A call to a standard library function is still subject to the as if rule. It doesn't have to manifest into a call instruction to a standard library function. Much like memcpy in source code doesn't have to manifest to a call instruction.
Me: I don't expect to be stabbed.
You: But you only might be stabbed. It isn't required to happen only permitted.
Me: I don't expect to be stabbed.
You: But you only might be stabbed. It isn't required to happen only permitted.