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| author | Rémi Denis-Courmont <remi@remlab.net> | 2023-11-19 13:24:29 +0200 |
|---|---|---|
| committer | Rémi Denis-Courmont <remi@remlab.net> | 2023-11-23 18:57:18 +0200 |
| commit | 3a134e82994ff49b784056d2dfce0230a8256ebd (patch) | |
| tree | 6f1c8083d50e9b8f089406fe5aa0c19614f99e2a | |
| parent | 4adb93dff05dd947878c67784d98c9a4e13b57a7 (diff) | |
| download | ffmpeg-3a134e82994ff49b784056d2dfce0230a8256ebd.tar.gz | |
lavu/fixed_dsp: optimise R-V V fmul_reverse
Gathers are (unsurprisingly) a notable exception to the rule that R-V V
gets faster with larger group multipliers. So roll the function to speed
it up.
Before:
vector_fmul_reverse_fixed_c: 2840.7
vector_fmul_reverse_fixed_rvv_i32: 2430.2
After:
vector_fmul_reverse_fixed_c: 2841.0
vector_fmul_reverse_fixed_rvv_i32: 962.2
It might be possible to further optimise the function by moving the
reverse-subtract out of the loop and adding ad-hoc tail handling.
| -rw-r--r-- | libavutil/riscv/fixed_dsp_rvv.S | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/libavutil/riscv/fixed_dsp_rvv.S b/libavutil/riscv/fixed_dsp_rvv.S index 5b666016a0..68de6d7e1b 100644 --- a/libavutil/riscv/fixed_dsp_rvv.S +++ b/libavutil/riscv/fixed_dsp_rvv.S @@ -83,16 +83,17 @@ endfunc func ff_vector_fmul_reverse_fixed_rvv, zve32x csrwi vxrm, 0 - vsetvli t0, zero, e16, m4, ta, ma + // e16/m4 and e32/m8 are possible but slow the gathers down. + vsetvli t0, zero, e16, m1, ta, ma sh2add a2, a3, a2 vid.v v0 vadd.vi v0, v0, 1 1: - vsetvli t0, a3, e16, m4, ta, ma + vsetvli t0, a3, e16, m1, ta, ma slli t1, t0, 2 vrsub.vx v4, v0, t0 // v4[i] = [VL-1, VL-2... 1, 0] sub a2, a2, t1 - vsetvli zero, zero, e32, m8, ta, ma + vsetvli zero, zero, e32, m2, ta, ma vle32.v v8, (a2) sub a3, a3, t0 vle32.v v16, (a1) |