[FFmpeg-cvslog] lavc/lpc: optimise RVV vector type for compute_autocorr

[Rémi Denis-Courmont]

ffmpeg | branch: master | Rémi Denis-Courmont <remi at remlab.net> | Sun May 26 08:25:16 2024 +0300| [c53d42380d3f57c318fa76329c8fdcb47a05093a] | committer: Rémi Denis-Courmont

lavc/lpc: optimise RVV vector type for compute_autocorr

On SpacemiT X60 (with len == 4000):
autocorr_10_c:       2303.7
autocorr_10_rvv_f64: 1411.5 (before)
autocorr_10_rvv_f64:  842.2 (after)

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=c53d42380d3f57c318fa76329c8fdcb47a05093a
---

 libavcodec/riscv/lpc_init.c | 3 ++-
 libavcodec/riscv/lpc_rvv.S  | 5 +++--
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/libavcodec/riscv/lpc_init.c b/libavcodec/riscv/lpc_init.c
index 08efae4da7..d9bcbbe604 100644
--- a/libavcodec/riscv/lpc_init.c
+++ b/libavcodec/riscv/lpc_init.c
@@ -36,7 +36,8 @@ av_cold void ff_lpc_init_riscv(LPCContext *c)
     if ((flags & AV_CPU_FLAG_RVV_F64) && (flags & AV_CPU_FLAG_RVB_ADDR)) {
         c->lpc_apply_welch_window = ff_lpc_apply_welch_window_rvv;
 
-        if (ff_get_rv_vlenb() > c->max_order)
+        if ((flags & AV_CPU_FLAG_RVB_BASIC) &&
+            ff_get_rv_vlenb() > c->max_order)
             c->lpc_compute_autocorr = ff_lpc_compute_autocorr_rvv;
     }
 #endif
diff --git a/libavcodec/riscv/lpc_rvv.S b/libavcodec/riscv/lpc_rvv.S
index 3fdf80ebed..8cf79963f1 100644
--- a/libavcodec/riscv/lpc_rvv.S
+++ b/libavcodec/riscv/lpc_rvv.S
@@ -86,10 +86,11 @@ func ff_lpc_apply_welch_window_rvv, zve64d
         ret
 endfunc
 
-func ff_lpc_compute_autocorr_rvv, zve64d
+func ff_lpc_compute_autocorr_rvv, zve64d, zbb
         addi      a2, a2, 1
+        vtype_vli t1, a2, t2, e64, ta, ma
         li        t0, 1
-        vsetvli   zero, a2, e64, m8, ta, ma
+        vsetvl    zero, a2, t1
         fcvt.d.l  ft0, t0
         vle64.v   v0, (a0)
         sh3add    a0, a2, a0   # data += lag