RFR: 8365053: Refresh hotspot precompiled.hpp with headers based on current frequency [v16]

[Magnus Ihse Bursie]

On Tue, 26 Aug 2025 07:59:33 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 one additional commit since the last revision:
> 
>   remove

The important thing is to record how this was created. But if you can spare the time to actually write it as a script, that would be the best. A runnable script is always better than a step-by-step instruction. That would allow us to rerun this with very little cost at a higher frequency (perhaps once a year, or once per release or so) to automatically keep Hotspot build time optimized.

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PR Comment: https://git.openjdk.org/jdk/pull/26681#issuecomment-3224868516