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

[Raffaello Giulietti]

On Sun, 13 Oct 2024 16:03:09 GMT, Raffaello Giulietti <rgiulietti at openjdk.org> wrote:

>> @rgiulietti Good, but I would not put the inequality `maxPowsOf5 <= m + 1` and say that `maxPowsOf5` is never off by more than 1 from the theoretical `m`, because it is not crucial as `m <= maxPowsOf5`, and because `m` is in function of `intVal`, while `maxPowsOf5` is in function of `2^b`, so it is not obvious that there's no power of five `pow` such that `intVal < pow < 2^b`...
>
> What's really crucial for _correctness_ is to ensure maxPowsOf5 >= k.
> 
> But for performance you also want maxPowsOf5 to be as small as possible. So, the fact that it turns out that maxPowsOf5 <= m + 1 guarantees that maxPowsOf5 is the best value that can be computed very efficiently. It's more a "quality of service" guarantee than anything fundamental.

Perhaps leave m <= maxPowsOf5 <= m + 1 and maxPowsOf5 >= k and drop the note "and is never off by more than 1 from the theoretical m"

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PR Review Comment: https://git.openjdk.org/jdk/pull/21323#discussion_r1798430974