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Faster popcnt_i32

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This commit is contained in:
Someon1e 2024-03-03 20:54:53 +00:00
parent d6b7a232ac
commit 8c0c3ed14c
1 changed files with 6 additions and 8 deletions
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14
codegen/luau/runtime/runtime.lua
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@ -182,14 +182,12 @@ do
local bit_countrz = bit32.countrz
local function popcnt_i32(num)
local count = 0
while num ~= 0 do
num = bit_and(num, num - 1)
count = count + 1
end
return count
num = bit_and(num, 0x55555555) + bit_and(bit_rshift(num, 1), 0x55555555)
num = bit_and(num, 0x33333333) + bit_and(bit_rshift(num, 2), 0x33333333)
num = bit_and(num, 0x0f0f0f0f) + bit_and(bit_rshift(num, 4), 0x0f0f0f0f)
num = bit_and(num, 0x00ff00ff) + bit_and(bit_rshift(num, 8), 0x00ff00ff)
num = bit_and(num, 0x0000ffff) + bit_and(bit_rshift(num, 16), 0x0000ffff)
return num
end
popcnt.i32 = popcnt_i32