RFR: 8316180: Thread-local backoff for secondary_super_cache updates [v3]

[Aleksey Shipilev]

On Wed, 20 Sep 2023 15:57:42 GMT, Andrew Haley <aph at openjdk.org> wrote:

>> Aleksey Shipilev has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Use proper 32-bit stores on AArch64
>
> src/hotspot/cpu/aarch64/macroAssembler_aarch64.cpp line 1545:
> 
>> 1543: 
>> 1544:     cmp(rscratch1, (u1) 0);
>> 1545:     br(Assembler::GT, L_skip);
> 
> Suggestion:
> 
>     subsw(rscratch1, rscratch1, 1);
>     strw(rscratch1, Address(rthread, JavaThread::backoff_secondary_super_miss_offset()));
>     br(Assembler::GT, L_skip);

So, does `subsw` have the same condition-code semantics as its x86 sibling? That's nice to know! Thanks, I applied both changes. And then I realized we can actually piggyback on a single counter update, and make a denser code. See new commit!

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PR Review Comment: https://git.openjdk.org/jdk/pull/15718#discussion_r1331882129