RFR: 8231497: [lworld] Inline type use of Access API (Runtime)

[David Simms]

I agree with your concern here; propose "value_alloc_copy_from_index()" 
for the return oop method ?


On 26/09/19 5:46 PM, Frederic Parain wrote:
> In addition of fixing some GCs issues, it also makes the code
> much cleaner!
>
> Thank you for having included the handling of empty values in
> the copy methods, it will be easier to maintain.
>
> I have an issue with method naming in valueArrayOop.hpp:
>
>   41   static oop value_copy_from_index(valueArrayHandle vah, int index, TRAPS);
>   42   void value_copy_from_index(int index, oop dst) const;
>
> Two methods with the same name, but one returns an oops, the other void,
> one is static, one is not. Even if arguments are different, I’m concerned
> that this overloaded name could lead to confusion.
>
> Regards,
>
> Fred
>
>
>
>> On Sep 26, 2019, at 10:23, David Simms <david.simms at oracle.com> wrote:
>>
>>
>>
>> Bug/RFE: https://bugs.openjdk.java.net/browse/JDK-8231497
>>
>> Webrev: http://cr.openjdk.java.net/~dsimms/valhalla/8231497/webrev0/
>>
>>
>>
>> Hi,
>>
>> So for the longest time Valhalla has completely ignored the Heap Access API, and gone and used write barriers directly, thereby breaking other GCs with different barrier requirements.
>>
>> Here is a 1st pass at adding the required Heap Access API for "inline types", and an runtime (C++) implementation for modBarrierSet and zBarrierSet. No compiler support as yet, I've open another bug[1] for that.
>>
>> Webrev notes:
>>
>> 	• Reviewed the actual Access API changes already with Erik Österlund, he's okayed it.
>> 	• There was some inline header file clean up required, sorry for the noise
>> 	• Hotspot convention uses the Access API in *Oop and * Klass implementation, not directly in runtime code
>> 		• ValueKlass has "value_copy_*" API since it deals with naked payload (inlined layout from different containers), not just oops (otherwise they could have gone into oop API)
>> 	• Rather than a single "value_store", gone with multiple methods so call-site can use the appropriate decorators
>> 		• Remove runtime conditions
>> 		• Feel free to have an opinion on the "value_copy*" API naming
>> 	• Passes testing
>> 		• ValueOops -Xint, C1 and C2 need further fix [1]
>>
>>
>> [1] https://bugs.openjdk.java.net/browse/JDK-8231498
>>