https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113206
--- Comment #4 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Pan Li <pa...@gcc.gnu.org>: https://gcc.gnu.org/g:4a0a8dc1b88408222b88e10278017189f6144602 commit r14-6902-g4a0a8dc1b88408222b88e10278017189f6144602 Author: Juzhe-Zhong <juzhe.zh...@rivai.ai> Date: Thu Jan 4 06:38:43 2024 +0800 RISC-V: Fix bug of earliest fusion for infinite loop[VSETVL PASS] As PR113206 and PR113209, the bugs happens on the following situation: li a4,32 ... vsetvli zero,a4,e8,m8,ta,ma ... slliw a4,a3,24 sraiw a4,a4,24 bge a3,a1,.L8 sb a4,%lo(e)(a0) vsetvli zero,a4,e8,m8,ta,ma --> a4 is polluted value not the expected "32". ... .L7: j .L7 ---> infinite loop. The root cause is that infinite loop confuse earliest computation and let earliest fusion happens on unexpected place. Disable blocks that belong to infinite loop to fix this bug since applying ealiest LCM fusion on infinite loop seems quite complicated and we don't see any benefits. Note that disabling earliest fusion on infinite loops doesn't hurt the vsetvli performance, instead, it does improve codegen of some cases. Tested on both RV32 and RV64 no regression. PR target/113206 PR target/113209 gcc/ChangeLog: * config/riscv/riscv-vsetvl.cc (invalid_opt_bb_p): New function. (pre_vsetvl::compute_lcm_local_properties): Disable earliest fusion on blocks belong to infinite loop. (pre_vsetvl::emit_vsetvl): Remove fake edges. * config/riscv/t-riscv: Add a new include file. gcc/testsuite/ChangeLog: * gcc.target/riscv/rvv/vsetvl/avl_single-23.c: Adapt test. * gcc.target/riscv/rvv/vsetvl/vlmax_call-1.c: Robostify test. * gcc.target/riscv/rvv/vsetvl/vlmax_call-2.c: Ditto. * gcc.target/riscv/rvv/vsetvl/vlmax_call-3.c: Ditto. * gcc.target/riscv/rvv/vsetvl/vlmax_conflict-5.c: Ditto. * gcc.target/riscv/rvv/vsetvl/vlmax_single_vtype-1.c: Ditto. * gcc.target/riscv/rvv/vsetvl/vlmax_single_vtype-2.c: Ditto. * gcc.target/riscv/rvv/vsetvl/vlmax_single_vtype-3.c: Ditto. * gcc.target/riscv/rvv/vsetvl/vlmax_single_vtype-4.c: Ditto. * gcc.target/riscv/rvv/vsetvl/vlmax_single_vtype-5.c: Ditto. * gcc.target/riscv/rvv/autovec/pr113206-1.c: New test. * gcc.target/riscv/rvv/autovec/pr113206-2.c: New test. * gcc.target/riscv/rvv/autovec/pr113209.c: New test.