{name: "RLLG", argLength: 2, reg: sh21, asm: "RLLG"},                  // arg0 rotate left arg1, rotate amount 0-63
		{name: "RLL", argLength: 2, reg: sh21, asm: "RLL"},                    // arg0 rotate left arg1, rotate amount 0-31
		{name: "RLLconst", argLength: 1, reg: gp11, asm: "RLL", aux: "UInt8"}, // arg0 rotate left auxint, rotate amount 0-31

		// Rotate then (and|or|xor|insert) selected bits instructions.
		//

// applying atomic AND operation to target word.
//
// *(*uint32)(ptr &^ 3) &= rotateleft(uint32(val) | 0xffffff00, ((3 << 3) ^ ((ptr & 3) << 3))
//
(AtomicAnd8 ptr val mem)
  => (LANfloor
       ptr
       (RLL <typ.UInt32>
         (ORWconst <typ.UInt32> val [-1<<8])
         (RXSBG <typ.UInt32> {s390x.NewRotateParams(59, 60, 3)} (MOVDconst [3<<3]) ptr))
       mem)

// Atomic or: *(*uint8)(ptr) |= val
//