switch r.Type() {
		default:
			return val, 0, false
		case objabi.R_LOONG64_ADDR_HI,
			objabi.R_LOONG64_ADDR_LO:
			// set up addend for eventual relocation via outer symbol.
			rs, _ := ld.FoldSubSymbolOffset(ldr, rs)
			rst := ldr.SymType(rs)
			if rst != sym.SHOSTOBJ && rst != sym.SDYNIMPORT && ldr.SymSect(rs) == nil {
				ldr.Errorf(s, "missing section for %s", ldr.SymName(rs))
			}
			return val, 1, true

	if target.IsExternal() {
		switch r.Type() {
		default:
			return val, 0, false

		case objabi.R_ADDRMIPS, objabi.R_ADDRMIPSU:
			// set up addend for eventual relocation via outer symbol.
			_, off := ld.FoldSubSymbolOffset(ldr, rs)
			xadd := r.Add() + off
			return applyrel(target.Arch, ldr, r.Type(), r.Off(), s, val, xadd), 1, true

		case objabi.R_ADDRMIPSTLS, objabi.R_CALLMIPS, objabi.R_JMPMIPS:

	rs := r.Sym()
	if target.IsExternal() {
		switch r.Type() {
		case objabi.R_CALLARM:
			// set up addend for eventual relocation via outer symbol.
			_, off := ld.FoldSubSymbolOffset(ldr, rs)
			xadd := int64(signext24(r.Add()&0xffffff))*4 + off
			if xadd/4 > 0x7fffff || xadd/4 < -0x800000 {
				ldr.Errorf(s, "direct call too far %d", xadd/4)
			}

		return true
	}
	// TODO: other architectures.
	return false
}

// FoldSubSymbolOffset computes the offset of symbol s to its top-level outer
// symbol. Returns the top-level symbol and the offset.
// This is used in generating external relocations.
func FoldSubSymbolOffset(ldr *loader.Loader, s loader.Sym) (loader.Sym, int64) {
	outer := ldr.OuterSym(s)
	off := int64(0)
	if outer != 0 {

			objabi.R_ARM64_PCREL_LDST16,
			objabi.R_ARM64_PCREL_LDST32,
			objabi.R_ARM64_PCREL_LDST64,
			objabi.R_ADDRARM64:

			// set up addend for eventual relocation via outer symbol.
			rs, off := ld.FoldSubSymbolOffset(ldr, rs)
			xadd := r.Add() + off
			rst := ldr.SymType(rs)
			if rst != sym.SHOSTOBJ && rst != sym.SDYNIMPORT && ldr.SymSect(rs) == nil {
				ldr.Errorf(s, "missing section for %s", ldr.SymName(rs))
			}

	// ok for them to have non-zero size (to allow for use of generator
	// symbols).
	if len(l.Data(c)) != 0 {
		panic("unexpected non-empty carrier symbol")
	}
	l.outer[s] = c
	// relocsym's foldSubSymbolOffset requires that we only
	// have a single level of containment-- enforce here.
	if l.outer[c] != 0 {
		panic("invalid nested carrier sym")
	}
}