On 18/09/10 17:07, Vasily Chekalkin wrote:
On Sat, Sep 18, 2010 at 11:20 PM, Nick Wellnhofer<[email protected]> wrote:
On 18/09/10 06:06, Luben Karavelov wrote:
The idea is that we could dynamically swap vtables of objects that
should be
barriered. The new vtable will contain functions that execute
barrier-ing
logic (card marking, scavenging etc.) and re-dispatch to the original
vtable
function.
That simply doesn't work. It's not enough to run a bit of code before every
vtable function. We have to check every PMC assignment in every vtable
function and all the functions it calls. There's no way around that. Note
that it's completely different in a purely functional language without
assignment like Haskell.
1. It does. All "assignments" are actually vtable calls. E.g.
VTABLE_set_integer_native, etc.
I'm talking about the PMC code here, not PIR. I mean all the assignments
that are done with SET_ATTR macros, or directly in aggregate PMCs.
2. We are not going to "run bit of code before every vtable call".
"Write barrier" vtable will just invoke something like
interp->gc_subsystem->write_barrier(SELF), replace SELF->vtable with
non-protected one and then redispatch call to normal vtable method.
3. When "GC" will move object into older generation it will just
replace PObj->vtable with "write barrier" version.
So you propose to replace every vtable function that does an assignment
to a PMC or STRING with a second version?
Nick
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