Put a label there.
The question is, where do you want the label? Do you want the end of literal executable code, or including ".data" and ".bss", if any? If there's a linker involved, you may need to figure out what the linker thinks is "last" - or figure out how to *tell* it what you want "last".
Give us more information about what you're doing (usually when they don't mention "What OS?", it's Windows... sigh), and perhaps we can provide an actual example...
Best,
Frank