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Optimize non-vectorized UTF-8 to UTF-16 comparison to US-ASCII

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This allows us to skip the surrogate pair decoding too, since it can't
match anyway.

Change-Id: Ied637aece2a7427b8a2dfffd16118183e5d76794
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
This commit is contained in:
Thiago Macieira 2020-05-22 17:42:26 -07:00
parent 45838673df
commit 274e07a339
1 changed files with 21 additions and 13 deletions
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34
src/corelib/text/qstringconverter.cpp
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@ -1,7 +1,7 @@
/****************************************************************************
**
** Copyright (C) 2020 The Qt Company Ltd.
** Copyright (C) 2018 Intel Corporation.
** Copyright (C) 2020 Intel Corporation.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the QtCore module of the Qt Toolkit.
@ -715,27 +715,35 @@ QUtf8::ValidUtf8Result QUtf8::isValidUtf8(const char *chars, qsizetype len)
int QUtf8::compareUtf8(const char *utf8, qsizetype u8len, const QChar *utf16, qsizetype u16len) noexcept
{
uint uc1, uc2;
auto src1 = reinterpret_cast<const uchar *>(utf8);
auto src1 = reinterpret_cast<const char8_t *>(utf8);
auto end1 = src1 + u8len;
QStringIterator src2(utf16, utf16 + u16len);
auto src2 = reinterpret_cast<const char16_t *>(utf16);
auto end2 = src2 + u16len;
while (src1 < end1 && src2.hasNext()) {
uchar b = *src1++;
uint *output = &uc1;
int res = QUtf8Functions::fromUtf8<QUtf8BaseTraits>(b, output, src1, end1);
if (res < 0) {
// decoding error
uc1 = QChar::ReplacementCharacter;
while (src1 < end1 && src2 < end2) {
char32_t uc1 = *src1++;
char32_t uc2 = *src2++;
if (uc1 >= 0x80) {
char32_t *output = &uc1;
int res = QUtf8Functions::fromUtf8<QUtf8BaseTraitsNoAscii>(uc1, output, src1, end1);
if (res < 0) {
// decoding error
uc1 = QChar::ReplacementCharacter;
}
// Only decode the UTF-16 surrogate pair if the UTF-8 code point
// wasn't US-ASCII (a surrogate cannot match US-ASCII).
if (QChar::isHighSurrogate(uc2) && src2 < end2 && QChar::isLowSurrogate(*src2))
uc2 = QChar::surrogateToUcs4(uc2, *src2++);
}
uc2 = src2.next();
if (uc1 != uc2)
return int(uc1) - int(uc2);
}
// the shorter string sorts first
return (end1 > src1) - int(src2.hasNext());
return (end1 > src1) - int(end2 > src2);
}
int QUtf8::compareUtf8(const char *utf8, qsizetype u8len, QLatin1String s)