RFR: 8339112: Move JVM Klass flags out of AccessFlags [v2]

[Dean Long]

On Thu, 29 Aug 2024 22:29:43 GMT, Dean Long <dlong at openjdk.org> wrote:

>> Coleen Phillimore has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Add in graal flags and a comment.
>
> src/hotspot/share/ci/ciKlass.cpp line 231:
> 
>> 229: // ------------------------------------------------------------------
>> 230: // ciKlass::misc_flags
>> 231: jint ciKlass::misc_flags() {
> 
> Suggestion:
> 
> u1 ciKlass::misc_flags() {
> 
> I think this should match what misc_flags() returns.  Ideally, I think it should be a typedef like KlassFlags_t so we don't have to make a lot of changes if grows to u2.

Also, using the correct, narrowed type will help with -Wconversion warnings later, because u1 can be converted to both int and size_t without a cast.

> src/hotspot/share/oops/klass.hpp line 436:
> 
>> 434: #endif
>> 435:   static ByteSize bitmap_offset()                { return byte_offset_of(Klass, _bitmap); }
>> 436:   static ByteSize misc_flags_offset()            { return byte_offset_of(Klass, _misc_flags); }
> 
> Suggestion:
> 
>   static ByteSize misc_flags_offset()            { return byte_offset_of(Klass, _misc_flags._flags); }

We probably shouldn't assume the _flags field starts at offset 0.

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PR Review Comment: https://git.openjdk.org/jdk/pull/20719#discussion_r1737296853
PR Review Comment: https://git.openjdk.org/jdk/pull/20719#discussion_r1737306718