qHash: implement an AES hasher for QLatin1StringView
It's the same aeshash() as before, except we're passing a template
parameter to indicate whether to read half and then zero-extend the
data. That is, it will perform a conversion from Latin1 on the fly.
When running in zero-extending mode, the length parameters are actually
doubled (counting the number of UTF-16 code units) and we then divide
again by 2 when advancing.
The implementation should have the following performance
characteristics:
* QLatin1StringView now will be roughly half as fast as Qt 6.7
* QLatin1StringView now will be roughly as fast as QStringView
For the aeshash128() in default builds of QtCore (will use SSE4.1), the
long loop (32 characters or more) is:
QStringView QLatin1StringView
movdqu -0x20(%rax),%xmm4 | pmovzxbw -0x10(%rdx),%xmm2
movdqu -0x10(%rax),%xmm5 | pmovzxbw -0x8(%rdx),%xmm3
add $0x20,%rax | add $0x10,%rdx
pxor %xmm4,%xmm0 | pxor %xmm2,%xmm0
pxor %xmm5,%xmm1 | pxor %xmm3,%xmm1
aesenc %xmm0,%xmm0 aesenc %xmm0,%xmm0
aesenc %xmm1,%xmm1 aesenc %xmm1,%xmm1
aesenc %xmm0,%xmm0 aesenc %xmm0,%xmm0
aesenc %xmm1,%xmm1 aesenc %xmm1,%xmm1
The number of instructions is identical, but there are actually 2 more
uops per iteration. LLVM-MCA simulation shows this should execute in the
same number of cycles on older CPUs that do not have support for VAES
(see <https://analysis.godbolt.org/z/x95Mrfrf7>).
For the VAES version in aeshash256() and the AVX10 version in
aeshash256_256():
QStringView QLatin1StringView
vpxor -0x40(%rax),%ymm1,%ym | vpmovzxbw -0x20(%rax),%ymm3
vpxor -0x20(%rax),%ymm0,%ym | vpmovzxbw -0x10(%rax),%ymm2
add $0x40,%rax | add $0x20,%rax
| vpxor %ymm3,%ymm0,%ymm0
| vpxor %ymm2,%ymm1,%ymm1
vaesenc %ymm1,%ymm1,%ymm1 <
vaesenc %ymm0,%ymm0,%ymm0 vaesenc %ymm0,%ymm0,%ymm0
vaesenc %ymm1,%ymm1,%ymm1 vaesenc %ymm1,%ymm1,%ymm1
vaesenc %ymm0,%ymm0,%ymm0 vaesenc %ymm0,%ymm0,%ymm0
> vaesenc %ymm1,%ymm1,%ymm1
In this case, the increase in number of instructions matches the
increase in number of uops. The LLVM-MCA simulation says that the
QLatin1StringView version is faster at 11 cycles/iteration vs 14 cyc/it
(see <https://analysis.godbolt.org/z/1Gv1coz13>), but that can't be
right.
Measured performance of CPU cycles, on an Intel Core i9-7940X (Skylake,
no VAES support), normalized on the QString performance (QByteArray is
used as a stand-in for the performance in Qt 6.7):
aeshash | siphash
QByteArray QL1SV QString QByteArray QString
dictionary 94.5% 79.7% 100.0% 150.5%* 159.8%
paths-small 90.2% 93.2% 100.0% 202.8% 290.3%
uuids 81.8% 100.7% 100.0% 215.2% 350.7%
longstrings 42.5% 100.8% 100.0% 185.7% 353.2%
numbers 95.5% 77.9% 100.0% 155.3%* 164.5%
On an Intel Core i7-1165G7 (Tiger Lake, capable of VAES and AVX512VL):
aeshash | siphash
QByteArray QL1SV QString QByteArray QString
dictionary 90.0% 91.1% 100.0% 103.3%* 157.1%
paths-small 99.4% 104.8% 100.0% 237.5% 358.0%
uuids 88.5% 117.6% 100.0% 274.5% 461.7%
longstrings 57.4% 111.2% 100.0% 503.0% 974.3%
numbers 90.6% 89.7% 100.0% 98.7%* 149.9%
On an Intel 4th Generation Xeon Scalable Platinum (Sapphire Rapids, same
Golden Cove core as Alder Lake):
aeshash | siphash
QByteArray QL1SV QString QByteArray QString
dictionary 89.9% 102.1% 100.0% 158.1%* 172.7%
paths-small 78.0% 89.4% 100.0% 159.4% 258.0%
uuids 109.1% 107.9% 100.0% 279.0% 496.3%
longstrings 52.1% 112.4% 100.0% 564.4% 1078.3%
numbers 85.8% 98.9% 100.0% 152.6%* 190.4%
* dictionary contains very short entries (6 characters)
* paths-small contains strings of varying length, but very few over 32
* uuids-list contains fixed-length strings (38 characters)
* longstrings is the same but 304 characters
* numbers also a lot contains very short strings (1 to 6 chars)
What this shows:
* For short strings, the performance difference is negligible between
all three
* For longer strings, QLatin1StringView now costs between 7 and 17% more
than QString on the tested machines instead of up to ~50% less, except on
the older machine (where I think the main QString hashing is suffering
from memory bandwidth limitations)
* The AES hash implementation is anywhere from 1.6 to 11x faster than
Siphash
* Murmurhash (marked with asterisk) is much faster than Siphash, but it
only managed to beat the AES hash in one test
Change-Id: I664b9f014ffc48cbb49bfffd17b045c1811ac0ed
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>
This commit is contained in:
Thiago Macieira
parent
970aad5418
commit
55959aefab
@ -616,8 +616,39 @@ namespace {
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// the scrambling round (step 3 in [1]) because it's just very good at
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// spreading the bits around.
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//
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// Note on Latin-1 hashing (ZX == ByteToWord): for simplicity of the
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// algorithm, we pass sizes equivalent to the UTF-16 content (ZX == None).
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// That means we must multiply by 2 on entry, divide by 2 on pointer
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// advancing, and load half as much data from memory (though we produce
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// exactly as much data in registers). The compilers appear to optimize
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// this out.
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//
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// [1] https://en.wikipedia.org/wiki/Advanced_Encryption_Standard#High-level_description_of_the_algorithm
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template <ZeroExtension ZX, typename T> static const T *advance(const T *ptr, ptrdiff_t n)
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{
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if constexpr (ZX == None)
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return ptr + n;
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// see note above on ZX == ByteToWord hashing
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auto p = reinterpret_cast<const uchar *>(ptr);
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n *= sizeof(T);
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return reinterpret_cast<const T *>(p + n/2);
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}
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template <ZeroExtension> static __m128i loadu128(const void *ptr);
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template <> Q_ALWAYS_INLINE QT_FUNCTION_TARGET(AES) __m128i loadu128<None>(const void *ptr)
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{
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return _mm_loadu_si128(reinterpret_cast<const __m128i *>(ptr));
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}
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template <> Q_ALWAYS_INLINE QT_FUNCTION_TARGET(AES) __m128i loadu128<ByteToWord>(const void *ptr)
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{
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// use a MOVQ followed by PMOVZXBW
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// the compiler usually combines them as a single, loading PMOVZXBW
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__m128i data = _mm_loadl_epi64(static_cast<const __m128i *>(ptr));
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return _mm_cvtepu8_epi16(data);
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}
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// hash 16 bytes, running 3 scramble rounds of AES on itself (like label "final1")
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static void Q_ALWAYS_INLINE QT_FUNCTION_TARGET(AES) QT_VECTORCALL
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hash16bytes(__m128i &state0, __m128i data)
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@ -629,11 +660,12 @@ namespace {
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}
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// hash twice 16 bytes, running 2 scramble rounds of AES on itself
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template <ZeroExtension ZX>
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static void QT_FUNCTION_TARGET(AES) QT_VECTORCALL
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hash2x16bytes(__m128i &state0, __m128i &state1, const __m128i *src0, const __m128i *src1)
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{
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__m128i data0 = _mm_loadu_si128(src0);
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__m128i data1 = _mm_loadu_si128(src1);
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__m128i data0 = loadu128<ZX>(src0);
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__m128i data1 = loadu128<ZX>(src1);
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state0 = _mm_xor_si128(data0, state0);
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state1 = _mm_xor_si128(data1, state1);
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state0 = _mm_aesenc_si128(state0, state0);
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@ -680,16 +712,18 @@ Q_ALWAYS_INLINE __m128i AESHashSeed::state1() const
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}
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}
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template <ZeroExtension ZX>
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static size_t QT_FUNCTION_TARGET(AES) QT_VECTORCALL
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aeshash128_16to32(__m128i state0, __m128i state1, const __m128i *src, const __m128i *srcend)
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{
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{
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if (src + 1 < srcend) {
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const __m128i *src2 = advance<ZX>(srcend, -1);
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if (advance<ZX>(src, 1) < srcend) {
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// epilogue: between 16 and 31 bytes
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hash2x16bytes(state0, state1, src, srcend - 1);
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hash2x16bytes<ZX>(state0, state1, src, src2);
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} else if (src != srcend) {
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// epilogue: between 1 and 16 bytes, overlap with the end
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__m128i data = _mm_loadu_si128(srcend - 1);
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__m128i data = loadu128<ZX>(src2);
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hash16bytes(state0, data);
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}
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@ -700,8 +734,21 @@ aeshash128_16to32(__m128i state0, __m128i state1, const __m128i *src, const __m1
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return mm_cvtsi128_sz(state0);
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}
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// load all 16 bytes and mask off the bytes past the end of the source
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static const qint8 maskarray[] = {
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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};
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// load 16 bytes ending at the data end, then shuffle them to the beginning
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static const qint8 shufflecontrol[] = {
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1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1
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};
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template <ZeroExtension ZX>
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static size_t QT_FUNCTION_TARGET(AES) QT_VECTORCALL
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aeshash128_lt16(__m128i state0, const uchar *p, size_t len)
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aeshash128_lt16(__m128i state0, const __m128i *src, const __m128i *srcend, size_t len)
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{
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if (len) {
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// We're going to load 16 bytes and mask zero the part we don't care
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@ -712,25 +759,15 @@ aeshash128_lt16(__m128i state0, const uchar *p, size_t len)
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constexpr quintptr PageSize = 4096;
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__m128i data;
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if ((quintptr(p) & (PageSize / 2)) == 0) {
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if ((quintptr(src) & (PageSize / 2)) == 0) {
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// lower half of the page:
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// load all 16 bytes and mask off the bytes past the end of the source
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static const qint8 maskarray[] = {
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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};
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__m128i mask = _mm_loadu_si128(reinterpret_cast<const __m128i *>(maskarray + 15 - len));
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data = _mm_loadu_si128(reinterpret_cast<const __m128i *>(p));
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data = loadu128<ZX>(src);
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data = _mm_and_si128(data, mask);
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} else {
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// upper half of the page:
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// load 16 bytes ending at the data end, then shuffle them to the beginning
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static const qint8 shufflecontrol[] = {
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1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1
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};
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__m128i control = _mm_loadu_si128(reinterpret_cast<const __m128i *>(shufflecontrol + 15 - len));
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data = _mm_loadu_si128(reinterpret_cast<const __m128i *>(p + len) - 1);
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data = loadu128<ZX>(advance<ZX>(srcend, -1));
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data = _mm_shuffle_epi8(data, control);
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}
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@ -739,24 +776,45 @@ aeshash128_lt16(__m128i state0, const uchar *p, size_t len)
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return mm_cvtsi128_sz(state0);
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}
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template <ZeroExtension ZX>
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static size_t QT_FUNCTION_TARGET(AES) QT_VECTORCALL
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aeshash128_ge32(__m128i state0, __m128i state1, const __m128i *src, const __m128i *srcend)
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{
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// main loop: scramble two 16-byte blocks
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for ( ; src + 2 < srcend; src += 2)
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hash2x16bytes(state0, state1, src, src + 1);
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for ( ; advance<ZX>(src, 2) < srcend; src = advance<ZX>(src, 2))
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hash2x16bytes<ZX>(state0, state1, src, advance<ZX>(src, 1));
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return aeshash128_16to32(state0, state1, src, srcend);
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return aeshash128_16to32<ZX>(state0, state1, src, srcend);
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}
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# if QT_COMPILER_SUPPORTS_HERE(VAES)
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template <ZeroExtension> static __m256i loadu256(const void *ptr);
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template <> Q_ALWAYS_INLINE QT_FUNCTION_TARGET(VAES) __m256i loadu256<None>(const void *ptr)
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{
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return _mm256_loadu_si256(reinterpret_cast<const __m256i *>(ptr));
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}
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template <> Q_ALWAYS_INLINE QT_FUNCTION_TARGET(VAES) __m256i loadu256<ByteToWord>(const void *ptr)
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{
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// VPMOVZXBW xmm, ymm
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__m128i data = _mm_loadu_si128(reinterpret_cast<const __m128i *>(ptr));
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return _mm256_cvtepu8_epi16(data);
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}
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template <ZeroExtension ZX>
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static size_t QT_FUNCTION_TARGET(VAES_AVX512) QT_VECTORCALL
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aeshash256_lt32_avx256(__m256i state0, const uchar *p, size_t len)
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{
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__m128i state0_128 = _mm256_castsi256_si128(state0);
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if (len) {
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__m256i data;
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if constexpr (ZX == None) {
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__mmask32 mask = _bzhi_u32(-1, unsigned(len));
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__m256i data = _mm256_maskz_loadu_epi8(mask, p);
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data = _mm256_maskz_loadu_epi8(mask, p);
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} else {
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__mmask16 mask = _bzhi_u32(-1, unsigned(len) / 2);
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__m128i data0 = _mm_maskz_loadu_epi8(mask, p);
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data = _mm256_cvtepu8_epi16(data0);
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}
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__m128i data0 = _mm256_castsi256_si128(data);
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if (len >= sizeof(__m128i)) {
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state0 = _mm256_xor_si256(state0, data);
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@ -776,8 +834,9 @@ aeshash256_lt32_avx256(__m256i state0, const uchar *p, size_t len)
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return mm_cvtsi128_sz(state0_128);
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}
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template <ZeroExtension ZX>
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static size_t QT_FUNCTION_TARGET(VAES) QT_VECTORCALL
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aeshash256_ge32(__m256i state0, const uchar *p, size_t len)
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aeshash256_ge32(__m256i state0, const __m128i *s, const __m128i *end, size_t len)
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{
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static const auto hash32bytes = [](__m256i &state0, __m256i data) QT_FUNCTION_TARGET(VAES) {
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state0 = _mm256_xor_si256(state0, data);
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@ -787,10 +846,10 @@ aeshash256_ge32(__m256i state0, const uchar *p, size_t len)
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};
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// hash twice 32 bytes, running 2 scramble rounds of AES on itself
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const auto hash2x32bytes = [](__m256i &state0, __m256i &state1, const __m256i *src0,
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const __m256i *src1) QT_FUNCTION_TARGET(VAES) {
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__m256i data0 = _mm256_loadu_si256(src0);
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__m256i data1 = _mm256_loadu_si256(src1);
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const auto hash2x32bytes = [](__m256i &state0, __m256i &state1, const void *src0,
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const void *src1) QT_FUNCTION_TARGET(VAES) {
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__m256i data0 = loadu256<ZX>(src0);
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__m256i data1 = loadu256<ZX>(src1);
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state0 = _mm256_xor_si256(data0, state0);
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state1 = _mm256_xor_si256(data1, state1);
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state0 = _mm256_aesenc_epi128(state0, state0);
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@ -799,21 +858,22 @@ aeshash256_ge32(__m256i state0, const uchar *p, size_t len)
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state1 = _mm256_aesenc_epi128(state1, state1);
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};
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const __m256i *src = reinterpret_cast<const __m256i *>(p);
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const __m256i *srcend = reinterpret_cast<const __m256i *>(p + len);
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const __m256i *src = reinterpret_cast<const __m256i *>(s);
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const __m256i *srcend = reinterpret_cast<const __m256i *>(end);
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__m256i state1 = _mm256_aesenc_epi128(state0, mm256_set1_epz(len));
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// main loop: scramble two 32-byte blocks
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for ( ; src + 2 < srcend; src += 2)
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hash2x32bytes(state0, state1, src, src + 1);
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for ( ; advance<ZX>(src, 2) < srcend; src = advance<ZX>(src, 2))
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hash2x32bytes(state0, state1, src, advance<ZX>(src, 1));
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if (src + 1 < srcend) {
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const __m256i *src2 = advance<ZX>(srcend, -1);
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if (advance<ZX>(src, 1) < srcend) {
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// epilogue: between 32 and 31 bytes
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hash2x32bytes(state0, state1, src, srcend - 1);
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hash2x32bytes(state0, state1, src, src2);
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} else if (src != srcend) {
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// epilogue: between 1 and 32 bytes, overlap with the end
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__m256i data = _mm256_loadu_si256(srcend - 1);
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__m256i data = loadu256<ZX>(src2);
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hash32bytes(state0, data);
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}
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@ -826,59 +886,69 @@ aeshash256_ge32(__m256i state0, const uchar *p, size_t len)
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return mm_cvtsi128_sz(_mm_xor_si128(low, high));
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}
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template <ZeroExtension ZX>
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static size_t QT_FUNCTION_TARGET(VAES)
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aeshash256(const uchar *p, size_t len, size_t seed, size_t seed2) noexcept
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{
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AESHashSeed state(seed, seed2);
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auto src = reinterpret_cast<const __m128i *>(p);
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const auto srcend = reinterpret_cast<const __m128i *>(p + len);
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const auto srcend = reinterpret_cast<const __m128i *>(advance<ZX>(p, len));
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if (len < sizeof(__m128i))
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return aeshash128_lt16(state.state0, p, len);
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return aeshash128_lt16<ZX>(state.state0, src, srcend, len);
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if (len <= sizeof(__m256i))
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return aeshash128_16to32(state.state0, state.state1(), src, srcend);
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return aeshash128_16to32<ZX>(state.state0, state.state1(), src, srcend);
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return aeshash256_ge32(state.state0_256(), p, len);
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return aeshash256_ge32<ZX>(state.state0_256(), src, srcend, len);
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}
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template <ZeroExtension ZX>
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static size_t QT_FUNCTION_TARGET(VAES_AVX512)
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aeshash256_avx256(const uchar *p, size_t len, size_t seed, size_t seed2) noexcept
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{
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AESHashSeed state(seed, seed2);
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if (len <= sizeof(__m256i))
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return aeshash256_lt32_avx256(state.state0_256(), p, len);
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auto src = reinterpret_cast<const __m128i *>(p);
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const auto srcend = reinterpret_cast<const __m128i *>(advance<ZX>(p, len));
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return aeshash256_ge32(state.state0_256(), p, len);
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if (len <= sizeof(__m256i))
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return aeshash256_lt32_avx256<ZX>(state.state0_256(), p, len);
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return aeshash256_ge32<ZX>(state.state0_256(), src, srcend, len);
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}
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# endif // VAES
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||||
|
||||
template <ZeroExtension ZX>
|
||||
static size_t QT_FUNCTION_TARGET(AES)
|
||||
aeshash128(const uchar *p, size_t len, size_t seed, size_t seed2) noexcept
|
||||
{
|
||||
AESHashSeed state(seed, seed2);
|
||||
auto src = reinterpret_cast<const __m128i *>(p);
|
||||
const auto srcend = reinterpret_cast<const __m128i *>(p + len);
|
||||
const auto srcend = reinterpret_cast<const __m128i *>(advance<ZX>(p, len));
|
||||
|
||||
if (len < sizeof(__m128i))
|
||||
return aeshash128_lt16(state.state0, p, len);
|
||||
return aeshash128_lt16<ZX>(state.state0, src, srcend, len);
|
||||
|
||||
if (len <= sizeof(__m256i))
|
||||
return aeshash128_16to32(state.state0, state.state1(), src, srcend);
|
||||
return aeshash128_16to32<ZX>(state.state0, state.state1(), src, srcend);
|
||||
|
||||
return aeshash128_ge32(state.state0, state.state1(), src, srcend);
|
||||
return aeshash128_ge32<ZX>(state.state0, state.state1(), src, srcend);
|
||||
}
|
||||
|
||||
template <ZeroExtension ZX = None>
|
||||
static size_t aeshash(const uchar *p, size_t len, size_t seed, size_t seed2) noexcept
|
||||
{
|
||||
if constexpr (ZX == ByteToWord)
|
||||
len *= 2; // see note above on ZX == ByteToWord hashing
|
||||
|
||||
# if QT_COMPILER_SUPPORTS_HERE(VAES)
|
||||
if (qCpuHasFeature(VAES)) {
|
||||
if (qCpuHasFeature(AVX512VL))
|
||||
return aeshash256_avx256(p, len, seed, seed2);
|
||||
return aeshash256(p, len, seed, seed2);
|
||||
return aeshash256_avx256<ZX>(p, len, seed, seed2);
|
||||
return aeshash256<ZX>(p, len, seed, seed2);
|
||||
}
|
||||
# endif
|
||||
return aeshash128(p, len, seed, seed2);
|
||||
return aeshash128<ZX>(p, len, seed, seed2);
|
||||
}
|
||||
#endif // x86 AESNI
|
||||
|
||||
@ -1090,6 +1160,10 @@ size_t qHash(QLatin1StringView key, size_t seed) noexcept
|
||||
if (seed)
|
||||
seed2 = qt_qhash_seed.currentSeed(1);
|
||||
|
||||
#if defined(AESHASH)
|
||||
if (seed && qCpuHasFeature(AES) && qCpuHasFeature(SSE4_2))
|
||||
return aeshash<ByteToWord>(data, size, seed, seed2);
|
||||
#endif
|
||||
return qHashBits_fallback<ByteToWord>(data, size, seed, seed2);
|
||||
}
|
||||
|
||||
|
||||
@ -289,10 +289,12 @@ void tst_QHashFunctions::stringConsistency_data()
|
||||
QTest::newRow("null") << QString();
|
||||
QTest::newRow("empty") << "";
|
||||
QTest::newRow("withnull") << QStringLiteral("A\0z");
|
||||
QTest::newRow("short-ascii") << "Hello";
|
||||
QTest::newRow("short-ascii") << "Hello"; // 10 bytes
|
||||
QTest::newRow("medium-ascii") << "Hello, World"; // 24 bytes
|
||||
QTest::newRow("long-ascii") << QStringLiteral("abcdefghijklmnopqrstuvxyz").repeated(16);
|
||||
|
||||
QTest::newRow("short-latin1") << "Bokmål";
|
||||
QTest::newRow("medium-latin1") << "Det går bra!"; // 24 bytes
|
||||
QTest::newRow("long-latin1")
|
||||
<< R"(Alle mennesker er født frie og med samme menneskeverd og menneskerettigheter.
|
||||
De er utstyrt med fornuft og samvittighet og bør handle mot hverandre i brorskapets ånd.)";
|
||||
@ -327,8 +329,6 @@ void tst_QHashFunctions::stringConsistency()
|
||||
QLatin1StringView l1sv(l1ba.data(), l1ba.size());
|
||||
#ifdef Q_PROCESSOR_ARM
|
||||
// zero-extending aeshash not implemented on ARM
|
||||
#elif defined(Q_PROCESSOR_X86)
|
||||
// zero-extending aeshash not implemented on x86
|
||||
#else
|
||||
if (value == l1sv)
|
||||
QCOMPARE(qHash(l1sv, seed), qHash(value, seed));
|
||||
|
||||
@ -5,7 +5,7 @@
|
||||
|
||||
QT_BEGIN_NAMESPACE
|
||||
|
||||
size_t qHash(const Qt4String &str)
|
||||
size_t qHash(const Qt4String &str, size_t /* never used */)
|
||||
{
|
||||
qsizetype n = str.size();
|
||||
const QChar *p = str.unicode();
|
||||
@ -40,7 +40,7 @@ size_t qHash(const Qt50String &key, size_t seed)
|
||||
// Still, we can avoid writing the multiplication as "(h << 5) - h"
|
||||
// -- the compiler will turn it into a shift and an addition anyway
|
||||
// (for instance, gcc 4.4 does that even at -O0).
|
||||
size_t qHash(const JavaString &str)
|
||||
size_t qHash(const JavaString &str, size_t /* never used */)
|
||||
{
|
||||
const auto *p = reinterpret_cast<const char16_t *>(str.constData());
|
||||
const qsizetype len = str.size();
|
||||
|
||||
@ -13,6 +13,8 @@
|
||||
#include <QUuid>
|
||||
#include <QTest>
|
||||
|
||||
static constexpr quint64 RandomSeed32 = 1045982819;
|
||||
static constexpr quint64 RandomSeed64 = QtPrivate::QHashCombine{}(RandomSeed32, RandomSeed32);
|
||||
|
||||
class tst_QHash : public QObject
|
||||
{
|
||||
@ -31,6 +33,8 @@ private slots:
|
||||
|
||||
void hashing_current_data() { data(); }
|
||||
void hashing_current() { hashing_template<QString>(); }
|
||||
void hashing_qbytearray_data() { data(); }
|
||||
void hashing_qbytearray() { hashing_template<QByteArray>(); }
|
||||
void hashing_qt50_data() { data(); }
|
||||
void hashing_qt50() { hashing_template<Qt50String>(); }
|
||||
void hashing_qt4_data() { data(); }
|
||||
@ -38,15 +42,25 @@ private slots:
|
||||
void hashing_javaString_data() { data(); }
|
||||
void hashing_javaString() { hashing_template<JavaString>(); }
|
||||
|
||||
void hashing_nonzero_current_data() { data(); }
|
||||
void hashing_nonzero_current() { hashing_nonzero_template<QString>(); }
|
||||
void hashing_nonzero_qbytearray_data() { data(); }
|
||||
void hashing_nonzero_qbytearray() { hashing_nonzero_template<QByteArray>(); }
|
||||
void hashing_nonzero_qlatin1string_data() { data(); }
|
||||
void hashing_nonzero_qlatin1string() { hashing_nonzero_template<OwningLatin1String>(); }
|
||||
|
||||
private:
|
||||
void data();
|
||||
template <typename String> void qhash_template();
|
||||
template <typename String> void hashing_template();
|
||||
template <typename String, size_t Seed = 0> void hashing_template();
|
||||
template <typename String> void hashing_nonzero_template()
|
||||
{ hashing_template<String, size_t(RandomSeed64)>(); }
|
||||
|
||||
QStringList smallFilePaths;
|
||||
QStringList uuids;
|
||||
QStringList dict;
|
||||
QStringList numbers;
|
||||
QStringList longstrings;
|
||||
};
|
||||
|
||||
///////////////////// QHash /////////////////////
|
||||
@ -68,10 +82,12 @@ void tst_QHash::initTestCase()
|
||||
// guaranteed to be completely random, generated by http://xkcd.com/221/
|
||||
QUuid ns = QUuid("{f43d2ef3-2fe9-4563-a6f5-5a0100c2d699}");
|
||||
uuids.reserve(smallFilePaths.size());
|
||||
longstrings.reserve(smallFilePaths.size());
|
||||
|
||||
foreach (const QString &path, smallFilePaths)
|
||||
uuids.append(QUuid::createUuidV5(ns, path).toString());
|
||||
|
||||
for (qsizetype i = 0; i < uuids.size(); ++i)
|
||||
longstrings.append(uuids.at(i).repeated(8));
|
||||
|
||||
// lots of strings with alphabetical characters, vaguely reminiscent of
|
||||
// a dictionary.
|
||||
@ -112,6 +128,7 @@ void tst_QHash::data()
|
||||
QTest::addColumn<QStringList>("items");
|
||||
QTest::newRow("paths-small") << smallFilePaths;
|
||||
QTest::newRow("uuids-list") << uuids;
|
||||
QTest::newRow("longstrings-list") << longstrings;
|
||||
QTest::newRow("dictionary") << dict;
|
||||
QTest::newRow("numbers") << numbers;
|
||||
}
|
||||
@ -132,19 +149,30 @@ template <typename String> void tst_QHash::qhash_template()
|
||||
}
|
||||
}
|
||||
|
||||
template <typename String> void tst_QHash::hashing_template()
|
||||
template <typename String, size_t Seed> void tst_QHash::hashing_template()
|
||||
{
|
||||
// just the hashing function
|
||||
QFETCH(QStringList, items);
|
||||
|
||||
QList<String> realitems;
|
||||
realitems.reserve(items.size());
|
||||
foreach (const QString &s, items)
|
||||
foreach (const QString &s, items) {
|
||||
if constexpr (std::is_same_v<QString::value_type, typename String::value_type>) {
|
||||
realitems.append(s);
|
||||
} else if constexpr (sizeof(typename String::value_type) == 1) {
|
||||
realitems.append(String(s.toLatin1()));
|
||||
}
|
||||
}
|
||||
|
||||
QBENCHMARK {
|
||||
for (int i = 0, n = realitems.size(); i != n; ++i)
|
||||
(void)qHash(realitems.at(i));
|
||||
for (int i = 0, n = realitems.size(); i != n; ++i) {
|
||||
volatile size_t h = qHash(realitems.at(i), Seed);
|
||||
(void)h;
|
||||
#ifdef Q_CC_GNU
|
||||
// "use" h
|
||||
asm ("" : "+r" (h));
|
||||
#endif
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
|
||||
@ -1,8 +1,20 @@
|
||||
// Copyright (C) 2016 The Qt Company Ltd.
|
||||
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only
|
||||
|
||||
#include <QHashFunctions>
|
||||
#include <QString>
|
||||
|
||||
struct OwningLatin1String : QByteArray
|
||||
{
|
||||
OwningLatin1String() = default;
|
||||
OwningLatin1String(const QByteArray &a) : QByteArray(a) {}
|
||||
OwningLatin1String(QByteArray &&a) : QByteArray(std::move(a)) {}
|
||||
};
|
||||
QT_BEGIN_NAMESPACE
|
||||
inline size_t qHash(const OwningLatin1String &s, size_t seed = 0)
|
||||
{ return qHash(QLatin1StringView(s), seed); }
|
||||
QT_END_NAMESPACE
|
||||
|
||||
struct Qt4String : QString
|
||||
{
|
||||
Qt4String() {}
|
||||
@ -10,7 +22,7 @@ struct Qt4String : QString
|
||||
};
|
||||
|
||||
QT_BEGIN_NAMESPACE
|
||||
size_t qHash(const Qt4String &);
|
||||
size_t qHash(const Qt4String &, size_t = 0);
|
||||
QT_END_NAMESPACE
|
||||
|
||||
struct Qt50String : QString
|
||||
@ -31,6 +43,6 @@ struct JavaString : QString
|
||||
};
|
||||
|
||||
QT_BEGIN_NAMESPACE
|
||||
size_t qHash(const JavaString &);
|
||||
size_t qHash(const JavaString &, size_t = 0);
|
||||
QT_END_NAMESPACE
|
||||
|
||||
|
||||
Loading…
x
Reference in New Issue
Block a user