Rip out object splitting

The splitter is an evil Perl script that processes assembler code.
Its job can be done better by the linker's --gc-sections flag. GHC
passes this flag to the linker whenever -split-sections is passed on
the command line.

This is based on @DemiMarie's D2768.

Fixes Trac #11315
Fixes Trac #9832
Fixes Trac #8964
Fixes Trac #8685
Fixes Trac #8629

15 files changed, 8 insertions, 108 deletions

diff --git a/hadrian/README.md b/hadrian/README.md
index 7b6646d655..179d9d07ce 100644
--- a/hadrian/README.md
+++ b/hadrian/README.md
@@ -114,10 +114,6 @@ four settings: `none`, `brief` (one line per build command; this is the default
 setting), `normal` (typically a box per build command), and `unicorn` (when
 `normal` just won't do).
 
-* `--split-objects`: generate split objects, which are switched off by default.
-Due to a GHC [bug][ghc-split-objs-bug], you need a full clean rebuild when using
-this flag.
-
 * `--verbose`: run Hadrian in verbose mode. In particular this prints diagnostic
 messages by Shake oracles.
 
@@ -263,7 +259,6 @@ projects), as well as Well-Typed.
 [ghc-preparation]: https://ghc.haskell.org/trac/ghc/wiki/Building/Preparation
 [ghc-windows-quick-build]: https://ghc.haskell.org/trac/ghc/wiki/Building/Preparation/Windows#AQuickBuild
 [windows-build]: https://gitlab.haskell.org/ghc/ghc/blob/master/hadrian/doc/windows.md
-[ghc-split-objs-bug]: https://ghc.haskell.org/trac/ghc/ticket/11315
 [test-issue]: https://github.com/snowleopard/hadrian/issues/197
 [validation-issue]: https://github.com/snowleopard/hadrian/issues/187
 [dynamic-windows-issue]: https://github.com/snowleopard/hadrian/issues/343
diff --git a/hadrian/cfg/system.config.in b/hadrian/cfg/system.config.in
index 4cae2b6783..affeeaa5d5 100644
--- a/hadrian/cfg/system.config.in
+++ b/hadrian/cfg/system.config.in
@@ -43,7 +43,6 @@ hs-cpp-args         = @HaskellCPPArgs@
 #===============
 
 solaris-broken-shld  = @SOLARIS_BROKEN_SHLD@
-split-objects-broken = @SplitObjsBroken@
 ghc-unregisterised   = @Unregisterised@
 ghc-source-path      = @hardtop@
 leading-underscore   = @LeadingUnderscore@
diff --git a/hadrian/doc/user-settings.md b/hadrian/doc/user-settings.md
index 68929d325a..d0531a3f3d 100644
--- a/hadrian/doc/user-settings.md
+++ b/hadrian/doc/user-settings.md
@@ -23,8 +23,6 @@ data Flavour = Flavour {
     libraryWays :: Ways,
     -- | Build RTS these ways.
     rtsWays :: Ways,
-    -- | Build split objects.
-    splitObjects :: Predicate,
     -- | Build dynamic GHC programs.
     dynamicGhcPrograms :: Action Bool,
     -- | Enable GHCi debugger.
@@ -275,13 +273,6 @@ their effects.
 
 ## Miscellaneous
 
-To change the default behaviour of Hadrian with respect to building split
-objects, override the `splitObjects` setting of the `Flavour` record:
-```haskell
-userFlavour :: Flavour
-userFlavour = defaultFlavour { name = "user", splitObjects = return False }
-```
-
 Hadrian prints various progress info during the build. You can change the colours
 used by default by overriding `buildProgressColour` and `successColour`:
 ```haskell
diff --git a/hadrian/src/Base.hs b/hadrian/src/Base.hs
index 47d9107669..19573de8fd 100644
--- a/hadrian/src/Base.hs
+++ b/hadrian/src/Base.hs
@@ -26,7 +26,6 @@ module Base (
     generatedDir, generatedPath, stageBinPath, stageLibPath, templateHscPath,
     ghcDeps, includesDependencies, haddockDeps, relativePackageDbPath,
     packageDbPath, packageDbStamp, mingwStamp,
-    ghcSplitPath
     ) where
 
 import Control.Applicative
@@ -138,12 +137,6 @@ haddockDeps stage = do
 templateHscPath :: Stage -> Action FilePath
 templateHscPath stage = stageLibPath stage <&> (-/- "template-hsc.h")
 
--- | @ghc-split@ is a Perl script used by GHC when run with @-split-objs@ flag.
--- It is generated in "Rules.Generate". This function returns the path relative
--- to the build root under which we will copy @ghc-split@.
-ghcSplitPath :: Stage -> FilePath
-ghcSplitPath stage = stageString stage -/- "bin" -/- "ghc-split"
-
 -- | We use this stamp file to track whether we've moved the mingw toolchain
 --   under the build root (to make it accessible to the GHCs we build on
 --   Windows). See "Rules.Program".
diff --git a/hadrian/src/Builder.hs b/hadrian/src/Builder.hs
index b56f9c1071..6c14eb4517 100644
--- a/hadrian/src/Builder.hs
+++ b/hadrian/src/Builder.hs
@@ -181,8 +181,7 @@ instance H.Builder Builder where
             unlitPath  <- builderPath Unlit
             ghcdeps <- ghcDeps stage
             ghcgens <- generatedGhcDependencies stage
-            return $ [ root -/- ghcSplitPath stage -- TODO: Make conditional on --split-objects
-                     , unlitPath ]
+            return $ [ unlitPath ]
                   ++ ghcdeps
                   ++ ghcgens
                   ++ [ touchyPath | win ]
diff --git a/hadrian/src/CommandLine.hs b/hadrian/src/CommandLine.hs
index 842fb037cc..75e981222a 100644
--- a/hadrian/src/CommandLine.hs
+++ b/hadrian/src/CommandLine.hs
@@ -1,6 +1,6 @@
 module CommandLine (
     optDescrs, cmdLineArgsMap, cmdFlavour, lookupFreeze1, cmdIntegerSimple,
-    cmdProgressColour, cmdProgressInfo, cmdConfigure, cmdSplitObjects,
+    cmdProgressColour, cmdProgressInfo, cmdConfigure,
     cmdDocsArgs, lookupBuildRoot, TestArgs(..), TestSpeed(..), defaultTestArgs
     ) where
 
@@ -25,7 +25,6 @@ data CommandLineArgs = CommandLineArgs
     , integerSimple  :: Bool
     , progressColour :: UseColour
     , progressInfo   :: ProgressInfo
-    , splitObjects   :: Bool
     , buildRoot      :: BuildRoot
     , testArgs       :: TestArgs
     , docTargets     :: DocTargets }
@@ -40,7 +39,6 @@ defaultCommandLineArgs = CommandLineArgs
     , integerSimple  = False
     , progressColour = Auto
     , progressInfo   = Brief
-    , splitObjects   = False
     , buildRoot      = BuildRoot "_build"
     , testArgs       = defaultTestArgs
     , docTargets     = Set.fromList [minBound..maxBound] }
@@ -121,9 +119,6 @@ readProgressInfo ms =
     set :: ProgressInfo -> CommandLineArgs -> CommandLineArgs
     set flag flags = flags { progressInfo = flag }
 
-readSplitObjects :: Either String (CommandLineArgs -> CommandLineArgs)
-readSplitObjects = Right $ \flags -> flags { splitObjects = True }
-
 readTestCompiler :: Maybe String -> Either String (CommandLineArgs -> CommandLineArgs)
 readTestCompiler compiler = maybe (Left "Cannot parse compiler") (Right . set) compiler
   where
@@ -220,8 +215,6 @@ optDescrs =
       "Use colours in progress info (Never, Auto or Always)."
     , Option [] ["progress-info"] (OptArg readProgressInfo "STYLE")
       "Progress info style (None, Brief, Normal or Unicorn)."
-    , Option [] ["split-objects"] (NoArg readSplitObjects)
-      "Generate split objects (requires a full clean rebuild)."
     , Option [] ["docs"] (OptArg readDocsArg "TARGET")
       "Strip down docs targets (none, no-haddocks, no-sphinx[-{html, pdfs, man}]."
     , Option [] ["test-compiler"] (OptArg readTestCompiler "TEST_COMPILER")
@@ -283,8 +276,5 @@ cmdProgressColour = progressColour <$> cmdLineArgs
 cmdProgressInfo :: Action ProgressInfo
 cmdProgressInfo = progressInfo <$> cmdLineArgs
 
-cmdSplitObjects :: Action Bool
-cmdSplitObjects = splitObjects <$> cmdLineArgs
-
 cmdDocsArgs :: Action DocTargets
 cmdDocsArgs = docTargets <$> cmdLineArgs
diff --git a/hadrian/src/Flavour.hs b/hadrian/src/Flavour.hs
index 4a71e80c45..06407e7022 100644
--- a/hadrian/src/Flavour.hs
+++ b/hadrian/src/Flavour.hs
@@ -26,8 +26,6 @@ data Flavour = Flavour {
     libraryWays :: Ways,
     -- | Build RTS these ways.
     rtsWays :: Ways,
-    -- | Build split objects.
-    splitObjects :: Predicate,
     -- | Build dynamic GHC programs.
     dynamicGhcPrograms :: Action Bool,
     -- | Enable GHCi debugger.
diff --git a/hadrian/src/Oracles/Flag.hs b/hadrian/src/Oracles/Flag.hs
index b294cebc93..4f5116bf41 100644
--- a/hadrian/src/Oracles/Flag.hs
+++ b/hadrian/src/Oracles/Flag.hs
@@ -1,6 +1,6 @@
 module Oracles.Flag (
     Flag (..), flag, getFlag, platformSupportsSharedLibs, ghcWithSMP,
-    ghcWithNativeCodeGen, supportsSplitObjects
+    ghcWithNativeCodeGen
     ) where
 
 import Hadrian.Oracles.TextFile
@@ -17,7 +17,6 @@ data Flag = ArSupportsAtFile
           | GmpFrameworkPref
           | LeadingUnderscore
           | SolarisBrokenShld
-          | SplitObjectsBroken
           | WithLibdw
           | HaveLibMingwEx
           | UseSystemFfi
@@ -35,7 +34,6 @@ flag f = do
             GmpFrameworkPref   -> "gmp-framework-preferred"
             LeadingUnderscore  -> "leading-underscore"
             SolarisBrokenShld  -> "solaris-broken-shld"
-            SplitObjectsBroken -> "split-objects-broken"
             WithLibdw          -> "with-libdw"
             HaveLibMingwEx     -> "have-lib-mingw-ex"
             UseSystemFfi       -> "use-system-ffi"
@@ -69,12 +67,3 @@ ghcWithNativeCodeGen = do
     badOs    <- anyTargetOs ["ios", "aix"]
     ghcUnreg <- flag GhcUnregisterised
     return $ goodArch && not badOs && not ghcUnreg
-
-supportsSplitObjects :: Action Bool
-supportsSplitObjects = do
-    broken   <- flag SplitObjectsBroken
-    ghcUnreg <- flag GhcUnregisterised
-    goodArch <- anyTargetArch [ "i386", "x86_64", "powerpc", "sparc" ]
-    goodOs   <- anyTargetOs [ "mingw32", "cygwin32", "linux", "darwin", "solaris2"
-                            , "freebsd", "dragonfly", "netbsd", "openbsd" ]
-    return $ not broken && not ghcUnreg && goodArch && goodOs
diff --git a/hadrian/src/Packages.hs b/hadrian/src/Packages.hs
index 75a74b2ae6..2738c6952d 100644
--- a/hadrian/src/Packages.hs
+++ b/hadrian/src/Packages.hs
@@ -4,7 +4,7 @@ module Packages (
     array, base, binary, bytestring, cabal, checkApiAnnotations, checkPpr,
     compareSizes, compiler, containers, deepseq, deriveConstants, directory,
     filepath, genapply, genprimopcode, ghc, ghcBoot, ghcBootTh, ghcCompact,
-    ghcHeap, ghci, ghcPkg, ghcPrim, ghcSplit, haddock, haskeline,
+    ghcHeap, ghci, ghcPkg, ghcPrim, haddock, haskeline,
     hsc2hs, hp2ps, hpc, hpcBin, integerGmp, integerSimple, iserv, libffi,
     libiserv, mtl, parsec, pretty, primitive, process, rts, runGhc,
     stm, templateHaskell, terminfo, text, time, timeout, touchy, transformers,
@@ -69,7 +69,6 @@ ghcHeap             = lib  "ghc-heap"
 ghci                = lib  "ghci"
 ghcPkg              = util "ghc-pkg"
 ghcPrim             = lib  "ghc-prim"
-ghcSplit            = util "ghc-split"
 haddock             = util "haddock"
 haskeline           = lib  "haskeline"
 hsc2hs              = util "hsc2hs"
diff --git a/hadrian/src/Rules/BinaryDist.hs b/hadrian/src/Rules/BinaryDist.hs
index d54ac3d140..609766d5ca 100644
--- a/hadrian/src/Rules/BinaryDist.hs
+++ b/hadrian/src/Rules/BinaryDist.hs
@@ -134,7 +134,7 @@ bindistRules = do
         need $ map (bindistFilesDir -/-)
                    (["configure", "Makefile"] ++ bindistInstallFiles)
         need $ map ((bindistFilesDir -/- "wrappers") -/-) ["check-api-annotations"
-                   , "check-ppr", "ghc", "ghc-iserv", "ghc-pkg", "ghc-split"
+                   , "check-ppr", "ghc", "ghc-iserv", "ghc-pkg"
                    , "ghci-script", "ghci", "haddock", "hpc", "hp2ps", "hsc2hs"
                    , "runghc"]
 
diff --git a/hadrian/src/Rules/Generate.hs b/hadrian/src/Rules/Generate.hs
index 13544f2a7d..032f6a68c1 100644
--- a/hadrian/src/Rules/Generate.hs
+++ b/hadrian/src/Rules/Generate.hs
@@ -174,11 +174,6 @@ generateRules = do
     priority 2.0 $ (root -/- generatedDir -/- "ghcplatform.h") <~ generateGhcPlatformH
     priority 2.0 $ (root -/- generatedDir -/-  "ghcversion.h") <~ generateGhcVersionH
 
-    forM_ [Stage0 ..] $ \stage ->
-        root -/- ghcSplitPath stage %> \path -> do
-            generate path emptyTarget generateGhcSplit
-            makeExecutable path
-
     -- TODO: simplify, get rid of fake rts context
     root -/- generatedDir ++ "//*" %> \file -> do
         withTempDir $ \dir -> build $
@@ -200,26 +195,6 @@ emptyTarget = vanillaContext (error "Rules.Generate.emptyTarget: unknown stage")
 cppify :: String -> String
 cppify = replaceEq '-' '_' . replaceEq '.' '_'
 
-ghcSplitSource :: FilePath
-ghcSplitSource = "driver/split/ghc-split.pl"
-
--- ref: rules/build-perl.mk
--- | Generate the @ghc-split@ Perl script.
-generateGhcSplit :: Expr String
-generateGhcSplit = do
-    trackGenerateHs
-    targetPlatform <- getSetting TargetPlatform
-    ghcEnableTNC   <- expr $ yesNo <$> ghcEnableTablesNextToCode
-    perlPath       <- getBuilderPath Perl
-    contents       <- expr $ readFileLines ghcSplitSource
-    return . unlines $
-        [ "#!" ++ perlPath
-        , "my $TARGETPLATFORM = " ++ show targetPlatform ++ ";"
-        -- I don't see where the ghc-split tool uses TNC, but
-        -- it's in the build-perl macro.
-        , "my $TABLES_NEXT_TO_CODE = " ++ show ghcEnableTNC ++ ";"
-        ] ++ contents
-
 -- | Generate @ghcplatform.h@ header.
 generateGhcPlatformH :: Expr String
 generateGhcPlatformH = do
@@ -289,7 +264,6 @@ generateConfigHs = do
             | intLib == integerGmp    = "IntegerGMP"
             | intLib == integerSimple = "IntegerSimple"
             | otherwise = error $ "Unknown integer library: " ++ pkgName intLib
-    cSupportsSplitObjs         <- expr $ yesNo <$> supportsSplitObjects
     cGhcWithInterpreter        <- expr $ yesNo <$> ghcWithInterpreter
     cGhcWithNativeCodeGen      <- expr $ yesNo <$> ghcWithNativeCodeGen
     cGhcWithSMP                <- expr $ yesNo <$> ghcWithSMP
@@ -341,8 +315,6 @@ generateConfigHs = do
         , "cIntegerLibrary       = " ++ show (pkgName intLib)
         , "cIntegerLibraryType   :: IntegerLibrary"
         , "cIntegerLibraryType   = " ++ cIntegerLibraryType
-        , "cSupportsSplitObjs    :: String"
-        , "cSupportsSplitObjs    = " ++ show cSupportsSplitObjs
         , "cGhcWithInterpreter   :: String"
         , "cGhcWithInterpreter   = " ++ show cGhcWithInterpreter
         , "cGhcWithNativeCodeGen :: String"
@@ -357,8 +329,6 @@ generateConfigHs = do
         , "cLeadingUnderscore    = " ++ show cLeadingUnderscore
         , "cGHC_UNLIT_PGM        :: String"
         , "cGHC_UNLIT_PGM        = " ++ show cGHC_UNLIT_PGM
-        , "cGHC_SPLIT_PGM        :: String"
-        , "cGHC_SPLIT_PGM        = " ++ show "ghc-split"
         , "cLibFFI               :: Bool"
         , "cLibFFI               = " ++ show cLibFFI
         , "cGhcThreaded :: Bool"
diff --git a/hadrian/src/Rules/Library.hs b/hadrian/src/Rules/Library.hs
index d19907bfa9..edec160cc2 100644
--- a/hadrian/src/Rules/Library.hs
+++ b/hadrian/src/Rules/Library.hs
@@ -121,18 +121,8 @@ libraryObjects :: Context -> Action [FilePath]
 libraryObjects context@Context{..} = do
     hsObjs   <- hsObjects    context
     noHsObjs <- nonHsObjects context
-
-    -- This will create split objects if required (we don't track them
-    -- explicitly as this would needlessly bloat the Shake database).
     need $ noHsObjs ++ hsObjs
-
-    split <- interpretInContext context =<< splitObjects <$> flavour
-    let getSplitObjs = concatForM hsObjs $ \obj -> do
-            let dir = dropExtension obj ++ "_" ++ osuf way ++ "_split"
-            contents <- liftIO $ IO.getDirectoryContents dir
-            return . map (dir -/-) $ filter (not . all (== '.')) contents
-
-    (noHsObjs ++) <$> if split then getSplitObjs else return hsObjs
+    return (noHsObjs ++ hsObjs)
 
 -- * Library paths types and parsers
 
diff --git a/hadrian/src/Settings/Builders/Ghc.hs b/hadrian/src/Settings/Builders/Ghc.hs
index 4bc10e5edd..b952a017bc 100644
--- a/hadrian/src/Settings/Builders/Ghc.hs
+++ b/hadrian/src/Settings/Builders/Ghc.hs
@@ -17,7 +17,6 @@ compileAndLinkHs :: Args
 compileAndLinkHs = (builder (Ghc CompileHs) ||^ builder (Ghc LinkHs)) ? do
     mconcat [ arg "-Wall"
             , commonGhcArgs
-            , splitObjects <$> flavour ? arg "-split-objs"
             , ghcLinkArgs
             , defaultGhcWarningsArgs
             , builder (Ghc CompileHs) ? arg "-c"
diff --git a/hadrian/src/Settings/Default.hs b/hadrian/src/Settings/Default.hs
index 084dcf3d42..b74ee09499 100644
--- a/hadrian/src/Settings/Default.hs
+++ b/hadrian/src/Settings/Default.hs
@@ -10,7 +10,7 @@ module Settings.Default (
     defaultArgs,
 
     -- * Default build flavour
-    defaultFlavour, defaultSplitObjects
+    defaultFlavour
     ) where
 
 import qualified Hadrian.Builder.Ar
@@ -210,7 +210,6 @@ defaultFlavour = Flavour
     , integerLibrary     = (\x -> if x then integerSimple else integerGmp) <$> cmdIntegerSimple
     , libraryWays        = defaultLibraryWays
     , rtsWays            = defaultRtsWays
-    , splitObjects       = defaultSplitObjects
     , dynamicGhcPrograms = defaultDynamicGhcPrograms
     , ghciWithDebugger   = False
     , ghcProfiled        = False
@@ -228,16 +227,6 @@ defaultDynamicGhcPrograms = do
   supportsShared <- platformSupportsSharedLibs
   return (not win && supportsShared)
 
--- | Default condition for building split objects.
-defaultSplitObjects :: Predicate
-defaultSplitObjects = do
-    goodStage <- notStage0 -- We don't split bootstrap (stage 0) packages
-    pkg       <- getPackage
-    supported <- expr supportsSplitObjects
-    split     <- expr cmdSplitObjects
-    let goodPackage = isLibrary pkg && pkg /= compiler && pkg /= rts
-    return $ split && goodStage && goodPackage && supported
-
 -- | All 'Builder'-dependent command line arguments.
 defaultBuilderArgs :: Args
 defaultBuilderArgs = mconcat
diff --git a/hadrian/src/Settings/Default.hs-boot b/hadrian/src/Settings/Default.hs-boot
index 30a28497e9..e2996d9c71 100644
--- a/hadrian/src/Settings/Default.hs-boot
+++ b/hadrian/src/Settings/Default.hs-boot
@@ -1,7 +1,7 @@
 module Settings.Default (
     SourceArgs (..), sourceArgs, defaultBuilderArgs, defaultPackageArgs,
     defaultArgs, defaultLibraryWays, defaultRtsWays,
-    defaultFlavour, defaultSplitObjects
+    defaultFlavour
     ) where
 
 import Flavour
@@ -18,4 +18,3 @@ sourceArgs :: SourceArgs -> Args
 defaultBuilderArgs, defaultPackageArgs, defaultArgs :: Args
 defaultLibraryWays, defaultRtsWays :: Ways
 defaultFlavour :: Flavour
-defaultSplitObjects :: Predicate