RFR: 8354471: Assertion failure with -XX:-EnableX86ECoreOpts

[Jatin Bhateja]

On Tue, 15 Apr 2025 03:46:13 GMT, Volodymyr Paprotski <vpaprotski at openjdk.org> wrote:

> The check to choose between AVX2 and AVX512 implementation was relying on `EnableX86ECoreOpts`. It should be relying on `supports_avxifma` and mirror the `UseIntPolyIntrinsics` check in `vm_version_x86.cpp`.
> 
> Note, in `stubGenerator_x86_64.cpp`, entry to the patched function is protected already:
> 
>   if (UseIntPolyIntrinsics) {
>     StubRoutines::_intpoly_montgomeryMult_P256 = generate_intpoly_montgomeryMult_P256();
>     StubRoutines::_intpoly_assign = generate_intpoly_assign();
>   }

src/hotspot/cpu/x86/stubGenerator_x86_64_poly_mont.cpp line 567:

> 565:   __ enter();
> 566: 
> 567:   if (VM_Version::supports_avxifma()) {

As per the latest architecture-instruction-set-extensions-programming-reference document, the upcoming Diamond Rapdis CPU has AVX-IFMA but its also a P-Core Xeon with 512 bit flavour of IFMA, do you think it is performant to generate montgomeryMultiplyAVX2 for it ?

![image](https://github.com/user-attachments/assets/f1247484-180d-4a65-9b79-745a388c0552)

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PR Review Comment: https://git.openjdk.org/jdk/pull/24644#discussion_r2044327464