mirror of
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318 lines
8.7 KiB
C++
318 lines
8.7 KiB
C++
#pragma once
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#include <cassert>
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#include <stdexcept> // for std::logic_error
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#include <string>
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#include <vector>
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#include <functional>
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#include <iosfwd>
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#include <common/types.h>
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#include <common/unaligned.h>
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#include <city.h>
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#if defined(__SSE2__)
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#include <emmintrin.h>
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#endif
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#if defined(__SSE4_2__)
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#include <smmintrin.h>
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#include <nmmintrin.h>
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#endif
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/**
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* The std::string_view-like container to avoid creating strings to find substrings in the hash table.
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*/
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struct StringRef
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{
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const char * data = nullptr;
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size_t size = 0;
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/// Non-constexpr due to reinterpret_cast.
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template <typename CharT, typename = std::enable_if_t<sizeof(CharT) == 1>>
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StringRef(const CharT * data_, size_t size_) : data(reinterpret_cast<const char *>(data_)), size(size_)
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{
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/// Sanity check for overflowed values.
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assert(size < 0x8000000000000000ULL);
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}
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constexpr StringRef(const char * data_, size_t size_) : data(data_), size(size_) {}
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StringRef(const std::string & s) : data(s.data()), size(s.size()) {}
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constexpr explicit StringRef(std::string_view s) : data(s.data()), size(s.size()) {}
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constexpr StringRef(const char * data_) : StringRef(std::string_view{data_}) {}
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constexpr StringRef() = default;
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std::string toString() const { return std::string(data, size); }
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explicit operator std::string() const { return toString(); }
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constexpr explicit operator std::string_view() const { return {data, size}; }
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};
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/// Here constexpr doesn't implicate inline, see https://www.viva64.com/en/w/v1043/
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/// nullptr can't be used because the StringRef values are used in SipHash's pointer arithmetic
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/// and the UBSan thinks that something like nullptr + 8 is UB.
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constexpr const inline char empty_string_ref_addr{};
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constexpr const inline StringRef EMPTY_STRING_REF{&empty_string_ref_addr, 0};
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using StringRefs = std::vector<StringRef>;
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#if defined(__SSE2__)
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/** Compare strings for equality.
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* The approach is controversial and does not win in all cases.
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* For more information, see hash_map_string_2.cpp
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*/
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inline bool compareSSE2(const char * p1, const char * p2)
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{
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return 0xFFFF == _mm_movemask_epi8(_mm_cmpeq_epi8(
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_mm_loadu_si128(reinterpret_cast<const __m128i *>(p1)),
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_mm_loadu_si128(reinterpret_cast<const __m128i *>(p2))));
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}
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inline bool compareSSE2x4(const char * p1, const char * p2)
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{
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return 0xFFFF == _mm_movemask_epi8(
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_mm_and_si128(
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_mm_and_si128(
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_mm_cmpeq_epi8(
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_mm_loadu_si128(reinterpret_cast<const __m128i *>(p1)),
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_mm_loadu_si128(reinterpret_cast<const __m128i *>(p2))),
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_mm_cmpeq_epi8(
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_mm_loadu_si128(reinterpret_cast<const __m128i *>(p1) + 1),
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_mm_loadu_si128(reinterpret_cast<const __m128i *>(p2) + 1))),
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_mm_and_si128(
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_mm_cmpeq_epi8(
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_mm_loadu_si128(reinterpret_cast<const __m128i *>(p1) + 2),
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_mm_loadu_si128(reinterpret_cast<const __m128i *>(p2) + 2)),
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_mm_cmpeq_epi8(
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_mm_loadu_si128(reinterpret_cast<const __m128i *>(p1) + 3),
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_mm_loadu_si128(reinterpret_cast<const __m128i *>(p2) + 3)))));
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}
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inline bool memequalSSE2Wide(const char * p1, const char * p2, size_t size)
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{
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while (size >= 64)
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{
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if (compareSSE2x4(p1, p2))
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{
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p1 += 64;
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p2 += 64;
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size -= 64;
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}
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else
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return false;
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}
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switch ((size % 64) / 16)
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{
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case 3: if (!compareSSE2(p1 + 32, p2 + 32)) return false; [[fallthrough]];
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case 2: if (!compareSSE2(p1 + 16, p2 + 16)) return false; [[fallthrough]];
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case 1: if (!compareSSE2(p1 , p2 )) return false; [[fallthrough]];
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case 0: break;
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}
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p1 += (size % 64) / 16 * 16;
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p2 += (size % 64) / 16 * 16;
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switch (size % 16)
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{
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case 15: if (p1[14] != p2[14]) return false; [[fallthrough]];
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case 14: if (p1[13] != p2[13]) return false; [[fallthrough]];
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case 13: if (p1[12] != p2[12]) return false; [[fallthrough]];
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case 12: if (unalignedLoad<uint32_t>(p1 + 8) == unalignedLoad<uint32_t>(p2 + 8)) goto l8; else return false;
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case 11: if (p1[10] != p2[10]) return false; [[fallthrough]];
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case 10: if (p1[9] != p2[9]) return false; [[fallthrough]];
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case 9: if (p1[8] != p2[8]) return false;
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l8: [[fallthrough]];
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case 8: return unalignedLoad<uint64_t>(p1) == unalignedLoad<uint64_t>(p2);
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case 7: if (p1[6] != p2[6]) return false; [[fallthrough]];
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case 6: if (p1[5] != p2[5]) return false; [[fallthrough]];
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case 5: if (p1[4] != p2[4]) return false; [[fallthrough]];
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case 4: return unalignedLoad<uint32_t>(p1) == unalignedLoad<uint32_t>(p2);
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case 3: if (p1[2] != p2[2]) return false; [[fallthrough]];
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case 2: return unalignedLoad<uint16_t>(p1) == unalignedLoad<uint16_t>(p2);
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case 1: if (p1[0] != p2[0]) return false; [[fallthrough]];
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case 0: break;
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}
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return true;
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}
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#endif
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inline bool operator== (StringRef lhs, StringRef rhs)
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{
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if (lhs.size != rhs.size)
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return false;
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if (lhs.size == 0)
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return true;
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#if defined(__SSE2__)
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return memequalSSE2Wide(lhs.data, rhs.data, lhs.size);
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#else
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return 0 == memcmp(lhs.data, rhs.data, lhs.size);
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#endif
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}
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inline bool operator!= (StringRef lhs, StringRef rhs)
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{
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return !(lhs == rhs);
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}
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inline bool operator< (StringRef lhs, StringRef rhs)
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{
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int cmp = memcmp(lhs.data, rhs.data, std::min(lhs.size, rhs.size));
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return cmp < 0 || (cmp == 0 && lhs.size < rhs.size);
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}
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inline bool operator> (StringRef lhs, StringRef rhs)
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{
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int cmp = memcmp(lhs.data, rhs.data, std::min(lhs.size, rhs.size));
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return cmp > 0 || (cmp == 0 && lhs.size > rhs.size);
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}
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/** Hash functions.
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* You can use either CityHash64,
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* or a function based on the crc32 statement,
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* which is obviously less qualitative, but on real data sets,
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* when used in a hash table, works much faster.
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* For more information, see hash_map_string_3.cpp
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*/
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struct StringRefHash64
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{
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size_t operator() (StringRef x) const
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{
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return CityHash_v1_0_2::CityHash64(x.data, x.size);
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}
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};
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#if defined(__SSE4_2__)
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/// Parts are taken from CityHash.
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inline UInt64 hashLen16(UInt64 u, UInt64 v)
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{
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return CityHash_v1_0_2::Hash128to64(CityHash_v1_0_2::uint128(u, v));
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}
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inline UInt64 shiftMix(UInt64 val)
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{
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return val ^ (val >> 47);
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}
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inline UInt64 rotateByAtLeast1(UInt64 val, int shift)
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{
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return (val >> shift) | (val << (64 - shift));
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}
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inline size_t hashLessThan8(const char * data, size_t size)
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{
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static constexpr UInt64 k2 = 0x9ae16a3b2f90404fULL;
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static constexpr UInt64 k3 = 0xc949d7c7509e6557ULL;
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if (size >= 4)
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{
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UInt64 a = unalignedLoad<uint32_t>(data);
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return hashLen16(size + (a << 3), unalignedLoad<uint32_t>(data + size - 4));
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}
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if (size > 0)
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{
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uint8_t a = data[0];
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uint8_t b = data[size >> 1];
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uint8_t c = data[size - 1];
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uint32_t y = static_cast<uint32_t>(a) + (static_cast<uint32_t>(b) << 8);
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uint32_t z = size + (static_cast<uint32_t>(c) << 2);
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return shiftMix(y * k2 ^ z * k3) * k2;
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}
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return k2;
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}
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inline size_t hashLessThan16(const char * data, size_t size)
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{
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if (size > 8)
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{
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UInt64 a = unalignedLoad<UInt64>(data);
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UInt64 b = unalignedLoad<UInt64>(data + size - 8);
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return hashLen16(a, rotateByAtLeast1(b + size, size)) ^ b;
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}
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return hashLessThan8(data, size);
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}
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struct CRC32Hash
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{
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size_t operator() (StringRef x) const
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{
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const char * pos = x.data;
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size_t size = x.size;
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if (size == 0)
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return 0;
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if (size < 8)
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{
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return hashLessThan8(x.data, x.size);
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}
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const char * end = pos + size;
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size_t res = -1ULL;
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do
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{
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UInt64 word = unalignedLoad<UInt64>(pos);
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res = _mm_crc32_u64(res, word);
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pos += 8;
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} while (pos + 8 < end);
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UInt64 word = unalignedLoad<UInt64>(end - 8); /// I'm not sure if this is normal.
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res = _mm_crc32_u64(res, word);
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return res;
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}
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};
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struct StringRefHash : CRC32Hash {};
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#else
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struct CRC32Hash
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{
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size_t operator() (StringRef /* x */) const
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{
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throw std::logic_error{"Not implemented CRC32Hash without SSE"};
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}
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};
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struct StringRefHash : StringRefHash64 {};
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#endif
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namespace std
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{
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template <>
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struct hash<StringRef> : public StringRefHash {};
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}
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namespace ZeroTraits
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{
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inline bool check(const StringRef & x) { return 0 == x.size; }
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inline void set(StringRef & x) { x.size = 0; }
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}
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std::ostream & operator<<(std::ostream & os, const StringRef & str);
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