https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95694
--- Comment #7 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-10 branch has been updated by Richard Sandiford <rsand...@gcc.gnu.org>: https://gcc.gnu.org/g:00bcb8380bf755c60d5ad605a21818f6d3ed9912 commit r10-9114-g00bcb8380bf755c60d5ad605a21818f6d3ed9912 Author: Richard Sandiford <richard.sandif...@arm.com> Date: Thu Dec 3 10:23:25 2020 +0000 expr: Fix REDUCE_BIT_FIELD for constants [PR95694, PR96151] This is yet another PR caused by constant integer rtxes not storing a mode. We were calling REDUCE_BIT_FIELD on a constant integer that didn't fit in poly_int64, and then tripped the as_a<scalar_int_mode> assert on VOIDmode. AFAICT REDUCE_BIT_FIELD is always passed rtxes that have TYPE_MODE (rather than some other mode) and it just fills in the redundant sign bits of that TYPE_MODE value. So it should be safe to get the mode from the type instead of the rtx. The patch does that and asserts that the modes agree, where information is available. That on its own is enough to fix the bug, but we might as well extend the folding case to all constant integers, not just those that fit poly_int64. gcc/ PR middle-end/95694 * expr.c (expand_expr_real_2): Get the mode from the type rather than the rtx, and assert that it is consistent with the mode of the rtx (where known). Optimize all constant integers, not just those that can be represented in poly_int64. gcc/testsuite/ PR middle-end/95694 * gcc.dg/pr95694.c: New test. (cherry picked from commit 760df6d296b8fc59796f42dca5eb14012fbfa28b)
