Integrated: Cleanup NumberSeq additions

[Aleksey Shipilev]

On Thu, 27 Apr 2023 15:31:58 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> I have been looking into how to decrease our upstream exposure for `NumberSeq` changes, and it seems to be not solvable in an easy way. Normally, I would add `AbsSeq::add(AbsSeq& other)` methods and get to that from `HdrSeq::add(HdrSeq& other)`, and that almost works. The remaining bit is figuring out the decaying average/variance thingie. 
> 
> I spent an hour trying to come up with easily provable equations for _combining_ the decaying average/variance. The decaying average is somewhat easy, although there are boundary problems (decaying average treats 0-th element without adjustments, which requires remembering the `_last` element to compensate). Decaying variance looks remarkably scary in the few of my approaches.
> 
> If we enter with current code upstream, it would be the uphill battle to implemented decays and prove they work. So instead, I took the alternative approach of doing everything inside Shenandoah code, except the decays. This reverts `numberSeq.*` to upstream state.
> 
> Additional testing:
>  - [x] Linux x86_64 fastdebug `hotspot_gc_shenandoah`
>  - [x] Linux AArch64 fastdebug `hotspot_gc_shenandoah`
>  - [x] GitFarm

This pull request has now been integrated.

Changeset: 58fa1410
Author:    Aleksey Shipilev <shade at openjdk.org>
URL:       https://git.openjdk.org/shenandoah/commit/58fa1410a8ad1462cbe7c035b7d64f44a0b62c85
Stats:     187 lines in 7 files changed: 71 ins; 69 del; 47 mod

Cleanup NumberSeq additions

Reviewed-by: ysr, rkennke

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PR: https://git.openjdk.org/shenandoah/pull/268