https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118103
--- Comment #16 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:1c8e6734d2dd3a6236d94c6e4e0c6780f35ede9f commit r15-7421-g1c8e6734d2dd3a6236d94c6e4e0c6780f35ede9f Author: Pan Li <pan2...@intel.com> Date: Fri Feb 7 14:21:35 2025 +0800 RISC-V: Make VXRM as global register [PR118103] Inspired by PR118103, the VXRM register should be treated almost the same as the FRM register, aka cooperatively-managed global register. Thus, add the VXRM to global_regs to avoid the elimination by the late-combine pass. For example as below code: 21 â 22 â void compute () 23 â { 24 â size_t vl = __riscv_vsetvl_e16m1 (N); 25 â vuint16m1_t va = __riscv_vle16_v_u16m1 (a, vl); 26 â vuint16m1_t vb = __riscv_vle16_v_u16m1 (b, vl); 27 â vuint16m1_t vc = __riscv_vaaddu_vv_u16m1 (va, vb, __RISCV_VXRM_RDN, vl); 28 â 29 â __riscv_vse16_v_u16m1 (c, vc, vl); 30 â } 31 â 32 â int main () 33 â { 34 â initialize (); 35 â compute(); 36 â 37 â return 0; 38 â } After compile with -march=rv64gcv -O3, we will have: 30 â compute: 31 â csrwi vxrm,2 32 â lui a3,%hi(a) 33 â lui a4,%hi(b) 34 â addi a4,a4,%lo(b) 35 â vsetivli zero,4,e16,m1,ta,ma 36 â addi a3,a3,%lo(a) 37 â vle16.v v2,0(a4) 38 â vle16.v v1,0(a3) 39 â lui a4,%hi(c) 40 â addi a4,a4,%lo(c) 41 â vaaddu.vv v1,v1,v2 42 â vse16.v v1,0(a4) 43 â ret 44 â .size compute, .-compute 45 â .section .text.startup,"ax",@progbits 46 â .align 1 47 â .globl main 48 â .type main, @function 49 â main: | // csrwi vxrm,2 deleted after inline 50 â addi sp,sp,-16 51 â sd ra,8(sp) 52 â call initialize 53 â lui a3,%hi(a) 54 â lui a4,%hi(b) 55 â vsetivli zero,4,e16,m1,ta,ma 56 â addi a4,a4,%lo(b) 57 â addi a3,a3,%lo(a) 58 â vle16.v v2,0(a4) 59 â vle16.v v1,0(a3) 60 â lui a4,%hi(c) 61 â addi a4,a4,%lo(c) 62 â li a0,0 63 â vaaddu.vv v1,v1,v2 The below test suites are passed for this patch. * The rv64gcv fully regression test. PR target/118103 gcc/ChangeLog: * config/riscv/riscv.cc (riscv_conditional_register_usage): Add the VXRM as the global_regs. gcc/testsuite/ChangeLog: * gcc.target/riscv/rvv/base/pr118103-2.c: New test. * gcc.target/riscv/rvv/base/pr118103-run-2.c: New test. Signed-off-by: Pan Li <pan2...@intel.com>
