symNodes := make(map[*objSymbol]graph.Nodes)
	for _, s := range symbols {
		// Gather samples for this symbol.
		for _, n := range ns {
			if address, err := s.file.ObjAddr(n.Info.Address); err == nil && address >= s.sym.Start && address < s.sym.End {
				symNodes[s] = append(symNodes[s], n)
			}
		}
	}
	return symNodes
}

type assemblyInstruction struct {

			args = args[1:]
		}

		// The code below assumes that we have handled all the ops
		// with sym effects already. Sanity check that here.
		// Ignore Args since they can't be autos.
		if v.Op.SymEffect() != SymNone && v.Op != OpArg {
			panic("unhandled op with sym effect")
		}

		if v.Uses == 0 && v.Op != OpNilCheck && !v.Op.IsCall() && !v.Op.HasSideEffects() || len(args) == 0 {

// identified by the symbol in its Aux field.
type SymEffect int8

const (
	SymRead SymEffect = 1 << iota
	SymWrite
	SymAddr

	SymRdWr = SymRead | SymWrite

	SymNone SymEffect = 0
)

// A Sym represents a symbolic offset from a base register.
// Currently a Sym can be one of 3 things:
//   - a *gc.Node, for an offset from SP (the stack pointer)

	{
		name:      "FwdRef",
		auxType:   auxSym,
		argLen:    0,
		symEffect: SymNone,
		generic:   true,
	},
	{
		name:    "Unknown",
		argLen:  0,
		generic: true,
	},
	{
		name:      "VarDef",
		auxType:   auxSym,
		argLen:    1,
		zeroWidth: true,
		symEffect: SymNone,
		generic:   true,
	},
	{
		name:      "VarLive",
		auxType:   auxSym,