Instruction Encoding in all spaces being RESERVED (Illegal Instruction
Trap if Unvectorizable) or not be allocated at all. This is required
as an inviolate hard rule governing Primary Opcode 9 that may not be
revoked under any circumstances. A useful way to think of this is that
the Prefix Encoding is, like the 8086 REP instruction, an independent
Instruction Encoding in all spaces being RESERVED (Illegal Instruction
Trap if Unvectorizable) or not be allocated at all. This is required
as an inviolate hard rule governing Primary Opcode 9 that may not be
revoked under any circumstances. A useful way to think of this is that
the Prefix Encoding is, like the 8086 REP instruction, an independent