diff options
| -rw-r--r-- | src/corelib/tools/qhash.cpp | 41 |
1 files changed, 20 insertions, 21 deletions
diff --git a/src/corelib/tools/qhash.cpp b/src/corelib/tools/qhash.cpp index 14adc2e8d3..e8ae490490 100644 --- a/src/corelib/tools/qhash.cpp +++ b/src/corelib/tools/qhash.cpp @@ -303,10 +303,7 @@ static inline uint64_t murmurhash(const void *key, uint64_t len, uint64_t seed) // This is an inlined version of the SipHash implementation that is // trying to avoid some memcpy's from uint64 to uint8[] and back. // -// The original algorithm uses a 128bit seed. Our public API only allows -// for a 64bit seed, so we mix in the length of the string to get some more -// bits for the seed. -// + // Use SipHash-1-2, which has similar performance characteristics as // stablehash() above, instead of the SipHash-2-4 default #define cROUNDS 1 @@ -333,7 +330,7 @@ static inline uint64_t murmurhash(const void *key, uint64_t len, uint64_t seed) } while (0) -static uint64_t siphash(const uint8_t *in, uint64_t inlen, const uint64_t seed) +static uint64_t siphash(const uint8_t *in, uint64_t inlen, uint64_t seed, uint64_t seed2) { /* "somepseudorandomlygeneratedbytes" */ uint64_t v0 = 0x736f6d6570736575ULL; @@ -342,7 +339,7 @@ static uint64_t siphash(const uint8_t *in, uint64_t inlen, const uint64_t seed) uint64_t v3 = 0x7465646279746573ULL; uint64_t b; uint64_t k0 = seed; - uint64_t k1 = seed ^ inlen; + uint64_t k1 = seed2; int i; const uint8_t *end = in + (inlen & ~7ULL); const int left = inlen & 7; @@ -438,7 +435,7 @@ static uint64_t siphash(const uint8_t *in, uint64_t inlen, const uint64_t seed) } while (0) -static uint siphash(const uint8_t *in, uint inlen, const uint seed) +static uint siphash(const uint8_t *in, uint inlen, uint seed, uint seed2) { /* "somepseudorandomlygeneratedbytes" */ uint v0 = 0x736f6d65U; @@ -447,7 +444,7 @@ static uint siphash(const uint8_t *in, uint inlen, const uint seed) uint v3 = 0x74656462U; uint b; uint k0 = seed; - uint k1 = seed ^ inlen; + uint k1 = seed2; int i; const uint8_t *end = in + (inlen & ~3ULL); const int left = inlen & 3; @@ -517,19 +514,17 @@ static uint siphash(const uint8_t *in, uint inlen, const uint seed) #undef QHASH_AES_SANITIZER_BUILD QT_FUNCTION_TARGET(AES) -static size_t aeshash(const uchar *p, size_t len, size_t seed) noexcept +static size_t aeshash(const uchar *p, size_t len, size_t seed, size_t seed2) noexcept { __m128i key; if (sizeof(size_t) == 8) { #ifdef Q_PROCESSOR_X86_64 - quint64 seededlen = seed ^ len; __m128i mseed = _mm_cvtsi64_si128(seed); - key = _mm_insert_epi64(mseed, seededlen, 1); + key = _mm_insert_epi64(mseed, seed2, 1); #endif } else { - quint32 replicated_len = quint16(len) | (quint32(quint16(len)) << 16); __m128i mseed = _mm_cvtsi32_si128(int(seed)); - key = _mm_insert_epi32(mseed, replicated_len, 1); + key = _mm_insert_epi32(mseed, int(seed2), 1); key = _mm_unpacklo_epi64(key, key); } @@ -641,17 +636,16 @@ lt16: #if defined(Q_PROCESSOR_ARM) && QT_COMPILER_SUPPORTS_HERE(AES) && !defined(QHASH_AES_SANITIZER_BUILD) && !defined(QT_BOOTSTRAPPED) QT_FUNCTION_TARGET(AES) -static size_t aeshash(const uchar *p, size_t len, size_t seed) noexcept +static size_t aeshash(const uchar *p, size_t len, size_t seed, size_t seed2) noexcept { uint8x16_t key; # if QT_POINTER_SIZE == 8 - quint64 seededlen = seed ^ len; - uint64x2_t vseed = vcombine_u64(vcreate_u64(seed), vcreate_u64(seededlen)); + uint64x2_t vseed = vcombine_u64(vcreate_u64(seed), vcreate_u64(seed2)); key = vreinterpretq_u8_u64(vseed); # else - quint32 replicated_len = quint16(len) | (quint32(quint16(len)) << 16); + uint32x2_t vseed = vmov_n_u32(seed); - vseed = vset_lane_u32(replicated_len, vseed, 1); + vseed = vset_lane_u32(seed2, vseed, 1); key = vreinterpretq_u8_u32(vcombine_u32(vseed, vseed)); # endif @@ -779,9 +773,14 @@ size_t qHashBits(const void *p, size_t size, size_t seed) noexcept // so help the compiler do dead code elimination seed = 0; #endif + // mix in the length as a secondary seed. For seed == 0, seed2 must be + // size, to match what we used to do prior to Qt 6.2. + size_t seed2 = size; + if (seed) + seed2 = qt_qhash_seed.currentSeed(1); #ifdef AESHASH if (seed && qCpuHasFeature(AES) && qCpuHasFeature(SSE4_2)) - return aeshash(reinterpret_cast<const uchar *>(p), size, seed); + return aeshash(reinterpret_cast<const uchar *>(p), size, seed, seed2); #elif defined(Q_PROCESSOR_ARM) && QT_COMPILER_SUPPORTS_HERE(AES) && !defined(QHASH_AES_SANITIZER_BUILD) && !defined(QT_BOOTSTRAPPED) # if defined(Q_OS_LINUX) // Do specific runtime-only check as Yocto hard enables Crypto extension for @@ -790,12 +789,12 @@ size_t qHashBits(const void *p, size_t size, size_t seed) noexcept # else if (seed && qCpuHasFeature(AES)) # endif - return aeshash(reinterpret_cast<const uchar *>(p), size, seed); + return aeshash(reinterpret_cast<const uchar *>(p), size, seed, seed2); #endif if (size <= QT_POINTER_SIZE) return murmurhash(p, size, seed); - return siphash(reinterpret_cast<const uchar *>(p), size, seed); + return siphash(reinterpret_cast<const uchar *>(p), size, seed, seed2); } size_t qHash(const QByteArray &key, size_t seed) noexcept |