RFR: 8281146: Replace StringCoding.hasNegatives with countPositives [v6]

[Claes Redestad]

On Tue, 1 Mar 2022 18:32:00 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

> @theRealAph , @a74nh or someone familiar with aarch64 code, please review aarch64 changes.

Note that the aarch64 changes I've put in for now implements `countPositives` to return `0` if there's a negative value anywhere, otherwise `len`. This way we can remove the intrinsic scaffolding for `hasNegatives` once I integrate s390 and ppc changes, but since no precise calculation is implemented for aarch64 then there's no speed-up on micros such as `encodeLatin1LongEnd` for now. I would like to defer such optimization work to a follow-up.

@RealLucy yes, I'd like to integrate your changes into this patch and drop the `HasNegativesNode` et.c. You mentioned in e-mail some issue with the code generation on s390 - has that been resolved or identified?

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PR: https://git.openjdk.java.net/jdk/pull/7231