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Re: getting rid of ggc_push_context


Jan Hubicka <jh@suse.cz> writes:

> I wonder how desirable is to get rid of ggc_push_context/ggc_pop_context
> machinery.  It should not be terribly dificult deal to make cse.c ggc
> safe but without using ggc_free that would bring other expenses.
> What GGC guys prefer?
>
> Perhaps it might be possible to trottle the cse memory consumption too.
> Does someone recall why this call has been added?

All else being equal, it is highly desirable to get rid of this
machinery.  In ggc-page, it's expensive and it ruins memory locality.
In ggc-zone, I'm not sure if it works at all.  Dan Jacobowitz would
know, but he's out of town.

I seriously wonder whether the ggc_collect call inside CSE is still
necessary.  With the tree optimizers in place, it probably isn't
generating nearly as much garbage as it used too.  And our
memory-pressure heuristic lets us chew up tons of memory before the GC
actually runs, anyway.  Dan had numbers on this, but again, he's out
of town. :(

zw


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