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This exploits an approach based on the sieve of Eratosthenes, a popular method for generating prime numbers. Tables are identical to previous ones. Tested with FATE with/without --enable-hardcoded-tables. Sample benchmark (Haswell, GNU/Linux+gcc): prev: 7860100 decicycles in cbrt_tableinit, 1 runs, 0 skips 7777490 decicycles in cbrt_tableinit, 2 runs, 0 skips [...] 7582339 decicycles in cbrt_tableinit, 256 runs, 0 skips 7563556 decicycles in cbrt_tableinit, 512 runs, 0 skips new: 2099480 decicycles in cbrt_tableinit, 1 runs, 0 skips 2044470 decicycles in cbrt_tableinit, 2 runs, 0 skips [...] 1796544 decicycles in cbrt_tableinit, 256 runs, 0 skips 1791631 decicycles in cbrt_tableinit, 512 runs, 0 skips Both small and large run count given as this is called once so small run count may give a better picture, small numbers are fairly consistent, and there is a consistent downward trend from small to large runs, at which point it stabilizes to a new value. Reviewed-by: Michael Niedermayer <michael@niedermayer.cc> Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>pull/172/head
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