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second attempt

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This commit is contained in:
joaquintides
2022-11-24 13:01:09 +01:00
parent cf2a0ef303
commit 09171776f7
1 changed files with 42 additions and 51 deletions
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93
include/boost/unordered/detail/foa.hpp
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@@ -656,7 +656,33 @@ private:
* these values and positioning to be as uncorrelated as possible.
*/
#if 0
#if 1
struct pow2_size_policy
{
static inline std::size_t size_index(std::size_t n)
{
// TODO: min size is 2, see if we can bring it down to 1 without loss
// of performance
std::size_t size_index_=sizeof(std::size_t)*CHAR_BIT-
(n<=2?1:((std::size_t)(boost::core::bit_width(n-1))));
std::size_t salt=xmx(size_index_)&~0xffu;
return salt|size_index_;
}
static inline std::size_t size(std::size_t size_index_)
{
return std::size_t(1)<<(sizeof(std::size_t)*CHAR_BIT-(size_index_&0xffu));
}
static constexpr std::size_t min_size(){return 2;}
static inline std::size_t position(std::size_t hash,std::size_t size_index_)
{
return hash>>(size_index_&0xffu);
}
};
#else
struct pow2_size_policy
{
static inline std::size_t size_index(std::size_t n)
@@ -677,50 +703,9 @@ struct pow2_size_policy
static inline std::size_t position(std::size_t hash,std::size_t size_index_)
{
return hash>>size_index_;
}
};
#else
struct pow2_size_policy
{
static inline std::size_t size_index(std::size_t n)
{
// TODO: min size is 2, see if we can bring it down to 1 without loss
// of performance
std::size_t used_bits_=n<=2?1:((std::size_t)(boost::core::bit_width(n-1)));
std::size_t unused_bits_=total_bits-used_bits_;
std::size_t unused_hi_=
unused_bits_>=10?(unused_bits_%6)*2:
unused_bits_>=6?(unused_bits_%4)*2:
0;
return (unused_hi_<<16)+(unused_bits_);
}
static inline std::size_t size(std::size_t size_index_)
{
return std::size_t(1)<<(total_bits-unused_bits(size_index_));
}
static constexpr std::size_t min_size(){return 2;}
static inline std::size_t position(std::size_t hash,std::size_t size_index_)
{
return (hash<<unused_hi(size_index_))>>unused_bits(size_index_);
}
private:
static constexpr std::size_t total_bits=sizeof(std::size_t)*CHAR_BIT;
static inline std::size_t unused_bits(std::size_t size_index_)
{
return size_index_&0xffffu;
}
static inline std::size_t unused_hi(std::size_t size_index_)
{
return size_index_>>16;
auto rot=(sizeof(std::size_t)*CHAR_BIT-size_index_)/4+1;
auto carry=hash>>(sizeof(std::size_t)*CHAR_BIT-rot);
return ((hash<<rot)>>size_index_)|carry;
}
};
#endif
@@ -770,18 +755,18 @@ private:
struct no_mix
{
template<typename Hash,typename T>
static inline std::size_t mix(const Hash& h,const T& x)
static inline std::size_t mix(const Hash& h,const T& x,std::size_t salt)
{
return h(x);
return boost::core::rotl(h(x),(2*salt)&(64-1));
}
};
struct xmx_mix
{
template<typename Hash,typename T>
static inline std::size_t mix(const Hash& h,const T& x)
static inline std::size_t mix(const Hash& h,const T& x,std::size_t salt)
{
return xmx(h(x));
return xmx(h(x)^salt);
}
};
@@ -1596,7 +1581,13 @@ private:
template<typename Key>
inline std::size_t hash_for(const Key& x)const
{
return mix_policy::mix(h(),x);
return hash_for(x,arrays);
}
template<typename Key>
inline std::size_t hash_for(const Key& x,const arrays_type& arrays_)const
{
return mix_policy::mix(h(),x,arrays_.groups_size_index);
}
inline std::size_t position_for(std::size_t hash)const
@@ -1811,7 +1802,7 @@ private:
value_type* p,const arrays_type& arrays_,std::size_t& num_destroyed)
{
nosize_transfer_element(
p,hash_for(key_from(*p)),arrays_,num_destroyed,
p,hash_for(key_from(*p),arrays_),arrays_,num_destroyed,
std::integral_constant< /* std::move_if_noexcept semantics */
bool,
std::is_nothrow_move_constructible<init_type>::value||