From 4489660aa2efc909cc134f66a58609592a33ab87 Mon Sep 17 00:00:00 2001
From: Max Horn <max@quendi.de>
Date: Fri, 27 Apr 2018 00:59:35 +0200
Subject: [PATCH] kernel: fix marking of precords and component objects

---
 src/objects.c |  4 ++--
 src/precord.c | 31 +++++++++++++++++++++++++++----
 src/precord.h |  4 ++++
 3 files changed, 33 insertions(+), 6 deletions(-)

diff --git a/src/objects.c b/src/objects.c
index 8463ead514..5a5076a0d3 100644
--- a/src/objects.c
+++ b/src/objects.c
@@ -2009,14 +2009,14 @@ static Int InitKernel (
 
     /* install the marking methods                                         */
     InfoBags[         T_COMOBJ          ].name = "object (component)";
-    InitMarkFuncBags( T_COMOBJ          , MarkAllSubBags  );
+    InitMarkFuncBags( T_COMOBJ          , MarkPRecSubBags );
     InfoBags[         T_POSOBJ          ].name = "object (positional)";
     InitMarkFuncBags( T_POSOBJ          , MarkAllSubBags  );
     InfoBags[         T_DATOBJ          ].name = "object (data)";
     InitMarkFuncBags( T_DATOBJ          , MarkOneSubBags  );
 #if !defined(USE_THREADSAFE_COPYING)
     InfoBags[         T_COMOBJ +COPYING ].name = "object (component,copied)";
-    InitMarkFuncBags( T_COMOBJ +COPYING , MarkAllSubBags  );
+    InitMarkFuncBags( T_COMOBJ +COPYING , MarkPRecSubBags );
     InfoBags[         T_POSOBJ +COPYING ].name = "object (positional,copied)";
     InitMarkFuncBags( T_POSOBJ +COPYING , MarkAllSubBags  );
     InfoBags[         T_DATOBJ +COPYING ].name = "object (data,copied)";
diff --git a/src/precord.c b/src/precord.c
index c10c42ce24..ee3558a57e 100644
--- a/src/precord.c
+++ b/src/precord.c
@@ -821,6 +821,29 @@ void LoadPRec( Obj prec )
     }
 }
 
+/****************************************************************************
+**
+*F  MarkPRecSubBags( <bag> ) . . . . marking function for precs and com. objs
+**
+**  'MarkPRecSubBags' is the marking function for bags of type 'T_PREC' or
+**  'T_COMOBJ'.
+*/
+void MarkPRecSubBags(Obj bag)
+{
+    const Bag * data = CONST_PTR_BAG(bag);
+    const UInt count = SIZE_BAG(bag) / sizeof(Bag);
+
+    // while data[0] is unused for regular precords, it used during copying
+    // to store a pointer to the copy; moreover, this mark function is also
+    // used for component objects, which store their type in slot 0
+    MarkBag(data[0]);
+
+    for (UInt i = 3; i < count; i += 2) {
+        MarkBag(data[i]);
+    }
+}
+
+
 /****************************************************************************
 **
 *F * * * * * * * * * * * * * initialize module * * * * * * * * * * * * * * *
@@ -864,11 +887,11 @@ static Int InitKernel (
     /* GASMAN marking functions and GASMAN names                           */
     InitBagNamesFromTable( BagNames );
 
-    InitMarkFuncBags( T_PREC                     , MarkAllSubBags );
-    InitMarkFuncBags( T_PREC +IMMUTABLE          , MarkAllSubBags );
+    InitMarkFuncBags( T_PREC                     , MarkPRecSubBags );
+    InitMarkFuncBags( T_PREC +IMMUTABLE          , MarkPRecSubBags );
 #if !defined(USE_THREADSAFE_COPYING)
-    InitMarkFuncBags( T_PREC            +COPYING , MarkAllSubBags );
-    InitMarkFuncBags( T_PREC +IMMUTABLE +COPYING , MarkAllSubBags );
+    InitMarkFuncBags( T_PREC            +COPYING , MarkPRecSubBags );
+    InitMarkFuncBags( T_PREC +IMMUTABLE +COPYING , MarkPRecSubBags );
 #endif
 
     /* Immutable records are public                                        */
diff --git a/src/precord.h b/src/precord.h
index e753f5c376..f2d23e9769 100644
--- a/src/precord.h
+++ b/src/precord.h
@@ -260,6 +260,10 @@ extern void CopyPRecord(Obj copy, Obj original);
 #endif
 
 
+
+extern void MarkPRecSubBags(Obj bag);
+
+
 /****************************************************************************
 **
 *F * * * * * * * * * * * * * initialize module * * * * * * * * * * * * * * *