RFR: 8347009: Speed ​​up parseInt and parseLong [v25]

[Chen Liang]

On Thu, 22 Jan 2026 01:31:27 GMT, Shaojin Wen <swen at openjdk.org> wrote:

>> This is an optimization for decimal Integer.parseInt and Long.parseLong, which improves performance by about 10%. The optimization includes:
>> 1. Improve performance by parsing 2 numbers at a time, which has performance improvements for numbers with length >= 3.
>> 2. It uses charAt(0) for the first number. Assuming that the optimization can eliminate boundary checks, this will be more friendly to parsing numbers with length 1.
>> 3. It removes the reliance on the Character.digit method and eliminates the reliance on the CharacterDataLatin1#DIGITS cache array, which avoids performance degradation caused by cache misses.
>
> Shaojin Wen has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 44 commits:
> 
>  - Merge branch 'master' into optim_parse_int_long_202501
>  - remove unsafe
>  - Merge remote-tracking branch 'upstream/master' into optim_parse_int_long_202501
>  - Merge remote-tracking branch 'origin/optim_parse_int_long_202501' into optim_parse_int_long_202501
>  - Merge remote-tracking branch 'upstream/master' into optim_parse_int_long_202501
>    
>    # Conflicts:
>    #	src/java.base/share/classes/java/lang/Integer.java
>    #	src/java.base/share/classes/java/lang/Long.java
>  - Merge remote-tracking branch 'upstream/master' into optim_parse_int_long_202501
>  - Merge remote-tracking branch 'upstream/master' into optim_parse_int_long_202501
>    
>    # Conflicts:
>    #	src/java.base/share/classes/java/lang/Integer.java
>    #	src/java.base/share/classes/java/lang/Long.java
>  - remove ForceInline
>  - fix comments
>  - fix comments
>  - ... and 34 more: https://git.openjdk.org/jdk/compare/a0ac5b34...90778ed9

src/java.base/share/classes/java/lang/Integer.java line 488:

> 486:         byte[] value;
> 487:         if (s == null || radix != 10 || (len = (value = s.value()).length) == 0 || !s.isLatin1()) {
> 488:             return parseInt0(s, radix);

I think you should put radix == 10 optimized code in `parseInt(String)` and redirect `radix == 10` there instead.

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PR Review Comment: https://git.openjdk.org/jdk/pull/22919#discussion_r2719080379