RFR: 8367780: Enable UseAPX on Intel CPUs only when both APX_F and APX_NCI_NDD_NF cpuid features are present [v4]

Fri Sep 19 16:27:06 UTC 2025

On Thu, 18 Sep 2025 21:55:13 GMT, Volodymyr Paprotski <vpaprotski at openjdk.org> wrote:

> Change looks good to me
> 
Thanks Vlad for going through the changes and reviewing the PR!

> src/hotspot/cpu/x86/vm_version_x86.cpp line 2928:
> 
>> 2926:   if (sefsl1_cpuid7_edx.bits.apx_f != 0 &&
>> 2927:       xem_xcr0_eax.bits.apx_f != 0 &&
>> 2928:       std_cpuid29_ebx.bits.apx_nci_ndd_nf != 0) {
> 
> was confused why the previous implementation was 'wrong'.. Please clarify that this was triggered "because" of the update to the spec (in the PR description).

Please see the updated PR description which clarifies that this PR was triggered because of the update to the Intel APX spec.

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PR Comment: https://git.openjdk.org/jdk/pull/27320#issuecomment-3312848532
PR Review Comment: https://git.openjdk.org/jdk/pull/27320#discussion_r2363522977