mirror of
https://github.com/ClickHouse/ClickHouse.git
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375 lines
9.1 KiB
C++
375 lines
9.1 KiB
C++
#pragma once
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#include <cstdint>
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#include <algorithm>
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#include <Core/Defines.h>
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namespace detail
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{
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template <typename T>
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inline int cmp(T a, T b)
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{
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if (a < b)
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return -1;
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if (a > b)
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return 1;
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return 0;
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}
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}
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/// We can process uninitialized memory in the functions below.
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/// Results don't depend on the values inside uninitialized memory but Memory Sanitizer cannot see it.
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/// Disable optimized functions if compile with Memory Sanitizer.
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#if defined(__SSE2__) && !defined(MEMORY_SANITIZER)
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#include <emmintrin.h>
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/** All functions works under the following assumptions:
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* - it's possible to read up to 15 excessive bytes after end of 'a' and 'b' region;
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* - memory regions are relatively small and extra loop unrolling is not worth to do.
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*/
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/** Variant when memory regions may have different sizes.
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*/
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template <typename Char>
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inline int memcmpSmallAllowOverflow15(const Char * a, size_t a_size, const Char * b, size_t b_size)
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{
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size_t min_size = std::min(a_size, b_size);
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for (size_t offset = 0; offset < min_size; offset += 16)
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{
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uint16_t mask = _mm_movemask_epi8(_mm_cmpeq_epi8(
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_mm_loadu_si128(reinterpret_cast<const __m128i *>(a + offset)),
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_mm_loadu_si128(reinterpret_cast<const __m128i *>(b + offset))));
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mask = ~mask;
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if (mask)
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{
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offset += __builtin_ctz(mask);
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if (offset >= min_size)
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break;
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return detail::cmp(a[offset], b[offset]);
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}
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}
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return detail::cmp(a_size, b_size);
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}
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/** Variant when memory regions may have different sizes.
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* But compare the regions as the smaller one is padded with zero bytes up to the size of the larger.
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* It's needed to hold that: toFixedString('abc', 5) = 'abc'
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* for compatibility with SQL standard.
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*/
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template <typename Char>
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inline int memcmpSmallLikeZeroPaddedAllowOverflow15(const Char * a, size_t a_size, const Char * b, size_t b_size)
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{
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size_t min_size = std::min(a_size, b_size);
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for (size_t offset = 0; offset < min_size; offset += 16)
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{
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uint16_t mask = _mm_movemask_epi8(_mm_cmpeq_epi8(
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_mm_loadu_si128(reinterpret_cast<const __m128i *>(a + offset)),
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_mm_loadu_si128(reinterpret_cast<const __m128i *>(b + offset))));
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mask = ~mask;
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if (mask)
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{
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offset += __builtin_ctz(mask);
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if (offset >= min_size)
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break;
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return detail::cmp(a[offset], b[offset]);
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}
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}
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/// The strings are equal up to min_size.
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/// If the rest of the larger string is zero bytes then the strings are considered equal.
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size_t max_size;
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const Char * longest;
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int cmp;
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if (a_size == b_size)
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{
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return 0;
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}
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else if (a_size > b_size)
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{
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max_size = a_size;
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longest = a;
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cmp = 1;
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}
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else
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{
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max_size = b_size;
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longest = b;
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cmp = -1;
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}
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const __m128i zero16 = _mm_setzero_si128();
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for (size_t offset = min_size; offset < max_size; offset += 16)
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{
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uint16_t mask = _mm_movemask_epi8(_mm_cmpgt_epi8(
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_mm_loadu_si128(reinterpret_cast<const __m128i *>(longest + offset)),
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zero16));
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if (mask)
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{
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offset += __builtin_ctz(mask);
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if (offset >= max_size)
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return 0;
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return cmp;
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}
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}
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return 0;
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}
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/** Variant when memory regions have same size.
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* TODO Check if the compiler can optimize previous function when the caller pass identical sizes.
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*/
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template <typename Char>
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inline int memcmpSmallAllowOverflow15(const Char * a, const Char * b, size_t size)
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{
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for (size_t offset = 0; offset < size; offset += 16)
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{
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uint16_t mask = _mm_movemask_epi8(_mm_cmpeq_epi8(
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_mm_loadu_si128(reinterpret_cast<const __m128i *>(a + offset)),
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_mm_loadu_si128(reinterpret_cast<const __m128i *>(b + offset))));
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mask = ~mask;
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if (mask)
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{
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offset += __builtin_ctz(mask);
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if (offset >= size)
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return 0;
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return detail::cmp(a[offset], b[offset]);
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}
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}
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return 0;
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}
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/** Compare memory regions for equality.
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*/
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template <typename Char>
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inline bool memequalSmallAllowOverflow15(const Char * a, size_t a_size, const Char * b, size_t b_size)
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{
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if (a_size != b_size)
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return false;
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for (size_t offset = 0; offset < a_size; offset += 16)
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{
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uint16_t mask = _mm_movemask_epi8(_mm_cmpeq_epi8(
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_mm_loadu_si128(reinterpret_cast<const __m128i *>(a + offset)),
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_mm_loadu_si128(reinterpret_cast<const __m128i *>(b + offset))));
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mask = ~mask;
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if (mask)
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{
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offset += __builtin_ctz(mask);
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return offset >= a_size;
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}
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}
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return true;
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}
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/** Variant when the caller know in advance that the size is a multiple of 16.
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*/
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template <typename Char>
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inline int memcmpSmallMultipleOf16(const Char * a, const Char * b, size_t size)
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{
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for (size_t offset = 0; offset < size; offset += 16)
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{
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uint16_t mask = _mm_movemask_epi8(_mm_cmpeq_epi8(
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_mm_loadu_si128(reinterpret_cast<const __m128i *>(a + offset)),
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_mm_loadu_si128(reinterpret_cast<const __m128i *>(b + offset))));
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mask = ~mask;
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if (mask)
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{
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offset += __builtin_ctz(mask);
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return detail::cmp(a[offset], b[offset]);
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}
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}
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return 0;
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}
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/** Variant when the size is 16 exactly.
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*/
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template <typename Char>
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inline int memcmp16(const Char * a, const Char * b)
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{
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uint16_t mask = _mm_movemask_epi8(_mm_cmpeq_epi8(
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_mm_loadu_si128(reinterpret_cast<const __m128i *>(a)),
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_mm_loadu_si128(reinterpret_cast<const __m128i *>(b))));
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mask = ~mask;
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if (mask)
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{
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auto offset = __builtin_ctz(mask);
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return detail::cmp(a[offset], b[offset]);
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}
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return 0;
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}
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/** Variant when the size is 16 exactly.
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*/
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inline bool memequal16(const void * a, const void * b)
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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 *>(a)),
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_mm_loadu_si128(reinterpret_cast<const __m128i *>(b))));
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}
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/** Compare memory region to zero */
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inline bool memoryIsZeroSmallAllowOverflow15(const void * data, size_t size)
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{
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const __m128i zero16 = _mm_setzero_si128();
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for (size_t offset = 0; offset < size; offset += 16)
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{
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uint16_t mask = _mm_movemask_epi8(_mm_cmpeq_epi8(zero16,
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_mm_loadu_si128(reinterpret_cast<const __m128i *>(reinterpret_cast<const char *>(data) + offset))));
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mask = ~mask;
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if (mask)
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{
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offset += __builtin_ctz(mask);
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return offset >= size;
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}
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}
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return true;
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}
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#else
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#include <cstring>
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template <typename Char>
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inline int memcmpSmallAllowOverflow15(const Char * a, size_t a_size, const Char * b, size_t b_size)
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{
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if (auto res = memcmp(a, b, std::min(a_size, b_size)))
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return res;
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else
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return detail::cmp(a_size, b_size);
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}
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template <typename Char>
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inline int memcmpSmallLikeZeroPaddedAllowOverflow15(const Char * a, size_t a_size, const Char * b, size_t b_size)
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{
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size_t min_size;
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size_t max_size;
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const Char * longest;
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int size_cmp;
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if (a_size == b_size)
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{
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min_size = a_size;
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max_size = a_size;
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longest = a;
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size_cmp = 0;
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}
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else if (a_size > b_size)
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{
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min_size = b_size;
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max_size = a_size;
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longest = a;
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size_cmp = 1;
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}
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else
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{
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min_size = a_size;
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max_size = b_size;
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longest = b;
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size_cmp = -1;
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}
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if (auto res = memcmp(a, b, min_size))
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return res;
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for (size_t i = min_size; i < max_size; ++i)
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if (longest[i] != 0)
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return size_cmp;
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return 0;
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}
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template <typename Char>
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inline int memcmpSmallAllowOverflow15(const Char * a, const Char * b, size_t size)
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{
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return memcmp(a, b, size);
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}
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template <typename Char>
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inline bool memequalSmallAllowOverflow15(const Char * a, size_t a_size, const Char * b, size_t b_size)
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{
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return a_size == b_size && 0 == memcmp(a, b, a_size);
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}
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template <typename Char>
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inline int memcmpSmallMultipleOf16(const Char * a, const Char * b, size_t size)
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{
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return memcmp(a, b, size);
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}
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template <typename Char>
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inline int memcmp16(const Char * a, const Char * b)
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{
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return memcmp(a, b, 16);
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}
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inline bool memequal16(const void * a, const void * b)
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{
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return 0 == memcmp(a, b, 16);
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}
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inline bool memoryIsZeroSmallAllowOverflow15(const void * data, size_t size)
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{
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const char * pos = reinterpret_cast<const char *>(data);
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const char * end = pos + size;
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for (; pos < end; ++pos)
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if (*pos)
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return false;
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return true;
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}
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#endif
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/** Compare memory regions for equality.
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* But if the sizes are different, compare the regions as the smaller one is padded with zero bytes up to the size of the larger.
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*/
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template <typename Char>
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inline bool memequalSmallLikeZeroPaddedAllowOverflow15(const Char * a, size_t a_size, const Char * b, size_t b_size)
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{
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return 0 == memcmpSmallLikeZeroPaddedAllowOverflow15(a, a_size, b, b_size);
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}
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