat_namespace -undefined suppress, which works on earlier versions,
    --   but it has other disadvantages.
    -- -single_module
    --   Build the dynamic library as a single "module", i.e. no dynamic binding
    --   nonsense when referring to symbols from within the library. The NCG
    --   assumes that this option is specified (on i386, at least).
    -- -install_name
    --   Mac OS/X stores the path where a dynamic library is (to be) installed
    --   in the library itself.  It's called the "install name" of the library.
    --   Then any library or executable that links against it before it's
    --   installed will search for it in its ultimate install location.  By
    --   default we set the install name to the absolute path at build time, but
    --   it can be overridden by the -dylib-install-name option passed to ghc.
    --   Cabal does this.
    -----------------------------------------------------------------------------

    let output_fn = case o_file of { Just s -> s; Nothing -> "a.out"; }

    instName <- case dylibInstallName dflags of
        Just n -> return n
        Nothing -> do
            pwd <- getCurrentDirectory
            return $ pwd `combine` output_fn
    SysTools.runLink dflags
         ([ SysTools.Option verb
          , SysTools.Option "-dynamiclib"
          , SysTools.Option "-o"
          , SysTools.FileOption "" output_fn
          ]
         ++ map SysTools.Option (
            md_c_flags
         ++ o_files
         ++ [ "-undefined", "dynamic_lookup", "-single_module",
              "-Wl,-read_only_relocs,suppress", "-install_name", instName ]
         ++ extra_ld_inputs
         ++ lib_path_opts
         ++ extra_ld_opts
         ++ pkg_lib_path_opts
         ++ rtsEnabledObj
         ++ pkg_link_opts
        ))
#else
    -----------------------------------------------------------------------------
    -- Making a DSO
    -----------------------------------------------------------------------------

    let output_fn = case o_file of { Just s -> s; Nothing -> "a.out"; }
    let buildingRts = thisPackage dflags == rtsPackageId
    let bsymbolicFlag = if buildingRts
                        then -- -Bsymbolic breaks the way we implement
                             -- hooks in the RTS
                             []
                        else -- we need symbolic linking to resolve
                             -- non-PIC intra-package-relocations
                             ["-Wl,-Bsymbolic"]

    SysTools.runLink dflags
         ([ SysTools.Option verb
          , SysTools.Option "-o"
          , SysTools.FileOption "" output_fn
          ]
         ++ map SysTools.Option (
            md_c_flags
         ++ o_files
         ++ [ "-shared" ]
         ++ bsymbolicFlag
         ++ [ "-Wl,-soname," ++ takeFileName output_fn ] -- set the library soname
         ++ extra_ld_inputs
         ++ lib_path_opts
         ++ extra_ld_opts
         ++ pkg_lib_path_opts
         ++ rtsEnabledObj
         ++ pkg_link_opts
        ))
#endif
-- -----------------------------------------------------------------------------
-- Running CPP

doCpp :: DynFlags -> Bool -> Bool -> FilePath -> FilePath -> IO ()
doCpp dflags raw include_cc_opts input_fn output_fn = do
    let hscpp_opts = getOpts dflags opt_P
    let cmdline_include_paths = includePaths dflags

    pkg_include_dirs <- getPackageIncludePath dflags []
    let include_paths = foldr (\ x xs -> "-I" : x : xs) []
                          (cmdline_include_paths ++ pkg_include_dirs)

    let verb = getVerbFlag dflags

    let cc_opts
          | not include_cc_opts = []
          | otherwise           = (optc ++ md_c_flags)
                where
                      optc = getOpts dflags opt_c
                      (md_c_flags, _) = machdepCCOpts dflags

    let cpp_prog args | raw       = SysTools.runCpp dflags args
                      | otherwise = SysTools.runCc dflags (SysTools.Option "-E" : args)

    let target_defs =
          [ "-D" ++ HOST_OS     ++ "_BUILD_OS=1",
            "-D" ++ HOST_ARCH   ++ "_BUILD_ARCH=1",
            "-D" ++ TARGET_OS   ++ "_HOST_OS=1",
            "-D" ++ TARGET_ARCH ++ "_HOST_ARCH=1" ]
        -- remember, in code we *compile*, the HOST is the same our TARGET,
        -- and BUILD is the same as our HOST.

    cpp_prog       ([SysTools.Option verb]
                    ++ map SysTools.Option include_paths
                    ++ map SysTools.Option hsSourceCppOpts
                    ++ map SysTools.Option target_defs
                    ++ map SysTools.Option hscpp_opts
                    ++ map SysTools.Option cc_opts
                    ++ [ SysTools.Option     "-x"
                       , SysTools.Option     "c"
                       , SysTools.Option     input_fn
        -- We hackily use Option instead of FileOption here, so that the file
        -- name is not back-slashed on Windows.  cpp is capable of
        -- dealing with / in filenames, so it works fine.  Furthermore
        -- if we put in backslashes, cpp outputs #line directives
        -- with *double* backslashes.   And that in turn means that
        -- our error messages get double backslashes in them.
        -- In due course we should arrange that the lexer deals
        -- with these \\ escapes properly.
                       , SysTools.Option     "-o"
                       , SysTools.FileOption "" output_fn
                       ])

hsSourceCppOpts :: [String]
-- Default CPP defines in Haskell source
hsSourceCppOpts =
        [ "-D__GLASGOW_HASKELL__="++cProjectVersionInt ]

-- ---------------------------------------------------------------------------
-- join object files into a single relocatable object file, using ld -r

joinObjectFiles :: DynFlags -> [FilePath] -> FilePath -> IO ()
joinObjectFiles dflags o_files output_fn = do
  let ld_r args = SysTools.runLink dflags ([
                            SysTools.Option "-nostdlib",
                            SysTools.Option "-nodefaultlibs",
                            SysTools.Option "-Wl,-r",
                            SysTools.Option ld_x_flag,
                            SysTools.Option "-o",
                            SysTools.FileOption "" output_fn ]
                         ++ map SysTools.Option md_c_flags
                         ++ args)
      ld_x_flag | null cLD_X = ""
                | otherwise  = "-Wl,-x"

      (md_c_flags, _) = machdepCCOpts dflags
  
  if cLdIsGNULd == "YES"
     then do
          script <- newTempName dflags "ldscript"
          writeFile script $ "INPUT(" ++ unwords o_files ++ ")"
          ld_r [SysTools.FileOption "" script]
     else do
          ld_r (map (SysTools.FileOption "") o_files)

-- -----------------------------------------------------------------------------
-- Misc.

hscNextPhase :: DynFlags -> HscSource -> HscTarget -> Phase
hscNextPhase _ HsBootFile _        =  StopLn
hscNextPhase dflags _ hsc_lang =
  case hsc_lang of
        HscC -> HCc
        HscAsm | dopt Opt_SplitObjs dflags -> SplitMangle
               | otherwise -> As
        HscLlvm        -> LlvmOpt
        HscNothing     -> StopLn
        HscInterpreted -> StopLn
        _other         -> StopLn


hscMaybeAdjustTarget :: DynFlags -> Phase -> HscSource -> HscTarget -> HscTarget
hscMaybeAdjustTarget dflags stop _ current_hsc_lang
  = hsc_lang
  where
        keep_hc = dopt Opt_KeepHcFiles dflags
        hsc_lang
                -- don't change the lang if we're interpreting
                 | current_hsc_lang == HscInterpreted = current_hsc_lang

                -- force -fvia-C if we are being asked for a .hc file
                 | HCc <- stop = HscC
                 | keep_hc     = HscC
                -- otherwise, stick to the plan
                 | otherwise = current_hsc_lang