Revert "Make globals use sharedCAF"

This reverts commit 6f7ed1e51bf360621a3c2a447045ab3012f68575 due to breakage of
the build on Windows.

2 files changed, 7 insertions, 34 deletions

diff --git a/compiler/utils/FastString.hs b/compiler/utils/FastString.hs
index 8f76584875..1496a8686e 100644
--- a/compiler/utils/FastString.hs
+++ b/compiler/utils/FastString.hs
@@ -285,6 +285,13 @@ originally assigned to those FastStrings.  Thus the lookup fails since the
 domain of the GlobalRdrEnv is affected by the RdrName's OccName's FastString's
 unique.
 
+The old `reinitializeGlobals` mechanism is enough to provide the plugin with
+read-access to the table, but it insufficient in the general case where the
+plugin may allocate FastStrings. This mutates the supply for the FastStrings'
+unique, and that needs to be propagated back to the compiler's instance of the
+global variable.  Such propagation is beyond the `reinitializeGlobals`
+mechanism.
+
 Maintaining synchronization of the two instances of this global is rather
 difficult because of the uses of `unsafePerformIO` in this module.  Not
 synchronizing them risks breaking the rather major invariant that two
diff --git a/compiler/utils/Util.hs b/compiler/utils/Util.hs
index 88b5090f0a..3104c747a1 100644
--- a/compiler/utils/Util.hs
+++ b/compiler/utils/Util.hs
@@ -104,7 +104,6 @@ module Util (
         hSetTranslit,
 
         global, consIORef, globalM,
-        sharedGlobal, sharedGlobalM,
 
         -- * Filenames and paths
         Suffix,
@@ -145,7 +144,6 @@ import qualified GHC.Stack
 import Control.Applicative ( liftA2 )
 import Control.Monad    ( liftM )
 import GHC.IO.Encoding (mkTextEncoding, textEncodingName)
-import GHC.Conc.Sync ( sharedCAF )
 import System.IO (Handle, hGetEncoding, hSetEncoding)
 import System.IO.Error as IO ( isDoesNotExistError )
 import System.Directory ( doesDirectoryExist, getModificationTime )
@@ -932,28 +930,6 @@ seqList :: [a] -> b -> b
 seqList [] b = b
 seqList (x:xs) b = x `seq` seqList xs b
 
-
-{-
-************************************************************************
-*                                                                      *
-                        Globals and the RTS
-*                                                                      *
-************************************************************************
-
-When a plugin is loaded, it currently gets linked against a *newly
-loaded* copy of the GHC package. This would not be a problem, except
-that the new copy has its own mutable state that is not shared with
-that state that has already been initialized by the original GHC
-package.
-
-(Note that if the GHC executable was dynamically linked this
-wouldn't be a problem, because we could share the GHC library it
-links to; this is only a problem if DYNAMIC_GHC_PROGRAMS=NO.)
-
-The solution is to make use of @sharedCAF@ through @sharedGlobal@
-for globals that are shared between multiple copies of ghc packages.
--}
-
 -- Global variables:
 
 global :: a -> IORef a
@@ -966,16 +942,6 @@ consIORef var x = do
 globalM :: IO a -> IORef a
 globalM ma = unsafePerformIO (ma >>= newIORef)
 
--- Shared global variables:
-
-sharedGlobal :: a -> (Ptr (IORef a) -> IO (Ptr (IORef a))) -> IORef a
-sharedGlobal a get_or_set = unsafePerformIO $
-  newIORef a >>= flip sharedCAF get_or_set
-
-sharedGlobalM :: IO a -> (Ptr (IORef a) -> IO (Ptr (IORef a))) -> IORef a
-sharedGlobalM ma get_or_set = unsafePerformIO $
-  ma >>= newIORef >>= flip sharedCAF get_or_set
-
 -- Module names:
 
 looksLikeModuleName :: String -> Bool