return 0
	}
	if b.Controls[1] == nil {
		return 1
	}
	return 2
}

// ControlValues returns a slice containing the non-nil control
// values of the block. The index of each control value will be
// the same as it is in the Controls property and can be used
// in ReplaceControl calls.
func (b *Block) ControlValues() []*Value {
	if b.Controls[0] == nil {
		return b.Controls[:0]
	}
	if b.Controls[1] == nil {

		for _, v := range b.Values {
			for i, a := range v.Args {
				if !valueMark[a.ID] {
					f.Fatalf("%v, arg %d of %s, is missing", a, i, v.LongString())
				}
			}
		}
		for _, c := range b.ControlValues() {
			if !valueMark[c.ID] {
				f.Fatalf("control value for %s is missing: %v", b, c)
			}
		}
	}
	for b := f.freeBlocks; b != nil; b = b.succstorage[0].b {
		if blockMark[b.ID] {

					if _, exist := t.defUse[arg]; !exist {
						t.defUse[arg] = make([]*Value, 0, arg.Uses)
					}
					t.defUse[arg] = append(t.defUse[arg], val)
				}
			}
		}
		for _, ctl := range block.ControlValues() {
			// for control values that can become constants, find their use blocks
			if possibleConst(ctl) {
				t.defBlock[ctl] = append(t.defBlock[ctl], block)
			}
		}
	}
}

				for _, a := range v.Args {
					if a.isFlagOp() {
						score[v.ID] = ScoreReadFlags
					}
				}
			}
		}
		for _, c := range b.ControlValues() {
			// Force the control values to be scheduled at the end,
			// unless they have other special priority.
			if c.Block != b || score[c.ID] < ScoreReadTuple {
				continue
			}

		changed := false
		for _, b := range f.Blocks {
			for _, v := range b.Values {
				changed = visit(v) || changed
			}
			// keep the auto if its address reaches a control value
			for _, c := range b.ControlValues() {
				if n, ok := addr[c]; ok && !used.Has(n) {
					used.Add(n)
					changed = true
				}
			}
		}
		if !changed {
			break
		}
	}

	// Eliminate stores to unread autos.

func (b *Block) replaceUses(old, new *Value) {
	for _, v := range b.Values {
		for i, a := range v.Args {
			if a == old {
				v.SetArg(i, new)
			}
		}
	}
	for i, v := range b.ControlValues() {
		if v == old {
			b.ReplaceControl(i, new)
		}
	}
}

// moveTo moves v to dst, adjusting the appropriate Block.Values slices.
// The caller is responsible for ensuring that this is safe.

	if b.Aux != nil {
		s += html.EscapeString(fmt.Sprintf(" {%v}", b.Aux))
	}
	if t := b.AuxIntString(); t != "" {
		s += html.EscapeString(fmt.Sprintf(" [%v]", t))
	}
	for _, c := range b.ControlValues() {
		s += fmt.Sprintf(" %s", c.HTML())
	}
	if len(b.Succs) > 0 {
		s += " →" // right arrow
		for _, e := range b.Succs {
			c := e.b
			s += " " + c.HTML()
		}
	}

	"cmd/internal/obj/s390x"
)

// ssaMarkMoves marks any MOVXconst ops that need to avoid clobbering flags.
func ssaMarkMoves(s *ssagen.State, b *ssa.Block) {
	flive := b.FlagsLiveAtEnd
	for _, c := range b.ControlValues() {
		flive = c.Type.IsFlags() || flive
	}
	for i := len(b.Values) - 1; i >= 0; i-- {
		v := b.Values[i]
		if flive && v.Op == ssa.OpS390XMOVDconst {
			// The "mark" is any non-nil Aux value.

	"cmd/internal/obj/x86"
)

// ssaMarkMoves marks any MOVXconst ops that need to avoid clobbering flags.
func ssaMarkMoves(s *ssagen.State, b *ssa.Block) {
	flive := b.FlagsLiveAtEnd
	for _, c := range b.ControlValues() {
		flive = c.Type.IsFlags() || flive
	}
	for i := len(b.Values) - 1; i >= 0; i-- {
		v := b.Values[i]
		if flive && v.Op == ssa.Op386MOVLconst {
			// The "mark" is any non-nil Aux value.
			v.Aux = ssa.AuxMark