https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88836
--- Comment #5 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Richard Sandiford <rsand...@gcc.gnu.org>: https://gcc.gnu.org/g:5a783f42d77b2f00a1ed171c119b020e8df8e521 commit r11-6723-g5a783f42d77b2f00a1ed171c119b020e8df8e521 Author: Richard Sandiford <richard.sandif...@arm.com> Date: Fri Jan 15 16:45:42 2021 +0000 aarch64: Add a minipass for fusing CC insns [PR88836] This patch adds a small target-specific pass to remove redundant SVE PTEST instructions. There are two important uses of this: - Removing PTESTs after WHILELOs (PR88836). The original testcase no longer exhibits the problem due to more recent optimisations, but it can still be seen in simple cases like the one in the patch. It also shows up in 450.soplex. - Removing PTESTs after RDFFRs in ACLE code. This is just an interim âsolutionâ for GCC 11. I hope to replace it with something generic and target-independent for GCC 12. However, the use cases above are very important for performance, so I'd rather not leave the bug unfixed for yet another release cycle. Since the pass is intended to be short-lived, I've not added a command-line option for it. The pass can be disabled using -fdisable-rtl-cc_fusion if necessary. Although what the pass does is independent of SVE, it's motivated only by SVE cases and doesn't trigger for any non-SVE test I've seen. I've therefore gated it on TARGET_SVE and restricted it to PTEST patterns. gcc/ PR target/88836 * config.gcc (aarch64*-*-*): Add aarch64-cc-fusion.o to extra_objs. * Makefile.in (RTL_SSA_H): New variable. * config/aarch64/t-aarch64 (aarch64-cc-fusion.o): New rule. * config/aarch64/aarch64-protos.h (make_pass_cc_fusion): Declare. * config/aarch64/aarch64-passes.def: Add pass_cc_fusion after pass_combine. * config/aarch64/aarch64-cc-fusion.cc: New file. gcc/testsuite/ PR target/88836 * gcc.target/aarch64/sve/acle/general/ldff1_8.c: New test. * gcc.target/aarch64/sve/ptest_1.c: Likewise.
