3 ms·

The checks were not correct for all possible representations. If the only representation were two’s complement, there could be fewer areas of undefined behavior

The checks were not correct for all possible representations. If the only representation were two’s complement, there could be fewer areas of undefined behavior, so simple and straightforward security checks would be much more likely to be correct. (Unfortunately it sounds like this proposal has been revised to leave overflow behavior as undefined. That’s a biggie. Oh well)

mannykannot 8y ago
> The checks were not correct for all possible representations. This raises the question of whether the optimization was valid, given the target architecture. I am assuming that, technically speaking, it was, because that is what the standard allowed, but that view leaves unexamined the question of whether it is contrary to the purposes for having and using the C language in the first place. I can imagine an argument pointing out that this optimization is applied at an abstract level of representation prior to code generation, and that it would be a violation of modularity to take into account the target architecture at that point. This, however, would be a point about the compiler architecture, which I think should, where practical, yield to concerns about the overall purpose and use of the compiler, where the principle of 'no (or minimal) surprises' is important.