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-rw-r--r--src/corelib/tools/qhash.cpp106
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)