Add support for StaticPointers in GHCiwip/ghci-staticptrs

Here we add support to GHCi for StaticPointers. This process begins by
adding remote GHCi messages for adding entries to the static pointer
table. We then collect binders needing SPT entries after linking and
send the interpreter a message adding entries with the appropriate
fingerprints.

3 files changed, 47 insertions, 20 deletions

diff --git a/compiler/main/HscMain.hs b/compiler/main/HscMain.hs
index 7d809126bf..fce61649fa 100644
--- a/compiler/main/HscMain.hs
+++ b/compiler/main/HscMain.hs
@@ -82,8 +82,10 @@ module HscMain
     ) where
 
 import Id
+import GHCi             ( addSptEntry )
 import GHCi.RemoteTypes ( ForeignHValue )
 import ByteCodeGen      ( byteCodeGen, coreExprToBCOs )
+import StaticPtrTable   ( collectStaticThings )
 import Linker
 import CoreTidy         ( tidyExpr )
 import Type             ( Type )
@@ -1566,6 +1568,15 @@ hscDeclsWithLocation hsc_env0 str source linenumber =
     let src_span = srcLocSpan interactiveSrcLoc
     liftIO $ linkDecls hsc_env src_span cbc
 
+#ifdef GHCI
+    {- Extract static pointer table entries -}
+    let add_spt_entry :: (Id, Fingerprint) -> Hsc ()
+        add_spt_entry (i, fpr) = do
+            val <- liftIO $ getHValue hsc_env (idName i)
+            liftIO $ addSptEntry hsc_env fpr val
+    mapM_ add_spt_entry (collectStaticThings prepd_binds)
+#endif
+
     let tcs = filterOut isImplicitTyCon (mg_tcs simpl_mg)
         patsyns = mg_patsyns simpl_mg
 
diff --git a/compiler/main/StaticPtrTable.hs b/compiler/main/StaticPtrTable.hs
index 9ec970f453..a64479724e 100644
--- a/compiler/main/StaticPtrTable.hs
+++ b/compiler/main/StaticPtrTable.hs
@@ -46,7 +46,12 @@
 --
 
 {-# LANGUAGE ViewPatterns #-}
-module StaticPtrTable (sptModuleInitCode) where
+{-# LANGUAGE TupleSections #-}
+
+module StaticPtrTable
+  ( sptModuleInitCode
+  , collectStaticThings
+  ) where
 
 -- See SimplCore Note [Grand plan for static forms]
 
@@ -70,24 +75,8 @@ import GHC.Fingerprint
 --
 sptModuleInitCode :: Module -> CoreProgram -> SDoc
 sptModuleInitCode this_mod binds =
-    sptInitCode $ catMaybes
-                $ map (\(b, e) -> ((,) b) <$> staticPtrFp e)
-                $ flattenBinds binds
+    sptInitCode $ collectStaticThings binds
   where
-    staticPtrFp :: CoreExpr -> Maybe Fingerprint
-    staticPtrFp (collectTyBinders -> (_, e))
-      | (Var v, _ : Lit lit0 : Lit lit1 : _) <- collectArgs e
-      , Just con <- isDataConId_maybe v
-      , dataConName con == staticPtrDataConName
-      , Just w0 <- fromPlatformWord64Rep lit0
-      , Just w1 <- fromPlatformWord64Rep lit1
-      = Just $ Fingerprint (fromInteger w0) (fromInteger w1)
-    staticPtrFp _ = Nothing
-
-    fromPlatformWord64Rep (MachWord w)   = Just w
-    fromPlatformWord64Rep (MachWord64 w) = Just w
-    fromPlatformWord64Rep _              = Nothing
-
     sptInitCode :: [(Id, Fingerprint)] -> SDoc
     sptInitCode [] = Outputable.empty
     sptInitCode entries = vcat
@@ -125,3 +114,24 @@ sptModuleInitCode this_mod binds =
                  [ integer (fromIntegral w1) <> text "ULL"
                  , integer (fromIntegral w2) <> text "ULL"
                  ]
+
+-- | Collect all of the bindings that should have static pointer table entries,
+-- along with their fingerprints.
+collectStaticThings :: CoreProgram -> [(Id, Fingerprint)]
+collectStaticThings binds =
+    mapMaybe (\(b, e) -> (b,) <$> staticPtrFp e)
+    $ flattenBinds binds
+  where
+    staticPtrFp :: CoreExpr -> Maybe Fingerprint
+    staticPtrFp (collectTyBinders -> (_, e))
+      | (Var v, _ : Lit lit0 : Lit lit1 : _) <- collectArgs e
+      , Just con <- isDataConId_maybe v
+      , dataConName con == staticPtrDataConName
+      , Just w0 <- fromPlatformWord64Rep lit0
+      , Just w1 <- fromPlatformWord64Rep lit1
+      = Just $ Fingerprint (fromInteger w0) (fromInteger w1)
+    staticPtrFp _ = Nothing
+
+    fromPlatformWord64Rep (MachWord w)   = Just w
+    fromPlatformWord64Rep (MachWord64 w) = Just w
+    fromPlatformWord64Rep _              = Nothing
diff --git a/compiler/main/TidyPgm.hs b/compiler/main/TidyPgm.hs
index 52137a4cd7..55e790b887 100644
--- a/compiler/main/TidyPgm.hs
+++ b/compiler/main/TidyPgm.hs
@@ -379,6 +379,13 @@ tidyProgram hsc_env  (ModGuts { mg_module    = mod
 
               -- See SimplCore Note [Grand plan for static forms]
               ; spt_init_code = sptModuleInitCode mod all_tidy_binds
+              ; add_spt_init_code =
+                  case hscTarget dflags of
+                    -- If we are compiling for the interpreter we will insert
+                    -- any necessary SPT entries dynamically
+                    HscInterpreted -> id
+                    -- otherwise add a C stub to do so
+                    _              -> (`appendStubC` spt_init_code)
 
               -- Get the TyCons to generate code for.  Careful!  We must use
               -- the untidied TypeEnv here, because we need
@@ -413,8 +420,7 @@ tidyProgram hsc_env  (ModGuts { mg_module    = mod
         ; return (CgGuts { cg_module   = mod,
                            cg_tycons   = alg_tycons,
                            cg_binds    = all_tidy_binds,
-                           cg_foreign  = foreign_stubs `appendStubC`
-                                         spt_init_code,
+                           cg_foreign  = add_spt_init_code foreign_stubs,
                            cg_dep_pkgs = map fst $ dep_pkgs deps,
                            cg_hpc_info = hpc_info,
                            cg_modBreaks = modBreaks },