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micro-optimized non-SIMD group15::match_impl

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joaquintides
2022-10-15 10:51:28 +02:00
parent e663812f24
commit 1532e301d1
1 changed files with 4 additions and 4 deletions
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8
include/boost/unordered/detail/foa.hpp
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@ -123,7 +123,7 @@ namespace foa{
* 64-bit words with *bit interleaving*, i.e. the least significant 16 bits of
* the first 64-bit word contain the least significant bits of each byte in the
* "logical" 128-bit word, and so forth. With this layout, match can be
* implemented with 5 ANDs, 3 shifts, 2 XORs and 2 NOTs.
* implemented with 4 ANDs, 3 shifts, 2 XORs, 1 OR and 1 NOT.
*/
#if defined(BOOST_UNORDERED_SSE2)
@ -568,9 +568,9 @@ private:
};
BOOST_ASSERT(n<256);
boost::uint64_t lo=~(m[0]^mask[n&0xFu]);
boost::uint64_t hi=~(m[1]^mask[n>>4])&lo;
boost::uint32_t y=static_cast<boost::uint32_t>(hi&(hi>>32));
boost::uint64_t x=m[0]^mask[n&0xFu];
x=~((m[1]^mask[n>>4])|x);
boost::uint32_t y=static_cast<boost::uint32_t>(x&(x>>32));
y&=y>>16;
return y&0x7FFF;
}