New issue 2212: black -> white pointer in the GC https://bitbucket.org/pypy/pypy/issues/2212/black-white-pointer-in-the-gc
Armin Rigo: It is possible to hit this assertion in our incremental GC: ``` #!python ll_assert(False, "black -> white pointer found") ``` because of the JIT's rewrite.py, which will not put a write barrier before a ``setfield(p0, p1)`` if ``p1`` is an old constant. But p1 might be white and p0 black. I've no clue why the problem doesn't show up more often, but it triggers the assert above with the proper `PYPY_GC_*` env vars. I think that it is not an important issue: in this case, the constant `p1` is also always reachable from the CompiledLoop itself. If we reach the assert in the GC, it's because the ``setfield`` was executed recently, during the same major collection iteration. The loop itself is alive during this iteration---running JIT assembler relies on the loop being alive. So we will anyway see the same ConstPtr from the loop. Is the above reasoning correct? Am I missing an edge case? _______________________________________________ pypy-issue mailing list pypy-issue@python.org https://mail.python.org/mailman/listinfo/pypy-issue
