Re: [rvm-research] Regarding GC

Hi Mike,
Thank you for the reply. I just don't want to assume anything. So just want
to know that before I make progress in my work.


On Wed, Aug 27, 2014 at 1:34 PM, Michael Hind <[email protected]> wrote:

> The single statement in your snippet  is eventually expanded by the
> compiler into a sequence of indirect loads (think assembly level
> programming).     A GCmap is (logically) created for each such
> (assembly-like) instruction that contains the current live stack roots.
>  So, before the snippet it will contain what head (a local variable) points
> to and then as the sequence is executed (one indirection at a time) and
> head is updated, the stack root set is updated.
>
> So the answer is
>   - yes, there are points in the sequence where a stack root is pointing
> to each node in the list 1-6, but
>   - no, there is not a single point in the sequence where the stack roots
> point to all these nodes
>
> Mike
> _____________________________________________________________
> Michael Hind, Senior Manager, Programming Technologies Department
> IBM T.J. Watson Research Center
> http://www.research.ibm.com/people/h/hind
> 914 945-2712
> My internal blog:  https://w3-connections.ibm.com/blogs/hindsight
>
>
>
> From:        Hari Krishnan <[email protected]>
> To:        "General discussion of Jikes RVM design, implementation,
> issues,        and plans" <[email protected]>
> Date:        08/27/2014 12:21 PM
> Subject:        [rvm-research] Regarding GC
> ------------------------------
>
>
>
> Hi,
>
> I have a question. I just want to make if a scenario is possible to
> happen. The scenario goes like this.
>
> I have a cycle of linked list. All nodes have id from 1 to 50 and they are
> arranged in order. There is a head pointer to a node with id 1. I am moving
> this head pointer to node with id 6. Does all the intermediate nodes have
> stack root pointing to them at the interim time during traversal?
>  for example
>
> fun(head){
> head = head->next->next->next->next->next;
> .........
>
>
> }
> In this above snippet,  do all of the intermediate nodes 2 through 5 has
> stack root ("head") pointing to them briefly? or VM figure out and
> calculate the address and move the root from node 1 to node 6 directly?
>
> Cheers
> Hari.
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