https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114768
--- Comment #7 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:9f295847a9c32081bdd0fe908ffba58e830a24fb commit r14-10035-g9f295847a9c32081bdd0fe908ffba58e830a24fb Author: Jakub Jelinek <ja...@redhat.com> Date: Fri Apr 19 08:47:53 2024 +0200 rtlanal: Fix set_noop_p for volatile loads or stores [PR114768] On the following testcase, combine propagates the mem/v load into mem store with the same address and then removes it, because noop_move_p says it is a no-op move. If it was the other way around, i.e. mem/v store and mem load, or both would be mem/v, it would be kept. The problem is that rtx_equal_p never checks any kind of flags on the rtxes (and I think it would be quite dangerous to change it at this point), and set_noop_p checks side_effects_p on just one of the operands, not both. In the MEM <- MEM set, it only checks it on the destination, in store to ZERO_EXTRACT only checks it on the source. The following patch adds the missing side_effects_p checks. 2024-04-19 Jakub Jelinek <ja...@redhat.com> PR rtl-optimization/114768 * rtlanal.cc (set_noop_p): Don't return true for MEM <- MEM sets if src has side-effects or for stores into ZERO_EXTRACT if ZERO_EXTRACT operand has side-effects. * gcc.dg/pr114768.c: New test.
