x86/opusdsp: implement FMA3 accelerated postfilter and deemphasis

58893 decicycles in deemphasis_c,  130548 runs,    524 skips
9475 decicycles in deemphasis_fma3,  130686 runs,    386 skips -> 6.21x speedup

24866 decicycles in postfilter_c,   65386 runs,    150 skips
5268 decicycles in postfilter_fma3,   65505 runs,     31 skips -> 4.72x speedup

Total decoder speedup: ~14%

Deemphasis SIMD based on the following unrolling:
const float c1 = CELT_EMPH_COEFF, c2 = c1*c1, c3 = c2*c1, c4 = c3*c1;
float state = coeff;

for (int i = 0; i < len; i += 4) {
    y[0] = x[0] + c1*state;
    y[1] = x[1] + c2*state + c1*x[0];
    y[2] = x[2] + c3*state + c1*x[1] + c2*x[0];
    y[3] = x[3] + c4*state + c1*x[2] + c2*x[1] + c3*x[0];

    state = y[3];
    y += 4;
    x += 4;
}

libavcodec/opusdsp.c

@@ -58,4 +58,7 @@ av_cold void ff_opus_dsp_init(OpusDSP *ctx)
 {
     ctx->postfilter = postfilter_c;
     ctx->deemphasis = deemphasis_c;
+
+    if (ARCH_X86)
+        ff_opus_dsp_init_x86(ctx);
 }

libavcodec/opusdsp.h

@@ -30,4 +30,6 @@ typedef struct OpusDSP {
 
 void ff_opus_dsp_init(OpusDSP *ctx);
 
+void ff_opus_dsp_init_x86(OpusDSP *ctx);
+
 #endif /* AVCODEC_OPUSDSP_H */

libavcodec/x86/Makefile

@@ -53,6 +53,7 @@ OBJS-$(CONFIG_CAVS_DECODER)            += x86/cavsdsp.o
 OBJS-$(CONFIG_DCA_DECODER)             += x86/dcadsp_init.o x86/synth_filter_init.o
 OBJS-$(CONFIG_DNXHD_ENCODER)           += x86/dnxhdenc_init.o
 OBJS-$(CONFIG_EXR_DECODER)             += x86/exrdsp_init.o
+OBJS-$(CONFIG_OPUS_DECODER)            += x86/opusdsp_init.o
 OBJS-$(CONFIG_OPUS_ENCODER)            += x86/celt_pvq_init.o
 OBJS-$(CONFIG_HEVC_DECODER)            += x86/hevcdsp_init.o
 OBJS-$(CONFIG_JPEG2000_DECODER)        += x86/jpeg2000dsp_init.o
@@ -126,6 +127,7 @@ X86ASM-OBJS-$(CONFIG_MDCT15)           += x86/mdct15.o
 X86ASM-OBJS-$(CONFIG_ME_CMP)           += x86/me_cmp.o
 X86ASM-OBJS-$(CONFIG_MPEGAUDIODSP)     += x86/imdct36.o
 X86ASM-OBJS-$(CONFIG_MPEGVIDEOENC)     += x86/mpegvideoencdsp.o
+X86ASM-OBJS-$(CONFIG_OPUS_DECODER)     += x86/opusdsp.o
 X86ASM-OBJS-$(CONFIG_OPUS_ENCODER)     += x86/celt_pvq_search.o
 X86ASM-OBJS-$(CONFIG_PIXBLOCKDSP)      += x86/pixblockdsp.o
 X86ASM-OBJS-$(CONFIG_QPELDSP)          += x86/qpeldsp.o                 \

libavcodec/x86/opusdsp.asm

+;******************************************************************************
+;* Opus SIMD functions
+;*
+;* This file is part of FFmpeg.
+;*
+;* FFmpeg is free software; you can redistribute it and/or
+;* modify it under the terms of the GNU Lesser General Public
+;* License as published by the Free Software Foundation; either
+;* version 2.1 of the License, or (at your option) any later version.
+;*
+;* FFmpeg is distributed in the hope that it will be useful,
+;* but WITHOUT ANY WARRANTY; without even the implied warranty of
+;* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+;* Lesser General Public License for more details.
+;*
+;* You should have received a copy of the GNU Lesser General Public
+;* License along with FFmpeg; if not, write to the Free Software
+;* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+;******************************************************************************
+
+%include "libavutil/x86/x86util.asm"
+
+SECTION_RODATA
+
+         ; 0.85..^1    0.85..^2    0.85..^3    0.85..^4
+tab_st: dd 0x3f599a00, 0x3f38f671, 0x3f1d382a, 0x3f05a32f
+tab_x0: dd 0x0,        0x3f599a00, 0x3f599a00, 0x3f599a00
+tab_x1: dd 0x0,        0x0,        0x3f38f671, 0x3f38f671
+tab_x2: dd 0x0,        0x0,        0x0,        0x3f1d382a
+
+SECTION .text
+
+INIT_XMM fma3
+%if UNIX64
+cglobal opus_deemphasis, 3, 3, 8, out, in, len
+%else
+cglobal opus_deemphasis, 4, 4, 8, out, in, coeff, len
+%endif
+%if ARCH_X86_32
+    VBROADCASTSS m0, coeffm
+%else
+%if WIN64
+    SWAP 0, 2
+%endif
+    shufps m0, m0, 0
+%endif
+
+    movaps m4, [tab_st]
+    movaps m5, [tab_x0]
+    movaps m6, [tab_x1]
+    movaps m7, [tab_x2]
+
+.loop:
+    movaps  m1, [inq]                ; x0, x1, x2, x3
+
+    pslldq  m2, m1, 4                ;  0, x0, x1, x2
+    pslldq  m3, m1, 8                ;  0,  0, x0, x1
+
+    fmaddps m2, m2, m5, m1           ; x + c1*x[0-2]
+    pslldq  m1, 12                   ;  0,  0,  0, x0
+
+    fmaddps m2, m3, m6, m2           ; x + c1*x[0-2] + c2*x[0-1]
+    fmaddps m1, m1, m7, m2           ; x + c1*x[0-2] + c2*x[0-1] + c3*x[0]
+    fmaddps m0, m0, m4, m1           ; x + c1*x[0-2] + c2*x[0-1] + c3*x[0] + c*s
+
+    movaps [outq], m0
+    shufps m0, m0, q3333             ; new state
+
+    add inq,  mmsize
+    add outq, mmsize
+    sub lenq, mmsize >> 2
+    jg .loop
+
+%if ARCH_X86_64 == 0
+    movss r0m, m0
+    fld dword r0m
+%endif
+    RET
+
+
+INIT_XMM fma3
+cglobal opus_postfilter, 4, 4, 8, data, period, gains, len
+    VBROADCASTSS m0, [gainsq + 0]
+    VBROADCASTSS m1, [gainsq + 4]
+    VBROADCASTSS m2, [gainsq + 8]
+
+    lea periodq, [periodq*4 + 8]
+    neg periodq
+
+    movups  m3, [dataq + periodq]
+    mulps   m3, m2
+
+.loop:
+    movups  m4, [dataq + periodq +  4]
+    movups  m5, [dataq + periodq +  8]
+    movups  m6, [dataq + periodq + 12]
+    movups  m7, [dataq + periodq + 16]
+
+    fmaddps m3, m7, m2, m3
+    addps   m6, m4
+
+    fmaddps m5, m5, m0, [dataq]
+    fmaddps m6, m6, m1, m3
+
+    addps   m5, m6
+    mulps   m3, m7, m2
+
+    movaps  [dataq], m5
+
+    add dataq, mmsize
+    sub lenq,  mmsize >> 2
+    jg .loop
+
+    RET

libavcodec/x86/opusdsp_init.c

+/*
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "config.h"
+
+#include "libavutil/x86/cpu.h"
+#include "libavcodec/opusdsp.h"
+
+void ff_opus_postfilter_fma3(float *data, int period, float *gains, int len);
+float ff_opus_deemphasis_fma3(float *out, float *in, float coeff, int len);
+
+av_cold void ff_opus_dsp_init_x86(OpusDSP *ctx)
+{
+    int cpu_flags = av_get_cpu_flags();
+
+    if (EXTERNAL_FMA3_FAST(cpu_flags)) {
+        ctx->postfilter = ff_opus_postfilter_fma3;
+        ctx->deemphasis = ff_opus_deemphasis_fma3;
+    }
+}