func (r RotateParams) InMask() uint64 {
	return bits.RotateLeft64(r.OutMask(), -int(r.Amount))
}

// OutMerge tries to generate a new set of parameters representing
// the intersection between the selected bits and the provided mask.
// If the intersection is unrepresentable (0 or not contiguous) nil
// will be returned.
func (r RotateParams) OutMerge(mask uint64) *RotateParams {
	mask &= r.OutMask()
	if mask == 0 {
		return nil
	}

	}

	for _, test := range tests {
		if r := test.src.InMerge(test.mask); !eq(r, test.in) {
			t.Errorf("%v merged with %#x (input): want %v, got %v", test.src, test.mask, test.in, r)
		}
		if r := test.src.OutMerge(test.mask); !eq(r, test.out) {
			t.Errorf("%v merged with %#x (output): want %v, got %v", test.src, test.mask, test.out, r)
		}
	}

// Absorb 'rotate then insert selected bits [into zero]' into zero extension.
(MOVWZreg (RISBGZ x {r})) && r.OutMerge(0xffffffff) != nil => (RISBGZ x {*r.OutMerge(0xffffffff)})
(MOVHZreg (RISBGZ x {r})) && r.OutMerge(0x0000ffff) != nil => (RISBGZ x {*r.OutMerge(0x0000ffff)})
(MOVBZreg (RISBGZ x {r})) && r.OutMerge(0x000000ff) != nil => (RISBGZ x {*r.OutMerge(0x000000ff)})

// Absorb shift into 'rotate then insert selected bits [into zero]'.
//

	// match: (MOVBZreg (RISBGZ x {r}))
	// cond: r.OutMerge(0x000000ff) != nil
	// result: (RISBGZ x {*r.OutMerge(0x000000ff)})
	for {
		if v_0.Op != OpS390XRISBGZ {
			break
		}
		r := auxToS390xRotateParams(v_0.Aux)
		x := v_0.Args[0]
		if !(r.OutMerge(0x000000ff) != nil) {
			break
		}
		v.reset(OpS390XRISBGZ)
		v.Aux = s390xRotateParamsToAux(*r.OutMerge(0x000000ff))
		v.AddArg(x)
		return true