Am 14.01.2014 19:26, schrieb Timon Gehr:
On 01/14/2014 06:56 PM, Benjamin Thaut wrote:
Am 14.01.2014 14:42, schrieb Timon Gehr:
On 01/14/2014 10:20 AM, Benjamin Thaut wrote:
Am 14.01.2014 09:15, schrieb Jacob Carlborg:
On 2014-01-13 22:23, Timon Gehr wrote:
Yes, there is a cost. The requirement to pin arbitrary objects at
arbitrary times, without the possibility to move at pinning time,
invalidates GC algorithms that depend on being able to move _all_
objects within some pool.
Can't these object be pinned somewhere else?
Yes, thats the usual approach. But that means that you have to copy
them
to a other space before pinning, or allocate them in a space that
allows
pinning in the first place.
Once it becomes known that an object should be pinned, it is too late
for moving. (There will then exist a potential pointer to the object.)
Well no, usually you have to pin objects _before_ passing them to
C-land. Pinning is not a automatic process its done manually (or by the
compiler).
Well, there is no such manual mechanism in place, so only strategies
implemented fully within the compiler work.
I think it is not very sensible to let the compiler insert call-backs to
eg. pin objects pointed to from unions. It might as well track occupied
pointer fields explicitly then.
In any case, I think we should just require manual marking of unions and
call it a day.
Yes, but pinning will still be necessary for passing data to C/C++
functions.
