Integrated: 8354348: Enable Extended EVEX to REX2/REX demotion for commutative operations with same dst and src2

[Srinivas Vamsi Parasa]

On Thu, 28 Aug 2025 21:09:03 GMT, Srinivas Vamsi Parasa <sparasa at openjdk.org> wrote:

> This change extends Extended EVEX (EEVEX) to REX2/REX demotion for Intel APX NDD instructions to handle commutative operations when the destination register and the second source register (src2) are the same.
> 
> Currently, EEVEX to REX2/REX demotion is only enabled when the first source (src1) and the destination are the same. This enhancement allows additional cases of valid demotion for commutative instructions (add, imul, and, or, xor).
> 
> For example:
> `eaddl r18, r25, r18` can be encoded as `addl r18, r25` using APX REX2 encoding
> `eaddl r2, r7, r2` can be encoded as `addl r2, r7` using non-APX legacy encoding

This pull request has now been integrated.

Changeset: c41add8d
Author:    Srinivas Vamsi Parasa <sparasa at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/c41add8d3e24be5f469f18cfbf0f476f2baf63a6
Stats:     3085 lines in 4 files changed: 518 ins; 169 del; 2398 mod

8354348: Enable Extended EVEX to REX2/REX demotion for commutative operations with same dst and src2

Reviewed-by: jbhateja, epeter, sviswanathan

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PR: https://git.openjdk.org/jdk/pull/26997