RFR: 8260617: Merge ZipFile encoding check with the initial hash calculation [v3]

[Lance Andersen]

On Sat, 30 Jan 2021 18:30:59 GMT, Claes Redestad <redestad at openjdk.org> wrote:

>> - Merge checkEncoding into the byte[]-based normalizedHash. The latter is only used from ZipFile.initCEN right after the checkEncoding today, so verifying this is equivalent is straightforward.
>> - Factor out the logic to calculate hash, check encoding etc into the addEntry method to allow JITs to chew off larger chunks of the logic early on
>> 
>> Roughly 1.2x speedup on the JarFileMeta microbenchmarks, which include the time required to open the jar file and thus exercising the optimized code.
>> 
>> Testing: tier1-4
>
> Claes Redestad has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Clarify comments, put normal path branch first in UTF8 checkedHash

Hi Claes

I gone through your changes a couple of times and with your latest updates, the patch looks good.  We should probably consider looking at Zip FS as its initCEN is similar at a future time.

Thank you for your efforts to optimize the performance in this area.

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Marked as reviewed by lancea (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/2306