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.

		}
	}

	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.