RFR: 8369312: Refactor Float.toHexString() to avoid use of regex

[Joe Darcy]

On Tue, 14 Oct 2025 06:43:05 GMT, Alan Bateman <alanb at openjdk.org> wrote:

> Are you planning to add a micro benchmark to go with this?

No; this code path is not performance sensitive, but the new code should run faster.

Hex floating-point output, while informative for testing and debugging, is not commonly used. Subnormal values, the subset of numbers affected here, are rarer still, so it is a corner-case squared situation.

>From a recent refactoring in Float16, one of the reviewers questioned the use of regular expressions for this kind of low-level code and it seemed reasonable to replace the idiom with plain string operations.

(If performance were a concern, we would replicate the tricky logic present to handle double subnormals.)

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PR Comment: https://git.openjdk.org/jdk/pull/27780#issuecomment-3402564984