//      z0   z1
	//       \   /
	//       exit
	fun = c.Fun("entry",
		Bloc("entry",
			Valu("mem", OpInitMem, types.TypeMem, 0, nil),
			Valu("c1", OpArg, c.config.Types.Bool, 0, nil),
			If("c1", "b0", "z0")),
		Bloc("b0",
			Valu("c2", OpArg, c.config.Types.Bool, 0, nil),
			If("c2", "z1", "z0")),
		Bloc("z0",
			Goto("exit")),
		Bloc("z1",
			Goto("exit")),
		Bloc("exit",
			Exit("mem"),

func TestSpillWithLoop(t *testing.T) {
	c := testConfig(t)
	f := c.Fun("entry",
		Bloc("entry",
			Valu("mem", OpInitMem, types.TypeMem, 0, nil),
			Valu("ptr", OpArg, c.config.Types.Int64.PtrTo(), 0, c.Temp(c.config.Types.Int64)),
			Valu("cond", OpArg, c.config.Types.Bool, 0, c.Temp(c.config.Types.Bool)),
			Valu("ld", OpAMD64MOVQload, c.config.Types.Int64, 0, nil, "ptr", "mem"), // this value needs a spill
			Goto("loop"),
		),

			Valu("r7", OpAdd64, c.config.Types.Int64, 0, nil, "arg3", "arg1"),
			Valu("r1", OpAdd64, c.config.Types.Int64, 0, nil, "arg1", "arg2"),
			Valu("arg1", OpArg, c.config.Types.Int64, 0, arg1Aux),
			Valu("arg2", OpArg, c.config.Types.Int64, 0, arg2Aux),
			Valu("arg3", OpArg, c.config.Types.Int64, 0, arg3Aux),
			Valu("r9", OpAdd64, c.config.Types.Int64, 0, nil, "r7", "r8"),
			Valu("r4", OpAdd64, c.config.Types.Int64, 0, nil, "r1", "r2"),

	for _, b := range f.Blocks {
		for _, v := range b.Values {
			if !opcodeTable[v.Op].generic {
				continue // lowered
			}
			switch v.Op {
			case OpSP, OpSPanchored, OpSB, OpInitMem, OpArg, OpArgIntReg, OpArgFloatReg, OpPhi, OpVarDef, OpVarLive, OpKeepAlive, OpSelect0, OpSelect1, OpSelectN, OpConvert, OpInlMark, OpWBend:
				continue // ok not to lower
			case OpMakeResult:
				if b.Controls[0] == v {
					continue

	for _, b := range f.Blocks {
		for _, v := range b.Values {
			if v.Op.isLoweredGetClosurePtr() {
				// Must stay in the entry block.
				continue
			}
			switch v.Op {
			case OpPhi, OpArg, OpArgIntReg, OpArgFloatReg, OpSelect0, OpSelect1, OpSelectN:
				// Phis need to stay in their block.
				// Arg must stay in the entry block.
				// Tuple selectors must stay with the tuple generator.

// boundary. Such values don't correspond to a user's understanding of a
// statement boundary.
func notStmtBoundary(op Op) bool {
	switch op {
	case OpCopy, OpPhi, OpVarDef, OpVarLive, OpUnknown, OpFwdRef, OpArg, OpArgIntReg, OpArgFloatReg:
		return true
	}
	return false
}

func (b *Block) FirstPossibleStmtValue() *Value {
	for _, v := range b.Values {
		if notStmtBoundary(v.Op) {
			continue
		}
		return v