pkgPrefix := obj.UnlinkablePkg
	if ctxt != nil {
		pkgPrefix = objabi.PathToPrefix(ctxt.Pkgpath)
	}
	return &Parser{
		ctxt:        ctxt,
		arch:        ar,
		lex:         lexer,
		labels:      make(map[string]*obj.Prog),
		dataAddr:    make(map[string]int64),
		errorWriter: os.Stderr,
		allowABI:    ctxt != nil && objabi.LookupPkgSpecial(ctxt.Pkgpath).AllowAsmABI,
		pkgPrefix:   pkgPrefix,
	}
}

	-gccgo
		Generate output for the gccgo compiler rather than the
		gc compiler.
	-gccgoprefix prefix
		The -fgo-prefix option to be used with gccgo.
	-gccgopkgpath path
		The -fgo-pkgpath option to be used with gccgo.
	-gccgo_define_cgoincomplete
		Define cgo.Incomplete locally rather than importing it from
		the "runtime/cgo" package. Used for old gccgo versions.
	-godefs