| Message ID | 20221003150642.5411-1-remi@remlab.net |
|---|---|
| State | Accepted |
| Commit | 96a83ceea434911d825223eaafa0f999e2a9d1fa |
| Headers | show |
| Series | [FFmpeg-devel] riscv: fix scalar product initialisation | expand |
| Context | Check | Description |
|---|---|---|
| andriy/make_x86 | success | Make finished |
| andriy/make_fate_x86 | success | Make fate finished |
Le maanantaina 3. lokakuuta 2022, 18.06.42 EEST remi@remlab.net a écrit : > From: Rémi Denis-Courmont <remi@remlab.net> > > VSETVLI xd, x0, ...' has rather nonobvious semantics: > - If xd is x0, then it preserves the current vector length. > - If xd is not x0, it sets the vector length to the supported maximum. > > Also somewhat confusingly, while VMV.X.S always does its thing > regardless of the selected vector length, VMV.S.X does _nothing_ if the > selected vector length is zero. > > So the current code breaks fails to initialise the accumulator if we > are unlucky to have a selected vector length of zero on entry. Fix it > by forcing the vector length to one. Ping. The issue becomes systematically reproducible with the checkasm support.
diff --git a/libavcodec/riscv/audiodsp_rvv.S b/libavcodec/riscv/audiodsp_rvv.S index f4308f27c5..8e8bbd2058 100644 --- a/libavcodec/riscv/audiodsp_rvv.S +++ b/libavcodec/riscv/audiodsp_rvv.S @@ -21,7 +21,7 @@ #include "libavutil/riscv/asm.S" func ff_scalarproduct_int16_rvv, zve32x - vsetvli zero, zero, e16, m1, ta, ma + vsetivli zero, 1, e16, m1, ta, ma vmv.s.x v8, zero 1: vsetvli t0, a2, e16, m1, ta, ma diff --git a/libavutil/riscv/float_dsp_rvv.S b/libavutil/riscv/float_dsp_rvv.S index ab2e0c42d7..e105f2d574 100644 --- a/libavutil/riscv/float_dsp_rvv.S +++ b/libavutil/riscv/float_dsp_rvv.S @@ -167,7 +167,7 @@ endfunc // a0 = (a0).(a1) [0..a2-1] func ff_scalarproduct_float_rvv, zve32f - vsetvli zero, zero, e32, m1, ta, ma + vsetivli zero, 1, e32, m1, ta, ma vmv.s.x v8, zero 1: vsetvli t0, a2, e32, m1, ta, ma
From: Rémi Denis-Courmont <remi@remlab.net> VSETVLI xd, x0, ...' has rather nonobvious semantics: - If xd is x0, then it preserves the current vector length. - If xd is not x0, it sets the vector length to the supported maximum. Also somewhat confusingly, while VMV.X.S always does its thing regardless of the selected vector length, VMV.S.X does _nothing_ if the selected vector length is zero. So the current code breaks fails to initialise the accumulator if we are unlucky to have a selected vector length of zero on entry. Fix it by forcing the vector length to one. --- libavcodec/riscv/audiodsp_rvv.S | 2 +- libavutil/riscv/float_dsp_rvv.S | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-)