https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119493
--- Comment #18 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jakub Jelinek <ja...@gcc.gnu.org>: https://gcc.gnu.org/g:02409a145946ca0d4f502f43fc3cc20de8b3dea1 commit r15-9125-g02409a145946ca0d4f502f43fc3cc20de8b3dea1 Author: Jakub Jelinek <ja...@redhat.com> Date: Tue Apr 1 11:43:16 2025 +0200 tailr: Punt on tail recursions that would break musttail [PR119493] While working on the previous tailc patch, I've noticed the following problem. The testcase below fails, because we decide to tail recursion optimize the call, but tail recursion (as documented in tree-tailcall.cc) needs to add some result multiplication and/or addition if any tail recursion uses accumulator, which is added right before the return. So, if there are musttail non-recurive calls in the function, successful tail recursion optimization will mean we'll later error on the musttail calls. musttail recursive calls are ok, those would be tail recursion optimized. So, the following patch punts on all tail recursion optimizations if it needs accumulators (add and/or mult) if there is at least one non-recursive musttail call. 2025-04-01 Jakub Jelinek <ja...@redhat.com> PR tree-optimization/119493 * tree-tailcall.cc (tree_optimize_tail_calls_1): Ignore tail recursion candidates which need accumulators if there is at least one musttail non-recursive call. * gcc.dg/pr119493-2.c: New test.
