RFR: 8350607: Consolidate MethodHandles::zero into MethodHandles::constant

[Chen Liang]

On Thu, 20 Feb 2025 02:33:59 GMT, Chen Liang <liach at openjdk.org> wrote:

> LF editor spins classes, this avoids the spinning overhead and should speed up non-capturing lambdas too.
> 
> There may need to be additional intrinsic work for MH combinator lf bytecode generation.

I think this version should be fine: Perfstartup-LambdaNoop's `MethodHandle.constant` instructions have decreased from 99032 to 48507 by eliding the generation of a LF via LambdaFormEditor. Tests seem to be fine too.

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PR Comment: https://git.openjdk.org/jdk/pull/23706#issuecomment-2679834729