RFR: 8268231: Aarch64: Use ldp in intrinsics for String.compareTo [v6]

[Andrew Dinn]

On Fri, 17 Sep 2021 07:13:24 GMT, Wu Yan <wuyan at openjdk.org> wrote:

>> It's fine. I don't think it'll affect any real programs, so it's rather pointless. I don't know if that's any reason not to approve it.
>
> Andrew, can you help us to approve this?

I agree with Andrew Haley that this patch is not going to make an improvement for anything but a very small number of applications. Processing of strings over a few 10s of bytes is rare. On the other hand the doesn't seem to cause any performance drop for the much more common case of processing short strings. so it does no harm. Also, the new and old code are much the same in terms of complexity so that is no reason to prefer one over the other. The only real concern I have is that any change involves the risk of error and the ratio of cases that might benefit to cases that might suffer from an error is very low. I don't think that's a reason to avoid pushing this patch upstream but it does suggest that we should not backport it.

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PR: https://git.openjdk.java.net/jdk/pull/4722