On Thu, Oct 21, 2021 at 4:04 PM Richard Henderson <richard.hender...@linaro.org> wrote: > > On 9/10/21 4:26 AM, Luis Pires wrote: > > Introduce uabs64(), a function that returns the absolute value of > > a 64-bit int as an unsigned value. This avoids the undefined behavior > > for common abs implementations, where abs of the most negative value is > > undefined. > > I do question the comment there wrt undefined. We compile with -fwrapv, which > means that > *no* overflow is undefined; we always have properly truncated twos-compliment > values.
Can we really assume that -fwrapv would make llabs(LLONG_MIN) not undefined? We would be calling a function compiled by somebody else (possibly without -fwrapv). -- Eduardo
