RFR: 8329032: C2 compiler register allocation support for APX EGPRs [v7]

[Jatin Bhateja]

On Wed, 19 Jun 2024 17:00:34 GMT, Sandhya Viswanathan <sviswanathan at openjdk.org> wrote:

>> Jatin Bhateja has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Review comments resolution.
>
> src/hotspot/cpu/x86/assembler_x86.cpp line 11080:
> 
>> 11078: void Assembler::vpgatherdd(XMMRegister dst, Address src, XMMRegister mask, int vector_len) {
>> 11079:   assert(VM_Version::supports_avx2(), "");
>> 11080:   assert(!needs_eevex(src.base(), src.index()), "does not support extended gprs as BASE or INDEX of address operand");
> 
> Why this new assert in vpgatherdd?

These are not promotable to extended EVEX encoding, BASE and INDEX registers of address operand must not be EGPRs. APX support is anyways enabled for AVX512 targets currently, but still it's good to add safety assertions for completeness.

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PR Review Comment: https://git.openjdk.org/jdk/pull/19042#discussion_r1646528050