arm: Add VFP-accelerated version of synth_filter_float

               Before           After
               Mean    StdDev   Mean    StdDev  Change
This function   9295.0 114.9     4853.2 83.5    +91.5%
Overall        23699.8 397.6    19285.5 292.0   +22.9%
Signed-off-by: Martin Storsjö <martin@martin.st>

libavcodec/arm/Makefile

@@ -52,6 +52,7 @@ ARMV6-OBJS-$(CONFIG_VP8_DECODER)       += arm/vp8_armv6.o               \
                                           arm/vp8dsp_init_armv6.o       \
                                           arm/vp8dsp_armv6.o
 
+VFP-OBJS-$(CONFIG_DCA_DECODER)         += arm/synth_filter_vfp.o
 VFP-OBJS-$(HAVE_ARMV6)                 += arm/fmtconvert_vfp.o
 
 NEON-OBJS                              += arm/fmtconvert_neon.o

libavcodec/arm/fft_init_arm.c

@@ -32,6 +32,12 @@ void ff_mdct_calc_neon(FFTContext *s, FFTSample *output, const FFTSample *input)
 
 void ff_rdft_calc_neon(struct RDFTContext *s, FFTSample *z);
 
+void ff_synth_filter_float_vfp(FFTContext *imdct,
+                               float *synth_buf_ptr, int *synth_buf_offset,
+                               float synth_buf2[32], const float window[512],
+                               float out[32], const float in[32],
+                               float scale);
+
 void ff_synth_filter_float_neon(FFTContext *imdct,
                                 float *synth_buf_ptr, int *synth_buf_offset,
                                 float synth_buf2[32], const float window[512],
@@ -69,6 +75,8 @@ av_cold void ff_synth_filter_init_arm(SynthFilterContext *s)
 {
     int cpu_flags = av_get_cpu_flags();
 
+    if (have_vfp(cpu_flags) && !have_vfpv3(cpu_flags))
+        s->synth_filter_float = ff_synth_filter_float_vfp;
     if (have_neon(cpu_flags))
         s->synth_filter_float = ff_synth_filter_float_neon;
 }

libavcodec/arm/synth_filter_vfp.S

+/*
+ * Copyright (c) 2013 RISC OS Open Ltd
+ * Author: Ben Avison <bavison@riscosopen.org>
+ *
+ * This file is part of Libav.
+ *
+ * Libav 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.
+ *
+ * Libav 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 Libav; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "libavutil/arm/asm.S"
+
+IMDCT         .req    r0
+ORIG_P_SB     .req    r1
+P_SB_OFF      .req    r2
+I             .req    r0
+P_SB2_UP      .req    r1
+OLDFPSCR      .req    r2
+P_SB2_DN      .req    r3
+P_WIN_DN      .req    r4
+P_OUT_DN      .req    r5
+P_SB          .req    r6
+J_WRAP        .req    r7
+P_WIN_UP      .req    r12
+P_OUT_UP      .req    r14
+
+SCALE         .req    s0
+SBUF_DAT_REV0 .req    s4
+SBUF_DAT_REV1 .req    s5
+SBUF_DAT_REV2 .req    s6
+SBUF_DAT_REV3 .req    s7
+VA0           .req    s8
+VA3           .req    s11
+VB0           .req    s12
+VB3           .req    s15
+VC0           .req    s8
+VC3           .req    s11
+VD0           .req    s12
+VD3           .req    s15
+SBUF_DAT0     .req    s16
+SBUF_DAT1     .req    s17
+SBUF_DAT2     .req    s18
+SBUF_DAT3     .req    s19
+SBUF_DAT_ALT0 .req    s20
+SBUF_DAT_ALT1 .req    s21
+SBUF_DAT_ALT2 .req    s22
+SBUF_DAT_ALT3 .req    s23
+WIN_DN_DAT0   .req    s24
+WIN_UP_DAT0   .req    s28
+
+
+.macro inner_loop  half, tail, head
+ .if (OFFSET & (64*4)) == 0                @ even numbered call
+        SBUF_DAT_THIS0 .req SBUF_DAT0
+        SBUF_DAT_THIS1 .req SBUF_DAT1
+        SBUF_DAT_THIS2 .req SBUF_DAT2
+        SBUF_DAT_THIS3 .req SBUF_DAT3
+  .ifnc "\head",""
+        vldr    d8, [P_SB, #OFFSET]        @ d8 = SBUF_DAT
+        vldr    d9, [P_SB, #OFFSET+8]
+  .endif
+ .else
+        SBUF_DAT_THIS0 .req SBUF_DAT_ALT0
+        SBUF_DAT_THIS1 .req SBUF_DAT_ALT1
+        SBUF_DAT_THIS2 .req SBUF_DAT_ALT2
+        SBUF_DAT_THIS3 .req SBUF_DAT_ALT3
+  .ifnc "\head",""
+        vldr    d10, [P_SB, #OFFSET]       @ d10 = SBUF_DAT_ALT
+        vldr    d11, [P_SB, #OFFSET+8]
+  .endif
+ .endif
+ .ifnc "\tail",""
+  .ifc "\half","ab"
+        vmls.f  VA0, SBUF_DAT_REV0, WIN_DN_DAT0  @ all operands treated as vectors
+  .else
+        vmla.f  VD0, SBUF_DAT_REV0, WIN_DN_DAT0  @ all operands treated as vectors
+  .endif
+ .endif
+ .ifnc "\head",""
+        vldr    d14, [P_WIN_UP, #OFFSET]   @ d14 = WIN_UP_DAT
+        vldr    d15, [P_WIN_UP, #OFFSET+8]
+        vldr    d12, [P_WIN_DN, #OFFSET]   @ d12 = WIN_DN_DAT
+        vldr    d13, [P_WIN_DN, #OFFSET+8]
+        vmov    SBUF_DAT_REV3, SBUF_DAT_THIS0
+        vmov    SBUF_DAT_REV2, SBUF_DAT_THIS1
+        vmov    SBUF_DAT_REV1, SBUF_DAT_THIS2
+        vmov    SBUF_DAT_REV0, SBUF_DAT_THIS3
+  .ifc "\half","ab"
+        vmla.f  VB0, SBUF_DAT_THIS0, WIN_UP_DAT0
+  .else
+        vmla.f  VC0, SBUF_DAT_THIS0, WIN_UP_DAT0
+  .endif
+        teq     J_WRAP, #J
+        bne     2f             @ strongly predictable, so better than cond exec in this case
+        sub     P_SB, P_SB, #512*4
+2:
+  .set J, J - 64
+  .set OFFSET, OFFSET + 64*4
+ .endif
+        .unreq  SBUF_DAT_THIS0
+        .unreq  SBUF_DAT_THIS1
+        .unreq  SBUF_DAT_THIS2
+        .unreq  SBUF_DAT_THIS3
+.endm
+
+
+/* void ff_synth_filter_float_vfp(FFTContext *imdct,
+ *                                float *synth_buf_ptr, int *synth_buf_offset,
+ *                                float synth_buf2[32], const float window[512],
+ *                                float out[32], const float in[32], float scale)
+ */
+function ff_synth_filter_float_vfp, export=1
+        push    {r3-r7,lr}
+        vpush   {s16-s31}
+        ldr     lr, [P_SB_OFF]
+        add     a2, ORIG_P_SB, lr, LSL #2 @ calculate synth_buf to pass to imdct_half
+        mov     P_SB, a2                  @ and keep a copy for ourselves
+        bic     J_WRAP, lr, #63           @ mangled to make testing for wrap easier in inner loop
+        sub     lr, lr, #32
+        and     lr, lr, #512-32
+        str     lr, [P_SB_OFF]            @ rotate offset, modulo buffer size, ready for next call
+        ldr     a3, [sp, #(16+6+2)*4]     @ fetch in from stack, to pass to imdct_half
+VFP     vmov    s16, SCALE                @ imdct_half is free to corrupt s0, but it contains one of our arguments in hardfp case
+        bl      ff_imdct_half_c
+VFP     vmov    SCALE, s16
+
+        fmrx    OLDFPSCR, FPSCR
+        ldr     lr, =0x03030000           @ RunFast mode, short vectors of length 4, stride 1
+        fmxr    FPSCR, lr
+        ldr     P_SB2_DN, [sp, #16*4]
+        ldr     P_WIN_DN, [sp, #(16+6+0)*4]
+        ldr     P_OUT_DN, [sp, #(16+6+1)*4]
+NOVFP   vldr    SCALE, [sp, #(16+6+3)*4]
+
+#define IMM_OFF_SKEW 956                   /* also valid immediate constant when you add 16*4 */
+        add     P_SB, P_SB, #IMM_OFF_SKEW  @ so we can use -ve offsets to use full immediate offset range
+        add     P_SB2_UP, P_SB2_DN, #16*4
+        add     P_WIN_UP, P_WIN_DN, #16*4+IMM_OFF_SKEW
+        add     P_OUT_UP, P_OUT_DN, #16*4
+        add     P_SB2_DN, P_SB2_DN, #16*4
+        add     P_WIN_DN, P_WIN_DN, #12*4+IMM_OFF_SKEW
+        add     P_OUT_DN, P_OUT_DN, #16*4
+        mov     I, #4
+1:
+        vldmia  P_SB2_UP!, {VB0-VB3}
+        vldmdb  P_SB2_DN!, {VA0-VA3}
+ .set J, 512 - 64
+ .set OFFSET, -IMM_OFF_SKEW
+        inner_loop  ab,, head
+ .rept 7
+        inner_loop  ab, tail, head
+ .endr
+        inner_loop  ab, tail
+        add     P_WIN_UP, P_WIN_UP, #4*4
+        sub     P_WIN_DN, P_WIN_DN, #4*4
+        vmul.f  VB0, VB0, SCALE      @ SCALE treated as scalar
+        add     P_SB, P_SB, #(512+4)*4
+        subs    I, I, #1
+        vmul.f  VA0, VA0, SCALE
+        vstmia  P_OUT_UP!, {VB0-VB3}
+        vstmdb  P_OUT_DN!, {VA0-VA3}
+        bne     1b
+
+        add     P_SB2_DN, P_SB2_DN, #(16+28-12)*4
+        sub     P_SB2_UP, P_SB2_UP, #(16+16)*4
+        add     P_WIN_DN, P_WIN_DN, #(32+16+28-12)*4
+        mov     I, #4
+1:
+        vldr.d  d4, zero             @ d4 = VC0
+        vldr.d  d5, zero
+        vldr.d  d6, zero             @ d6 = VD0
+        vldr.d  d7, zero
+ .set J, 512 - 64
+ .set OFFSET, -IMM_OFF_SKEW
+        inner_loop  cd,, head
+ .rept 7
+        inner_loop  cd, tail, head
+ .endr
+        inner_loop  cd, tail
+        add     P_WIN_UP, P_WIN_UP, #4*4
+        sub     P_WIN_DN, P_WIN_DN, #4*4
+        add     P_SB, P_SB, #(512+4)*4
+        subs    I, I, #1
+        vstmia  P_SB2_UP!, {VC0-VC3}
+        vstmdb  P_SB2_DN!, {VD0-VD3}
+        bne     1b
+
+        fmxr    FPSCR, OLDFPSCR
+        vpop    {s16-s31}
+        pop     {r3-r7,pc}
+endfunc
+
+        .unreq  IMDCT
+        .unreq  ORIG_P_SB
+        .unreq  P_SB_OFF
+        .unreq  I
+        .unreq  P_SB2_UP
+        .unreq  OLDFPSCR
+        .unreq  P_SB2_DN
+        .unreq  P_WIN_DN
+        .unreq  P_OUT_DN
+        .unreq  P_SB
+        .unreq  J_WRAP
+        .unreq  P_WIN_UP
+        .unreq  P_OUT_UP
+
+        .unreq  SCALE
+        .unreq  SBUF_DAT_REV0
+        .unreq  SBUF_DAT_REV1
+        .unreq  SBUF_DAT_REV2
+        .unreq  SBUF_DAT_REV3
+        .unreq  VA0
+        .unreq  VA3
+        .unreq  VB0
+        .unreq  VB3
+        .unreq  VC0
+        .unreq  VC3
+        .unreq  VD0
+        .unreq  VD3
+        .unreq  SBUF_DAT0
+        .unreq  SBUF_DAT1
+        .unreq  SBUF_DAT2
+        .unreq  SBUF_DAT3
+        .unreq  SBUF_DAT_ALT0
+        .unreq  SBUF_DAT_ALT1
+        .unreq  SBUF_DAT_ALT2
+        .unreq  SBUF_DAT_ALT3
+        .unreq  WIN_DN_DAT0
+        .unreq  WIN_UP_DAT0
+
+        .align  3
+zero:   .word   0, 0