RFR: 8318915: Enhance checks in BigDecimal.toPlainString() [v2]

[Raffaello Giulietti]

On Wed, 8 Nov 2023 00:23:22 GMT, Brian Burkhalter <bpb at openjdk.org> wrote:

>> Raffaello Giulietti has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Using repeat() instead of loop.
>
> src/java.base/share/classes/java/math/BigDecimal.java line 3510:
> 
>> 3508:                 : intVal.toString();
>> 3509:             int len = str.length() + trailingZeros;
>> 3510:             if (len < 0) {
> 
> One could use `Math.addExact`, which has an intrinsic, and convert any thrown `ArithmeticException` into an OOME but I am not sure it's worth it.

Yes, I considered that but I'm not sure how the throwing and catching of `ArithmeticException` with `*Exact` intrinsics is optimized by C2, so I have a manual overflow check for the addition.

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PR Review Comment: https://git.openjdk.org/jdk/pull/16457#discussion_r1386307618