RFR: 8359965: Enable paired pushp and popp instruction usage for APX enabled CPUs [v2]

[Srinivas Vamsi Parasa]

On Tue, 15 Jul 2025 22:41:17 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:
>> 
>>   rename to paired_push and paired_pop
>
> src/hotspot/cpu/x86/gc/z/zBarrierSetAssembler_x86.cpp line 198:
> 
>> 196:       }
>> 197:     } else {
>> 198:       __ paired_pop(r11);
> 
> No need to use paired pop on this else path as this is for non-APX.

Thanks for the catch! Removed the pushp/popp for the non-APX else path in the updated code.

> src/hotspot/cpu/x86/vm_version_x86.cpp line 156:
> 
>> 154:     // rcx and rdx are first and second argument registers on windows
>> 155: 
>> 156:     __ paired_push(rbp);
> 
> We should not use paired push/pop in vm_version_x86.cpp.

Please see the updated code removing the pushp/popp from vm_version_x86.cpp.

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PR Review Comment: https://git.openjdk.org/jdk/pull/25889#discussion_r2208915438
PR Review Comment: https://git.openjdk.org/jdk/pull/25889#discussion_r2208913711