RFR: Enable string deduplication in all marking phases

[Aleksey Shipilev]

On 10/02/2018 05:51 PM, Zhengyu Gu wrote:
> Aleksey found that Shenandoah is inconsistent on honoring string deduplication flag.
> 
> Shenandoah string deduplication was initially designed for concurrent marking phases only. Over the
> courses, it diverged. e.g. Traversal GC also performs deduplication in init and final pauses.
> 
> So, let's make it consistent:
> 
> Webrev: http://cr.openjdk.java.net/~zgu/shenandoah/dedup_all_phases/webrev.00/

Good stuff.

*) code_blobs became unused, and instead we are always going via MarkingCodeBlobClosure on product
path? That's very unfortunate. Can we maybe pass the ShenandoahInitMarkRootsClosure into the
do_work, and leave the rest of the code intact? Or even specialize ShenandoahInitMarkRootsTask with
STRING_DEDUP?

*) If thing above is not an issue, let's clean up this block a bit:
    - L105 needs the space after comma.
    - "cldCl" and "blobsCl" need to be "cld_cl" and "blobs_cl", respectively

 104     if (ShenandoahStringDedup::is_enabled()) {
 105       ShenandoahInitMarkRootsClosure<UPDATE_REFS,ENQUEUE_DEDUP> mark_cl(q);
 106       CLDToOopClosure cldCl(&mark_cl);
 107       MarkingCodeBlobClosure blobsCl(&mark_cl, ! CodeBlobToOopClosure::FixRelocations);
 108       do_work(heap, &mark_cl, _process_refs ? NULL : &mark_cl, &cldCl, &blobsCl, worker_id);
 109     } else {
 110       ShenandoahInitMarkRootsClosure<UPDATE_REFS, NO_DEDUP> mark_cl(q);
 111       CLDToOopClosure cldCl(&mark_cl);
 112       MarkingCodeBlobClosure blobsCl(&mark_cl, ! CodeBlobToOopClosure::FixRelocations);
 113       do_work(heap, &mark_cl, _process_refs ? NULL : &mark_cl, &cldCl, &blobsCl, worker_id);
 114     }


Thanks,
-Aleksey