Integrated: 8348426: Generate binary file for -XX:AOTMode=record -XX:AOTConfiguration=file

[Ioi Lam]

On Thu, 6 Feb 2025 05:58:51 GMT, Ioi Lam <iklam at openjdk.org> wrote:

> Currently, with `java -XX:AOTMode=record -XX:AOTConfiguration=file ...`, a text file is written. The file contains the names of loaded classes, indices of resolved constant pools entries, etc, that are easily represented in text.
> 
> With the upcoming 2nd JEP of the Leyden project, [JDK-8325147](https://bugs.openjdk.org/browse/JDK-8325147) (Ahead-of-Time Method Profiling), the AOT config file needs to record complex data structures that are difficult to represent in text (we would need code for serializing hierarchical data structures to/from text). Also, a next step after [JDK-8325147](https://bugs.openjdk.org/browse/JDK-8325147) would be to support hidden classes that have no predictable names. Representing such classes with textual names would become another challenge.
> 
> To prepare for  [JDK-8325147](https://bugs.openjdk.org/browse/JDK-8325147), this PR writes the AOT configuration file in a **binary format** (essentially the same format as a CDS archive file). This allows arbitrary data associated with the cached classes to be processed and stored using the existing `MetaspaceClosure` API (which can recursively copy C++ objects). Such a change in the file format is allowed by [JEP 483](https://openjdk.org/jeps/483):
> 
>> the format of the configuration and cache files is not specified and is subject to change without notice.
> 
> **Notes for reviewers:**
> 
> - Although the new config file format is essentially the same as a CDS "static" archive, for sanity, we use a different magic number so that the config file cannot be accidentally used as a CDS archive. See new tests inside AOTFlags.java.
> - After this PR, the CDS "static" archive can be dumped in three modes: "classic", "preimage", and "final". See new comments in cdsConfig.hpp.
> - The main starting point of this PR is `CDSConfig::check_aot_flags()` - it checks the existence of `-XX:AOTConfiguration` and `-XX:AOTMode` to configure the JVM to dump the CDS "preimage" or "final" archives as necessary.
> - Most of the other changes are checks for `CDSConfig::is_dumping_preimage_static_archive()` and `CDSConfig::is_dumping_final_static_archive()` to handle subtlle differences between the different dumping modes.
> - I also updated the UL messages to use the new JEP 483 terminology ("AOT cache", "AOT configuration file",  etc) when JEP 483 options are specified.
> 
> **Misc Note**
> - The changes in [CDS.java and RunTests.gmk](https://github.com/iklam/jdk/commit/0e77a35c25a968c7d931931bc108ccba6dcce4a3) will be integrated separ...

This pull request has now been integrated.

Changeset: 86024ebd
Author:    Ioi Lam <iklam at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/86024ebdb0f06517925c03e52246fbda0bad8f7c
Stats:     1231 lines in 42 files changed: 1014 ins; 47 del; 170 mod

8348426: Generate binary file for -XX:AOTMode=record -XX:AOTConfiguration=file

Reviewed-by: ccheung, asmehra, kvn, iveresov

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PR: https://git.openjdk.org/jdk/pull/23484