https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120050
--- Comment #10 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Xi Ruoyao <xry...@gcc.gnu.org>: https://gcc.gnu.org/g:65f3a439c4f76fe780a30ac66969f51035c4bf98 commit r16-1110-g65f3a439c4f76fe780a30ac66969f51035c4bf98 Author: Xi Ruoyao <xry...@xry111.site> Date: Sun May 11 16:44:31 2025 +0800 ext-dce: Don't refine live width with SUBREG mode if !TRULY_NOOP_TRUNCATION_MODES_P [PR 120050] If we see a promoted subreg and TRULY_NOOP_TRUNCATION says the truncation is not a noop, then all bits of the inner reg are live. We cannot reduce the live mask to that of the mode of the subreg. gcc/ChangeLog: PR rtl-optimization/120050 * ext-dce.cc (ext_dce_process_uses): Break early if a SUBREG in rhs is promoted and the truncation from the inner mode to the outer mode is not a noop when handling SETs.
