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QUrl: Add qustrchr() and use it to speed up the fast URL full decoding 

The character search in the findChar() static function in qstring.cpp is
more efficient than what we had in qurlrecode.cpp and there's no point
in duplicating it. It also has a Neon implementation. So make the
implementation available for use in QtPrivate::qustrchr().

This also simplifies the implementation.

Change-Id: Ib48364abee9f464c96c6fffd152eedd0cd8ad7f8
Reviewed-by: Samuel Gaist <samuel.gaist@idiap.ch>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
bb10
Thiago Macieira 2018-05-15 14:13:24 -07:00
parent 98dda3f5ac
commit dc8d4fe30f
3 changed files with 106 additions and 107 deletions
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84
src/corelib/io/qurlrecode.cpp
View File

@ -500,9 +500,7 @@ static bool simdCheckNonEncoded(ushort *&output, const ushort *&input, const ush
__m256i data = _mm256_loadu_si256(reinterpret_cast<const __m256i *>(input + offset));
__m256i comparison = _mm256_cmpeq_epi16(data, percents256);
mask = _mm256_movemask_epi8(comparison);
if (output)
_mm256_storeu_si256(reinterpret_cast<__m256i *>(output + offset), data);
_mm256_storeu_si256(reinterpret_cast<__m256i *>(output + offset), data);
# else
// do 32 bytes at a time using unrolled SSE2
__m128i data1 = _mm_loadu_si128(reinterpret_cast<const __m128i *>(input + offset));
@ -512,11 +510,9 @@ static bool simdCheckNonEncoded(ushort *&output, const ushort *&input, const ush
uint mask1 = _mm_movemask_epi8(comparison1);
uint mask2 = _mm_movemask_epi8(comparison2);
if (output) {
_mm_storeu_si128(reinterpret_cast<__m128i *>(output + offset), data1);
if (!mask1)
_mm_storeu_si128(reinterpret_cast<__m128i *>(output + offset + 8), data2);
}
_mm_storeu_si128(reinterpret_cast<__m128i *>(output + offset), data1);
if (!mask1)
_mm_storeu_si128(reinterpret_cast<__m128i *>(output + offset + 8), data2);
mask = mask1 | (mask2 << 16);
# endif
@ -534,21 +530,14 @@ static bool simdCheckNonEncoded(ushort *&output, const ushort *&input, const ush
__m128i data = _mm_loadu_si128(reinterpret_cast<const __m128i *>(input));
__m128i comparison = _mm_cmpeq_epi16(data, percents);
mask = _mm_movemask_epi8(comparison);
// speculatively store everything
if (output)
_mm_storeu_si128(reinterpret_cast<__m128i *>(output), data);
_mm_storeu_si128(reinterpret_cast<__m128i *>(output), data);
idx = qCountTrailingZeroBits(quint16(mask)) / 2;
} else if (input + 4 <= end) {
// do 8 bytes only
__m128i data = _mm_loadl_epi64(reinterpret_cast<const __m128i *>(input));
__m128i comparison = _mm_cmpeq_epi16(data, percents);
mask = _mm_movemask_epi8(comparison) & 0xffu;
if (output)
_mm_storel_epi64(reinterpret_cast<__m128i *>(output), data);
_mm_storel_epi64(reinterpret_cast<__m128i *>(output), data);
idx = qCountTrailingZeroBits(quint8(mask)) / 2;
} else {
// no percents found (because we didn't check)
@ -557,8 +546,7 @@ static bool simdCheckNonEncoded(ushort *&output, const ushort *&input, const ush
// advance to the next non-encoded
input += idx;
if (output)
output += idx;
output += idx;
return !mask;
}
@ -592,26 +580,22 @@ static bool simdCheckNonEncoded(...)
*/
static int decode(QString &appendTo, const ushort *begin, const ushort *end)
{
// fast check whether there's anything to be decoded in the first place
const ushort *input = QtPrivate::qustrchr(QStringView(begin, end), '%');
if (Q_LIKELY(input == end))
return 0; // nothing to do, it was already decoded!
// detach
const int origSize = appendTo.size();
const ushort *input = begin;
ushort *output = 0;
appendTo.resize(origSize + (end - begin));
ushort *output = reinterpret_cast<ushort *>(appendTo.begin()) + origSize;
memcpy(static_cast<void *>(output), static_cast<const void *>(begin), (input - begin) * sizeof(ushort));
output += input - begin;
while (input != end) {
if (simdCheckNonEncoded(output, input, end)) {
ushort uc = 0;
while (input != end) {
uc = *input;
if (uc == '%')
break;
if (output)
*output++ = uc;
++input;
}
if (uc != '%')
break; // we're done
}
// something was encoded
Q_ASSERT(*input == '%');
if (Q_UNLIKELY(end - input < 3 || !isHex(input[1]) || !isHex(input[2]))) {
// badly-encoded data
appendTo.resize(origSize + (end - begin));
@ -619,27 +603,27 @@ static int decode(QString &appendTo, const ushort *begin, const ushort *end)
return end - begin;
}
if (Q_UNLIKELY(!output)) {
// detach
appendTo.resize(origSize + (end - begin));
output = reinterpret_cast<ushort *>(appendTo.begin()) + origSize;
memcpy(static_cast<void *>(output), static_cast<const void *>(begin), (input - begin) * sizeof(ushort));
output += input - begin;
}
++input;
*output++ = decodeNibble(input[0]) << 4 | decodeNibble(input[1]);
if (output[-1] >= 0x80)
output[-1] = QChar::ReplacementCharacter;
input += 2;
// search for the next percent, copying from input to output
if (simdCheckNonEncoded(output, input, end)) {
while (input != end) {
ushort uc = *input;
if (uc == '%')
break;
*output++ = uc;
++input;
}
}
}
if (output) {
int len = output - reinterpret_cast<ushort *>(appendTo.begin());
appendTo.truncate(len);
return len - origSize;
}
return 0;
int len = output - reinterpret_cast<ushort *>(appendTo.begin());
appendTo.truncate(len);
return len - origSize;
}
template <size_t N>

128
src/corelib/tools/qstring.cpp
View File

@ -227,10 +227,8 @@ template <uint MaxCount> struct UnrollTailLoop
return returnIfExited;
bool check = loopCheck(i);
if (check) {
const RetType &retval = returnIfFailed(i);
return retval;
}
if (check)
return returnIfFailed(i);
return UnrollTailLoop<MaxCount - 1>::exec(count - 1, returnIfExited, loopCheck, returnIfFailed, i + 1);
}
@ -253,6 +251,72 @@ inline RetType UnrollTailLoop<0>::exec(Number, RetType returnIfExited, Functor1,
}
#endif
/*!
* \internal
*
* Searches for character \a \c in the string \a str and returns a pointer to
* it. Unlike strchr() and wcschr() (but like glibc's strchrnul()), if the
* character is not found, this function returns a pointer to the end of the
* string -- that is, \c{str.end()}.
*/
const ushort *QtPrivate::qustrchr(QStringView str, ushort c) noexcept
{
const ushort *n = reinterpret_cast<const ushort *>(str.begin());
const ushort *e = reinterpret_cast<const ushort *>(str.end());
#ifdef __SSE2__
__m128i mch = _mm_set1_epi32(c | (c << 16));
// we're going to read n[0..7] (16 bytes)
for (const ushort *next = n + 8; next <= e; n = next, next += 8) {
__m128i data = _mm_loadu_si128(reinterpret_cast<const __m128i *>(n));
__m128i result = _mm_cmpeq_epi16(data, mch);
uint mask = _mm_movemask_epi8(result);
if (ushort(mask)) {
// found a match
return n + (qCountTrailingZeroBits(mask) >> 1);
}
}
# if !defined(__OPTIMIZE_SIZE__)
// we're going to read n[0..3] (8 bytes)
if (e - n > 3) {
__m128i data = _mm_loadl_epi64(reinterpret_cast<const __m128i *>(n));
__m128i result = _mm_cmpeq_epi16(data, mch);
uint mask = _mm_movemask_epi8(result);
if (uchar(mask)) {
// found a match
return n + (qCountTrailingZeroBits(mask) >> 1);
}
n += 4;
}
return UnrollTailLoop<3>::exec(e - n, e,
[=](int i) { return n[i] == c; },
[=](int i) { return n + i; });
# endif
#elif defined(__ARM_NEON__) && defined(Q_PROCESSOR_ARM_64) // vaddv is only available on Aarch64
const uint16x8_t vmask = { 1, 1 << 1, 1 << 2, 1 << 3, 1 << 4, 1 << 5, 1 << 6, 1 << 7 };
const uint16x8_t ch_vec = vdupq_n_u16(c);
for (const ushort *next = n + 8; next <= e; n = next, next += 8) {
uint16x8_t data = vld1q_u16(n);
uint mask = vaddvq_u16(vandq_u16(vceqq_u16(data, ch_vec), vmask));
if (ushort(mask)) {
// found a match
return n + qCountTrailingZeroBits(mask);
}
}
#endif // aarch64
--n;
while (++n != e)
if (*n == c)
return n;
return n;
}
#ifdef __SSE2__
// Scans from \a ptr to \a end until \a maskval is non-zero. Returns true if
// the no non-zero was found. Returns false and updates \a ptr to point to the
@ -1183,59 +1247,9 @@ static int findChar(const QChar *str, int len, QChar ch, int from,
const ushort *n = s + from;
const ushort *e = s + len;
if (cs == Qt::CaseSensitive) {
#ifdef __SSE2__
__m128i mch = _mm_set1_epi32(c | (c << 16));
// we're going to read n[0..7] (16 bytes)
for (const ushort *next = n + 8; next <= e; n = next, next += 8) {
__m128i data = _mm_loadu_si128((const __m128i*)n);
__m128i result = _mm_cmpeq_epi16(data, mch);
uint mask = _mm_movemask_epi8(result);
if (ushort(mask)) {
// found a match
// same as: return n - s + _bit_scan_forward(mask) / 2
return (reinterpret_cast<const char *>(n) - reinterpret_cast<const char *>(s)
+ qCountTrailingZeroBits(mask)) >> 1;
}
}
# if !defined(__OPTIMIZE_SIZE__)
// we're going to read n[0..3] (8 bytes)
if (e - n > 3) {
__m128i data = _mm_loadl_epi64(reinterpret_cast<const __m128i *>(n));
__m128i result = _mm_cmpeq_epi16(data, mch);
uint mask = _mm_movemask_epi8(result);
if (uchar(mask)) {
// found a match
// same as: return n - s + _bit_scan_forward(mask) / 2
return (reinterpret_cast<const char *>(n) - reinterpret_cast<const char *>(s)
+ qCountTrailingZeroBits(mask)) >> 1;
}
n += 4;
}
return UnrollTailLoop<3>::exec(e - n, -1,
[=](int i) { return n[i] == c; },
[=](int i) { return n - s + i; });
# endif
#endif
#if defined(__ARM_NEON__) && defined(Q_PROCESSOR_ARM_64) // vaddv is only available on Aarch64
const uint16x8_t vmask = { 1, 1 << 1, 1 << 2, 1 << 3, 1 << 4, 1 << 5, 1 << 6, 1 << 7 };
const uint16x8_t ch_vec = vdupq_n_u16(c);
for (const ushort *next = n + 8; next <= e; n = next, next += 8) {
uint16x8_t data = vld1q_u16(n);
uint mask = vaddvq_u16(vandq_u16(vceqq_u16(data, ch_vec), vmask));
if (ushort(mask)) {
// found a match
return n - s + qCountTrailingZeroBits(mask);
}
}
#endif // aarch64
--n;
while (++n != e)
if (*n == c)
return n - s;
n = QtPrivate::qustrchr(QStringView(n, e), c);
if (n != e)
return n - s;
} else {
c = foldCase(c);
--n;

1
src/corelib/tools/qstringalgorithms.h
View File

@ -56,6 +56,7 @@ template <typename T> class QVector;
namespace QtPrivate {
Q_REQUIRED_RESULT Q_CORE_EXPORT Q_DECL_PURE_FUNCTION qsizetype qustrlen(const ushort *str) Q_DECL_NOTHROW;
Q_REQUIRED_RESULT Q_CORE_EXPORT Q_DECL_PURE_FUNCTION const ushort *qustrchr(QStringView str, ushort ch) noexcept;
Q_REQUIRED_RESULT Q_CORE_EXPORT Q_DECL_PURE_FUNCTION int compareStrings(QStringView lhs, QStringView rhs, Qt::CaseSensitivity cs = Qt::CaseSensitive) Q_DECL_NOTHROW;
Q_REQUIRED_RESULT Q_CORE_EXPORT Q_DECL_PURE_FUNCTION int compareStrings(QStringView lhs, QLatin1String rhs, Qt::CaseSensitivity cs = Qt::CaseSensitive) Q_DECL_NOTHROW;