To be fair, that's because it was optimized out. Mark it as volatile and try again. It will almost definitely segfault. The other points still stand, though - t

To be fair, that's because it was optimized out. Mark it as volatile and try again. It will almost definitely segfault. The other points still stand, though - that's just because Linux is forced to respond to a page fault exception and chooses to signal that to the process.