Even though they have the same size, and typically the same alignment,
uint32_t and float are under no circumstances compatible types in C.
The casts from float * to uint32_t * are invalid here. Insofar as the
resulting pointers are dereferenced, this is undefined behaviour.
This patch uses av_float2int() / av_int2float() instead.
RV64G supports MIN & MAX instructions natively only on floating point
registers, not general purpose ones. The later would require the Zbb
extension. Due to that, it is actually faster to perform the clipping
"properly" in FPU.
Benchmarks on SiFive U74-MC (courtesy of Shanghai StarFive Tech):
audiodsp.vector_clipf_c: 29551.5
audiodsp.vector_clipf_rvf: 17871.0
Also tried unrolling with 2 or 8 elements but it gets worse either way.
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>
Fixes: signed integer overflow: 2145417478 + 76702564 cannot be represented in type 'int'
Fixes: 20313/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_RA_144_fuzzer-5734487724130304
Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
Rémi Denis-Courmont
Andreas Rheinhardt
Michael Niedermayer
Anton Khirnov
Diego Biurrun