On Thu, 25 Dec 2025 02:01:31 GMT, Shaojin Wen <[email protected]> wrote:
>> In PR #22928, UUID introduced long-based vectorized hexadecimal to string >> conversion, which can also be used in Integer::toHexString and >> Long::toHexString to eliminate table lookups. The benefit of eliminating >> table lookups is that the performance is better when cache misses occur. > > Shaojin Wen has updated the pull request with a new target base due to a > merge or a rebase. The pull request now contains 24 commits: > > - Merge remote-tracking branch 'upstream/master' into optim_to_hex_202501 > - fix merge error > - Merge branch 'master' into optim_to_hex_202501 > - Merge branch 'master' into optim_to_hex_202501 > - Update src/java.base/share/classes/java/util/UUID.java > > Co-authored-by: ExE Boss <[email protected]> > - Merge remote-tracking branch 'upstream/master' into optim_to_hex_202501 > - use right shift > - use right shift > - fix benchmark > - Merge remote-tracking branch 'upstream/master' into optim_to_hex_202501 > - ... and 14 more: https://git.openjdk.org/jdk/compare/73a8629c...d896e365 Changes requested by liach (Reviewer). src/java.base/share/classes/jdk/internal/util/HexDigits.java line 157: > 155: * </pre> > 156: * > 157: */ Documentation here is too long, hard for reading. I recommend something simple like: Prints an unsigned 4-byte number into 8 hexadecimal digits in an ASCII character buffer. The buffer is represented as a big-endian 8 byte integer. Input: 0xA__B__C__D__E__F__0__1 Output: 0x61_62_63_64_65_66_30_31 You can just use `///` to write markdown, which is easier to read too. The performance tricks are in the method already, so I think you can drop them. Also, let's rename this method to `hex8Be` to indicate the return result is big endian, and change the input type to `int` to indicate only the int bits are used. src/java.base/share/classes/jdk/internal/util/HexDigits.java line 181: > 179: long m = (i + 0x0606_0606_0606_0606L) & 0x1010_1010_1010_1010L; > 180: > 181: // Calculate final ASCII values and reverse bytes for proper > ordering Outdated comments, you no longer reverse the bytes ------------- PR Review: https://git.openjdk.org/jdk/pull/22942#pullrequestreview-3695099240 PR Review Comment: https://git.openjdk.org/jdk/pull/22942#discussion_r2719048886 PR Review Comment: https://git.openjdk.org/jdk/pull/22942#discussion_r2719051562
