diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/corelib/tools/qhash.cpp | 106 |
1 files changed, 54 insertions, 52 deletions
diff --git a/src/corelib/tools/qhash.cpp b/src/corelib/tools/qhash.cpp index c6373ee11d..c8cf1a496e 100644 --- a/src/corelib/tools/qhash.cpp +++ b/src/corelib/tools/qhash.cpp @@ -516,21 +516,9 @@ static uint siphash(const uint8_t *in, uint inlen, uint seed, uint seed2) QT_FUNCTION_TARGET(AES) 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 - __m128i mseed = _mm_cvtsi64_si128(seed); - key = _mm_insert_epi64(mseed, seed2, 1); -#endif - } else { - __m128i mseed = _mm_cvtsi32_si128(int(seed)); - key = _mm_insert_epi32(mseed, int(seed2), 1); - key = _mm_unpacklo_epi64(key, key); - } - // This is inspired by the algorithm in the Go language. See: - // https://github.com/golang/go/blob/894abb5f680c040777f17f9f8ee5a5ab3a03cb94/src/runtime/asm_386.s#L902 - // https://github.com/golang/go/blob/894abb5f680c040777f17f9f8ee5a5ab3a03cb94/src/runtime/asm_amd64.s#L903 + // https://github.com/golang/go/blob/01b6cf09fc9f272d9db3d30b4c93982f4911d120/src/runtime/asm_amd64.s#L1105 + // https://github.com/golang/go/blob/01b6cf09fc9f272d9db3d30b4c93982f4911d120/src/runtime/asm_386.s#L908 // // Even though we're using the AESENC instruction from the CPU, this code // is not encryption and this routine makes no claim to be @@ -548,50 +536,64 @@ static size_t aeshash(const uchar *p, size_t len, size_t seed, size_t seed2) noe state0 = _mm_aesenc_si128(state0, state0); }; - __m128i state0 = key; - auto src = reinterpret_cast<const __m128i *>(p); + // hash twice 16 bytes, running 2 scramble rounds of AES on itself + const auto hash2x16bytes = [](__m128i &state0, __m128i &state1, const __m128i *src0, + const __m128i *src1) QT_FUNCTION_TARGET(AES) { + __m128i data0 = _mm_loadu_si128(src0); + __m128i data1 = _mm_loadu_si128(src1); + state0 = _mm_xor_si128(data0, state0); + state1 = _mm_xor_si128(data1, state1); + state0 = _mm_aesenc_si128(state0, state0); + state1 = _mm_aesenc_si128(state1, state1); + state0 = _mm_aesenc_si128(state0, state0); + state1 = _mm_aesenc_si128(state1, state1); + }; - if (len < 16) - goto lt16; - if (len < 32) - goto lt32; + __m128i mseed, mseed2; + if (sizeof(size_t) == 8) { +#ifdef Q_PROCESSOR_X86_64 + mseed = _mm_cvtsi64_si128(seed); + mseed2 = _mm_set1_epi64x(seed2); +#endif + } else { + mseed = _mm_cvtsi32_si128(int(seed)); + mseed2 = _mm_set1_epi32(int(seed2)); + } - // rounds of 32 bytes - { - // Make state1 = ~state0: - __m128i one = _mm_cmpeq_epi64(key, key); - __m128i state1 = _mm_xor_si128(state0, one); + // mseed (epi16) = [ seed, seed >> 16, seed >> 32, seed >> 48, len, 0, 0, 0 ] + mseed = _mm_insert_epi16(mseed, short(seed), 4); + // mseed (epi16) = [ seed, seed >> 16, seed >> 32, seed >> 48, len, len, len, len ] + mseed = _mm_shufflehi_epi16(mseed, 0); + + // merge with the process-global seed + __m128i key = _mm_xor_si128(mseed, mseed2); + + // scramble the key + __m128i state0 = _mm_aesenc_si128(key, key); + + auto src = reinterpret_cast<const __m128i *>(p); + if (len >= sizeof(__m128i)) { + // unlike the Go code, we don't have more per-process seed + __m128i state1 = _mm_aesenc_si128(state0, mseed2); - // do simplified rounds of 32 bytes: unlike the Go code, we only - // scramble twice and we keep 256 bits of state const auto srcend = reinterpret_cast<const __m128i *>(p + len); - while (src + 2 <= srcend) { - __m128i data0 = _mm_loadu_si128(src); - __m128i data1 = _mm_loadu_si128(src + 1); - state0 = _mm_xor_si128(data0, state0); - state1 = _mm_xor_si128(data1, state1); - state0 = _mm_aesenc_si128(state0, state0); - state1 = _mm_aesenc_si128(state1, state1); - state0 = _mm_aesenc_si128(state0, state0); - state1 = _mm_aesenc_si128(state1, state1); - src += 2; - } - state0 = _mm_xor_si128(state0, state1); - } - len &= 0x1f; - // do we still have 16 or more bytes? - if (len & 0x10) { -lt32: - __m128i data = _mm_loadu_si128(src); - hash16bytes(state0, data); - ++src; - } - len &= 0xf; + // main loop: scramble two 16-byte blocks + for ( ; src + 2 < srcend; src += 2) + hash2x16bytes(state0, state1, src, src + 1); + + if (src + 1 < srcend) { + // epilogue: between 16 and 31 bytes + hash2x16bytes(state0, state1, src, srcend - 1); + } else if (src != srcend) { + // epilogue: between 1 and 16 bytes, overlap with the end + __m128i data = _mm_loadu_si128(srcend - 1); + hash16bytes(state0, data); + } -lt16: - if (len) { - // load the last chunk of data + // combine results: + state0 = _mm_xor_si128(state0, state1); + } else if (len) { // We're going to load 16 bytes and mask zero the part we don't care // (the hash of a short string is different from the hash of a longer // including NULLs at the end because the length is in the key) |