RFR: 8365053: Refresh hotspot precompiled.hpp with headers based on current frequency [v8]

[Quan Anh Mai]

On Fri, 8 Aug 2025 14:50:01 GMT, Francesco Andreuzzi <duke at openjdk.org> wrote:

>> In this PR I propose to refresh the included headers in hotspot `precompiled.hpp`. The current set of precompiled headers was refreshed in 2018, 7 years ago. I repeated the same operations and measurements after refreshing the set of precompiled headers according to the current usage frequency.
>> 
>> These are the results I observed. Depending on the platform, the improvement is between 10 and 20% in terms of total work (user+sys). The results are in seconds.
>> 
>> 
>> linux-x64 GCC
>> master      real 81.39 user 3352.15 sys 287.49
>> JDK-8365053 real 81.94 user 3030.24 sys 295.82
>> 
>> linux-x64 Clang
>> master      real 43.44 user 2082.93 sys 130.70
>> JDK-8365053 real 38.44 user 1723.80 sys 117.68
>> 
>> linux-aarch64 GCC
>> master      real 1188.08 user 2015.22 sys 175.53
>> JDK-8365053 real 1019.85 user 1667.45 sys 171.86
>> 
>> linux-aarch64 clang
>> master      real 981.77 user 1645.05 sys 118.60
>> JDK-8365053 real 791.96 user 1262.92 sys 101.50
>
> Francesco Andreuzzi has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - two times might be too much
>  - ops

Marked as reviewed by qamai (Committer).

src/utils/PrecompiledHeaders/PrecompiledHeaders.java line 85:

> 83:                         try {
> 84:                             // The first line contains the object name
> 85:                             return Files.lines(file).skip(1);

Or maybe `return Files.lines(file).skip(1).distinct()`?

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PR Review: https://git.openjdk.org/jdk/pull/26681#pullrequestreview-3101235921
PR Review Comment: https://git.openjdk.org/jdk/pull/26681#discussion_r2263282801