(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)
(MOVDstore [i] {s} p w3 x:(STMG3 [i-24] {s} p w0 w1 w2 mem))
  && x.Uses == 1
  && is20Bit(int64(i)-24)
  && setPos(v, x.Pos)
  && clobber(x)
  => (STMG4 [i-24] {s} p w0 w1 w2 w3 mem)

			asm:            "STMG",
			faultOnNilArg0: true,
			symEffect:      "Write",
			clobberFlags:   true, // TODO(mundaym): currently uses AGFI to handle large offsets
		},
		{
			name:           "STMG3",
			argLength:      5,
			reg:            regInfo{inputs: []regMask{ptrsp, buildReg("R1"), buildReg("R2"), buildReg("R3"), 0}},
			aux:            "SymOff",
			typ:            "Mem",
			asm:            "STMG",

		v.AddArg4(p, w0, w1, mem)
		return true
	}
	// match: (MOVDstore [i] {s} p w2 x:(STMG2 [i-16] {s} p w0 w1 mem))
	// cond: x.Uses == 1 && is20Bit(int64(i)-16) && setPos(v, x.Pos) && clobber(x)
	// result: (STMG3 [i-16] {s} p w0 w1 w2 mem)
	for {
		i := auxIntToInt32(v.AuxInt)
		s := auxToSym(v.Aux)
		p := v_0
		w2 := v_1
		x := v_2

		reg: regInfo{
			inputs: []inputInfo{
				{1, 2},     // R1
				{2, 4},     // R2
				{0, 56318}, // R1 R2 R3 R4 R5 R6 R7 R8 R9 R11 R12 R14 SP
			},
		},
	},
	{
		name:           "STMG3",
		auxType:        auxSymOff,
		argLen:         5,
		clobberFlags:   true,
		faultOnNilArg0: true,
		symEffect:      SymWrite,
		asm:            s390x.ASTMG,
		reg: regInfo{