From: simonmar <unknown>
Date: Fri, 18 Jul 2003 14:39:06 +0000 (+0000)
Subject: [project @ 2003-07-18 14:39:05 by simonmar]
X-Git-Tag: Approx_11550_changesets_converted~679
X-Git-Url: http://git.megacz.com/?a=commitdiff_plain;h=7ede37c94402b0b8586135172e805445052cb298;p=ghc-hetmet.git

[project @ 2003-07-18 14:39:05 by simonmar]
When doing update-in-place, there is a (small) chance that the thunk
may have been blackholed and another thread might be waiting on it.
We can't therefore just splat it with the value; we have to check
whether it is a blocking queue and awaken any threads that might be
waiting on it if so.

Should fix the scavenge_mutable_list crash reported recently.  If it
does, it will be merged to STABLE.
---

diff --git a/ghc/compiler/absCSyn/AbsCSyn.lhs b/ghc/compiler/absCSyn/AbsCSyn.lhs
index cff7ace..bf9b4ab 100644
--- a/ghc/compiler/absCSyn/AbsCSyn.lhs
+++ b/ghc/compiler/absCSyn/AbsCSyn.lhs
@@ -1,7 +1,7 @@
 %
 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
 %
-% $Id: AbsCSyn.lhs,v 1.53 2003/07/02 13:12:33 simonpj Exp $
+% $Id: AbsCSyn.lhs,v 1.54 2003/07/18 14:39:06 simonmar Exp $
 %
 \section[AbstractC]{Abstract C: the last stop before machine code}
 
@@ -251,6 +251,8 @@ data CStmtMacro
       -- dataToTag# primop -- *only* used in unregisterised builds.
       -- (see AbsCUtils.dsCOpStmt)
   | DATA_TO_TAGZH
+  | AWAKEN_BQ_CLOSURE			-- possibly awaken a blocking quuee
+					-- (used for in-place updates)
 
   | REGISTER_FOREIGN_EXPORT		-- register a foreign exported fun
   | REGISTER_IMPORT			-- register an imported module
diff --git a/ghc/compiler/absCSyn/PprAbsC.lhs b/ghc/compiler/absCSyn/PprAbsC.lhs
index 300b5f4..00c8a73 100644
--- a/ghc/compiler/absCSyn/PprAbsC.lhs
+++ b/ghc/compiler/absCSyn/PprAbsC.lhs
@@ -1306,6 +1306,7 @@ cStmtMacroText UPD_BH_SINGLE_ENTRY	= SLIT("UPD_BH_SINGLE_ENTRY")
 cStmtMacroText PUSH_UPD_FRAME		= SLIT("PUSH_UPD_FRAME")
 cStmtMacroText SET_TAG			= SLIT("SET_TAG")
 cStmtMacroText DATA_TO_TAGZH            = SLIT("dataToTagzh")
+cStmtMacroText AWAKEN_BQ_CLOSURE        = SLIT("AWAKEN_BQ_CLOSURE")
 cStmtMacroText REGISTER_FOREIGN_EXPORT	= SLIT("REGISTER_FOREIGN_EXPORT")
 cStmtMacroText REGISTER_IMPORT		= SLIT("REGISTER_IMPORT")
 cStmtMacroText REGISTER_DIMPORT		= SLIT("REGISTER_DIMPORT")
diff --git a/ghc/compiler/codeGen/CgHeapery.lhs b/ghc/compiler/codeGen/CgHeapery.lhs
index d68c1e4..7cf05ca 100644
--- a/ghc/compiler/codeGen/CgHeapery.lhs
+++ b/ghc/compiler/codeGen/CgHeapery.lhs
@@ -1,7 +1,7 @@
 %
 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
 %
-% $Id: CgHeapery.lhs,v 1.37 2003/07/02 13:12:36 simonpj Exp $
+% $Id: CgHeapery.lhs,v 1.38 2003/07/18 14:39:06 simonmar Exp $
 %
 \section[CgHeapery]{Heap management functions}
 
@@ -372,8 +372,6 @@ allocDynClosure closure_info use_cc blame_cc amodes_with_offsets
 Occasionally we can update a closure in place instead of allocating
 new space for it.  This is the function that does the business, assuming:
 
-	- node points to the closure to be overwritten
-
 	- the new closure doesn't contain any pointers if we're
 	  using a generational collector.
 
@@ -396,6 +394,12 @@ inPlaceAllocDynClosure closure_info head use_cc amodes_with_offsets
     in
 	-- GENERATE THE CODE
     absC ( mkAbstractCs (
-	   [ CInitHdr closure_info head use_cc 0{-no alloc-} ]
+	   [ 
+		-- don't forget to AWAKEN_BQ_CLOSURE: even though we're
+		-- doing update-in-place, the thunk might still have been
+		-- blackholed and another thread might be waiting on it.
+		CMacroStmt AWAKEN_BQ_CLOSURE [head],
+	        CInitHdr closure_info head use_cc 0{-no alloc-}
+ 	   ]
 	   ++ (map do_move amodes_with_offsets)))
 \end{code}
diff --git a/ghc/includes/Updates.h b/ghc/includes/Updates.h
index 952f4d1..0467c07 100644
--- a/ghc/includes/Updates.h
+++ b/ghc/includes/Updates.h
@@ -1,5 +1,5 @@
 /* -----------------------------------------------------------------------------
- * $Id: Updates.h,v 1.31 2003/04/08 15:32:38 sof Exp $
+ * $Id: Updates.h,v 1.32 2003/07/18 14:39:05 simonmar Exp $
  *
  * (c) The GHC Team, 1998-1999
  *
@@ -133,6 +133,13 @@
    Awaken any threads waiting on this computation
    -------------------------------------------------------------------------- */
 
+#define AWAKEN_BQ_CLOSURE(closure)			\
+  {							\
+      const StgInfoTable *info;				\
+      info = ((StgClosure *)closure)->header.info;	\
+      AWAKEN_BQ(info,closure);				\
+  }
+
 #if defined(PAR) 
 
 /*