RFR: 8341402: BigDecimal's square root optimization [v2]

[Joe Darcy]

On Thu, 3 Oct 2024 00:05:17 GMT, fabioromano1 <duke at openjdk.org> wrote:

>> After changing `BigInteger.sqrt()` algorithm, this can be also used to speed up `BigDecimal.sqrt()` implementation. Here is how I made it.
>> 
>> The main steps of the algorithm are as follows:
>> first argument reduce the value to an integer using the following relations:
>> 
>> x = y * 10 ^ exp
>> sqrt(x) = sqrt(y) * 10^(exp / 2) if exp is even
>> sqrt(x) = sqrt(y*10) * 10^((exp-1)/2) is exp is odd
>> 
>> Then use BigInteger.sqrt() on the reduced value to compute the numerical digits of the desired result.
>> 
>> Finally, scale back to the desired exponent range and perform any adjustment to get the preferred scale in the representation.
>
> fabioromano1 has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Removed stripZerosToEvenScale to simplify the code

I've skimmed the PR; it will likely take me several weeks to come back for an in-depth review.

My initial question is what additional regression test cases should be added to probe the new code.

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PR Comment: https://git.openjdk.org/jdk/pull/21301#issuecomment-2390287137