RFR: 8360023: Add an insertion sort implementation to Hotspot [v4]

Quan Anh Mai qamai at openjdk.org
Thu Jun 19 17:15:22 UTC 2025


> Hi,
> 
> This PR adds an implementation of insertion sort to Hotspot. It is an algorithm that is inplace and stable, and it is the ideal algorithm for arrays with small numbers of elements. The motivation for this is [JDK-8357186](https://bugs.openjdk.org/browse/JDK-8357186) in which a stable sort is desired and the number of elements is small. Additionally, since insertion sort is the most efficient sorting algorithm for small arrays, it can be used in non-stable sort as well.
> 
> In addition, I make some improvements to `GrowableArrayIterator`:
> 
> - Make a non-const variant (our current iterator is const only).
> - Add various utility operators to align with a typical iterator.
> 
> [JDK-8360032](https://bugs.openjdk.org/browse/JDK-8360032) is a follow-up work that will build a stable merge-insertion sort on top of this PR.
> 
> Please take a look and share your thoughts. Thanks very much.

Quan Anh Mai has updated the pull request incrementally with one additional commit since the last revision:

  give up on RandomIt

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/25895/files
  - new: https://git.openjdk.org/jdk/pull/25895/files/ef934f6e..f13d739e

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=25895&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=25895&range=02-03

  Stats: 123 lines in 3 files changed: 17 ins; 71 del; 35 mod
  Patch: https://git.openjdk.org/jdk/pull/25895.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25895/head:pull/25895

PR: https://git.openjdk.org/jdk/pull/25895


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