[Bug middle-end/113982] Poor codegen for 64-bit add with carry widening functions

[jakub at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113982

--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
With signed +- overflow not sure what exactly to pattern match, people can be
really creative there.  I guess
w = (__int128) x + y;
r = (long long) w;
ovf = (w >> 64) != (w >> 63);
or
w = (__int128) x + y;
r = (long long) w;
ovf = (w >> 63) + (unsigned __int128) 1 <= 1
etc.