Don't include the function pointer table in the code segment
in arm mode.
This shouldn't have any significant performance effect. It does
end up as a few more instructions than before, for ARM, but
only at the entry to this function, not within the fft functions
themselves.
Signed-off-by: Martin Storsjö <martin@martin.st>
These function pointers already existed in the ARM code. Adding them globally
allows calls to the function pointers to access arch-optimized versions of the
functions transparently.
Initialise VC1DSPContext for parser as well as for decoder.
Note, the VC-1 code doesn't actually use the function pointer yet.
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
The previous implementation targeted DTS Coherent Acoustics, which only
requires nbits == 4 (fft16()). This case was (and still is) linked directly
rather than being indirected through ff_fft_calc_vfp(), but now the full
range from radix-4 up to radix-65536 is available. This benefits other codecs
such as AAC and AC3.
The implementaion is based upon the C version, with each routine larger than
radix-16 calling a hierarchy of smaller FFT functions, then performing a
post-processing pass. This pass benefits a lot from loop unrolling to
counter the long pipelines in the VFP. A relaxed calling standard also
reduces the overhead of the call hierarchy, and avoiding the excessive
inlining performed by GCC probably helps with I-cache utilisation too.
I benchmarked the result by measuring the number of gperftools samples that
hit anywhere in the AAC decoder (starting from aac_decode_frame()) or
specifically in the FFT routines (fft4() to fft512() and pass()) for the
same sample AAC stream:
Before After
Mean StdDev Mean StdDev Confidence Change
Audio decode 2245.5 53.1 1599.6 43.8 100.0% +40.4%
FFT routines 940.6 22.0 348.1 20.8 100.0% +170.2%
Signed-off-by: Martin Storsjö <martin@martin.st>
The previous implementation targeted DTS Coherent Acoustics, which only
requires mdct_bits == 6. This relatively small size lent itself to
unrolling the loops a small number of times, and encoding offsets
calculated at assembly time within the load/store instructions of each
iteration.
In the more general case (codecs such as AAC and AC3) much larger arrays
are used - mdct_bits == [8, 9, 11]. The old method does not scale for
these cases, so more integer registers are used with non-unrolled versions
of the loops (and with some stack spillage). The postrotation filter loop
is still unrolled by a factor of 2 to permit the double-buffering of some
VFP registers to facilitate overlap of neighbouring iterations.
I benchmarked the result by measuring the number of gperftools samples
that hit anywhere in the AAC decoder (starting from aac_decode_frame())
or specifically in ff_imdct_half_c / ff_imdct_half_vfp, for the same
example AAC stream:
Before After
Mean StdDev Mean StdDev Confidence Change
aac_decode_frame 2368.1 35.8 2117.2 35.3 100.0% +11.8%
ff_imdct_half_* 457.5 22.4 251.2 16.2 100.0% +82.1%
Signed-off-by: Martin Storsjö <martin@martin.st>
Move the GNU as check before the arch specific asm checks since the .dn
check requires gas compatible assembler.
Disable the VC-1 motion compensation NEON asm which is the only part
using that directive. The integrated assembler in the upcoming clang 3.5
does not support .dn/.qn without plans to change that. Too much effort
to implement it while it is rarely used.
http://llvm.org/bugs/show_bug.cgi?id=18199.
Further performance improvements and security fixes by
Vittorio Giovara, Luca Barbato and Diego Biurrun.
Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
Signed-off-by: Diego Biurrun <diego@biurrun.de>
Profiling results for overall decode and the output_data function in
particular are as follows:
Before After
Mean StdDev Mean StdDev Confidence Change
6:2 total 339.6 15.1 329.3 16.0 95.8% +3.1% (insignificant)
6:2 function 24.6 6.0 9.9 3.1 100.0% +148.5%
8:2 total 324.5 15.5 323.6 14.3 15.2% +0.3% (insignificant)
8:2 function 20.4 3.9 9.9 3.4 100.0% +104.7%
6:6 total 572.8 20.6 539.9 24.2 100.0% +6.1%
6:6 function 54.5 5.6 16.0 3.8 100.0% +240.9%
8:8 total 741.5 21.2 702.5 18.5 100.0% +5.6%
8:8 function 63.9 7.6 18.4 4.8 100.0% +247.3%
The assembly version has also been tested with a fuzz tester to ensure that
any combinations of inputs not exercised by my available test streams still
generate mathematically identical results to the C version.
Signed-off-by: Martin Storsjö <martin@martin.st>
Profiling results for overall audio decode and the rematrix_channels function
in particular are as follows:
Before After
Mean StdDev Mean StdDev Confidence Change
6:2 total 370.8 17.0 348.8 20.1 99.9% +6.3%
6:2 function 46.4 8.4 45.8 6.6 18.0% +1.2% (insignificant)
8:2 total 343.2 19.0 339.1 15.4 54.7% +1.2% (insignificant)
8:2 function 38.9 3.9 40.2 6.9 52.4% -3.2% (insignificant)
6:6 total 658.4 15.7 604.6 20.8 100.0% +8.9%
6:6 function 109.0 8.7 59.5 5.4 100.0% +83.3%
8:8 total 896.2 24.5 766.4 17.6 100.0% +16.9%
8:8 function 223.4 12.8 93.8 5.0 100.0% +138.3%
The assembly version has also been tested with a fuzz tester to ensure that
any combinations of inputs not exercised by my available test streams still
generate mathematically identical results to the C version.
Signed-off-by: Martin Storsjö <martin@martin.st>
