Mplab xc8 / 16 builtin_constant_p

I searched for this in the mplab compiler user manual but found nothing. I am asking here to confirm that I am not blind or something:

The GCC compiler provides some very interesting and useful built-in functions like __builtin_constant_p (x) or similar things. I've never found anything like this in microchip compilers, and I don't think there is.

So the question is: do Microchip XCxx compilers provide any non-standard built-in functions other than device-specific (such as declaring variables at a given register address or declaring an interrupt function)?

EDIT: To clarify something else: I'm most interested in retrieving information from the compiler. Something like builtin_constant would be a good example, as it makes information available to a program that is not normally used. But I am not limiting this question to finding constant expressions only.