RFR: 8310813: Simplify and modernize equals, hashCode, and compareTo for BigInteger [v11]

[Roger Riggs]

On Wed, 10 Jan 2024 11:27:53 GMT, Pavel Rappo <prappo at openjdk.org> wrote:

>> Please review this PR to use modern APIs and language features to simplify equals, hashCode, and compareTo for BigInteger. If you have any performance concerns, please raise them.
>> 
>> This PR is cherry-picked from a bigger, not-yet-published PR, to test the waters. That latter PR will be published soon.
>
> Pavel Rappo has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 20 commits:
> 
>  - Use Integer.compareUnsigned
>  - Update copyright years and headers
>  - Merge branch 'master' into 8310813
>  - Merge branch 'master' into 8310813
>  - Merge branch 'master' into 8310813
>  - Merge branch 'master' into 8310813
>  - Merge branch 'master' into 8310813
>  - Fix bugs in Shared.createSingle
>  - Merge branch 'master' into 8310813
>  - Group params coarser (suggested by @cl4es)
>    
>    - Splits 20 params into 3 groups: (S)mall, (M)edium and (L)arge.
>      Every testXYZ method invokes M operations, where M is the maximum
>      number of elements in a group. Shorter groups are cyclically padded.
>    - Uses the org.openjdk.jmh.infra.Blackhole API and increases
>      benchmark time.
>    - Fixes a bug in Shared that precluded 0 from being in a pair.
>  - ... and 10 more: https://git.openjdk.org/jdk/compare/bc05893f...08e6adca

src/java.base/share/classes/java/math/BigInteger.java line 3998:

> 3996:         int i = ArraysSupport.mismatch(m1, m2, len1);
> 3997:         if (i != -1)
> 3998:             return Integer.compareUnsigned(m1[i], m2[i]) < 0 ? -1 : 1;

Just an observation.  The (Java and intrinsic) implementation of Integer.compareUnsigned already returns -1, 0, 1.
Returning `Integer.compareUnsigned(m1[i], m2[i])` would yield the same result without the tertiary expression.

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PR Review Comment: https://git.openjdk.org/jdk/pull/14630#discussion_r1447488470