Oh, the real fun begins with SSE4.2 and things like PCMPISTRM (the whole PCMPxSTRx family), where you not only have the mnemonics, but also an 8-bit immediate w

Oh, the real fun begins with SSE4.2 and things like PCMPISTRM (the whole PCMPxSTRx family), where you not only have the mnemonics, but also an 8-bit immediate with each bit specifying a different aspect of operation for the string comparison engine.