https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113087
--- Comment #8 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:008b80e42eb7cb55c6a2ef55728241b8733dfd17 commit r14-6761-g008b80e42eb7cb55c6a2ef55728241b8733dfd17 Author: Juzhe-Zhong <juzhe.zh...@rivai.ai> Date: Wed Dec 20 14:55:26 2023 +0800 RISC-V: Optimize SELECT_VL codegen when length is known as smaller than VF While trying to fix bugs of PR113097, notice this following situation we generate redundant vsetvli _255 = SELECT_VL (3, POLY_INT_CST [4, 4]); COND_LEN (..., _255) Before this patch: vsetivli a5, 3... ... vadd.vv (use a5) After this patch: ... vadd.vv (use AVL = 3) The reason we can do this is because known_ge (3, [4,4]) is true. It's safe to apply such optimization Tested on both RV32 and RV64 full coverage testing, no regression. PR target/113087 gcc/ChangeLog: * config/riscv/riscv-v.cc (expand_select_vl): Optimize SELECT_VL. gcc/testsuite/ChangeLog: * gcc.target/riscv/rvv/autovec/pr113087-2.c: New test.