Hacker News Reader

I think it's pretty rare for copying GC to be extended to the JIT'd machine code. That is, it only makes a difference if you're moving around the machine code in memory, not if you're moving around data. (The vtables can still be moved around.. all of the function pointers in them are absolute.)

Does Ravenbook also use copying for machine code?

View on HN

There is the caveat that generated machine code can embed addresses of objects that get relocated by the GC. In this case the code needs to be patched even though the code itself doesn't move.

I'm not familiar with Ravenbook. How does it handle GC roots outside the managed heap? I presume it updates the GC roots as it moves the objects they point to, or does it not support GC roots outside the managed heap? If the code refers to managed objects, you need to mark those locations in the machine code as containing GC roots, otherwise, you might GC the referenced objects, which is just as bad as moving them.

Reply on news.ycombinator.com