RFR: 8351994: Enable Extended EVEX to REX2/REX demotion when src and dst are the same [v25]

[Srinivas Vamsi Parasa]

On Thu, 15 May 2025 14:22:24 GMT, Jatin Bhateja <jbhateja at openjdk.org> wrote:

>> Same may also apply to following pattern pairs.
>> 
>> instruct xorI_rReg_mem_rReg_ndd(rRegI dst, memory src1, rRegI src2, rFlagsReg cr)
>> instruct xorI_rReg_rReg_mem_ndd(rRegI dst, rRegI src1, memory src2, rFlagsReg cr)
>> 
>> instruct andL_rReg_mem_rReg_ndd(rRegL dst, memory src1, rRegL src2, rFlagsReg cr)
>> instruct andL_rReg_rReg_mem_ndd(rRegL dst, rRegL src1, memory src2, rFlagsReg cr)
>> 
>> instruct xorL_rReg_mem_rReg_ndd(rRegL dst, memory src1, rRegL src2, rFlagsReg cr)
>> instruct xorL_rReg_rReg_mem_ndd(rRegL dst, rRegL src1, memory src2, rFlagsReg cr)
>
> We should perefer retaining pattens which are opcode affinity towards demoted instrctuon.

Please see the updated x86_64.ad file with the redundant rReg_rReg_mem patterns removed.

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PR Review Comment: https://git.openjdk.org/jdk/pull/24431#discussion_r2091928151