On Wed, Dec 08, 2021 at 04:17:33PM -0700, Jeff Law via Gcc-help wrote: > On 12/7/2021 3:38 PM, Bradley Lucier via Gcc-help wrote: > >So I've been investigating whether gcc's -foptimize-sibling-calls > >option (for which I've found very little documentation) might produce > >similar results. > The option has been around for probably 20+ years at this point, you > just might not have been aware of it. They try, but do not guarantee > tail call optimization. They have all kinds of checks that might cause > any particular call site to be rejected for tail call elimination. It's > enabled by default at O2 or higher. (Including -Os.) GCC will never not do a tail call if it knows any way to do it. A very low-tech way of checking if all your threaded code words got proper tail calls is to simply look if there are any "return" instructions in the generated machine code :-) Segher
