[takeda]

I would imagine that if a compiler would be able to make this kind of optimization it would also be able to warn that this is an error. Also optimizers supposed to replace code with a simpler equivalent ones, in your example actually the if statement should block the optimization i.e. if there was no "if", the x would be used directly, and the pointer was ignored.

Here's the bug: https://svnweb.freebsd.org/base/releng/12.1/crypto/openssl/s...

Value NULL is generally (void *)0 (could be different on different architectures, but it supposed to point to invalid value in memory, so when that memory address is accessed it will trigger segmentation fault.