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

[Andrew Haley]

On Tue, 1 Mar 2022 19:12:17 GMT, Claes Redestad <redestad 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 

Sure. And we don't have to check which of the 8 bytes in a word has its top bit set, so we don't have to do any more work, just return the count when we stopped searching. So there's no possible performance regression on AArch64 as far as I can see.

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