RFR: JDK-8266431: Dual-Pivot Quicksort improvements (Radix sort) [v4]

[Laurent Bourgès]

> * Optimized mixed insertion sort
>     * Optimized insertion sort
>     * Optimized Radix sort
>     * Updated microbenchmark
> 
> I am going on previous PR by Vladimir Yaroslavskyi: https://github.com/openjdk/jdk/pull/3938

Laurent Bourgès has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains four additional commits since the last revision:

 - Merge branch 'openjdk:master' into dpqs23
 - rewritten radix sort condition + fixed max buffer size
 - optimized radix sort heuristic
 - JDK-8266431: Dual-Pivot Quicksort improvements (Radix sort)
       * Optimized mixed insertion sort
       * Optimized insertion sort
       * Optimized Radix sort
       * Updated microbenchmark

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/13568/files
  - new: https://git.openjdk.org/jdk/pull/13568/files/ff6b7fcf..1d4af827

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13568&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13568&range=02-03

  Stats: 6880 lines in 138 files changed: 3660 ins; 2487 del; 733 mod
  Patch: https://git.openjdk.org/jdk/pull/13568.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13568/head:pull/13568

PR: https://git.openjdk.org/jdk/pull/13568