RFR: 8261137: Optimization of Box nodes in uncommon_trap [v8]

[Wang Huang]

On Tue, 23 Mar 2021 17:17:29 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

>> src/hotspot/share/opto/callGenerator.cpp line 597:
>> 
>>> 595:     Node* sobj = new SafePointScalarObjectNode(gvn.type(res)->isa_oopptr(),
>>> 596: #ifdef ASSERT
>>> 597:                                                   call->isa_Allocate(),
>> 
>> It is always `NULL` since `call` can't be an `Allocate`.
>
> It was my suggestion to pass `call` node as allocation so that we could trace back for what node SafePointScalarObject was created because you may have several Box objects for which we create SafePointScalarObject nodes.
> I think we can change argument (and field type) to CallNode. And have assert in SafePointScalarObject constructor to check that it is either Allocate node or Boxing Call node.

Thank you for your review. I will change the  SafePointScalarObject constructor in next push.

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PR: https://git.openjdk.java.net/jdk/pull/2401