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Posted to commits@harmony.apache.org by "Xiao-Feng Li (JIRA)" <ji...@apache.org> on 2007/06/26 10:05:26 UTC
[jira] Assigned: (HARMONY-4282) [drlvm][gc] obj_info agreement
between VM and GC
[ https://issues.apache.org/jira/browse/HARMONY-4282?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Xiao-Feng Li reassigned HARMONY-4282:
-------------------------------------
Assignee: Xiao-Feng Li
> [drlvm][gc] obj_info agreement between VM and GC
> ------------------------------------------------
>
> Key: HARMONY-4282
> URL: https://issues.apache.org/jira/browse/HARMONY-4282
> Project: Harmony
> Issue Type: Wish
> Components: DRLVM
> Environment: All
> Reporter: Li-Gang Wang
> Assignee: Xiao-Feng Li
>
> The original assumption on obj_info is new object has no obj_info. But I think this is not convenient or necessarily correct to utilize obj_info sufficiently.
> For example, in order to know an object is a small (<= small_threshold) or large (>large_threshold) object, checking a bit in obj_info is more time-saving than searching its size through function vm_object_size. This needs the according bit in obj_info to be set while allocating. But under the original assumption, VM will reset obj_info after allocation sometimes, so that this bit will be misleading. The following is the code resetting obj_info:
> jobject object_clone(JNIEnv *jenv, jobject jobj)
> {
> ......
> result = (ManagedObject*)vm_new_vector_using_vtable_and_thread_pointer(length, vt->clss->get_allocation_handle(), vm_get_gc_thread_local()); // call gc_alloc
> ......
> memcpy(result, h->object, size); // copy the old object
> result->set_obj_info(0); // obj_info is reset here
> ......
> }
> I suggest that we'd better modify the original assumption so that VM and GC could manipulate bits in obj_info they are in charge of without interfering each other.
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