On Wed, 15 Oct 2025 00:02:58 GMT, Shaojin Wen <[email protected]> wrote:
>> This PR refactors the Double.toHexString method to improve its performance >> by eliminating the use of StringBuilder and regex operations. The new >> implementation uses a direct byte array approach to construct the hex string >> representation, which avoids the overhead of StringBuilder operations and >> regex pattern matching. >> >> Existing tests in `java/lang/Double/ToHexString.java`. > > The test results run under Mac Book M1 Pro are as follows > > # before 3f11c4307ee1ca918926c8c522d2fc496947980e > -Benchmark Mode Cnt Score Error Units > -Doubles.toHexString avgt 15 228.383 ± 17.172 ns/op > > # after c18f7632f2f2cf0752b3f4651d4cadf95bb859c6 > +Benchmark Mode Cnt Score Error Units > +Doubles.toHexString avgt 15 15.138 ± 1.070 ns/op > > More than 10 times performance improvement > @wenshao What's wrong with my other suggestions? In particular, the `abs()` > line can be moved after the check for `0.0`, and I cannot see the need for > the `0x1000_0000_0000_0000L` bit in `signifBits`. Your suggestion is fine, but I have to deal with them one by one. They should be done by now. Is there anything I missed? ------------- PR Comment: https://git.openjdk.org/jdk/pull/27811#issuecomment-3422618871
