search for: rl265912

...overflow, 1 store i1 %overflow, i1* %res_i1 store i64 %uadd, i64* %res_i64 ret void } Now if we _know_ that the arithmetic result is used only if it does not overflow, then we can "pretend" that the arithmetic was nsw/nuw. This is what I tried to do in http://reviews.llvm.org/rL265912, but I had to back out the change due to an unrelated issue with SCEV. -- Sanjoy Nuno Lopes via llvm-dev wrote: >>> Or do you mean that the result of an add may not even be defined? In that case would reading it be considered UB in >>> the case where the overflow bit was set? &...

Hi Pete, > Or do you mean that the result of an add may not even be defined? In that case would reading it be considered UB in the case where the overflow bit was set? Yeah, this is the case I'm worried about: that for example sadd.with.overflow(INT_MAX, 1) might be designed to return { poison, true } instead of giving a useful result in the first element of the struct. John