[llvm-dev] (no subject)

[Yafei Liu via llvm-dev]

Correct me if I'm wrong:
Relocation in this conversation "relocation" means GC trying to move
objects in the heap for optimization (make the data more impact for bigger
room for example), this move is invisible to a programmer, and if a
compiler support to " relocate objects directly reachable from running
code", a variable (Foo foo) may points to a different address after a GC
happens, while a programmer could still use the name foo in the code as if
nothing happened.

On Sun, Oct 20, 2019 at 4:35 AM Philip Reames via llvm-dev <
llvm-dev at lists.llvm.org> wrote:

> Exactly this.  (As the person who wrote the line in question.)
> On 10/18/19 8:50 AM, Hiroshi Yamauchi via llvm-dev wrote:
>
> I think it's referring to a "moving" garbage collector (as opposed to a
> "non-moving" garbage collector that never moves/relocates objects.) The
> difference is that for a moving one, all pointers need to be tracked and
> potentially updated, whereas for a non-moving one, it's sufficient that at
> least one pointer to a live object is seen (when there may be other
> pointers to the same object elsewhere) for correctness.
>
> On Fri, Oct 18, 2019 at 2:12 AM Yafei Liu via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
>
>> Hi all,
>>
>> I'm investigating on integrating a gc to my llvm project, and when I read this
>> document <http://llvm.org/docs/Statepoints.html>, one sentence confused
>> me:
>>
>> However, for a collector which wishes to relocate objects directly
>> reachable from running code, a higher standard is required.
>>
>> I don't understand what the move "relocate objects directly reachable
>> from running code" trying to do.
>>
>> For my information, the concept "relocate" means the gc pointer refereed
>> to a new location of an object, for example:
>>
>> in Java:
>>
>> Foo foo = new Foo();
>>
>> foo = new Foo(); // ---> a relocation happens
>>
>> So can anyone explain what the "relocate objects directly reachable from
>> running code" trying to do?
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>>
>
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