RFR: 8355003: Implement JEP 515: Ahead-of-Time Method Profiling [v15]

[Dan Heidinga]

On Mon, 12 May 2025 19:29:18 GMT, Igor Veresov <iveresov at openjdk.org> wrote:

>> Improve warm-up time by making profile data from a previous run of an application instantly available, when the HotSpot Java Virtual Machine starts. Specifically, enhance the [AOT cache](https://openjdk.org/jeps/483) to store method execution profiles from training runs, reducing profiling delays in subsequent production runs.
>> 
>> More details in the JEP: https://bugs.openjdk.org/browse/JDK-8325147
>
> Igor Veresov has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 45 commits:
> 
>  - Merge branch 'master' into pp2
>  - Address review comments
>  - Merge branch 'master' into pp2
>  - Fix compile
>  - Fix additional issues
>  - Make sure command line flags that affect MDO layout are consistent
>  - Fix semantics change from the previous commit
>  - Port 8355915: [leyden] Crash in MDO clearing the unloaded array type
>  - Fix flag behavior
>  - Fix log tags
>  - ... and 35 more: https://git.openjdk.org/jdk/compare/45dfc2c6...ae332887

src/hotspot/share/cds/filemap.hpp line 120:

> 118:   bool    _compressed_class_ptrs;                 // save the flag UseCompressedClassPointers
> 119:   int     _narrow_klass_pointer_bits;             // save number of bits in narrowKlass
> 120:   int     _narrow_klass_shift;                    // save shift width used to pre-compute narrowKlass IDs in archived heap objectsa

Suggestion:

  int     _narrow_klass_shift;                    // save shift width used to pre-compute narrowKlass IDs in archived heap objects


Minor typo, don't bother fixing if it will result in a re-review cycle

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/24886#discussion_r2085360465