RFR: 8265129: Add intrinsic support for JVM.getClassId [v2]

[Denghui Dong]

On Tue, 27 Apr 2021 09:28:46 GMT, Yi Yang <yyang at openjdk.org> wrote:

>> Denghui Dong has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   add doc
>
> src/hotspot/share/c1/c1_LIRGenerator.cpp line 3049:
> 
>> 3047: 
>> 3048: #ifdef JFR_HAVE_INTRINSICS
>> 3049: void LIRGenerator::do_ClassIDIntrinsic(Intrinsic* x) {
> 
> Is this method really important and hot enough that we need to intrinsify it both in C1 and C2?

This optimization works when user-defined events contain fields of class type, so I think it is necessary to implement it in both C1 and C2

> src/hotspot/share/c1/c1_LIRGenerator.cpp line 3095:
> 
>> 3093: 
>> 3094:   LIR_Opr epoch = new_register(T_INT);
>> 3095:   LIR_Opr epoch_address = new_register(T_LONG);
> 
> new_pointer_register

fixed, thanks.

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PR: https://git.openjdk.java.net/jdk/pull/3470