void initParameterNames(MethodSymbol sym) {
        // make allowance for synthetic parameters.
        final int excessSlots = 4;
        int expectedParameterSlots =
                Code.width(sym.type.getParameterTypes()) + excessSlots;
        if (parameterNameIndices == null
                || parameterNameIndices.length < expectedParameterSlots) {
            parameterNameIndices = new int[expectedParameterSlots];
        } else
            Arrays.fill(parameterNameIndices, 0);
        haveParameterNameIndices = false;
    }