RFR: 8265129: Add intrinsic support for JVM.getClassId [v6]

[Vladimir Kozlov]

On Mon, 17 May 2021 07:20:18 GMT, Denghui Dong <ddong at openjdk.org> wrote:

>> 8265129: Add intrinsic support for JVM.getClassId
>
> Denghui Dong has updated the pull request incrementally with one additional commit since the last revision:
> 
>   fix crash problem

So if most frequent path is *the* check then I can understand why inlining it (as intrinsic) will help.

I suggest, first set `prob` parameter for ` __ if_then()` to move slow code from main path. See:
https://github.com/openjdk/jdk/blob/master/src/hotspot/share/gc/g1/c2/g1BarrierSetC2.cpp#L241

Second, if possible move all code under ` __ if_then()` into runtime and make call to it.

Code for arrays looks simple so we can keep it inlined.

And remove code from C1.

-------------

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