Re: [FFmpeg-devel] [PATCH 2/2] lavc/flacdsp: implement wasted32 DSP function for VSX on POWER

["Rémi Denis-Courmont" <remi@remlab.net>]

Le 4 juillet 2024 04:23:30 GMT+03:00, Sean McGovern <gseanmcg@gmail.com> a écrit :
>RaptorCS POWER9 (8c4t) @ 2.2GHz:
>flac_wasted_32_c: 50.1
>flac_wasted_32_vsx: 17.3
>---
> libavcodec/flacdsp.c          |  2 ++
> libavcodec/flacdsp.h          |  1 +
> libavcodec/ppc/Makefile       |  2 ++
> libavcodec/ppc/flacdsp_init.c | 38 ++++++++++++++++++++++++++++
> libavcodec/ppc/flacdsp_vsx.c  | 47 +++++++++++++++++++++++++++++++++++
> 5 files changed, 90 insertions(+)
> create mode 100644 libavcodec/ppc/flacdsp_init.c
> create mode 100644 libavcodec/ppc/flacdsp_vsx.c
>
>diff --git a/libavcodec/flacdsp.c b/libavcodec/flacdsp.c
>index f5362bf66f..b63d55ddcd 100644
>--- a/libavcodec/flacdsp.c
>+++ b/libavcodec/flacdsp.c
>@@ -156,5 +156,7 @@ av_cold void ff_flacdsp_init(FLACDSPContext *c, enum AVSampleFormat fmt, int cha
>     ff_flacdsp_init_riscv(c, fmt, channels);
> #elif ARCH_X86
>     ff_flacdsp_init_x86(c, fmt, channels);
>+#elif ARCH_PPC
>+    ff_flacdsp_init_ppc(c, fmt, channels);
> #endif
> }
>diff --git a/libavcodec/flacdsp.h b/libavcodec/flacdsp.h
>index 3b7b35a112..941536ef16 100644
>--- a/libavcodec/flacdsp.h
>+++ b/libavcodec/flacdsp.h
>@@ -45,5 +45,6 @@ void ff_flacdsp_init(FLACDSPContext *c, enum AVSampleFormat fmt, int channels);
> void ff_flacdsp_init_arm(FLACDSPContext *c, enum AVSampleFormat fmt, int channels);
> void ff_flacdsp_init_riscv(FLACDSPContext *c, enum AVSampleFormat fmt, int channels);
> void ff_flacdsp_init_x86(FLACDSPContext *c, enum AVSampleFormat fmt, int channels);
>+void ff_flacdsp_init_ppc(FLACDSPContext *c, enum AVSampleFormat fmt, int channels);
> 
> #endif /* AVCODEC_FLACDSP_H */
>diff --git a/libavcodec/ppc/Makefile b/libavcodec/ppc/Makefile
>index 10b9ca60da..7f81a8aa34 100644
>--- a/libavcodec/ppc/Makefile
>+++ b/libavcodec/ppc/Makefile
>@@ -2,6 +2,8 @@
> OBJS-$(CONFIG_AUDIODSP)                += ppc/audiodsp.o
> OBJS-$(CONFIG_BLOCKDSP)                += ppc/blockdsp.o
> OBJS-$(CONFIG_FDCTDSP)                 += ppc/fdctdsp.o
>+OBJS-$(CONFIG_FLAC_DECODER)            += ppc/flacdsp_init.o
>+VSX-OBJS-$(CONFIG_FLAC_DECODER)        += ppc/flacdsp_vsx.o
> OBJS-$(CONFIG_FMTCONVERT)              += ppc/fmtconvert_altivec.o
> OBJS-$(CONFIG_H264CHROMA)              += ppc/h264chroma_init.o
> OBJS-$(CONFIG_H264DSP)                 += ppc/h264dsp.o ppc/hpeldsp_altivec.o
>diff --git a/libavcodec/ppc/flacdsp_init.c b/libavcodec/ppc/flacdsp_init.c
>new file mode 100644
>index 0000000000..526bddddbf
>--- /dev/null
>+++ b/libavcodec/ppc/flacdsp_init.c
>@@ -0,0 +1,38 @@
>+/*
>+ * Copyright (c) 2024 Sean McGovern <gseanmcg@gmail.com>
>+ *
>+ * 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/attributes.h"
>+#include "libavutil/cpu.h"
>+#include "libavutil/ppc/cpu.h"
>+#include "libavcodec/flacdsp.h"
>+
>+void ff_flac_wasted32_vsx(int32_t *, int wasted, int len);
>+
>+av_cold void ff_flacdsp_init_ppc(FLACDSPContext *c, enum AVSampleFormat fmt, int channels)
>+{
>+#if HAVE_VSX
>+    if (!PPC_VSX(av_get_cpu_flags()))
>+        return;
>+
>+    c->wasted32 = ff_flac_wasted32_vsx;
>+#endif
>+}
>diff --git a/libavcodec/ppc/flacdsp_vsx.c b/libavcodec/ppc/flacdsp_vsx.c
>new file mode 100644
>index 0000000000..c31566458c
>--- /dev/null
>+++ b/libavcodec/ppc/flacdsp_vsx.c
>@@ -0,0 +1,47 @@
>+/*
>+ * Copyright (c) 2024 Sean McGovern <gseanmcg@gmail.com>
>+ *
>+ * 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/attributes.h"
>+#include "libavutil/cpu.h"
>+#include "libavutil/ppc/cpu.h"
>+#include "libavutil/ppc/util_altivec.h"
>+#include "libavcodec/flacdsp.h"
>+
>+void ff_flac_wasted32_vsx(int32_t *, int wasted, int len);
>+
>+#if HAVE_VSX
>+
>+void ff_flac_wasted32_vsx(int32_t *decoded, int wasted, int len)
>+{
>+    register vec_s32 vec1;
>+    const register vec_u32 vec2 = vec_splats((unsigned)wasted);
>+    register vec_s32 shifted;
>+
>+    for (int i = 0; i < len; i+=sizeof(int32_t)) {

len in elements, so why is the increment in bytes? Looks like heterogeneous measurement units.

>+        vec1 = vec_xl(0, decoded);
>+        shifted = vec_sl(vec1, vec2);
>+        vec_xst(shifted, 0, decoded);

Judging by other AltiVec code, this lacks unrolling.

>+        decoded += sizeof(int32_t);
>+    }
>+}
>+
>+#endif /* HAVE_VSX */
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