RFR: 8253899: Make IsClassUnloadingEnabled signature match specification

[David Holmes]

Hi Vladimir,

On 2/10/2020 5:37 pm, Vladimir Kempik wrote:
> On Fri, 2 Oct 2020 07:27:17 GMT, David Holmes <dholmes at openjdk.org> wrote:
> 
>> Okay but look at the example that documentation gives:
>>
>>> For example, if the jvmtiParamInfo returned by GetExtensionEvents indicates that there is a jint parameter, the event
>>> handler should be declared: ```
>>>      void JNICALL myHandler(jvmtiEnv* jvmti_env, jint myInt, ...)
>>> ```
>>
>> The myInt is explicit, just as our "jboolean* enabled" is explicit. I think they key point is that the signature must
>> end with "..." which it does.
>> I don't see anything here that needs to be fixed.
> 
> Hello David. On majority of platforms this would be fine.
> 
> But on some platforms, variadic arguments and non variadic arguments are passed differently ( for example on
> macos-aarch64, variadic args are passed always on stack, non variadic on registers (and on stack for 9th+ arg) , that
> causes issues.

Okay - I see the potential for a problme here but ...

> If you still see no issues here we can delay and make this changeset part of JEP-391.
> But since this changeset isn't much macos-aarch64 specific, I thought it would be good to integrate it separately from
> jep-391.

... this change actually goes against the example in the spec, so if you 
make this change it indicates the spec needs to be updated too.

Cheers,
David
-----

> Regards, Vladimir
> 
> -------------
> 
> PR: https://git.openjdk.java.net/jdk/pull/466
>