RFR: 8316180: Thread-local backoff for secondary_super_cache updates [v4]

[Aleksey Shipilev]

On Mon, 25 Sep 2023 06:23:47 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> src/hotspot/cpu/aarch64/macroAssembler_aarch64.cpp line 1542:
>> 
>>> 1540:     ldrw(rscratch1, Address(rthread, JavaThread::backoff_secondary_super_miss_offset()));
>>> 1541:     subsw(rscratch1, rscratch1, 1);
>>> 1542:     br(Assembler::GT, L_skip);
>> 
>> Suggestion:
>> 
>>     subw(rscratch1, rscratch1, 1);
>>     cbzw(rscratch1, 31, L_skip);
>> 
>> 
>> I know this is >= 0 rather than > 0, but that doesn't matter, and we should make this code small.
>
> Did you mean `tbz(rscratch1, 31, L_skip);` here?

Did `tbz` in the new commit. AFAICS, this indeed makes the flag restoration unnecessary, removed those too. Testing now...

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PR Review Comment: https://git.openjdk.org/jdk/pull/15718#discussion_r1335465467