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f5cb08e3d1
Use SipHash-2-4 to replace llvm::MD5 as the hashing implementation backing Fingerprints and the interface hash.
103 lines
2.6 KiB
C++
103 lines
2.6 KiB
C++
//===--- StableHasher.cpp - Stable Hasher ---------------------------------===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2021 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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#include "swift/Basic/StableHasher.h"
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using namespace swift;
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#define ROTATE_LEFT(ROTAND, DISTANCE) \
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(uint64_t)((ROTAND) << (DISTANCE)) | ((ROTAND) >> (64 - (DISTANCE)))
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namespace {
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static inline void sip_round(uint64_t &v0, uint64_t &v1, uint64_t &v2,
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uint64_t &v3) {
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v0 += v1;
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v1 = ROTATE_LEFT(v1, 13);
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v1 ^= v0;
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v0 = ROTATE_LEFT(v0, 32);
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v2 += v3;
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v3 = ROTATE_LEFT(v3, 16);
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v3 ^= v2;
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v0 += v3;
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v3 = ROTATE_LEFT(v3, 21);
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v3 ^= v0;
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v2 += v1;
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v1 = ROTATE_LEFT(v1, 17);
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v1 ^= v2;
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v2 = ROTATE_LEFT(v2, 32);
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}
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}; // end anonymous namespace
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void StableHasher::compress(uint64_t value) {
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state.v3 ^= value;
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for (unsigned i = 0; i < 2; ++i) {
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::sip_round(state.v0, state.v1, state.v2, state.v3);
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}
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state.v0 ^= value;
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}
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std::pair<uint64_t, uint64_t> StableHasher::finalize() && {
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auto fillBitsFromBuffer = [](uint64_t fill, uint8_t *bits) {
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uint64_t head = 0;
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switch (fill) {
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case 7:
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head |= uint64_t(bits[6]) << 48;
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LLVM_FALLTHROUGH;
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case 6:
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head |= uint64_t(bits[5]) << 40;
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LLVM_FALLTHROUGH;
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case 5:
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head |= uint64_t(bits[4]) << 32;
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LLVM_FALLTHROUGH;
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case 4:
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head |= uint64_t(bits[3]) << 24;
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LLVM_FALLTHROUGH;
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case 3:
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head |= uint64_t(bits[2]) << 16;
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LLVM_FALLTHROUGH;
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case 2:
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head |= uint64_t(bits[1]) << 8;
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LLVM_FALLTHROUGH;
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case 1:
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head |= uint64_t(bits[0]);
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break;
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case 0:
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break;
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default:
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break;
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}
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return head;
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};
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const uint64_t b = fillBitsFromBuffer(getBufferLength(), byteBuffer);
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compress(((getDigestLength() & 0xFF) << 56) | b);
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state.v2 ^= 0xEE;
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for (unsigned i = 0; i < 4; ++i) {
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::sip_round(state.v0, state.v1, state.v2, state.v3);
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}
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const uint64_t h1 = state.v0 ^ state.v1 ^ state.v2 ^ state.v3;
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state.v1 ^= 0xDD;
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for (unsigned i = 0; i < 4; ++i) {
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::sip_round(state.v0, state.v1, state.v2, state.v3);
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}
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const uint64_t h2 = state.v0 ^ state.v1 ^ state.v2 ^ state.v3;
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return std::make_pair(h1, h2);
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}
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