https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93505
--- Comment #19 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-9 branch has been updated by Jakub Jelinek <ja...@gcc.gnu.org>: https://gcc.gnu.org/g:329475795c6eeaa2b122672091c9119b9d6c5564 commit r9-8217-g329475795c6eeaa2b122672091c9119b9d6c5564 Author: Jakub Jelinek <ja...@redhat.com> Date: Thu Jan 30 21:28:17 2020 +0100 combine: Punt on out of range rotate counts [PR93505] What happens on this testcase is with the out of bounds rotate we get: Trying 13 -> 16: 13: r129:SI=r132:DI#0<-<0x20 REG_DEAD r132:DI 16: r123:DI=r129:SI<0 REG_DEAD r129:SI Successfully matched this instruction: (set (reg/v:DI 123 [ <retval> ]) (const_int 0 [0])) during combine. So, perhaps we could also change simplify-rtx.c to punt if it is out of bounds rather than trying to optimize anything. Or, but probably GCC11 material, if we decide that ROTATE/ROTATERT doesn't have out of bounds counts or introduce targetm.rotate_truncation_mask, we should truncate the argument instead of punting. Punting is better for backports though. 2020-01-30 Jakub Jelinek <ja...@redhat.com> PR middle-end/93505 * combine.c (simplify_comparison) <case ROTATE>: Punt on out of range rotate counts. * gcc.c-torture/compile/pr93505.c: New test.
