RFR: 8341470: BigDecimal.stripTrailingZeros() optimization [v42]

[j3graham]

On Sun, 13 Oct 2024 17:48:15 GMT, j3graham <duke at openjdk.org> wrote:

>> src/java.base/share/classes/java/math/BigDecimal.java line 5234:
>> 
>>> 5232:      */
>>> 5233:     private static BigInteger fiveToTwoToThe(int n) {
>>> 5234:         int i = Math.min(n, FIVE_TO_2_TO.length - 1);
>> 
>> BigInteger has “getRadixConversionCache” which could be made accessible and used here - perhaps with a better name.
>
>> @j3graham The benchmarks using `getRadixConversionCache()` look good (see below). The problem with this is that the cache maintained by that method is unlimited, whereas the one controlled by `fiveToTwoToThe()` has modest memory requirements.
>> 
>> ```
> 
> The method here could use the radix cache up to a safe value, and continue the calculation as it currently does beyond that. The benefit would be the existing incremental evaluation.

> I already wrote about that method previously [here](https://github.com/openjdk/jdk/pull/21323#discussion_r1790787304).

Sorry, missed that comment.

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PR Review Comment: https://git.openjdk.org/jdk/pull/21323#discussion_r1798470618