series of switchpoints or better

[Charles Oliver Nutter]

On Oct 5, 2016 17:43, "Jochen Theodorou" <blackdrag at gmx.org> wrote:
> I see... the problem is actually similar, only that I do not have to do
something like that on a per "subclass added" event, but on a per "method
crud operation" event. And instead of going up to check for a
devirtualization, I have to actually propagate the change to all meta
classes of subclasses... and interface implementation (if the change was
made to an interface). So far I was thinking of making this lazy... but
maybe I should actually mark the classes as "dirty" eagerly... sorry... not
part of the discussion I guess ;)

Oh I think it is certainly relevant! JRuby does this invalidation eagerly,
but the cost can be high for changes to classes close to the root of the
hierarchy. You have fewer guards at each call site, though.

John's description of how Hotspot does this is also helpful; at least in
JRuby, searching up-hierarchy for overridden methods is just a name lookup
since Ruby does not overload. I've prototyped a similar system, with a
SwitchPoint per method, but ran into some hairy class structures that made
it complicated. The override search may be the answer for me.

- Charlie (mobile)
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