RFR: 8339290: Optimize ClassFile Utf8EntryImpl#writeTo [v10]

[Shaojin Wen]

On Tue, 3 Sep 2024 00:38:40 GMT, Shaojin Wen <swen at openjdk.org> wrote:

>> Use fast path for ascii characters 1 to 127 to improve the performance of writing Utf8Entry to BufferWriter.
>
> Shaojin Wen has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - code style
>  - remove unsafe

I also found this point. Using Unsafe does not improve performance. It may require the implementation of instrinsic to be better than C2.

I also changed the code style of BufWriterImpl::writeUTF to make it more similar to DataOutputStream::writeUTF, and plan to use countGreaterThanZero in DataOutputStream#writeUTF later.

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PR Comment: https://git.openjdk.org/jdk/pull/20772#issuecomment-2325422751