//===- Hash.cpp - PDB Hash Functions --------------------------------------===// // // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. // See https://llvm.org/LICENSE.txt for license information. // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception // //===----------------------------------------------------------------------===// #include "llvm/DebugInfo/PDB/Native/Hash.h" #include "llvm/ADT/ArrayRef.h" #include "llvm/Support/CRC.h" #include "llvm/Support/Endian.h" #include <cstdint> using namespace llvm; using namespace llvm::support; // Corresponds to `Hasher::lhashPbCb` in PDB/include/misc.h. // Used for name hash table and TPI/IPI hashes. uint32_t pdb::hashStringV1(StringRef Str) { uint32_t Result = 0; uint32_t Size = Str.size(); ArrayRef<ulittle32_t> Longs(reinterpret_cast<const ulittle32_t *>(Str.data()), Size / 4); for (auto Value : Longs) Result ^= Value; const uint8_t *Remainder = reinterpret_cast<const uint8_t *>(Longs.end()); uint32_t RemainderSize = Size % 4; // Maximum of 3 bytes left. Hash a 2 byte word if possible, then hash the // possibly remaining 1 byte. if (RemainderSize >= 2) { uint16_t Value = *reinterpret_cast<const ulittle16_t *>(Remainder); Result ^= static_cast<uint32_t>(Value); Remainder += 2; RemainderSize -= 2; } // hash possible odd byte if (RemainderSize == 1) { Result ^= *(Remainder++); } const uint32_t toLowerMask = 0x20202020; Result |= toLowerMask; Result ^= (Result >> 11); return Result ^ (Result >> 16); } // Corresponds to `HasherV2::HashULONG` in PDB/include/misc.h. // Used for name hash table. uint32_t pdb::hashStringV2(StringRef Str) { uint32_t Hash = 0xb170a1bf; ArrayRef<char> Buffer(Str.begin(), Str.end()); ArrayRef<ulittle32_t> Items( reinterpret_cast<const ulittle32_t *>(Buffer.data()), Buffer.size() / sizeof(ulittle32_t)); for (ulittle32_t Item : Items) { Hash += Item; Hash += (Hash << 10); Hash ^= (Hash >> 6); } Buffer = Buffer.slice(Items.size() * sizeof(ulittle32_t)); for (uint8_t Item : Buffer) { Hash += Item; Hash += (Hash << 10); Hash ^= (Hash >> 6); } return Hash * 1664525U + 1013904223U; } // Corresponds to `SigForPbCb` in langapi/shared/crc32.h. uint32_t pdb::hashBufferV8(ArrayRef<uint8_t> Buf) { JamCRC JC(/*Init=*/0U); JC.update(Buf); return JC.getCRC(); } |