Here's the pending GCC 15 release notes: https://gcc.gnu.org/gcc-15/changes.html (since the link in the article points to GCC 14) - I'd love to see godbolt examples of the sort of optimizations [[unsequenced]] and [[reproducible]] can do. - GCC has always been in my experience smart enough to know how to optimize normal C code into ROL and ROR instructions. I've never had any issues with it. So what's the point of __…
> What I wish GCC and Clang would do instead, is formally document the magic ANSI C89 incantations that trigger the optimization, e.g. `#define ROL(x, n) (((x) > (64 - (n))))`. That way we can have clean portable code with less #ifdef hell along with assurances it'll go fast when -O is passed.
Well they don’t commit to that happening, so they want to provide you with an alternative.