Optimize classfile read/write

[liach]

This patch tries to optimize classfile reading and writing with multibyte reading and writing utilities in the JDK. If #14636 is integrated first, this patch can be updated to use the improved ByteArray.

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Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
• Change must not contain extraneous whitespace
• Commit message must refer to an issue

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk.git pull/14637/head:pull/14637
$ git checkout pull/14637

Update a local copy of the PR:
$ git checkout pull/14637
$ git pull https://git.openjdk.org/jdk.git pull/14637/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 14637

View PR using the GUI difftool:
$ git pr show -t 14637

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk/pull/14637.diff

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[openjdk]

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[liach]

The results in jdk.classfile.Write benchmark shows no discernable difference. Might need other benchmarks to check out actual performance differences.

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[bridgekeeper]

@liach This pull request has been inactive for more than 16 weeks and will now be automatically closed. If you would like to continue working on this pull request in the future, feel free to reopen it! This can be done using the /open pull request command.