RFR: 8253566: clazz.isAssignableFrom will return false for interface implementors [v2]

[Roland Westrelin]

On Mon, 5 Oct 2020 07:30:47 GMT, Nils Eliasson <neliasso at openjdk.org> wrote:

>> Roland Westrelin has updated the pull request with a new target base due to a merge or a rebase. The pull request now
>> contains three commits:
>>  - comment
>>  - test
>>  - trichotomy opt should not be applied to subtype check
>
> src/hotspot/share/opto/cfgnode.cpp line 818:
> 
>> 816:   if (!cmp1->is_Cmp() || !cmp2->is_Cmp()) {
>> 817:     return false; // No comparison
>> 818:   } else if (cmp1->Opcode() == Op_CmpF || cmp1->Opcode() == Op_CmpD ||
> 
> This table is getting rather large. Time to add an abstraction on cmp-nodes?

Thanks for reviewing this. The rationale for the existing ones is described here:

https://mail.openjdk.java.net/pipermail/hotspot-compiler-dev/2018-October/030928.html

The reasons for excluding floating point number, pointer comparison and SubTypeCheck don't seem to all fall under a
single common justification that could be abstracted away,

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PR: https://git.openjdk.java.net/jdk/pull/422