RFR: JDK-8311009: Long.toUnsignedString(long, int) doesn't have to create a BigInteger [v2]
Raffaello Giulietti
rgiulietti at openjdk.org
Wed Jun 28 08:09:05 UTC 2023
On Wed, 28 Jun 2023 07:57:25 GMT, Tingjun Yuan <duke at openjdk.org> wrote:
>> This PR changes the implementation of `Long.toUnsignedString(long, int)` for "default" radices, which avoids creating a `BigInteger` and makes use of `Long.divideUnsigned` and `Long.remainderUnsigned`.
>>
>> I've run the test on `test/jdk/java/lang/Long/Unsigned.java` and it works correctly. I believe that there is no need to add more test cases.
>>
>> I've added a benchmark case to `test/micro/org/openjdk/bench/java/lang/Longs.java` for this method. Here is the benchmark result tested on my machine:
>>
>> Before (JDK 20.0.1):
>>
>>
>> Benchmark (size) Mode Cnt Score Error Units
>> Longs.toUnsignedStringNegative 500 avgt 15 6428.711 ± 63.142 us/op
>>
>>
>> After:
>>
>>
>> Benchmark (size) Mode Cnt Score Error Units
>> Longs.toUnsignedStringNegative 500 avgt 15 3823.655 ± 146.171 us/op
>>
>>
>> No CSR needed since the behavior is not changed.
>
> Tingjun Yuan has updated the pull request incrementally with one additional commit since the last revision:
>
> Update copyright year
I checked whether the method is ever searched for reflectively: this seems _not_ be the case in the JDK codebase. So I guess it can be removed from `Long.java`.
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PR Comment: https://git.openjdk.org/jdk/pull/14654#issuecomment-1610958354
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