https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100075
--- Comment #2 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:47f42744f6e10ad41db926d739306e6f237fd3ac commit r11-8215-g47f42744f6e10ad41db926d739306e6f237fd3ac Author: Jakub Jelinek <ja...@redhat.com> Date: Fri Apr 16 13:44:23 2021 +0200 aarch64: Fix up 2 other combine opt regressions vs. GCC8 [PR100075] The testcase used to be compiled at -O2 by GCC8 and earlier to: f1: neg w1, w0, asr 16 and w1, w1, 65535 orr w0, w1, w0, lsl 16 ret f2: neg w1, w0 extr w0, w1, w0, 16 ret but since GCC9 (r9-3594 for f1 and r9-6926 for f2) we compile it into: f1: mov w1, w0 sbfx x0, x1, 16, 16 neg w0, w0 bfi w0, w1, 16, 16 ret f2: neg w1, w0 sbfx x0, x0, 16, 16 bfi w0, w1, 16, 16 ret instead, i.e. one insn longer each. With this patch we get: f1: mov w1, w0 neg w0, w1, asr 16 bfi w0, w1, 16, 16 ret f2: neg w1, w0 extr w0, w1, w0, 16 ret i.e. identical f2 and same number of insns as in GCC8 in f1. The combiner unfortunately doesn't try splitters when doing 2 -> 1 combination, so it can't be implemented as combine splitters, but it could be implemented as define_insn_and_split if desirable. 2021-04-16 Jakub Jelinek <ja...@redhat.com> PR target/100075 * config/aarch64/aarch64.md (*neg_asr_si2_extr, *extrsi5_insn_di): New define_insn patterns. * gcc.target/aarch64/pr100075.c: New test.
