On Tue, 4 Feb 2025 14:43:51 GMT, Coleen Phillimore <cole...@openjdk.org> wrote:
>> The Class.getModifiers() method is implemented as a native method in
>> java.lang.Class to access a field that we've calculated when creating the
>> mirror. The field is final after that point. The VM doesn't need it
>> anymore, so there's no real need for the jdk code to call into the VM to get
>> it. This moves the field to Java and removes the intrinsic code. I
>> promoted the compute_modifiers() functions to return int since that's how
>> java.lang.Class uses the value. It should really be an unsigned short
>> though.
>>
>> There's a couple of JMH benchmarks added with this change. One does show
>> that for array classes for non-bootstrap class loader, this results in one
>> extra load which in a long loop of just that, is observable. I don't think
>> this is real life code. The other benchmarks added show no regression.
>>
>> Tested with tier1-8.
>
> Coleen Phillimore has updated the pull request incrementally with one
> additional commit since the last revision:
>
> Fix copyright and param name
test/micro/org/openjdk/bench/java/lang/reflect/Clazz.java line 73:
> 71: public int getAppArrayModifiers() {
> 72: return clazzArray.getClass().getModifiers();
> 73: }
I'm guessing this is the benchmark that shows an extra load. How about adding
a benchmark that makes the Clazz[] final or @Stable, and see if that makes the
extra load go away?
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PR Review Comment: https://git.openjdk.org/jdk/pull/22652#discussion_r1942114565
