continue
		}
		// TODO: Consider making two passes where the first
		// just prefetches the mark bits.
		mbits := span.markBitsForIndex(objIndex)
		if mbits.isMarked() {
			continue
		}
		mbits.setMarked()

		// Mark span.
		arena, pageIdx, pageMask := pageIndexOf(span.base())
		if arena.pageMarks[pageIdx]&pageMask == 0 {
			atomic.Or8(&arena.pageMarks[pageIdx], pageMask)
		}

			gcDumpObject("obj", obj, ^uintptr(0))
			getg().m.traceback = 2
			throw("marking free object")
		}

		// If marked we have nothing to do.
		if mbits.isMarked() {
			return
		}
		mbits.setMarked()

		// Mark span.
		arena, pageIdx, pageMask := pageIndexOf(span.base())
		if arena.pageMarks[pageIdx]&pageMask == 0 {
			atomic.Or8(&arena.pageMarks[pageIdx], pageMask)
		}

}

// isMarked reports whether mark bit m is set.
func (m markBits) isMarked() bool {
	return *m.bytep&m.mask != 0
}

// setMarked sets the marked bit in the markbits, atomically.
func (m markBits) setMarked() {
	// Might be racing with other updates, so use atomic update always.
	// We used to be clever here and use a non-atomic update in certain
	// cases, but it's not worth the risk.

	if x > 2 {
		panic(fmt.Sprintf("cannot SetTypecheck %d", x))
	}
	n.bits.set2(miniTypecheckShift, x)
}

func (n *miniNode) Walked() bool     { return n.bits&miniWalked != 0 }
func (n *miniNode) SetWalked(x bool) { n.bits.set(miniWalked, x) }

// Empty, immutable graph structure.

func (n *miniNode) Init() Nodes { return Nodes{} }

// Additional functionality unavailable.

	//
	// Don't add the closure function to compilation queue more than once, since when
	// compiling a function twice would lead to an ICE.
	if !clofn.Walked() {
		clofn.SetWalked(true)
		ir.CurFunc.Closures = append(ir.CurFunc.Closures, clofn)
	}

	typ := typecheck.ClosureType(clo)

	clos := ir.NewCompLitExpr(base.Pos, ir.OCOMPLIT, typ, nil)
	clos.SetEsc(clo.Esc())

	"cmd/compile/internal/types"
	"cmd/internal/src"
)

func walkSelect(sel *ir.SelectStmt) {
	lno := ir.SetPos(sel)
	if sel.Walked() {
		base.Fatalf("double walkSelect")
	}
	sel.SetWalked(true)

	init := ir.TakeInit(sel)

	init = append(init, walkSelectCases(sel.Cases)...)
	sel.Cases = nil

	sel.Compiled = init
	walkStmtList(sel.Compiled)

	base.Pos = lno
}

		}
	}

	walkCall1(n, init)
	return n
}

func walkCall1(n *ir.CallExpr, init *ir.Nodes) {
	if n.Walked() {
		return // already walked
	}
	n.SetWalked(true)

	if n.Op() == ir.OCALLMETH {
		base.FatalfAt(n.Pos(), "OCALLMETH missed by typecheck")
	}

	args := n.Args
	params := n.Fun.Type().Params()

	n.Fun = walkExpr(n.Fun, init)

func walkSwitch(sw *ir.SwitchStmt) {
	// Guard against double walk, see #25776.
	if sw.Walked() {
		return // Was fatal, but eliminating every possible source of double-walking is hard
	}
	sw.SetWalked(true)

	if sw.Tag != nil && sw.Tag.Op() == ir.OTYPESW {
		walkSwitchType(sw)
	} else {
		walkSwitchExpr(sw)
	}
}

// walkSwitchExpr generates an AST implementing sw.  sw is an
// expression switch.