// 64-bit
(MOVDstore [i] {s} p w1 x:(MOVDstore [i-8] {s} p w0 mem))
  && p.Op != OpSB
  && x.Uses == 1
  && is20Bit(int64(i)-8)
  && setPos(v, x.Pos)
  && clobber(x)
  => (STMG2 [i-8] {s} p w0 w1 mem)
(MOVDstore [i] {s} p w2 x:(STMG2 [i-16] {s} p w0 w1 mem))
  && x.Uses == 1
  && is20Bit(int64(i)-16)
  && setPos(v, x.Pos)
  && clobber(x)
  => (STMG3 [i-16] {s} p w0 w1 w2 mem)

		{name: "SumBytes8", argLength: 1, typ: "UInt8"}, // sum all the bytes in arg0 ignoring overflow

		// store multiple
		{
			name:           "STMG2",
			argLength:      4,
			reg:            regInfo{inputs: []regMask{ptrsp, buildReg("R1"), buildReg("R2"), 0}},
			aux:            "SymOff",
			typ:            "Mem",
			asm:            "STMG",

		return true
	}
	return false
}
func rewriteValueS390X_OpS390XSTMG2(v *Value) bool {
	v_3 := v.Args[3]
	v_2 := v.Args[2]
	v_1 := v.Args[1]
	v_0 := v.Args[0]
	// match: (STMG2 [i] {s} p w2 w3 x:(STMG2 [i-16] {s} p w0 w1 mem))
	// cond: x.Uses == 1 && is20Bit(int64(i)-16) && setPos(v, x.Pos) && clobber(x)
	// result: (STMG4 [i-16] {s} p w0 w1 w2 w3 mem)
	for {
		i := auxIntToInt32(v.AuxInt)

	},
	{
		name:   "SumBytes4",
		argLen: 1,
		reg:    regInfo{},
	},
	{
		name:   "SumBytes8",
		argLen: 1,
		reg:    regInfo{},
	},
	{
		name:           "STMG2",
		auxType:        auxSymOff,
		argLen:         4,
		clobberFlags:   true,
		faultOnNilArg0: true,
		symEffect:      SymWrite,
		asm:            s390x.ASTMG,
		reg: regInfo{