RFR (XS): 8141677: Improve java.lang.invoke.MemberName hashCode implementation

[Vladimir Ivanov]

Reviewed.

Best regards,
Vladimir Ivanov

On 11/9/15 5:26 PM, Claes Redestad wrote:
> Vladimir,
>
> I instrumented and counted 7 invocations of MethodName.hashCode during
> initialization, so I agree the only real concern from a startup point of
> view is avoiding Byte$ByteCache:
>
> http://cr.openjdk.java.net/~redestad/8141677/webrev.02/
>
> Thanks!
>
> /Claes
>
> On 2015-11-09 12:33, Vladimir Ivanov wrote:
>> Claes,
>>
>> If you want to avoid Byte$ByteCache initialization, don't you achieve
>> the same just by wrapping reference kind manually [1]?
>>
>> Regarding getting rid of varags method call (Objects.hashCode), do you
>> see any measurable improvements? I'm reluctant to see such changes
>> (manual method body inlining) unless the affected code is really hot.
>>
>> Best regards,
>> Vladimir Ivanov
>>
>> [1] diff --git
>> a/src/java.base/share/classes/java/lang/invoke/MemberName.java
>> b/src/java.base/share/classes/java/lang/invoke/MemberName.java
>> --- a/src/java.base/share/classes/java/lang/invoke/MemberName.java
>> +++ b/src/java.base/share/classes/java/lang/invoke/MemberName.java
>> @@ -694,7 +694,7 @@
>>
>>      @Override
>>      public int hashCode() {
>> -        return Objects.hash(clazz, getReferenceKind(), name, getType());
>> +        return Objects.hash(clazz, new Byte(getReferenceKind()),
>> name, getType());
>>      }
>>      @Override
>>      public boolean equals(Object that) {
>>
>> On 11/8/15 3:30 PM, Claes Redestad wrote:
>>> Hi,
>>>
>>> MemberName::hashCode is exercised during startup of jake, and is
>>> currently implemented using Objects.hash(...), which allocates Object[]s
>>> and boxes bytes.
>>>
>>> Inlining this makes this slightly more efficient before the JIT kicks
>>> in, but more measurably allows initialization of Byte$ByteCache to be
>>> deferred from startup:
>>>
>>> bug: https://bugs.openjdk.java.net/browse/JDK-8141677
>>> webrev: http://cr.openjdk.java.net/~redestad/8141677/webrev.01/
>>>
>>> /Claes
>