Make the one-time initialization in av_get_cpu_flags() thread-safe. The
static variable |cpu_flags| in libavutil/cpu.c is read and written using
normal load and store operations. These are considered as data races.
The fix is to use atomic load and store operations.

The fix can be verified by running the libavutil/tests/cpu_init.c test
program under ThreadSanitizer:
    ./configure --toolchain=clang-tsan
    make libavutil/tests/cpu_init
    libavutil/tests/cpu_init

There should be no warnings from ThreadSanitizer.

Co-author: Dmitry Vyukov of Google, who suggested the data race fix.
Signed-off-by: Wan-Teh Chang <wtc@google.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

Make the one-time initialization in av_get_cpu_flags() thread-safe. The
static variables |flags|, |cpuflags_mask|, and |checked| in
libavutil/cpu.c are read and written using normal load and store
operations. These are considered as data races. The fix is to use atomic
load and store operations.

Remove the |checked| variable because the invalid value of -1 for
|flags| can be used to indicate the same condition. Rename |flags| to
|cpu_flags| and move it to file scope.

The fix can be verified by running the libavutil/tests/cpu_init.c test
program under ThreadSanitizer:
    ./configure --toolchain=clang-tsan
    make libavutil/tests/cpu_init
    libavutil/tests/cpu_init

There should be no warnings from ThreadSanitizer.

Co-author: Dmitry Vyukov of Google, who suggested the data race fix.
Signed-off-by: Wan-Teh Chang <wtc@google.com>

Signed-off-by: Lou Logan <lou@lrcd.com>

The vector mode was deprecated in ARMv7-A/VFPv3 and various cpu
implementations do not support it in hardware. Vector mode code will
depending the OS either be emulated in software or result in an illegal
instruction on cpus which does not support it. This was not really
problem in practice since NEON implementations of the same functions are
preferred. It will however become a problem for checkasm which tests
every cpu flag separately.

Since this is a cpu feature newer cpu do not support anymore the
behaviour of this flag differs from the other flags. It can be only
activated by runtime cpu feature selection.

Deprecated in 11/2012.

Signed-off-by: James Almer <jamrial@gmail.com>
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>

Reviewed-by: Michael Niedermayer <michaelni@gmx.at>
Signed-off-by: James Almer <jamrial@gmail.com>

this allows disabling and enabling it
it also prevents crashes if vfpv3 and neon are disabled which previously
would have enabled the flag

And last but not least one can enable setend on cpus like cortex-a8 where
its fast but disabled by default
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

Based on x264 code
Signed-off-by: James Almer <jamrial@gmail.com>

Based on x264 code
Signed-off-by: James Almer <jamrial@gmail.com>

Based on x264 code
Signed-off-by: James Almer <jamrial@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

Based on x264 code
Signed-off-by: James Almer <jamrial@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

Patch based on x264's AVX2 detection
Signed-off-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>

It will be useful in lavfi, and could conceivably be useful to the user
applications as well.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

This function is problematic in several ways, its also quite
unpredictable which flags it ends up turning on
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

Refactoring mmx2/mmxext YASM code with cpuflags will force renames.
So switching to a consistent naming scheme beforehand is sensible.
The name "mmxext" is more official and widespread and also the name
of the CPU flag, as reported e.g. by the Linux kernel.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

and suggest that av_parse_cpu_caps() be used.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

This moves the cpu flag parsing code from avconv to avutil so
it can be accessed elsewhere.
Signed-off-by: Mans Rullgard <mans@mansr.com>

This allows masking CPU features with the -cpuflags avconv option
which is useful for testing different optimisations without rebuilding.
Signed-off-by: Mans Rullgard <mans@mansr.com>

The were broken since August of 2010 without anyone noticing until
three weeks ago. Nobody cares about it anymore and hopefully Marvell
will support NEON like in the PXA978 from now on.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

Some MMX-only CPUs do not have support for CMOV.
All SSE/MMX2 CPUs should be fine, thus no check was
added to those functions.
See also https://sourceforge.net/tracker/?func=detail&aid=3358347&group_id=205275&atid=992986Signed-off-by: Reimar Döffinger <Reimar.Doeffinger@gmx.de>

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>