F and D extensions are included in all RISC-V application profiles ever
made (so starting from RV64GC a.k.a. RVA20). Realistically they need to be
selected at compilation time.
Currently, there are no consumers for these two flags. If there is ever a
need to reintroduce F- or D-specific optimisations, we can always use
__riscv_f or __riscv_d compiler predefined macros respectively.
The B extension was finally ratified in May 2024, encompassing:
- Zba (addresses),
- Zbb (basics) and
- Zbs (single bits).
It does not include Zbc (base-2 polynomials).
C11 required to use ATOMIC_VAR_INIT to statically initialize
atomic objects with static storage duration. Yet this macro
was unsuitable for initializing structures [1] and was actually
unneeded for all known implementations (this includes our
compatibility fallback implementations which simply wrap the value
in parentheses: #define ATOMIC_VAR_INIT(value) (value)).
Therefore C17 deprecated the macro and C23 actually removed it [2].
Since commit 5ff0eb34d2 we default
to C17 if the compiler supports it; Clang warns about ATOMIC_VAR_INIT
in this mode. Given that no implementation ever needed this macro,
this commit stops using it to avoid this warning.
[1]: https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2396.htm#dr_485
[2]: https://en.cppreference.com/w/c/atomic/ATOMIC_VAR_INIT
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
Unnecessary since acf63d5350adeae551d412db699f8ca03f7e76b9;
also avoids relocations.
Reviewed-by: Anton Khirnov <anton@khirnov.net>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
The names of the cpu flags, when parsed from a string with
av_parse_cpu_caps, are parsed by the libavutil eval functions. These
interpret dashes as subtractions. Therefore, these previous cpu flag
names haven't been possible to set.
Use the official names for these extensions, as the previous ad-hoc
names wasn't parseable.
libavutil/tests/cpu tests that the cpu flags can be set, and prints
the detected flags.
Acked-by: Rémi Denis-Courmont <remi@remlab.net>
Signed-off-by: Martin Storsjö <martin@martin.st>
The code was blindly assuming that Zbb or V implied Zba. While the
earlier is practically always true, the later broke some QEMU setups,
as V was introduced earlier than Zba.
Unfortunately, it is common, and will remain so, that the Bit
manipulations are not enabled at compilation time. This is an official
policy for Debian ports in general (though they do not support RISC-V
officially as of yet) to stick to the minimal target baseline, which
does not include the B extension or even its Zbb subset.
For inline helpers (CPOP, REV8), compiler builtins (CTZ, CLZ) or
even plain C code (MIN, MAX, MINU, MAXU), run-time detection seems
impractical. But at least it can work for the byte-swap DSP functions.
RVV defines a total of 12 different extensions, including:
- 5 different instruction subsets:
- Zve32x: 8-, 16- and 32-bit integers,
- Zve32f: Zve32x plus single precision floats,
- Zve64x: Zve32x plus 64-bit integers,
- Zve64f: Zve32f plus Zve64x,
- Zve64d: Zve64f plus double precision floats.
- 6 different vector lengths:
- Zvl32b (embedded only),
- Zvl64b (embedded only),
- Zvl128b,
- Zvl256b,
- Zvl512b,
- Zvl1024b,
- and the V extension proper: equivalent to Zve64f and Zvl128b.
In total, there are 6 different possible sets of supported instructions
(including the empty set), but for convenience we allocate one bit for
each type sets: up-to-32-bit ints (RVV_I32), floats (RVV_F32),
64-bit ints (RVV_I64) and doubles (RVV_F64).
Whence the vector size is needed, it can be retrieved by reading the
unprivileged read-only vlenb CSR. This should probably be a separate
helper macro if needed at a later point.
This introduces compile-time and run-time CPU detection on RISC-V. In
practice, I doubt that FFmpeg will ever see a RISC-V CPU without all of
I, F and D extensions, and if it does, it probably won't have run-time
detection. So the flags are essentially always set.
But as things stand, checkasm wants them that way. Compare the ARMV8
flag on AArch64. We are nowhere near running short on CPU flag bits.
This is more spec-compliant because it does not rely
on dead-code elimination by the compiler. Especially
MSVC has problems with this, as can be seen in
https://ffmpeg.org/pipermail/ffmpeg-devel/2022-May/296373.html
or
https://ffmpeg.org/pipermail/ffmpeg-devel/2022-May/297022.html
This commit does not eliminate every instance where we rely
on dead code elimination: It only tackles branching to
the initialization of arch-specific dsp code, not e.g. all
uses of CONFIG_ and HAVE_ checks. But maybe it is already
enough to compile FFmpeg with MSVC with whole-programm-optimizations
enabled (if one does not disable too many components).
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
Otherwise its effect might not work causing CPU_COUNT to not get defined.
Fixes cpu count detection to actually use sched_getaffinity if available.
Signed-off-by: Marton Balint <cus@passwd.hu>
LSX and LASX is loongarch SIMD extention.
They are enabled by default if compiler support it, and can be disabled
with '--disable-lsx' '--disable-lasx'.
Change-Id: Ie2608ea61dbd9b7fffadbf0ec2348bad6c124476
Reviewed-by: Shiyou Yin <yinshiyou-hf@loongson.cn>
Reviewed-by: guxiwei <guxiwei-hf@loongson.cn>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
av_set_cpu_flags_mask() has been deprecated in the commit which merged
it: 6df42f98746be06c883ce683563e07c9a2af983f; av_parse_cpu_flags() has
been deprecated in 4b529edff8.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
av_cpu_count() intends to emit a debug message containing the number of
logical cores when called the first time. The check currently works with
a static volatile int; yet this does not help at all in case of
concurrent accesses by multiple threads. So replace this with an
atomic_int.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
Add MMI & MSA runtime detection for MIPS.
Basically there are two code pathes. For systems that
natively support CPUCFG instruction or kernel emulated
that instruction, we'll sense this feature from HWCAP and
report the flags according to values grab from CPUCFG. For
systems that have no CPUCFG (or not export it in HWCAP),
we'll parse /proc/cpuinfo instead.
Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Reviewed-by: Shiyou Yin <yinshiyou-hf@loongson.cn>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
* commit 'e6bff23f1e11aefb16a2b5d6ee72bf7469c5a66e':
cpu: add a function for querying maximum required data alignment
Adapted to work with the arbitrary runtime cpuflag changes av_force_cpu_flags()
can generate.
Merged-by: James Almer <jamrial@gmail.com>
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>
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>
* commit 'd12b5b2f135aade4099f4b26b0fe678656158c13':
build: Split test programs off into separate files
Some conversions done by: James Almer <jamrial@gmail.com>
Merged-by: Derek Buitenhuis <derek.buitenhuis@gmail.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.
