Hi! I recently started looking through the JavaScriptCore codebase, and discovered that working on the GC would be a nice way to contribute.
A starting point, I think, would be to implement code that allows moving objects around. I was thinking of doing this by adding a third field to the MethodTable which takes a hashtable mapping addresses of old objects to their new addresses. This function should then modify the structure in question accordingly (to modify the fields to point to the new memory locations wherever needed). This way a basic moving and compacting collector (with two spaces) could be implemented like: 1. Figure out the live objects. 2. Allocate space for them in the other allocation space. Put the old and new address pairs in a map. 3. Ask every live (old) object to re-orient itself using the map generated in (2). 4. Copy the old objects to their designated new locations. Does this make sense? I'm still pretty new to the JSC codebase so I'm not sure about most of what I just said. Another way is, of course, to keep references to references, as mentioned in [1]. I found this approach better since all the heavy lifting happens at GC time, and does not burden the runtime with a double deref. Thank you for your time! [1] http://trac.webkit.org/wiki/JS%20Core%20Garbage%20Collector -- Sanjoy Das http://playingwithpointers.com _______________________________________________ webkit-dev mailing list [email protected] http://lists.webkit.org/mailman/listinfo.cgi/webkit-dev
