The long time HotSpot feature of CDS has been rebranded as AOT since JEP 483. For a consistent user experience, we should allow the user to print logs related to AOT using -Xlog:aot.

We have many existing logs that start with the [cds] tag.


The MAJORITY of these logs are for trouble shooting the internal implementation by HotSpot developers. Such logs should be unconditionally converted to use the [aot] tag.

Example:

      if (log_is_enabled(Debug, cds)) {
        ResourceMark rm(THREAD);
        log_debug(cds)(" calling %s", method->name_and_sig_as_C_string());
      }

->

      if (log_is_enabled(Debug, aot)) {
        ResourceMark rm(THREAD);
        log_debug(aot)(" calling %s", method->name_and_sig_as_C_string());
      }

However, there are a few logs that are related to failure conditions with using the CDS archive/AOT cache. Existing user scripts may run with -Xlog:cds and depend on the contents of these logs for diagnostic purposes. E.g.

      log_info(aot)("trying to map %s%s", info, _full_path);
      log_warning(cds)("Unable to read the file header.");

To ease the transition from CDS to AOT, we should try to make such diagnostic logs available under both -Xlog:cds and -Xlog:aot. The proposal is to convert such logs in the HotSpot source code to:

      aot_log_info(aot)("trying to map %s%s", info, _full_path);
      aot_log_warning(aot)("Unable to read the file header.");

When running the "new" AOT workflow, these logs appear in the [aot] channel

     $ java -Xlog:aot -XX:AOTCache=bad.aot ...
     [0.020s][info][cds] trying to map bad.jsa
     [0.020s][warning][cds] Unable to read the file header

However, when running with the "old" CDS workflow, these logs appear in the [cds] channel, so that they can be parsed be existing user scripts.

      $ java -Xlog:cds -XX:SharedArchiveFile=bad.jsa ...
      [0.020s][info][cds] trying to map bad.jsa
      [0.020s][warning][cds] Unable to read the file header

This output flexibility is implemented by the new aot_log_xxx macros. The implementation will be described in the Pull Request.