RFR: 8357267: ZGC: Handle APX EGPRs spilling in ZRuntimeCallSpill [v4]

[Roberto Castañeda Lozano]

On Mon, 26 May 2025 12:56:24 GMT, Jatin Bhateja <jbhateja at openjdk.org> wrote:

>> Patch spills APX EGPRs across runtime calls to slow-path barriers using PUSH2P/POP2 instructions with PPX hints.
>> These instructions operate over a pair of registers resulting into an smaller save/restoration JIT code, on the hind side they have hard alignment and balancing constraints, as they operate over 16-byte aligned stack address.
>> ZRuntimeCallSpill is agnostic to live register, thus resulting SPILL sequence should not modify the contents of the register.
>> 
>> Patch has been verified using Intel SDE all test under test/hotspot/jtreg/compiler/gcbarriers are green.
>> 
>> Kindly review and share your feedback.
>> 
>> Best Regards,
>> Jatin
>
> Jatin Bhateja has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Axel's comments incorporated

Test results look good!

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Marked as reviewed by rcastanedalo (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/25351#pullrequestreview-2869935527