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

[Srinivas Vamsi Parasa]

On Sun, 18 May 2025 01:14:21 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 6827:
> 
>> 6825: 
>> 6826: void Assembler::eshrdl(Register dst, Register src1, Register src2, int8_t imm8, bool no_flags) {
>> 6827:   evex_opcode_prefix_and_encode(dst->encoding(), src1->encoding(), src2->encoding(), imm8, VEX_SIMD_NONE, VEX_OPCODE_0F_3C /* MAP4 */, EVEX_32bit, 0xAC, no_flags, true /* is_map1 */);
> 
> Suggestion:
> 
>   emit_eevex_or_demote(dst->encoding(), src1->encoding(), src2->encoding(), imm8, VEX_SIMD_NONE, VEX_OPCODE_0F_3C /* MAP4 */, EVEX_32bit, 0xAC, no_flags, true /* is_map1 */);
> 
> 
> Above nomenclature looks more appropriate here.

Please see the name changed in the latest update.

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PR Review Comment: https://git.openjdk.org/jdk/pull/24431#discussion_r2099066617