On Tue, Mar 19, 2019 at 4:57 PM Ed Smith-Rowland via gcc-patches <gcc-patches@gcc.gnu.org> wrote: > > On 3/18/19 6:18 PM, Jonathan Wakely wrote: > > On 17/03/19 22:54 -0400, Ed Smith-Rowland via libstdc++ wrote: > > I'm very surprised that none of the algos that dispatch to > > __builtin_memove need changes, because those optimizations won't work > > in constant expressions. I would expect to have to use > > std::is_constant_evaluated to disable the optimizations when used in > > constant expressions. > > > As am I. As I mentioned on IRC I could roll a constexpr memmove. > > I was wondering if somehow I'm not checking what I think I'm checking > (but I don't see how.) > > I wonder if the builtins are handled differently somehow by the front > end. I'm still not sure why __builtin_memcmp is OK for array == array > but not array != array. In that case I just do element by element > compare for constexpr now anyway.
Is there a PR about making these builtins work in constexpr? Jason
