Robert Dewar <[EMAIL PROTECTED]> writes: > > You're right, I shouldn't have said "implementation defined." > > What will happen with -fno-strict-overflow is whatever the processor > > ISA happens to do when a signed arithmetic operation overflows. For > > ordinary machines it will just wrap. > > Given that all ordinary machines wrap, is there really enough > difference in performance in practice between -fno-strict-overflow > and -fwrapv to justify adding this vague and rather dubious (given > it is vague) switch. Saying "whatever the processor does" is not > enough, since on some processors there are multiple addition > instructions (e.g. trapping and non-trapping variants)
I believe there is a comprehensible distinction between "compiler will not assume that signed overflow is undefined behaviour" and "compiler will cause all arithmetic to wrap around." In any case, I have no plans to continue working on this. I described my work in considerable detail as I did it and the patches have gone through multiple rounds of review. I would be happy to see your concrete proposal. Ian
