RFR: 8351016: RA support for EVEX to REX/REX2 demotion to optimize NDD instructions [v8]

[Jatin Bhateja]

On Wed, 29 Oct 2025 22:44:28 GMT, Dean Long <dlong at openjdk.org> wrote:

>> Jatin Bhateja has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Removing redundant interferecne check from biasing
>
> src/hotspot/cpu/x86/x86_64.ad line 498:
> 
>> 496:     case xorL_rReg_im1_ndd_rule:
>> 497:     case xorL_rReg_ndd_rule:
>> 498:     case xorL_rReg_rReg_mem_ndd_rule:
> 
> Having a list that needs adjusting as new rules are added seems fragile.  Is there a way to detect that a rule is missing here?  Is there an alternative way of implementing this?

Hi @iwanowww , @dean-long , I have moved the demotion candidate marking to the AD file. This will help in better correlation with selection patterns.

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PR Review Comment: https://git.openjdk.org/jdk/pull/26283#discussion_r2516655029