LGTM
On Fri, Jun 2, 2023 at 2:32 PM <juzhe.zh...@rivai.ai> wrote:
>
> From: Juzhe-Zhong <juzhe.zh...@rivai.ai>
>
> This patch optimizes the following seriese vector:
> [nunits - 1, nunits - 2, ...., 0]
>
> Before this patch:
> vid
> vmul
> vadd
>
> After this patch:
> vid
> vrsub
>
> This patch is an obvious and simple optimization, ok for trunk?
>
> gcc/ChangeLog:
>
> * config/riscv/riscv-v.cc (expand_vec_series): Optimize reverse
> series index vector.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.target/riscv/rvv/autovec/vls-vlmax/perm-4.c: Add assembly check.
>
> ---
> gcc/config/riscv/riscv-v.cc | 17 +++++++++++++++++
> .../riscv/rvv/autovec/vls-vlmax/perm-4.c | 2 ++
> 2 files changed, 19 insertions(+)
>
> diff --git a/gcc/config/riscv/riscv-v.cc b/gcc/config/riscv/riscv-v.cc
> index 1cd3bd3438e..75cf00b7eba 100644
> --- a/gcc/config/riscv/riscv-v.cc
> +++ b/gcc/config/riscv/riscv-v.cc
> @@ -530,6 +530,8 @@ expand_vec_series (rtx dest, rtx base, rtx step)
> machine_mode mode = GET_MODE (dest);
> machine_mode mask_mode;
> gcc_assert (get_mask_mode (mode).exists (&mask_mode));
> + poly_int64 nunits_m1 = GET_MODE_NUNITS (mode) - 1;
> + poly_int64 value;
>
> /* VECT_IV = BASE + I * STEP. */
>
> @@ -545,6 +547,21 @@ expand_vec_series (rtx dest, rtx base, rtx step)
> rtx step_adj;
> if (rtx_equal_p (step, const1_rtx))
> step_adj = vid;
> + else if (rtx_equal_p (step, constm1_rtx) && poly_int_rtx_p (base, &value)
> + && known_eq (nunits_m1, value))
> + {
> + /* Special case:
> + {nunits - 1, nunits - 2, ... , 0}.
> + nunits can be either const_int or const_poly_int.
> +
> + Code sequence:
> + vid.v v
> + vrsub nunits - 1, v. */
> + rtx ops[] = {dest, vid, gen_int_mode (nunits_m1, GET_MODE_INNER
> (mode))};
> + insn_code icode = code_for_pred_sub_reverse_scalar (mode);
> + emit_vlmax_insn (icode, RVV_BINOP, ops);
> + return;
> + }
> else
> {
> step_adj = gen_reg_rtx (mode);
> diff --git a/gcc/testsuite/gcc.target/riscv/rvv/autovec/vls-vlmax/perm-4.c
> b/gcc/testsuite/gcc.target/riscv/rvv/autovec/vls-vlmax/perm-4.c
> index 179c8274a92..aa328810c30 100644
> --- a/gcc/testsuite/gcc.target/riscv/rvv/autovec/vls-vlmax/perm-4.c
> +++ b/gcc/testsuite/gcc.target/riscv/rvv/autovec/vls-vlmax/perm-4.c
> @@ -56,3 +56,5 @@
> TEST_ALL (PERMUTE)
>
> /* { dg-final { scan-assembler-times
> {vrgather\.vv\tv[0-9]+,\s*v[0-9]+,\s*v[0-9]+} 31 } } */
> +/* { dg-final { scan-assembler-times {vrsub\.vi} 24 } } */
> +/* { dg-final { scan-assembler-times {vrsub\.vx} 7 } } */
> --
> 2.36.1
>
