Yeah. That sort of thing works, right up until some compiler gets released that optimizes it out. It's "portable C", but the behavior it's trying to produce is

Yeah. That sort of thing works, right up until some compiler gets released that optimizes it out. It's "portable C", but the behavior it's trying to produce is non-portable. Especially note his guideline to look at the assembly output. The best guarantee is to simply check that the compiler did what you wanted. There are also some aspects that a compiler is unlikely to alter. EG if you write code with no secret-dependent branches, no normal compiler will insert any secret-dependent branches during optimization. It's generally safe to rely on the compiler not being actively malicious or de-optimizing code.