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From: cvs at opencores.org<cvs@o...>
Date: Wed Jan 30 20:33:44 CET 2008
Subject: [cvs-checkins] MODIFIED: jop ...
Date: 00/08/01 30:20:33

Modified: jop/java/target/src/common/com/jopdesign/sys GC.java
Log:
- Created a new method to provide support for a write barrier.



Method created:

690: public static final void writeBarrier(int handle, int index)




Revision Changes Path
1.52 jop/java/target/src/common/com/jopdesign/sys/GC.java

http://www.opencores.org/cvsweb.shtml/jop/java/target/src/common/com/jopdesign/sys/GC.java.diff?r1=1.51&r2=1.52

(In the diff below, changes in quantity of whitespace are not shown.)

Index: GC.java
===================================================================
RCS file: /cvsroot/paulo/jop/java/target/src/common/com/jopdesign/sys/GC.java,v
retrieving revision 1.51
retrieving revision 1.52
diff -u -b -r1.51 -r1.52
--- GC.java 18 Jan 2008 22:45:10 -0000 1.51
+++ GC.java 30 Jan 2008 19:33:44 -0000 1.52
@@ -680,6 +680,90 @@
return isValid;
}

+ /**
+ * Write barrier for an object field. May be used with regular objects
+ * and reference arrays.
+ *
+ * @param handle the object handle
+ * @param index the field index
+ */
+ public static final void writeBarrier(int handle, int index)
+ {
+ boolean shouldExecuteBarrier = false;
+ int gcInfo;
+
+// log("WriteBarrier: snapshot-at-beginning.");
+
+ if (handle == 0)
+ {
+ throw new NullPointerException();
+ }
+
+ synchronized (GC.mutex)
+ {
+ // ignore objects with size zero (is this correct?)
+ if(Native.rdMem(handle) == 0)
+ {
+// log("ignore objects with size zero");
+ return;
+ }
+
+ // get information on the object type.
+ int type = Native.rdMem(handle + GC.OFF_TYPE);
+
+ // if it's an object or reference array, execute the barrier
+ if(type == GC.IS_REFARR)
+ {
+// log("Reference array.");
+ shouldExecuteBarrier = true;
+ }
+
+ if(type == GC.IS_OBJ)
+ {
+// log("Regular object.");
+ // get the object GC info from the class structure.
+ gcInfo = Native.rdMem(handle + GC.OFF_MTAB_ALEN) + Const.MTAB2GC_INFO;
+
+ // if the correct bit is set for the field, it may hold a reference.
+ // then, execute the write barrier.
+ if((gcInfo & (0x01 << index)) != 0)
+ {
+// log("Field can hold a reference. Execute barrier!");
+ shouldExecuteBarrier = true;
+ }
+ }
+
+ // execute the write barrier, if necessary.
+ if(shouldExecuteBarrier)
+ {
+ // handle indirection
+ handle = Native.rdMem(handle);
+ // snapshot-at-beginning barrier
+ int oldVal = Native.rdMem(handle+index);
+
+// log("Old val: ", oldVal);
+// if(oldVal != 0)
+// {
+// log("Current space: ", Native.rdMem(oldVal+GC.OFF_SPACE));
+// }
+// else
+// {
+// log("Current space: NULL object."); +// } +// log("toSpace: ", GC.toSpace); + + if (oldVal!=0 && Native.rdMem(oldVal+GC.OFF_SPACE)!=GC.toSpace) { +// log("Executing write barrier for old handle: ", handle); + GC.push(oldVal); + } + } +// else +// { +// log("Should not execute the barrier."); +// } + } + } + /************************************************************************************************/