RFR: 8330851: C2: More efficient TypeFunc creation

[Vladimir Ivanov]

On Sat, 16 Nov 2024 00:51:21 GMT, Dean Long <dlong at openjdk.org> wrote:

> For example, new_array_Type() when passes NOTNULL and INT and returns NOTNULL could be represented by something like "NIN".

There's definitely some room for improvement here, but, frankly speaking, stringy descriptors don't look appealing to me. Why not simply introduce `TypeFunc` factory methods which explicitly accept argument/return `Type`s instead? Probably, variadic functions are a good fit here, but even if it's not the case, there are rather few arities used (single return value - void, 1 slot, or 2 slots, plus up to 8 arguments). And that would eliminate lots of boilerplate code as well.

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PR Comment: https://git.openjdk.org/jdk/pull/21782#issuecomment-2480303644