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>
Remove the |checked| variable because the invalid value of -1 for
|flags| can be used to indicate the same condition. Also rename |flags|
to |cpu_flags| because there are a local variable and a function
parameter named |flags| in the same file.
Co-author: Dmitry Vyukov of Google
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
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.
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>
Errors go to stderr, but the cpu stats are non error output for cputest
This fixes echoing the cpu test results
Reviewed-by: James Almer <jamrial@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
libavutil/cpu-test prints raw and effective cpu flags to STDERR. Detected
cpu flags can be useful for debugging fate errors.
No comparison of the result against a expected result since that would
require fate config specific references.
Fixes various runtime failures with manually set flags that represent no
existing CPU
Fixes Ticket3653
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
NEON and VFP are currently mandatory for all ARMv8 profiles. Both are
handled as extensions as far as cpuflags are concerned. This is
consistent with handling x86_64 which always has SSE2, but still
handles it as an extension.
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.
Wan-Teh Chang
Diego Biurrun
Hendrik Leppkes
Janne Grunau
Rodger Combs
wang-bin
James Almer
Michael Niedermayer
Janne Grunau
Kieran Kunhya
Martin Storsjö
Anton Khirnov
Mans Rullgard