https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113281
--- Comment #12 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The trunk branch has been updated by Lehua Ding <lh...@gcc.gnu.org>: https://gcc.gnu.org/g:405096f908e1ceb0d6a1b5420ded20ad85ddae9e commit r14-7244-g405096f908e1ceb0d6a1b5420ded20ad85ddae9e Author: Juzhe-Zhong <juzhe.zh...@rivai.ai> Date: Mon Jan 15 09:22:40 2024 +0800 RISC-V: Adjust loop len by costing 1 when NITER < VF Rebase in v3: Rebase to the trunk and commit it as it's approved by Robin. Update in v2: Add dynmaic lmul test. This patch fixes the regression between GCC 13.2.0 and trunk GCC (GCC-14) GCC 13.2.0: lui a5,%hi(a) li a4,19 sb a4,%lo(a)(a5) li a0,0 ret Trunk GCC: vsetvli a5,zero,e8,mf2,ta,ma li a4,-32768 vid.v v1 vsetvli zero,zero,e16,m1,ta,ma addiw a4,a4,104 vmv.v.i v3,15 lui a1,%hi(a) li a0,19 vsetvli zero,zero,e8,mf2,ta,ma vadd.vi v1,v1,1 sb a0,%lo(a)(a1) vsetvli zero,zero,e16,m1,ta,ma vzext.vf2 v2,v1 vmv.v.x v1,a4 vminu.vv v2,v2,v3 vsrl.vv v1,v1,v2 vslidedown.vi v1,v1,17 vmv.x.s a0,v1 snez a0,a0 ret The root cause we are vectorizing the codes inefficiently since we doesn't cost len when NITERS < VF. Leverage loop control of mask targets or rs6000 fixes the regression. Tested no regression. Ok for trunk ? PR target/113281 gcc/ChangeLog: * config/riscv/riscv-vector-costs.cc (costs::adjust_vect_cost_per_loop): New function. (costs::finish_cost): Adjust cost for LOOP LEN with NITERS < VF. * config/riscv/riscv-vector-costs.h: New function. gcc/testsuite/ChangeLog: * gcc.dg/vect/costmodel/riscv/rvv/pr113281-3.c: New test. * gcc.dg/vect/costmodel/riscv/rvv/pr113281-4.c: New test. * gcc.dg/vect/costmodel/riscv/rvv/pr113281-5.c: New test.
