RFR: 8339983: [s390x] secondary_super_cache does not scale well: C1 and interpreter

[Amit Kumar]

On Mon, 2 Dec 2024 11:55:31 GMT, Andrew Haley <aph-open at littlepinkcloud.com> wrote:

> Are there any performance figures? Does the change help, or at least do no harm, on s390?

Hi @RealLucy, 

I guess I made a mistake. So by default `SecondarySupersTable` flag is `enabled/set to true`. By this piece of code: 

  if (FLAG_IS_DEFAULT(UseSecondarySupersTable)) {
    FLAG_SET_DEFAULT(UseSecondarySupersTable, VM_Version::supports_secondary_supers_table());
  } else if (UseSecondarySupersTable && !VM_Version::supports_secondary_supers_table()) {
    warning("UseSecondarySupersTable is not supported");
    FLAG_SET_DEFAULT(UseSecondarySupersTable, false);
  }
  if (!UseSecondarySupersTable) {
    FLAG_SET_DEFAULT(StressSecondarySupers, false);
    FLAG_SET_DEFAULT(VerifySecondarySupers, false);
  }


specifically `FLAG_SET_DEFAULT(UseSecondarySupersTable, VM_Version::supports_secondary_supers_table());`.

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PR Comment: https://git.openjdk.org/jdk/pull/22341#issuecomment-2511385622