RFR: 8331341: secondary_super_cache does not scale well: C1 and interpreter [v23]

[Dean Long]

On Mon, 14 Oct 2024 11:01:29 GMT, Andrew Haley <aph at openjdk.org> wrote:

>> src/hotspot/share/oops/klass.cpp line 406:
>> 
>>> 404:     }
>>> 405:     assert(i == secondaries->length(), "mismatch");
>>> 406:     postcond((int)population_count(bitmap) <= secondaries->length());
>> 
>> This helps explain my confusion reading fallback_search_secondary_supers().  Could we refer to this invariant there?  And could this be strengthened to :
>> `population_count(bitmap) == secondaries->length() || (population_count(bitmap) == SECONDARY_SUPERS_TABLE_SIZE && secondaries->length() > SECONDARY_SUPERS_TABLE_SIZE)`
>> ?
>
> We can't assert that here, because at this point we know `length <= SECONDARY_SUPERS_TABLE_SIZE - 2`.

Doesn't that mean `population_count(bitmap) == secondaries->length()`?

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PR Review Comment: https://git.openjdk.org/jdk/pull/19989#discussion_r1799980535