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QString: add a method to do a conversion to Latin1 without checking 

If the input is already known to be Latin 1, we don't need to check and
merge in question marks. QJsonObject already needed this code, now we
can make it more efficient.

I'll need the same code in CBOR.

Change-Id: Ib48364abee9f464c96c6fffd152e508f078404e5
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>
bb10
Thiago Macieira 2018-05-13 14:11:38 -07:00
parent 1e95a07a5c
commit bd0905db95
2 changed files with 43 additions and 36 deletions
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32
src/corelib/serialization/qjson_p.h
View File

@ -69,6 +69,9 @@
QT_BEGIN_NAMESPACE
// in qstring.cpp
void qt_to_latin1_unchecked(uchar *dst, const ushort *uc, qsizetype len);
/*
This defines a binary data structure for Json data. The data structure is optimised for fast reading
and minimum allocations. The whole data structure can be mmap'ed and used directly.
@ -294,31 +297,10 @@ public:
int len = d->length = str.length();
uchar *l = (uchar *)d->latin1;
const ushort *uc = (const ushort *)str.unicode();
int i = 0;
#ifdef __SSE2__
for ( ; i + 16 <= len; i += 16) {
__m128i chunk1 = _mm_loadu_si128((__m128i*)&uc[i]); // load
__m128i chunk2 = _mm_loadu_si128((__m128i*)&uc[i + 8]); // load
// pack the two vector to 16 x 8bits elements
const __m128i result = _mm_packus_epi16(chunk1, chunk2);
_mm_storeu_si128((__m128i*)&l[i], result); // store
}
# ifdef Q_PROCESSOR_X86_64
// we can do one more round, of 8 characters
if (i + 8 <= len) {
__m128i chunk = _mm_loadu_si128((__m128i*)&uc[i]); // load
// pack with itself, we'll discard the high part anyway
chunk = _mm_packus_epi16(chunk, chunk);
// unaligned 64-bit store
qToUnaligned(_mm_cvtsi128_si64(chunk), l + i);
i += 8;
}
# endif
#endif
for ( ; i < len; ++i)
l[i] = uc[i];
for ( ; (quintptr)(l+i) & 0x3; ++i)
l[i] = 0;
qt_to_latin1_unchecked(l, uc, len);
for ( ; (quintptr)(l+len) & 0x3; ++len)
l[len] = 0;
return *this;
}

47
src/corelib/tools/qstring.cpp
View File

@ -591,7 +591,8 @@ static inline __m128i mergeQuestionMarks(__m128i chunk)
}
#endif
static void qt_to_latin1(uchar *dst, const ushort *src, int length)
template <bool Checked>
static void qt_to_latin1_internal(uchar *dst, const ushort *src, qsizetype length)
{
#if defined(__SSE2__)
uchar *e = dst + length;
@ -600,10 +601,12 @@ static void qt_to_latin1(uchar *dst, const ushort *src, int length)
// we're going to write to dst[offset..offset+15] (16 bytes)
for ( ; dst + offset + 15 < e; offset += 16) {
__m128i chunk1 = _mm_loadu_si128((const __m128i*)(src + offset)); // load
chunk1 = mergeQuestionMarks(chunk1);
if (Checked)
chunk1 = mergeQuestionMarks(chunk1);
__m128i chunk2 = _mm_loadu_si128((const __m128i*)(src + offset + 8)); // load
chunk2 = mergeQuestionMarks(chunk2);
if (Checked)
chunk2 = mergeQuestionMarks(chunk2);
// pack the two vector to 16 x 8bits elements
const __m128i result = _mm_packus_epi16(chunk1, chunk2);
@ -614,7 +617,8 @@ static void qt_to_latin1(uchar *dst, const ushort *src, int length)
// we're going to write to dst[offset..offset+7] (8 bytes)
if (dst + offset + 7 < e) {
__m128i chunk = _mm_loadu_si128(reinterpret_cast<const __m128i *>(src + offset));
chunk = mergeQuestionMarks(chunk);
if (Checked)
chunk = mergeQuestionMarks(chunk);
// pack, where the upper half is ignored
const __m128i result = _mm_packus_epi16(chunk, chunk);
@ -625,7 +629,8 @@ static void qt_to_latin1(uchar *dst, const ushort *src, int length)
// we're going to write to dst[offset..offset+3] (4 bytes)
if (dst + offset + 3 < e) {
__m128i chunk = _mm_loadl_epi64(reinterpret_cast<const __m128i *>(src + offset));
chunk = mergeQuestionMarks(chunk);
if (Checked)
chunk = mergeQuestionMarks(chunk);
// pack, we'll the upper three quarters
const __m128i result = _mm_packus_epi16(chunk, chunk);
@ -637,7 +642,12 @@ static void qt_to_latin1(uchar *dst, const ushort *src, int length)
dst += offset;
src += offset;
return UnrollTailLoop<3>::exec(length, [=](int i) { dst[i] = (src[i]>0xff) ? '?' : (uchar) src[i]; });
return UnrollTailLoop<3>::exec(length, [=](int i) {
if (Checked)
dst[i] = (src[i]>0xff) ? '?' : (uchar) src[i];
else
dst[i] = src[i];
});
# endif
#elif defined(__ARM_NEON__)
// Refer to the documentation of the SSE2 implementation
@ -652,10 +662,12 @@ static void qt_to_latin1(uchar *dst, const ushort *src, int length)
uint16x8_t chunk = vld1q_u16((uint16_t *)src); // load
src += 8;
const uint16x8_t offLimitMask = vcgtq_u16(chunk, thresholdMask); // chunk > thresholdMask
const uint16x8_t offLimitQuestionMark = vandq_u16(offLimitMask, questionMark); // offLimitMask & questionMark
const uint16x8_t correctBytes = vbicq_u16(chunk, offLimitMask); // !offLimitMask & chunk
chunk = vorrq_u16(correctBytes, offLimitQuestionMark); // correctBytes | offLimitQuestionMark
if (Checked) {
const uint16x8_t offLimitMask = vcgtq_u16(chunk, thresholdMask); // chunk > thresholdMask
const uint16x8_t offLimitQuestionMark = vandq_u16(offLimitMask, questionMark); // offLimitMask & questionMark
const uint16x8_t correctBytes = vbicq_u16(chunk, offLimitMask); // !offLimitMask & chunk
chunk = vorrq_u16(correctBytes, offLimitQuestionMark); // correctBytes | offLimitQuestionMark
}
const uint8x8_t result = vmovn_u16(chunk); // narrowing move->packing
vst1_u8(dst, result); // store
dst += 8;
@ -667,12 +679,25 @@ static void qt_to_latin1(uchar *dst, const ushort *src, int length)
qt_toLatin1_mips_dsp_asm(dst, src, length);
#else
while (length--) {
*dst++ = (*src>0xff) ? '?' : (uchar) *src;
if (Checked)
*dst++ = (*src>0xff) ? '?' : (uchar) *src;
else
*dst++ = *src;
++src;
}
#endif
}
static void qt_to_latin1(uchar *dst, const ushort *src, qsizetype length)
{
qt_to_latin1_internal<true>(dst, src, length);
}
void qt_to_latin1_unchecked(uchar *dst, const ushort *src, qsizetype length)
{
qt_to_latin1_internal<false>(dst, src, length);
}
// Unicode case-insensitive comparison
static int ucstricmp(const QChar *a, const QChar *ae, const QChar *b, const QChar *be)
{