https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98190
--- Comment #17 from CVS 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:3e60ddeb8220ed388819bb3f14e8caa9309fd3c2 commit r11-5927-g3e60ddeb8220ed388819bb3f14e8caa9309fd3c2 Author: Jakub Jelinek <ja...@redhat.com> Date: Fri Dec 11 11:10:17 2020 +0100 expansion: Sign or zero extend on MEM_REF stores into SUBREG with SUBREG_PROMOTED_VAR_P [PR98190] Some targets decide to promote certain scalar variables to wider mode, so their DECL_RTL is a SUBREG with SUBREG_PROMOTED_VAR_P. When storing to such vars, store_expr takes care of sign or zero extending, but if we store e.g. through MEM_REF into them, no sign or zero extension happens and that leads to wrong-code e.g. on the following testcase on aarch64-linux. The following patch uses store_expr if we overwrite all the bits and it is not reversed storage order, i.e. something that store_expr handles normally, and otherwise (if the most significant bit is (or for pdp11 might be, but pdp11 doesn't promote) being modified), the code extends manually. 2020-12-11 Jakub Jelinek <ja...@redhat.com> PR middle-end/98190 * expr.c (expand_assignment): If to_rtx is a promoted SUBREG, ensure sign or zero extension either through use of store_expr or by extending manually. * gcc.dg/pr98190.c: New test.
