RFR: 8360559: Optimize Math.sinh for x86 64 bit platforms

[Mohamed Issa]

On Mon, 7 Jul 2025 18:03:54 GMT, Joe Darcy <darcy at openjdk.org> wrote:

> A large fraction of floating-point numbers are in the [-2^(-28), 2^(-28)] range where there is a performance degradation with the new implementation.
> 
> What is the expected distribution of arguments to sinh?

I don't know about an expected distribution of distribution of arguments to sinh. From glancing through research papers though, I get the sense that the [-2^(-28), 2^(-28)] range isn't used all that much. A couple of papers showing this are linked below.

1. [An Analysis of the Hyperbolic Bid Stacking Technique's Use in Modeling Power Prices](https://dl.acm.org/doi/10.1145/3640115.3640182)
2. [Experimental Validation of a 3GPP compliant 5G-based Positioning System](https://dl.acm.org/doi/10.1145/3636534.3697324)

I think the [-2^(-28), 2^(-28)] range isn't all that interesting for sinh anyway as it just returns the input itself. So, I doubt any applications are relying all that heavily on it.

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PR Comment: https://git.openjdk.org/jdk/pull/26152#issuecomment-3046818744