On Fri, 12 Apr 2024 14:57:45 GMT, Claes Redestad <redes...@openjdk.org> wrote:
>> src/java.base/share/classes/java/lang/invoke/StringConcatFactory.java line
>> 1437:
>>
>>> 1435: for (int c = 0; c < args.parameterCount();
>>> c++) {
>>> 1436: if (constants[c] != null) {
>>> 1437: cb.ldc(constants[c]);
>>
>> I think for Remi's approach, we change:
>> 1. Insert an extra String array (maybe need a way to mark it stable?) arg
>> representing constants
>> 2. Change this ldc into aload + aaload (or List.get if we use immutable List)
>> 3. Call `bindTo(constantStrings)` on the resulting MH
>>
>> This approach can significantly reduce the number of classes spinned instead
>> of generating one class per constant array; might need to measure
>> performance to see if this is a good tradeoff
>>
>> Oh, I just noticed that we need to erase everything to the generic method
>> type. I think Remi's "value class" means there's no overhead for converting
>> primitives into wrappers in this conversion to generic method type.
>
> I'd prefer considering such optimizations as follow-ups. We need to think
> about where to define such shared classes in a way that considers the full
> lifecycle, facilitates class unloading (one cache per classloader?) while
> still getting good reuse.
I think `Invokers` might be a good place. Its lifetime is bound to its MT, and
MT already handles class unloading well. If we are doing erased then a plain
array suffices.
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PR Review Comment: https://git.openjdk.org/jdk/pull/18690#discussion_r1562686793
