s := ctxt.loader.LookupOrCreateSym(".machosymstr", 0)
	sb := ctxt.loader.MakeSymbolUpdater(s)

	sb.SetType(sym.SMACHOSYMSTR)
	sb.SetReachable(true)
	sb.AddUint8(' ')
	sb.AddUint8('\x00')

	s = ctxt.loader.LookupOrCreateSym(".machosymtab", 0)
	sb = ctxt.loader.MakeSymbolUpdater(s)
	sb.SetType(sym.SMACHOSYMTAB)
	sb.SetReachable(true)

	if ctxt.IsInternal() {

	case BuildModeCShared, BuildModePlugin:
		symIdx := ctxt.loader.LookupOrCreateSym("runtime.islibrary", 0)
		sb := ctxt.loader.MakeSymbolUpdater(symIdx)
		sb.SetType(sym.SNOPTRDATA)
		sb.AddUint8(1)
	case BuildModeCArchive:
		symIdx := ctxt.loader.LookupOrCreateSym("runtime.isarchive", 0)
		sb := ctxt.loader.MakeSymbolUpdater(symIdx)
		sb.SetType(sym.SNOPTRDATA)
		sb.AddUint8(1)
	}

	}
}

func elfadddynsym(ldr *loader.Loader, target *Target, syms *ArchSyms, s loader.Sym) {
	ldr.SetSymDynid(s, int32(Nelfsym))
	Nelfsym++
	d := ldr.MakeSymbolUpdater(syms.DynSym)
	name := ldr.SymExtname(s)
	dstru := ldr.MakeSymbolUpdater(syms.DynStr)
	st := ldr.SymType(s)
	cgoeStatic := ldr.AttrCgoExportStatic(s)
	cgoeDynamic := ldr.AttrCgoExportDynamic(s)
	cgoexp := (cgoeStatic || cgoeDynamic)

			// these symbols are undefined and that's OK.
			if target.IsShared() || target.IsPlugin() {
				if ldr.SymName(rs) == "main.main" || (!target.IsPlugin() && ldr.SymName(rs) == "main..inittask") {
					sb := ldr.MakeSymbolUpdater(rs)
					sb.SetType(sym.SDYNIMPORT)
				} else if strings.HasPrefix(ldr.SymName(rs), "go:info.") {
					// Skip go.info symbols. They are only needed to communicate
					// DWARF info between the compiler and linker.

				if d.ctxt.Debugvlog > 1 {
					d.ctxt.Logf("deadcode: %s rewrite %s ref to %s\n",
						d.ldr.SymName(idx), rsn,
						d.ldr.SymName(d.mapinitnoop))
				}
				if su == nil {
					su = d.ldr.MakeSymbolUpdater(idx)
				}
				su.SetRelocSym(i, d.mapinitnoop)
			}
		}
	}
}

func (d *deadcodePass) mark(symIdx, parent loader.Sym) {
	if symIdx != 0 && !d.ldr.AttrReachable(symIdx) {
		d.wq.push(symIdx)