https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127256
--- Comment #11 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-16 branch has been updated by Robin Dapp <[email protected]>: https://gcc.gnu.org/g:a88df55edc15ebfa61cc348c604205ce508d6473 commit r16-9644-ga88df55edc15ebfa61cc348c604205ce508d6473 Author: Robin Dapp <[email protected]> Date: Wed Sep 9 09:12:07 2026 +0200 lower-subreg: Avoid unsplittable modes. [PR127256] This is split off of r17-3907-gec58d736cd572b. The patch mainly avoids splitting subregs whose outer mode can be split but the inner cannot like in (subreg:TI (reg:VNx4SI 665) 0). Also, it filters out unsplittable modes and doesn't assert that an outermode in simplify_subreg_concatn is interesting. It suffices that its size is constant so we can build subregs. PR middle-end/127256 gcc/ChangeLog: * lower-subreg.cc (interesting_mode_p): Don't consider unsplittable modes as interesting. (simple_move_operand): Don't split subregs whose outer mode can be split but the inner mode cannot. (simplify_subreg_concatn): Don't insist the outer mode is interesting but rather check that its size is constant. gcc/testsuite/ChangeLog: * g++.target/aarch64/pr127256.C: New test.
