Comment by wren6991

Surprised an article published on September 28, 2025 does not include any mention of the P (packed integer SIMD) extension.

P adds instructions like integer multiply-accumulate, which have a third register read (for rd). So, they're taking the opportunity to add a few forms of 3-register select instructions:

   MVM     Move Masked
           for each bit i:  X(rd)[i] = X(rs2)[i] ? X(rs1)[i] : X(rd)[i]

   MVMN    Move Masked Not
           for each bit i:  X(rd)[i] = X(rs2)[i] ? X(rd)[i]  : X(rs1)[i]

   MERGE   Merge
           for each bit i:  X(rd)[i] = X(rd)[i]  ? X(rs2)[i] : X(rs1)[i]

Actually I say I'm surprised but given the way the spec is currently spread around different parts of the internet, it's easy to miss if you're not following the mailing lists!