On Thu, Oct 21, 2021 at 4:04 PM Richard Henderson
<richard.henderson@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).