#656: Optimization in src/pmc/RetContinuation.pmc:invoke causes segfault
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Reporter: whiteknight | Owner:
Type: todo | Status: new
Priority: normal | Milestone:
Component: none | Version: 1.1.0
Severity: medium | Keywords:
Lang: | Patch:
Platform: |
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After the GC API refactor, there is now a line in
src/pmc/retcontinuation.pmc:invoke() that is commented out:
{{{
/* Parrot_gc_free_pmc_header(interp, SELF); */
}}}
Prior to the refactor, this line was replaced by this sequence:
{{{
VTABLE_destroy(interp, SELF);
{
Arenas *arena_base = interp->arena_base;
Small_Object_Pool *pool = arena_base->pmc_pool;
Small_Object_Pool *ext_pool = arena_base->pmc_ext_pool;
ext_pool->add_free_object(interp, ext_pool,
(PObj *)SELF->pmc_ext);
PObj_flags_SETTO((PObj *)SELF, PObj_on_free_list_FLAG);
pool->add_free_object(interp, pool, (PObj *)SELF);
pool->num_free_objects++;
}
}}}
As far as I can trace it, the two sequences should perform the same exact
sequence of steps in the same order (call the destroy VTABLE, free the
pmc_ext, set the on_free_list flag for the pmc, free the pmc, increment
the number of items on the free list).
After the refactor, this line of code causes a segfault in
t/pmc/packfiledirectory.t, for reasons that I can't figure out. If we can
figure out the segfault, we can uncomment this line and get a performance
win. (I think chromatic said it was something like 2.25%).
--
Ticket URL: <https://trac.parrot.org/parrot/ticket/656>
Parrot <https://trac.parrot.org/parrot/>
Parrot Development
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