It makes no sense whatsoever to do this at each function call; we
already have a table for this.
Yields a 2x improvement in find_min_book (x86-64, Haswell+GCC):
ffmpeg -i sin.flac -acodec aac -y sin.aac
find_min_book
old
605 decicycles in find_min_book, 8388453 runs, 155 skips.9x
606 decicycles in find_min_book,16776912 runs, 304 skips.9x
607 decicycles in find_min_book,33553819 runs, 613 skips.2x
607 decicycles in find_min_book,67107668 runs, 1196 skips.3x
607 decicycles in find_min_book,134215360 runs, 2368 skips3x
new
359 decicycles in find_min_book, 8388552 runs, 56 skips.3x
360 decicycles in find_min_book,16777112 runs, 104 skips.1x
361 decicycles in find_min_book,33554218 runs, 214 skips.4x
361 decicycles in find_min_book,67108381 runs, 483 skips.5x
361 decicycles in find_min_book,134216725 runs, 1003 skips5x
and more importantly a non-negligible speedup (~ 8%) to overall AAC encoding:
old:
ffmpeg -i sin.flac -acodec aac -strict -2 -y sin_new.aac 6.82s user 0.03s system 104% cpu 6.565 total
new:
ffmpeg -i sin.flac -acodec aac -strict -2 -y sin_old.aac 6.24s user 0.03s system 104% cpu 5.993 total
This also improves accuracy of the expression by ~ 2 ulp in some cases.
Reviewed-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>
Reviewed-by: Rostislav Pehlivanov <atomnuker@gmail.com>
Signed-off-by: Ganesh Ajjanagadde <gajjanag@gmail.com>