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Use find8 and find16 in AdaptiveStringSearcher #28403
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Original file line number | Diff line number | Diff line change |
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@@ -65,51 +65,30 @@ class AdaptiveStringSearcherBase { | |
static constexpr bool exceedsOneByte(LChar) { return false; } | ||
static constexpr bool exceedsOneByte(UChar c) { return c > 0xff; } | ||
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template <typename T, typename U> | ||
static inline T alignDown(T value, U alignment) | ||
{ | ||
return reinterpret_cast<T>((reinterpret_cast<uintptr_t>(value) & ~(alignment - 1))); | ||
} | ||
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static constexpr uint8_t getHighestValueByte(LChar character) { return character; } | ||
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static constexpr uint8_t getHighestValueByte(UChar character) | ||
{ | ||
return std::max<unsigned>(static_cast<uint8_t>(character & 0xFF), static_cast<uint8_t>(character >> 8)); | ||
} | ||
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template <typename PatternChar, typename SubjectChar> | ||
static inline int findFirstCharacter(std::span<const PatternChar> pattern, std::span<const SubjectChar> subject, int index) | ||
{ | ||
const auto* subjectPtr = subject.data(); | ||
const PatternChar patternFirstChar = pattern[0]; | ||
const int maxN = (subject.size() - pattern.size() + 1); | ||
PatternChar patternFirstChar = pattern[0]; | ||
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if (sizeof(SubjectChar) == 2 && !patternFirstChar) { | ||
// Special-case looking for the 0 char in other than one-byte strings. | ||
// memchr mostly fails in this case due to every other byte being 0 in text | ||
// that is mostly ascii characters. | ||
for (int i = index; i < maxN; ++i) { | ||
if (!subjectPtr[i]) | ||
return i; | ||
} | ||
return -1; | ||
} | ||
const uint8_t searchByte = getHighestValueByte(patternFirstChar); | ||
const SubjectChar searchChar = static_cast<SubjectChar>(patternFirstChar); | ||
int pos = index; | ||
do { | ||
ASSERT(maxN - pos >= 0); | ||
const SubjectChar* charPos = reinterpret_cast<const SubjectChar*>(memchr(subjectPtr + pos, searchByte, (maxN - pos) * sizeof(SubjectChar))); | ||
if (charPos == nullptr) | ||
if constexpr (sizeof(PatternChar) == 2 && sizeof(SubjectChar) == 1) { | ||
if (!isLatin1(patternFirstChar)) | ||
Comment on lines
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There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Why could we handle this case before and not now? There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Because the previous one was using memchr and a hack for both 16 / 8 bit cases. Now the logic is completely different. |
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return -1; | ||
charPos = alignDown(charPos, sizeof(SubjectChar)); | ||
pos = static_cast<int>(charPos - subjectPtr); | ||
if (subjectPtr[pos] == searchChar) | ||
return pos; | ||
} while (++pos < maxN); | ||
} | ||
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return -1; | ||
const int maxN = (subject.size() - pattern.size() + 1); | ||
const SubjectChar searchCharacter = static_cast<SubjectChar>(patternFirstChar); | ||
const auto* start = subjectPtr + index; | ||
const auto searchLength = maxN - index; | ||
const SubjectChar* charPos = nullptr; | ||
ASSERT(maxN - index >= 0); | ||
if constexpr (sizeof(SubjectChar) == 2) | ||
charPos = bitwise_cast<const SubjectChar*>(find16(bitwise_cast<const uint16_t*>(start), searchCharacter, searchLength)); | ||
else | ||
charPos = bitwise_cast<const SubjectChar*>(find8(bitwise_cast<const uint8_t*>(start), searchCharacter, searchLength)); | ||
if (charPos == nullptr) | ||
return -1; | ||
return static_cast<int>(charPos - subjectPtr); | ||
} | ||
}; | ||
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Does this no longer apply? Or is it just not worth the upfront runtime?
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This no longer applies since we use find16 instead of memchr.