def negate_real(builder, val):
    """
    Negate real number *val*, with proper handling of zeros.
    """
    # The negative zero forces LLVM to handle signed zeros properly.
    return builder.fsub(Constant(val.type, -0.0), val)

    Negate real number *val*, with proper handling of zeros.
    
numba/cpython/new_mathimpl.py