RFR: 8349452: Fix performance regression for Arrays.fill() with AVX512 [v7]

[Srinivas Vamsi Parasa]

On Mon, 24 Nov 2025 20:46:37 GMT, Sandhya Viswanathan <sviswanathan at openjdk.org> wrote:

>> Srinivas Vamsi Parasa has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   remove all masked stores altogether
>
> src/hotspot/cpu/x86/macroAssembler_x86.cpp line 5642:
> 
>> 5640:   BIND(L_tail);
>> 5641:   addptr(cnt, 4);
>> 5642:   jcc(Assembler::lessEqual, L_end);
> 
> This also might work with jccb.

Verified that jcc at 5642 is needed. The jcc at 5624 can be reverted to jccb.

> src/hotspot/cpu/x86/macroAssembler_x86.cpp line 5768:
> 
>> 5766: 
>> 5767:     decrement(cnt);
>> 5768:     jcc(Assembler::negative, DONE); // Zero length
> 
> This could remain as jccb.

Verified that this jccb to jcc change is needed.

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PR Review Comment: https://git.openjdk.org/jdk/pull/28442#discussion_r2557724635
PR Review Comment: https://git.openjdk.org/jdk/pull/28442#discussion_r2557727935