https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93372
--- Comment #7 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Hans-Peter Nilsson <h...@gcc.gnu.org>: https://gcc.gnu.org/g:0e6c51de8ec47bf5f0dfaabfd1898c722d0485b4 commit r11-2814-g0e6c51de8ec47bf5f0dfaabfd1898c722d0485b4 Author: Hans-Peter Nilsson <h...@axis.com> Date: Mon Aug 24 03:15:21 2020 +0200 reorg.c (fill_slots_from_thread): Improve for TARGET_FLAGS_REGNUM This handles TARGET_FLAGS_REGNUM clobbering insns as delay-slot fillers using a method similar to that in commit 33c2207d3fda, where care was taken for fill_simple_delay_slots to allow such insns when scanning for delay-slot fillers *backwards* (before the insn). A TARGET_FLAGS_REGNUM target is typically a former cc0 target. For cc0 targets, insns don't mention clobbering cc0, so the clobbers are mentioned in the "resources" only as a special entity and only for compare-insns and branches, where the cc0 value matters. In contrast, with TARGET_FLAGS_REGNUM, most insns clobber it and the register liveness detection in reorg.c / resource.c treats that as a blocker (for other insns mentioning it, i.e. most) when looking for delay-slot-filling candidates. This means that when comparing core and performance for a delay-slot cc0 target before and after the de-cc0 conversion, the inability to fill a delay slot after conversion manifests as a regression. This was one such case, for CRIS, with random_bitstring in gcc.c-torture/execute/arith-rand-ll.c as well as the target libgcc division function. After this, all known performance regressions compared to cc0 are fixed. gcc: PR target/93372 * reorg.c (fill_slots_from_thread): Allow trial insns that clobber TARGET_FLAGS_REGNUM as delay-slot fillers. gcc/testsuite: PR target/93372 * gcc.target/cris/pr93372-47.c: New test.
