RFR: 8351994: Enable Extended EVEX to REX2/REX demotion when src and dst are the same [v27]

[Srinivas Vamsi Parasa]

On Sat, 17 May 2025 11:54:29 GMT, Jatin Bhateja <jbhateja at openjdk.org> wrote:

>> Srinivas Vamsi Parasa has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Update x86-asmtest.py to enable demotion by default and make test generation optional
>
> src/hotspot/cpu/x86/assembler_x86.cpp line 1657:
> 
>> 1655: void Assembler::eandl(Register dst, Register src1, Address src2, bool no_flags) {
>> 1656:   InstructionMark im(this);
>> 1657:   evex_prefix_int8_operand(dst, src1, src2, VEX_SIMD_NONE, VEX_OPCODE_0F_3C /* MAP4 */, EVEX_32bit, 0x23, no_flags);
> 
> Nomenclature of routine is not very clear here, what do you mean by int8 operand, this is operating over 32bit word.

Please see the name changed to `evex_opcode_prefix_and_encode` in the updated code.

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PR Review Comment: https://git.openjdk.org/jdk/pull/24431#discussion_r2099012422