[Measter]

Only if that memory page is unmapped, and only if the optimizer doesn't detect that it's a null pointer and start deleting verification code because derefing null is UB, and UB is assumed to never happen.

[charlie90]

How common is this in practice?

[adrianN]

Compilers regularly delete null pointer checks when they can see that the pointer is dereferenced.

[Smaug123]

(GCC controls this with `-fno-delete-null-pointer-checks` https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html#ind... )