RFR: 8329433: Reduce nmethod header size [v3]

[Vladimir Kozlov]

On Tue, 16 Apr 2024 02:28:14 GMT, Dean Long <dlong at openjdk.org> wrote:

>> Vladimir Kozlov has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Union fields which usages do not overlap
>
> src/hotspot/share/code/nmethod.hpp line 282:
> 
>> 280:           _has_flushed_dependencies:1, // Used for maintenance of dependencies (under CodeCache_lock)
>> 281:           _is_unlinked:1,              // mark during class unloading
>> 282:           _load_reported:1;            // used by jvmti to track if an event has been posted for this nmethod
> 
> It seems like the type could be changed from uint8_t to bool.

Is there difference in generated code when you use bool instead of uint8_t?
I used uint8_t to easy change to uint16_t in a future if needed.

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PR Review Comment: https://git.openjdk.org/jdk/pull/18768#discussion_r1566653582