if platformToolDir == "." {
		return errors.New("failed to locate cmd/compile for target platform")
	}
	relToolDir, err := filepath.Rel(filepath.Join(goroot), platformToolDir)
	if err != nil {
		return err
	}
	if err := adb("push", platformToolDir, path.Join(deviceGoroot, relToolDir)); err != nil {
		return err
	}

	// Copy all other files from GOROOT.
	dirents, err := os.ReadDir(goroot)
	if err != nil {