[FFmpeg-cvslog] opus_pvq_search: split functions into exactness and only use the exact if its faster
Rostislav Pehlivanov
git at videolan.org
Fri Aug 18 21:33:35 EEST 2017
ffmpeg | branch: master | Rostislav Pehlivanov <atomnuker at gmail.com> | Fri Aug 18 19:29:33 2017 +0100| [3c99523a2864af729a8576c3fffe81fb884fa0d5] | committer: Rostislav Pehlivanov
opus_pvq_search: split functions into exactness and only use the exact if its faster
This splits the asm function into exact and non-exact version. The exact
version is as fast or faster on newer CPUs (which EXTERNAL_AVX_FAST describes
well) whilst the non-exact version is faster than the exact on older CPUs.
Also fixes yasm compilation which doesn't accept !cpuflags(avx) syntax.
Signed-off-by: Rostislav Pehlivanov <atomnuker at gmail.com>
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=3c99523a2864af729a8576c3fffe81fb884fa0d5
---
libavcodec/x86/opus_dsp_init.c | 14 +++++++-------
libavcodec/x86/opus_pvq_search.asm | 34 +++++++++++++++++++++-------------
2 files changed, 28 insertions(+), 20 deletions(-)
diff --git a/libavcodec/x86/opus_dsp_init.c b/libavcodec/x86/opus_dsp_init.c
index c51f786ee8..a9f8a96159 100644
--- a/libavcodec/x86/opus_dsp_init.c
+++ b/libavcodec/x86/opus_dsp_init.c
@@ -24,9 +24,9 @@
#include "libavutil/x86/cpu.h"
#include "libavcodec/opus_pvq.h"
-extern float ff_pvq_search_sse2(float *X, int *y, int K, int N);
-extern float ff_pvq_search_sse4(float *X, int *y, int K, int N);
-extern float ff_pvq_search_avx (float *X, int *y, int K, int N);
+extern float ff_pvq_search_approx_sse2(float *X, int *y, int K, int N);
+extern float ff_pvq_search_approx_sse4(float *X, int *y, int K, int N);
+extern float ff_pvq_search_exact_avx (float *X, int *y, int K, int N);
av_cold void ff_opus_dsp_init_x86(CeltPVQ *s)
{
@@ -34,12 +34,12 @@ av_cold void ff_opus_dsp_init_x86(CeltPVQ *s)
#if CONFIG_OPUS_ENCODER
if (EXTERNAL_SSE2(cpu_flags))
- s->pvq_search = ff_pvq_search_sse2;
+ s->pvq_search = ff_pvq_search_approx_sse2;
if (EXTERNAL_SSE4(cpu_flags))
- s->pvq_search = ff_pvq_search_sse4;
+ s->pvq_search = ff_pvq_search_approx_sse4;
- if (EXTERNAL_AVX(cpu_flags))
- s->pvq_search = ff_pvq_search_avx;
+ if (EXTERNAL_AVX_FAST(cpu_flags))
+ s->pvq_search = ff_pvq_search_exact_avx;
#endif
}
diff --git a/libavcodec/x86/opus_pvq_search.asm b/libavcodec/x86/opus_pvq_search.asm
index 2f4864c95c..8cf040465d 100644
--- a/libavcodec/x86/opus_pvq_search.asm
+++ b/libavcodec/x86/opus_pvq_search.asm
@@ -82,7 +82,7 @@ SECTION .text
%endif
%endmacro
-%macro PULSES_SEARCH 1
+%macro PULSES_SEARCH 2 ; %1 - add or sub, %2 - use approximation
; m6 Syy_norm
; m7 Sxy_norm
addps m6, mm_const_float_0_5 ; Syy_norm += 1.0/2
@@ -96,7 +96,7 @@ align 16
movaps m4, [tmpY + r4] ; y[i]
movaps m5, [tmpX + r4] ; X[i]
-%if !cpuflag(avx) ; for crappy ancient CPUs that have slow packed divs but fast 1/sqrt
+%if %2
xorps m0, m0
cmpps m0, m0, m5, 4 ; m0 = (X[i] != 0.0)
%endif
@@ -104,7 +104,7 @@ align 16
addps m4, m6 ; m4 = Syy_new = y[i] + Syy_norm
addps m5, m7 ; m5 = Sxy_new = X[i] + Sxy_norm
-%if !cpuflag(avx)
+%if %2
andps m5, m0 ; if(X[i] == 0) Sxy_new = 0; Prevent aproximation error from setting pulses in array padding.
%endif
@@ -119,7 +119,7 @@ align 16
andps m5, m0 ; (0<y)?m5:0
%endif
-%if !cpuflag(avx)
+%if %2
rsqrtps m4, m4
mulps m5, m4 ; m5 = p = Sxy_new*approx(1/sqrt(Syy) )
%else
@@ -211,8 +211,13 @@ align 16
; uint32 K - Number of pulses to have after quantizations.
; uint32 N - Number of vector elements. Must be 0 < N < 256
;
-%macro PVQ_FAST_SEARCH 0
-cglobal pvq_search, 4, 5+num_pic_regs, 11, 256*4, inX, outY, K, N
+%macro PVQ_FAST_SEARCH 1 ; %1 - use approximation
+%if %1
+cglobal pvq_search_approx, 4, 5+num_pic_regs, 11, 256*4, inX, outY, K, N
+%else
+cglobal pvq_search_exact, 4, 5+num_pic_regs, 11, 256*4, inX, outY, K, N
+%endif
+
%define tmpX rsp
%define tmpY outYq
@@ -255,7 +260,7 @@ align 16
jz %%zero_input ; if (Sx==0) goto zero_input
cvtsi2ss xm0, dword Kd ; m0 = K
-%if !cpuflag(avx)
+%if %1
rcpss xm1, xm1 ; m1 = approx(1/Sx)
mulss xm0, xm1 ; m0 = K*(1/Sx)
%else
@@ -308,7 +313,7 @@ align 16
align 16 ; K - pulses > 0
%%add_pulses_loop:
- PULSES_SEARCH add ; m6 Syy_norm ; m7 Sxy_norm
+ PULSES_SEARCH add, %1 ; m6 Syy_norm ; m7 Sxy_norm
sub Kd, 1
jnz %%add_pulses_loop
@@ -320,7 +325,7 @@ align 16 ; K - pulses > 0
align 16
%%remove_pulses_loop:
- PULSES_SEARCH sub ; m6 Syy_norm ; m7 Sxy_norm
+ PULSES_SEARCH sub, %1 ; m6 Syy_norm ; m7 Sxy_norm
add Kd, 1
jnz %%remove_pulses_loop
@@ -367,12 +372,15 @@ align 16
jmp %%return
%endmacro
-
+; if 1, use a float op that give half precision but execute for around 3 cycles.
+; On Skylake & Ryzen the division is much faster (around 11c/3),
+; that makes the full precision code about 2% slower.
+; Opus also does use rsqrt approximation in their intrinsics code.
INIT_XMM sse2
-PVQ_FAST_SEARCH
+PVQ_FAST_SEARCH 1
INIT_XMM sse4
-PVQ_FAST_SEARCH
+PVQ_FAST_SEARCH 1
INIT_XMM avx
-PVQ_FAST_SEARCH
+PVQ_FAST_SEARCH 0
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