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Use dense precomputed fixed shift magics #1352

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Use dense precomputed fixed shift magics #1352

wants to merge 1 commit into from

Commits on Dec 31, 2017

  1. Use dense precomputed fixed shift magics 

    These densely packed fixed shift magics computed by Volker Annuss
achieve a considerably smaller table size than the current magics with
variable shift.

PEXT-Bitboards do not benefit (and replacing them would be a regression
on bmi2).

Speedup on x86-64-modern:

base =    2617754 +/- 14080
test =    2641738 +/- 15657
diff =      23983 +/- 28896
speedup = 0.009162

No regression on x86-64-bmi2:

base =    2671199 +/- 16640
test =    2673814 +/- 16103
diff =       2614 +/- 31224
speedup = 0.000979

STC with disabled bmi2:

LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 46087 W: 8656 L: 8331 D: 29100

No functional change.
    @niklasf
    niklasf committed Dec 31, 2017
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