[commit: ghc] master: include FastString.string_table in CoreMonad.reinitializeGlobals (163de25)

[Simon Peyton-Jones]

Do you put the FS table back after running the plugin? If not, the same unique may be allocated more than once.

S

| -----Original Message-----
| From: ghc-commits-bounces at haskell.org [mailto:ghc-commits-
| bounces at haskell.org] On Behalf Of Nicolas Frisby
| Sent: 04 July 2013 05:13
| To: ghc-commits at haskell.org
| Subject: [commit: ghc] master: include FastString.string_table in
| CoreMonad.reinitializeGlobals (163de25)
| 
| Repository : http://darcs.haskell.org/ghc.git/
| 
| On branch  : master
| 
| https://github.com/ghc/ghc/commit/163de25813d12764aa5ded1666af7c06fee0d6
| 7e
| 
| >---------------------------------------------------------------
| 
| commit 163de25813d12764aa5ded1666af7c06fee0d67e
| Author: Nicolas Frisby <nicolas.frisby at gmail.com>
| Date:   Wed Jul 3 18:23:54 2013 -0500
| 
|     include FastString.string_table in CoreMonad.reinitializeGlobals
| 
| >---------------------------------------------------------------
| 
|  compiler/simplCore/CoreMonad.lhs | 36 +++++++++++++++++++++++++++++++--
| ---
|  compiler/utils/FastString.lhs    | 15 ++++++++++++++-
|  2 files changed, 45 insertions(+), 6 deletions(-)
| 
| diff --git a/compiler/simplCore/CoreMonad.lhs
| b/compiler/simplCore/CoreMonad.lhs
| index e11c139..7fe5554 100644
| --- a/compiler/simplCore/CoreMonad.lhs
| +++ b/compiler/simplCore/CoreMonad.lhs
| @@ -722,11 +722,12 @@ data CoreReader = CoreReader {
|          cr_hsc_env :: HscEnv,
|          cr_rule_base :: RuleBase,
|          cr_module :: Module,
| -        cr_globals :: ((Bool, [String]),
| +        cr_globals :: (,,)    (Bool, [String]) -- from StaticFlags
| +                              FastStringTable  -- from FastString
|  #ifdef GHCI
| -                       (MVar PersistentLinkerState, Bool))
| +                              (MVar PersistentLinkerState, Bool) --
| from Linker
|  #else
| -                       ())
| +                              ()
|  #endif
|  }
| 
| @@ -789,7 +790,7 @@ runCoreM :: HscEnv
|           -> CoreM a
|           -> IO (a, SimplCount)
|  runCoreM hsc_env rule_base us mod m = do
| -        glbls <- liftM2 (,) saveStaticFlagGlobals saveLinkerGlobals
| +        glbls <- liftM3 (,,) saveStaticFlagGlobals saveFSTable
| saveLinkerGlobals
|          liftM extract $ runIOEnv (reader glbls) $ unCoreM m state
|    where
|      reader glbls = CoreReader {
| @@ -891,6 +892,8 @@ getOrigNameCache = do
|  %*									*
| 
| %***********************************************************************
| *
| 
| +Note [Initializing globals]
| +
|  This is a rather annoying function. 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
| @@ -921,13 +924,36 @@ I've threaded the cr_globals through CoreM rather
| than giving them as an
|  argument to the plugin function so that we can turn this function into
|  (return ()) without breaking any plugins when we eventually get 1.
| working.
| 
| +-----
| +
| +We include the FastString table in this mechanism, because we'd like
| +FastStrings created by the plugin to have the same uniques as similar
| strings
| +created by the host compiler itself.  For example, this allows plugins
| to
| +lookup known names (eg `mkTcOcc "MySpecialType"`) in the GlobalRdrEnv
| or even
| +re-invoke the parser.
| +
| +In particular, the following little sanity test was failing in a plugin
| +prototyping safe newtype-coercions.
| +
| +   let rdrName = mkModuleName "GHC.NT.Type" `mkRdrQual` mkTcOcc "NT"
| +   putMsgS $ showSDoc dflags $ ppr $ lookupGRE_RdrName rdrName $
| mg_rdr_env guts
| +
| +`mkTcOcc` involves the lookup (or creation) of a FastString.  Since the
| +plugin's FastString.string_table is empty, constructing the RdrName
| also
| +allocates new uniques for the FastStrings "GHC.NT.Type" and "NT".
| These
| +uniques are almost certainly unequal to the ones that the host compiler
| +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.
| +
|  \begin{code}
|  reinitializeGlobals :: CoreM ()
|  reinitializeGlobals = do
| -    (sf_globals, linker_globals) <- read cr_globals
| +    (sf_globals, fs_table, linker_globals) <- read cr_globals
|      hsc_env <- getHscEnv
|      let dflags = hsc_dflags hsc_env
|      liftIO $ restoreStaticFlagGlobals sf_globals
| +    liftIO $ restoreFSTable fs_table
|      liftIO $ restoreLinkerGlobals linker_globals
|      liftIO $ setUnsafeGlobalDynFlags dflags
|  \end{code}
| diff --git a/compiler/utils/FastString.lhs
| b/compiler/utils/FastString.lhs
| index 36b1b1e..0bdf0a0 100644
| --- a/compiler/utils/FastString.lhs
| +++ b/compiler/utils/FastString.lhs
| @@ -91,7 +91,10 @@ module FastString
|          unpackLitString,
| 
|          -- ** Operations
| -        lengthLS
| +        lengthLS,
| +
| +        -- * Saving/restoring globals
| +        saveFSTable, restoreFSTable, FastStringTable
|         ) where
| 
|  #include "HsVersions.h"
| @@ -573,4 +576,14 @@ fsLit x = mkFastString x
|      forall x . sLit  (unpackCString# x) = mkLitString#  x #-}
|  {-# RULES "fslit"
|      forall x . fsLit (unpackCString# x) = mkFastString# x #-}
| +
| +
| +--------------------
| +-- for plugins; see Note [Initializing globals] in CoreMonad
| +
| +saveFSTable :: IO FastStringTable
| +saveFSTable = readIORef string_table
| +
| +restoreFSTable :: FastStringTable -> IO ()
| +restoreFSTable = writeIORef string_table
|  \end{code}
| 
| 
| 
| _______________________________________________
| ghc-commits mailing list
| ghc-commits at haskell.org
| http://www.haskell.org/mailman/listinfo/ghc-commits