RFR: 8272120: Avoid looking for standard encodings in "java." modules

[Sergey Bylokhov]

On Tue, 10 Aug 2021 09:18:39 GMT, Alan Bateman <alanb at openjdk.org> wrote:

> It would be useful to get up to date performance data on using Charset vs. charset name. At least historically, the charset name versions were faster (see [JDK-6764325](https://bugs.openjdk.java.net/browse/JDK-6764325)).

The code in question was changed a few times since then, the last change was done by the https://github.com/openjdk/jdk/pull/2102. So currently the code for string.getBytes String/Charset uses the same code paths, except that the string version has an additional call to lookup the charset.
The string version:
https://github.com/openjdk/jdk/blob/66d1faa7847b645f20ab2e966adf0a523e3ffeb2/src/java.base/share/classes/java/lang/String.java#L1753
The charset version:
https://github.com/openjdk/jdk/blob/66d1faa7847b645f20ab2e966adf0a523e3ffeb2/src/java.base/share/classes/java/lang/String.java#L1777

I checked the performance and the charset is always faster, depending on the string size, up to x20.

@cl4es please confirm my observation since you did it already for https://github.com/openjdk/jdk/pull/2102

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PR: https://git.openjdk.java.net/jdk/pull/5063