RFR: 8359424: Eliminate table lookup in Integer/Long toHexString [v7]

[Chen Liang]

On Fri, 23 Jan 2026 01:30:31 GMT, Shaojin Wen <swen at openjdk.org> 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 incrementally with one additional commit since the last revision:
> 
>   from liach

src/java.base/share/classes/java/lang/Long.java line 313:

> 311:         int mag = Long.SIZE - Long.numberOfLeadingZeros(i);
> 312:         int len = Math.max(((mag + 3) >> 2), 1);
> 313:         long x = HexDigits.hex8Be((int)i);

Suggestion:

        long x = HexDigits.hex8Be((int) i);

src/java.base/share/classes/java/lang/Long.java line 319:

> 317:                 len -= 8;
> 318:                 Unsafe.getUnsafe().putLongUnaligned(chars, Unsafe.ARRAY_BYTE_BASE_OFFSET + len, x, true);
> 319:                 x = HexDigits.hex8Be((int)(i >>> 32));

Suggestion:

                x = HexDigits.hex8Be((int) (i >>> 32));

Similar indents elsewhere.

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PR Review Comment: https://git.openjdk.org/jdk/pull/22942#discussion_r2719343056
PR Review Comment: https://git.openjdk.org/jdk/pull/22942#discussion_r2719343405