RFR: 8349814: [leyden] Reduce uncommon traps in preload code [v8]

[Vladimir Ivanov]

On Tue, 1 Apr 2025 16:58:19 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> Preload code is the C2 code we load very early, before it gets substituted by more advanced C2 code. We are seeing lots of uncommon traps from the preloaded code, though, which invalidates it too early. We can do precompile code without uncommon traps to alleviate this. 
>> 
>> Additional testing:
>>  - [x] Ad-hoc perf tests (see comment below)
>>  - [x] Linux x86_64 server fastdebug, `runtime/cds`
>
> Aleksey Shipilev has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Also a script

Thanks, Aleksey!

Even though the class may be shared (and loaded), `str->is_unresolved_klass()` check prunes not-yet-executed (or effectively dead) code by ensuring that corresponding CP entry is resolved. During assembly phase, CP entries are pre-resolved, so the bug may lurk there. 

I'll take a look. (But I don't see the link to the branch yet.)

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PR Comment: https://git.openjdk.org/leyden/pull/38#issuecomment-2770197755