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Aarch64: Vectorize ucstrncmp of QChar arrays

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Change-Id: I0b3f9d975bfdf6839b97f5753f299074dbf8face
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>
This commit is contained in:
Erik Verbruggen 2016-10-07 12:14:58 +02:00
parent 6ad1012758
commit c877af847a
1 changed files with 24 additions and 0 deletions
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24
src/corelib/tools/qstring.cpp
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@ -491,6 +491,30 @@ static int ucstrncmp(const QChar *a, const QChar *b, int l)
return UnrollTailLoop<7>::exec(l, 0, lambda, lambda);
# endif
#endif
#if defined(__ARM_NEON__) && defined(Q_PROCESSOR_ARM_64) // vaddv is only available on Aarch64
if (l >= 8) {
const QChar *end = a + l;
const uint16x8_t mask = { 1, 1 << 1, 1 << 2, 1 << 3, 1 << 4, 1 << 5, 1 << 6, 1 << 7 };
while (a + 8 < end) {
uint16x8_t da = vld1q_u16(reinterpret_cast<const uint16_t *>(a));
uint16x8_t db = vld1q_u16(reinterpret_cast<const uint16_t *>(b));
uint8_t r = ~(uint8_t)vaddvq_u16(vandq_u16(vceqq_u16(da, db), mask));
if (r) {
// found a different QChar
uint idx = qCountTrailingZeroBits(r);
return (int)a[idx].unicode() - (int)b[idx].unicode();
}
a += 8;
b += 8;
}
l &= 7;
}
const auto &lambda = [=](int i) -> int {
return a[i].unicode() - b[i].unicode();
};
return UnrollTailLoop<7>::exec(l, 0, lambda, lambda);
#endif // __ARM_NEON__
if (!l)
return 0;