Hi Mariano, �Hi All,<div><br></div><div>�� �response below. �But does anyone have any tests for the image segment primitives? �I&#39;m refactoring them and would like some tests.<br><br><div class="gmail_quote">2010/6/3 Mariano Martinez Peck <span dir="ltr">&lt;<a href="mailto:marianopeck@gmail.com">marianopeck@gmail.com</a>&gt;</span><br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">Hi. ImageSegment uses GC to compute the out pointers. Basically, to a given array of roots (a graph) it does:<br><br>1) It marks the rootArray and all root objects by turning on the Garbage Collector bit in the object header of those particular objects.<br>

2) Then does a mark pass over all objects.� This will stop at our marked roots leaving our segment unmarked in their shadow. <br>3) Finally, it unmarks the rootArray and all root objects. <br>4) Only external objects are now marked. <br>

<br>The unmarked objects in the graph of objects of the arrays are those who will be put in the WordArray (the segment) and those who are marked to the outPointers.<br><br>However, I don&#39;t see where step 2) is done in Interpreter &gt;&gt; primitiveStoreImageSegment<br>

<br>In a piece of such method it does:<br><br><br>&quot;Then do a mark pass over all objects.� This will stop at our marked roots,<br>��� thus leaving our segment unmarked in their shadow.&quot;<br>��� savedYoungStart := youngStart.<br>

��� youngStart := self startOfMemory.� &quot;process all of memory&quot;<br>��� ��� &quot;clear the recycled context lists&quot;<br>��� ��� freeContexts := NilContext.<br>��� ��� freeLargeContexts := NilContext.<br>��� self markAndTraceInterpreterOops.��� &quot;and special objects array&quot;<br>

��� youngStart := savedYoungStart.<br>��� <br>&quot;Finally unmark the rootArray and all root objects.&quot;<br>��� self longAt: arrayOfRoots put: ((self longAt: arrayOfRoots) bitAnd: AllButMarkBit).<br>......continue.......<br>

<br>But here I see it is only marking Interpreter oops, not all objects. And I don&#39;t see where all objects are marked even in the code that follows this little piece.<br></blockquote><div><br></div><div>markInterpreterOops marks all objects accessible from the interpreter oops, including the specialObjectsArray, recursively marking any unmarked objects and their referents. �i.e. it marks all objects reachable from the roots of the system. �This would mark all objects in the system were it not for the fact that the primitive marks the rootArray and so�markInterpreterOops does not marl objects /only/ reachable from the rootArray. �So once the rootArray objects have been unmarked, only those objects that should go in the image segment are unmarked.</div>
<div><br></div><div>So the primitive works by</div><div>- marking the objects in rootArray, preventing marking of objects reachable from them in the next step</div><div>- recursively marking all objects reachable from the roots (except those already marked)</div>
<div>- unmarking root objects, leaving the transitive closure of objects accessible from the roots and no where else unmarked</div><div>- writing the unmarked objects to an image segment</div><div><br></div><div><br></div>
<div>HTH</div><div>Eliot</div><div><br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"><br>You can see the comment: &quot;Then do a mark pass over all objects&quot; and even without the comment it makes sense to mark all objects in order to detect outPointers. <br>

<br>Does anyone has a hint?<br><br>Thanks<br><font color="#888888"><br>Mariano<br>
</font><br>_______________________________________________<br>
Pharo-project mailing list<br>
<a href="mailto:Pharo-project@lists.gforge.inria.fr">Pharo-project@lists.gforge.inria.fr</a><br>
<a href="http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project" target="_blank">http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project</a><br></blockquote></div><br></div>