On date Tuesday 2015-06-16 10:20:31 +0200, wm4 encoded:
> On Mon, 15 Jun 2015 17:55:35 +0200
> Stefano Sabatini <stefa...@gmail.com> wrote:
>
> > On date Monday 2015-06-15 11:56:13 +0200, Stefano Sabatini encoded:
> > [...]
> > > From 3a75ef1e86360cd6f30b8e550307404d0d1c1dba Mon Sep 17 00:00:00 2001
> > > From: Stefano Sabatini <stefa...@gmail.com>
> > > Date: Mon, 15 Jun 2015 11:02:50 +0200
> > > Subject: [PATCH] lavu/mem: add av_memcpynt() function with x86
> > > optimizations
> > >
> > > Assembly based on code from vlc dxva2.c, commit 62107e56 by Laurent Aimar
> > > <fen...@videolan.org>.
> > >
> > > TODO: bump minor, update APIchanges
> > > ---
> > > libavutil/mem.c | 9 +++++
> > > libavutil/mem.h | 14 ++++++++
> > > libavutil/mem_internal.h | 26 +++++++++++++++
> > > libavutil/x86/Makefile | 1 +
> > > libavutil/x86/mem.c | 85
> > > ++++++++++++++++++++++++++++++++++++++++++++++++
> > > 5 files changed, 135 insertions(+)
> > > create mode 100644 libavutil/mem_internal.h
> > > create mode 100644 libavutil/x86/mem.c
> > >
> > > diff --git a/libavutil/mem.c b/libavutil/mem.c
> > > index da291fb..0e1eb01 100644
> > > --- a/libavutil/mem.c
> > > +++ b/libavutil/mem.c
> > > @@ -42,6 +42,7 @@
> > > #include "dynarray.h"
> > > #include "intreadwrite.h"
> > > #include "mem.h"
> > > +#include "mem_internal.h"
> > >
> > > #ifdef MALLOC_PREFIX
> > >
> > > @@ -515,3 +516,11 @@ void av_fast_malloc(void *ptr, unsigned int *size,
> > > size_t min_size)
> > > ff_fast_malloc(ptr, size, min_size, 0);
> > > }
> > >
> > > +void av_memcpynt(void *dst, const void *src, size_t size, int cpu_flags)
> > > +{
> > > +#if ARCH_X86
> > > + ff_memcpynt_x86(dst, src, size, cpu_flags);
> > > +#else
> > > + memcpy(dst, src, size, cpu_flags);
> > > +#endif
> > > +}
> >
> > Alternatively, what about something like:
> >
> > av_memcpynt_fn av_memcpynt_get_fn(void);
> >
> > modeled after av_pixelutils_get_sad_fn()? This would skip the need for
> > a wrapper calling the right function.
>
> I don't see much value in this, unless determining the right function
> causes too much overhead.
I see two advantages, 1. no branch and function call when the function
is called, 2. the cpu_flags must not be passed around, so it's somehow
safer.
I have no strong preference though, updated (untested patch) in
attachment.
--
FFmpeg = Fierce and Forgiving Merciless Powered Extroverse Gargoyle
>From c005ff5405dd48e6b0fed24ed94947f69bfe2783 Mon Sep 17 00:00:00 2001
From: Stefano Sabatini <stefa...@gmail.com>
Date: Mon, 15 Jun 2015 11:02:50 +0200
Subject: [PATCH] lavu/mem: add av_memcpynt_get_fn()
Assembly based on code from vlc dxva2.c, commit 62107e56 by Laurent Aimar
<fen...@videolan.org>.
TODO: remove use of inline assembly, bump minor, update APIchanges
---
libavutil/mem.c | 9 +++++
libavutil/mem.h | 13 +++++++
libavutil/mem_internal.h | 26 +++++++++++++
libavutil/x86/Makefile | 1 +
libavutil/x86/mem.c | 98 ++++++++++++++++++++++++++++++++++++++++++++++++
5 files changed, 147 insertions(+)
create mode 100644 libavutil/mem_internal.h
create mode 100644 libavutil/x86/mem.c
diff --git a/libavutil/mem.c b/libavutil/mem.c
index da291fb..325bfc9 100644
--- a/libavutil/mem.c
+++ b/libavutil/mem.c
@@ -42,6 +42,7 @@
#include "dynarray.h"
#include "intreadwrite.h"
#include "mem.h"
+#include "mem_internal.h"
#ifdef MALLOC_PREFIX
@@ -515,3 +516,11 @@ void av_fast_malloc(void *ptr, unsigned int *size, size_t min_size)
ff_fast_malloc(ptr, size, min_size, 0);
}
+av_memcpynt_fn av_memcpynt_get_fn(void)
+{
+#if ARCH_X86
+ return ff_memcpynt_get_fn_x86();
+#else
+ return memcpy;
+#endif
+}
diff --git a/libavutil/mem.h b/libavutil/mem.h
index 2a1e36d..d9f1b7a 100644
--- a/libavutil/mem.h
+++ b/libavutil/mem.h
@@ -382,6 +382,19 @@ void *av_fast_realloc(void *ptr, unsigned int *size, size_t min_size);
*/
void av_fast_malloc(void *ptr, unsigned int *size, size_t min_size);
+typedef void* (*av_memcpynt_fn)(void *dst, const void *src, size_t size);
+
+/**
+ * Return possibly optimized function to copy size bytes from from src
+ * to dst, using non-temporal copy.
+ *
+ * The returned function works as memcpy, but adopts non-temporal
+ * instructios when available. This can lead to better performances
+ * when transferring data from source to destination is expensive, for
+ * example when reading from GPU memory.
+ */
+av_memcpynt_fn av_memcpynt_get_fn(void);
+
/**
* @}
*/
diff --git a/libavutil/mem_internal.h b/libavutil/mem_internal.h
new file mode 100644
index 0000000..de61cba
--- /dev/null
+++ b/libavutil/mem_internal.h
@@ -0,0 +1,26 @@
+/*
+ * 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
+ */
+
+#ifndef AVUTIL_MEM_INTERNAL_H
+#define AVUTIL_MEM_INTERNAL_H
+
+#include "mem.h"
+
+av_memcpynt_fn ff_memcpynt_get_fn_x86(void);
+
+#endif /* AVUTIL_MEM_INTERNAL_H */
diff --git a/libavutil/x86/Makefile b/libavutil/x86/Makefile
index a719c00..171c351 100644
--- a/libavutil/x86/Makefile
+++ b/libavutil/x86/Makefile
@@ -2,6 +2,7 @@ OBJS += x86/cpu.o \
x86/float_dsp_init.o \
x86/imgutils.o \
x86/lls_init.o \
+ x86/mem.o \
OBJS-$(CONFIG_PIXELUTILS) += x86/pixelutils_init.o \
diff --git a/libavutil/x86/mem.c b/libavutil/x86/mem.c
new file mode 100644
index 0000000..6326c90
--- /dev/null
+++ b/libavutil/x86/mem.c
@@ -0,0 +1,98 @@
+/*
+ * 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 <inttypes.h>
+#include "config.h"
+#include "libavutil/avassert.h"
+#include "libavutil/mem_internal.h"
+
+#if HAVE_SSE2
+/* Copy 16/64 bytes from srcp to dstp loading data with the SSE>=2 instruction
+ * load and storing data with the SSE>=2 instruction store.
+ */
+#define COPY16(dstp, srcp, load, store) \
+ __asm__ volatile ( \
+ load " 0(%[src]), %%xmm1\n" \
+ store " %%xmm1, 0(%[dst])\n" \
+ : : [dst]"r"(dstp), [src]"r"(srcp) : "memory", "xmm1")
+
+#define COPY64(dstp, srcp, load, store) \
+ __asm__ volatile ( \
+ load " 0(%[src]), %%xmm1\n" \
+ load " 16(%[src]), %%xmm2\n" \
+ load " 32(%[src]), %%xmm3\n" \
+ load " 48(%[src]), %%xmm4\n" \
+ store " %%xmm1, 0(%[dst])\n" \
+ store " %%xmm2, 16(%[dst])\n" \
+ store " %%xmm3, 32(%[dst])\n" \
+ store " %%xmm4, 48(%[dst])\n" \
+ : : [dst]"r"(dstp), [src]"r"(srcp) : "memory", "xmm1", "xmm2", "xmm3", "xmm4")
+#endif
+
+#define COPY_LINE(dstp, srcp, size, load) \
+ const unsigned unaligned = (-(uintptr_t)srcp) & 0x0f; \
+ unsigned x = unaligned; \
+ \
+ av_assert0(((intptr_t)dstp & 0x0f) == 0); \
+ \
+ __asm__ volatile ("mfence"); \
+ if (!unaligned) { \
+ for (; x+63 < size; x += 64) \
+ COPY64(&dstp[x], &srcp[x], load, "movdqa"); \
+ } else { \
+ COPY16(dst, src, "movdqu", "movdqa"); \
+ for (; x+63 < size; x += 64) \
+ COPY64(&dstp[x], &srcp[x], load, "movdqu"); \
+ } \
+ \
+ for (; x < size; x++) \
+ dstp[x] = srcp[x]; \
+ __asm__ volatile ("mfence");
+
+static void* ff_memcpynt_sse4(void *dst, const void *src, size_t size)
+{
+ uint8_t *dstu = dst;
+ const uint8_t *srcu = src;
+
+ COPY_LINE(dstu, srcu, size, "movntdqa");
+ return dst;
+}
+
+static void* ff_memcpynt_sse2(void *dst, const void *src, size_t size)
+{
+ uint8_t *dstu = dst;
+ const uint8_t *srcu = src;
+
+ COPY_LINE(dstu, srcu, size, "movntdqa");
+ return dst;
+}
+
+av_memcpynt_fn ff_memcpynt_get_fn_x86()
+{
+ int cpu_flags = av_get_cpu_flags();
+
+#if HAVE_SSE4
+ if (cpu_flags & AV_CPU_FLAG_SSE4)
+ return ff_memcpynt_sse4;
+#endif
+#if HAVE_SSE2
+ if (cpu_flags & AV_CPU_FLAG_SSE2)
+ return ff_memcpynt_sse2;
+#endif
+ return memcpy;
+}
--
1.9.1
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