https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115877
--- Comment #12 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jeff Law <l...@gcc.gnu.org>: https://gcc.gnu.org/g:ab7c0aed52054976d0b5e12c52e82239d4277b98 commit r15-2203-gab7c0aed52054976d0b5e12c52e82239d4277b98 Author: Jeff Law <j...@ventanamicro.com> Date: Mon Jul 22 10:11:57 2024 -0600 [4/n][PR rtl-optimization/115877] Correct SUBREG handling in a destination If we encounter something during SET handling that we can not handle, the safe thing to do is to ignore the destination and continue the loop. We've actually been trying to do slightly better with SUBREG destinations by iterating into SUBREG_REG. It turns out that wasn't working as expected. The problem is once we "continue" we lose the state that we were inside the SET and thus we ended up ignoring the destination completely rather than tracking the SUBREG_REG object. This could be fixed by restarting SET processing, but I just don't see this as all that important to handle. So rather than leave the code as-is, not working per design, I'm twiddling it to use the common 'skip subrtxs and continue' idiom used elsewhere. This is a prerequisite for another patch in this series. Specifically I have a patch that explicitly tracks if we skipped a destination rather than trying to imply it from the state of LIVE_TMP. So this is probably NFC right now, but that's a short-lived NFC. Bootstrapped and regression tested on x86 and also run as part of a larger kit on the crosses in my tester. PR rtl-optimization/115877 gcc/ * ext-dce.cc (ext_dce_process_sets): More correctly handle SUBREG destinations.
