Merge branch 'master' of darcs.haskell.org:/srv/darcs//ghc

compiler/codeGen/CgClosure.lhs

@@ -506,9 +506,10 @@ setupUpdate closure_info code
       else do
           tickyPushUpdateFrame
           dflags <- getDynFlags
-          if not opt_SccProfilingOn && dopt Opt_EagerBlackHoling dflags
-              then pushBHUpdateFrame (CmmReg nodeReg) code
-              else pushUpdateFrame   (CmmReg nodeReg) code
+          if blackHoleOnEntry closure_info &&
+             not opt_SccProfilingOn && dopt Opt_EagerBlackHoling dflags
+               then pushBHUpdateFrame (CmmReg nodeReg) code
+               else pushUpdateFrame   (CmmReg nodeReg) code
   
   | otherwise	-- A static closure
   = do 	{ tickyUpdateBhCaf closure_info

compiler/codeGen/ClosureInfo.lhs

@@ -731,7 +731,7 @@ blackHoleOnEntry cl_info
   = case closureLFInfo cl_info of
 	LFReEntrant _ _ _ _	  -> False
         LFLetNoEscape _           -> False
-        LFThunk _ no_fvs _updatable _ _ -> not no_fvs -- to plug space-leaks.
+        LFThunk _ _no_fvs _updatable _ _ -> True
         _other -> panic "blackHoleOnEntry"      -- Should never happen
 
 isKnownFun :: LambdaFormInfo -> Bool

compiler/codeGen/StgCmmBind.hs

@@ -565,12 +565,15 @@ setupUpdate closure_info node body
       then do tickyUpdateFrameOmitted; body
       else do
           tickyPushUpdateFrame
-          --dflags <- getDynFlags
-          let es = [CmmReg (CmmLocal node), mkLblExpr mkUpdInfoLabel]
-          --if not opt_SccProfilingOn && dopt Opt_EagerBlackHoling dflags
-          --  then pushUpdateFrame es body -- XXX black hole
-          --  else pushUpdateFrame es body
-          pushUpdateFrame es body
+          dflags <- getDynFlags
+          let
+              bh = blackHoleOnEntry closure_info &&
+                   not opt_SccProfilingOn && dopt Opt_EagerBlackHoling dflags
+
+              lbl | bh        = mkBHUpdInfoLabel
+                  | otherwise = mkUpdInfoLabel
+
+          pushUpdateFrame [CmmReg (CmmLocal node), mkLblExpr lbl] body
 
   | otherwise	-- A static closure
   = do 	{ tickyUpdateBhCaf closure_info
@@ -579,7 +582,7 @@ setupUpdate closure_info node body
 	  then do	-- Blackhole the (updatable) CAF:
                 { upd_closure <- link_caf True
 		; pushUpdateFrame [CmmReg (CmmLocal upd_closure),
-                                     mkLblExpr mkUpdInfoLabel] body } -- XXX black hole
+                                   mkLblExpr mkBHUpdInfoLabel] body }
 	  else do {tickyUpdateFrameOmitted; body}
     }
 

compiler/codeGen/StgCmmClosure.hs

@@ -728,7 +728,7 @@ blackHoleOnEntry cl_info
   = case closureLFInfo cl_info of
 	LFReEntrant _ _ _ _	  -> False
 	LFLetNoEscape 		  -> False
-        LFThunk _ no_fvs _updatable _ _ -> not no_fvs -- to plug space-leaks.
+        LFThunk _ _no_fvs _updatable _ _ -> True
         _other -> panic "blackHoleOnEntry"      -- Should never happen
 
 isStaticClosure :: ClosureInfo -> Bool

rts/RaiseAsync.c

@@ -156,8 +156,7 @@ throwTo (Capability *cap,	// the Capability we hold
     MessageThrowTo *msg;
 
     msg = (MessageThrowTo *) allocate(cap, sizeofW(MessageThrowTo));
-    // message starts locked; the caller has to unlock it when it is
-    // ready.
+    // the message starts locked; see below
     SET_HDR(msg, &stg_WHITEHOLE_info, CCS_SYSTEM);
     msg->source      = source;
     msg->target      = target;
@@ -166,9 +165,16 @@ throwTo (Capability *cap,	// the Capability we hold
     switch (throwToMsg(cap, msg))
     {
     case THROWTO_SUCCESS:
+        // unlock the message now, otherwise we leave a WHITEHOLE in
+        // the heap (#6103)
+        SET_HDR(msg, &stg_MSG_THROWTO_info, CCS_SYSTEM);
         return NULL;
+
     case THROWTO_BLOCKED:
     default:
+        // the caller will unlock the message when it is ready.  We
+        // cannot unlock it yet, because the calling thread will need
+        // to tidy up its state first.
         return msg;
     }
 }