This is mainly to present the direction in which future work
is going, and gather early feedback.
Yes, it incidentally does: D6915 is meant to test that the name mangling happens correctly, and incidentally uses gc.statepoint, gc.relocate to achieve its ends. This is specifically about testing the assembly of lowering.
Can you give me a hint about how vector relocations are supposed to look in assembly? I aim to include changes to SelectionDAG/StatepointLowering with this patch: the first step is to figure out what is wrong with the lowering.