RFR: 8268764: Use Long.hashCode() instead of int-cast where applicable [v4]

[Sergey Bylokhov]

On Thu, 1 Jul 2021 12:19:53 GMT, Сергей Цыпанов <duke at openjdk.java.net> wrote:

>> In some JDK classes there's still the following hashCode() implementation:
>> 
>> long objNum;
>> 
>> public int hashCode() {
>>     return (int) objNum;
>> }
>> 
>> This outdated expression should be replaced with Long.hashCode(long) as it
>> 
>> - uses all bits of the original value, does not discard any information upfront. For example, depending on how you are generating the IDs, the upper bits could change more frequently (or the opposite).
>> 
>> - does not introduce any bias towards values with more ones (zeros), as it would be the case if the two halves were combined with an OR (AND) operation.
>> 
>> See https://stackoverflow.com/a/4045083
>> 
>> This is related to https://github.com/openjdk/jdk/pull/4309
>
> Сергей Цыпанов has updated the pull request incrementally with one additional commit since the last revision:
> 
>   8268764: Update copy-right year

Marked as reviewed by serb (Reviewer).

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PR: https://git.openjdk.java.net/jdk/pull/4491