Remove dll-split.

This patch removes dll-split from the code base, the reason is dll-split
no longer makes any sense. It was designed to split a dll in two, but we
now already have many more symbols than would fit inside two dlls. So we
need a third one. This means there's no point in having to maintain this
list as it'll never work anyway and the solution isn't scalable.

Test Plan: ./validate

Reviewers: austin, bgamari

Reviewed By: bgamari

Subscribers: rwbarton, thomie, #ghc_windows_task_force

GHC Trac Issues: #5987

Differential Revision: https://phabricator.haskell.org/D3882

4 files changed, 17 insertions, 191 deletions

diff --git a/compiler/ghc.mk b/compiler/ghc.mk
index bfd75ab26c..ab52a1ecf3 100644
--- a/compiler/ghc.mk
+++ b/compiler/ghc.mk
@@ -428,154 +428,6 @@ compiler_stage1_SplitSections = NO
 compiler_stage2_SplitSections = NO
 compiler_stage3_SplitSections = NO
 
-# There are too many symbols in the ghc package for a Windows DLL
-# (due to a limitation of bfd ld, see Trac #5987). We therefore need to split
-# some of the modules off into a separate DLL. This clump are the modules
-# reachable from DynFlags:
-compiler_stage2_dll0_START_MODULE = DynFlags
-compiler_stage2_dll0_MODULES = \
-	Annotations \
-	ApiAnnotation \
-	Avail \
-	Bag \
-	BasicTypes \
-	Binary \
-	BinFingerprint \
-	BooleanFormula \
-	BufWrite \
-	ByteCodeTypes \
-	Class \
-	CmdLineParser \
-	CmmType \
-	CoAxiom \
-	ConLike \
-	Coercion \
-	Config \
-	Constants \
-	CoreArity \
-	CoreFVs \
-	CoreSubst \
-	CoreOpt \
-	CoreSyn \
-	CoreTidy \
-	CoreUnfold \
-	CoreUtils \
-	CoreSeq \
-	CoreStats \
-	CostCentre \
-	DataCon \
-	Demand \
-	Digraph \
-	DriverPhases \
-	DynFlags \
-	Encoding \
-	EnumSet \
-	ErrUtils \
-	Exception \
-	FamInstEnv \
-	FastFunctions \
-	FastMutInt \
-	FastString \
-	FastStringEnv \
-	FieldLabel \
-	FileCleanup \
-	Fingerprint \
-	FiniteMap \
-	ForeignCall \
-	FV \
-	Hooks \
-	HsBinds \
-	HsDecls \
-	HsDoc \
-	HsExpr \
-	HsImpExp \
-	HsLit \
-	PlaceHolder \
-	HsExtension \
-	PmExpr \
-	HsPat \
-	HsSyn \
-	HsTypes \
-	HsUtils \
-	HscTypes \
-	IOEnv \
-	NameCache \
-	Id \
-	IdInfo \
-	IfaceSyn \
-	IfaceType \
-	InteractiveEvalTypes \
-	Json \
-	ToIface \
-	InstEnv \
-	Kind \
-	KnownUniques \
-	Lexeme \
-	ListSetOps \
-	Literal \
-	Maybes \
-	MkCore \
-	MkId \
-	Module \
-	MonadUtils \
-	Name \
-	NameEnv \
-	NameSet \
-	OccName \
-	OccurAnal \
-	OptCoercion \
-	OrdList \
-	Outputable \
-	PackageConfig \
-	Packages \
-	Pair \
-	Panic \
-	PatSyn \
-	PipelineMonad \
-	Platform \
-	PlatformConstants \
-	PprColour \
-	PprCore \
-	PrelNames \
-	PrelRules \
-	Pretty \
-	PrimOp \
-	RepType \
-	RdrName \
-	Rules \
-	SrcLoc \
-	StringBuffer \
-	SysTools.Terminal \
-	TcEvidence \
-	TcRnTypes \
-	TcType \
-	TrieMap \
-	TyCon \
-	Type \
-	TyCoRep \
-	TysPrim \
-	TysWiredIn \
-	Unify \
-	UniqDFM \
-	UniqDSet \
-	UniqFM \
-	UniqSet \
-	UniqSupply \
-	Unique \
-	Util \
-	Var \
-	VarEnv \
-	VarSet
-
-ifeq "$(GhcWithInterpreter)" "YES"
-# These files are reacheable from DynFlags
-# only by GHCi-enabled code (see #9552)
-compiler_stage2_dll0_MODULES += # none
-endif
-
-compiler_stage2_dll0_HS_OBJS = \
-    $(patsubst %,compiler/stage2/build/%.$(dyn_osuf),$(subst .,/,$(compiler_stage2_dll0_MODULES)))
-
 # if stage is set to something other than "1" or "", disable stage 1
 # See Note [Stage1Only vs stage=1] in mk/config.mk.in.
 ifneq "$(filter-out 1,$(stage))" ""
diff --git a/compiler/main/DynFlags.hs b/compiler/main/DynFlags.hs
index 45b7e36b09..c15943c7f3 100644
--- a/compiler/main/DynFlags.hs
+++ b/compiler/main/DynFlags.hs
@@ -766,14 +766,6 @@ data DynFlags = DynFlags {
   dynObjectSuf          :: String,
   dynHiSuf              :: String,
 
-  -- Packages.isDllName needs to know whether a call is within a
-  -- single DLL or not. Normally it does this by seeing if the call
-  -- is to the same package, but for the ghc package, we split the
-  -- package between 2 DLLs. The dllSplit tells us which sets of
-  -- modules are in which package.
-  dllSplitFile          :: Maybe FilePath,
-  dllSplit              :: Maybe [Set String],
-
   outputFile            :: Maybe String,
   dynOutputFile         :: Maybe String,
   outputHi              :: Maybe String,
@@ -1606,9 +1598,6 @@ defaultDynFlags mySettings =
         dynObjectSuf            = "dyn_" ++ phaseInputExt StopLn,
         dynHiSuf                = "dyn_hi",
 
-        dllSplitFile            = Nothing,
-        dllSplit                = Nothing,
-
         pluginModNames          = [],
         pluginModNameOpts       = [],
         frontendPluginOpts      = [],
@@ -2422,27 +2411,13 @@ parseDynamicFlagsFull activeFlags cmdline dflags0 args = do
 
   let (dflags5, consistency_warnings) = makeDynFlagsConsistent dflags4
 
-  dflags6 <- case dllSplitFile dflags5 of
-             Nothing -> return (dflags5 { dllSplit = Nothing })
-             Just f ->
-                 case dllSplit dflags5 of
-                 Just _ ->
-                     -- If dllSplit is out of date then it would have
-                     -- been set to Nothing. As it's a Just, it must be
-                     -- up-to-date.
-                     return dflags5
-                 Nothing ->
-                     do xs <- liftIO $ readFile f
-                        let ss = map (Set.fromList . words) (lines xs)
-                        return $ dflags5 { dllSplit = Just ss }
-
   -- Set timer stats & heap size
-  when (enableTimeStats dflags6) $ liftIO enableTimingStats
-  case (ghcHeapSize dflags6) of
+  when (enableTimeStats dflags5) $ liftIO enableTimingStats
+  case (ghcHeapSize dflags5) of
     Just x -> liftIO (setHeapSize x)
     _      -> return ()
 
-  dflags7 <- liftIO $ setLogAction dflags6
+  dflags7 <- liftIO $ setLogAction dflags5
 
   liftIO $ setUnsafeGlobalDynFlags dflags7
 
@@ -2751,9 +2726,6 @@ dynamic_flags_deps = [
         (noArg (\d -> d { ghcLink=LinkStaticLib }))
   , make_ord_flag defGhcFlag "dynload"            (hasArg parseDynLibLoaderMode)
   , make_ord_flag defGhcFlag "dylib-install-name" (hasArg setDylibInstallName)
-    -- -dll-split is an internal flag, used only during the GHC build
-  , make_ord_flag defHiddenFlag "dll-split"
-      (hasArg (\f d -> d { dllSplitFile = Just f, dllSplit = Nothing }))
 
         ------- Libraries ---------------------------------------------------
   , make_ord_flag defFlag "L"   (Prefix addLibraryPath)
diff --git a/compiler/main/Hooks.hs b/compiler/main/Hooks.hs
index 59126e98d5..2e228d5a9a 100644
--- a/compiler/main/Hooks.hs
+++ b/compiler/main/Hooks.hs
@@ -2,8 +2,6 @@
 
 -- NB: this module is SOURCE-imported by DynFlags, and should primarily
 --     refer to *types*, rather than *code*
--- If you import too muchhere , then the revolting compiler_stage2_dll0_MODULES
--- stuff in compiler/ghc.mk makes DynFlags link to too much stuff
 
 {-# LANGUAGE CPP #-}
 module Hooks ( Hooks
diff --git a/compiler/main/Packages.hs b/compiler/main/Packages.hs
index 50b9967e01..01d66cb740 100644
--- a/compiler/main/Packages.hs
+++ b/compiler/main/Packages.hs
@@ -71,6 +71,7 @@ import UniqSet
 import Module
 import Util
 import Panic
+import Platform
 import Outputable
 import Maybes
 
@@ -1966,16 +1967,19 @@ isDllName dflags this_mod name
     -- In the mean time, always force dynamic indirections to be
     -- generated: when the module name isn't the module being
     -- compiled, references are dynamic.
-    = if mod /= this_mod
-      then True
-      else case dllSplit dflags of
-           Nothing -> False
-           Just ss ->
-               let findMod m = let modStr = moduleNameString (moduleName m)
-                               in case find (modStr `Set.member`) ss of
-                                  Just i -> i
-                                  Nothing -> panic ("Can't find " ++ modStr ++ "in DLL split")
-               in findMod mod /= findMod this_mod
+    = case platformOS $ targetPlatform dflags of
+        -- On Windows the hack for #8696 makes it unlinkable.
+        -- As the entire setup of the code from Cmm down to the RTS expects
+        -- the use of trampolines for the imported functions only when
+        -- doing intra-package linking, e.g. refering to a symbol defined in the same
+        -- package should not use a trampoline.
+        -- I much rather have dynamic TH not supported than the entire Dynamic linking
+        -- not due to a hack.
+        -- Also not sure this would break on Windows anyway.
+        OSMinGW32 -> moduleUnitId mod /= moduleUnitId this_mod
+
+        -- For the other platforms, still perform the hack
+        _         -> mod /= this_mod
 
   | otherwise = False  -- no, it is not even an external name