RFR: 8315585: Optimization for decimal to string [v5]

[Claes Redestad]

On Thu, 12 Oct 2023 21:49:00 GMT, Shaojin Wen <duke at openjdk.org> wrote:

>> I submitted PR #15555 before, and there were too many changes. I split it into multiple PRs with small changes. This one is one of them.
>> 
>> this PR removed the duplicate code for getChars in BigDecimal#StringBuilderHelper, i also make performance faster.
>> Please review and don't hesitate to critique my approach and patch.
>
> Shaojin Wen has updated the pull request incrementally with one additional commit since the last revision:
> 
>   refactor based on @cl4es 's review

Thanks for simplifying. It seems that even regular `StringBuilder`-based concat gives numbers that are competitive with the baseline this way. I'll file an RFE to examine if we can enable ISC for this.

I've requested another reviewer for this, since I don't have the sufficient floating point domain expertise to review these changes alone.

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Marked as reviewed by redestad (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/16006#pullrequestreview-1676418305