85 lines · cpp
1//===- Hash.cpp - PDB Hash Functions --------------------------------------===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8 9#include "llvm/DebugInfo/PDB/Native/Hash.h"10#include "llvm/ADT/ArrayRef.h"11#include "llvm/Support/CRC.h"12#include "llvm/Support/Endian.h"13#include <cstdint>14 15using namespace llvm;16using namespace llvm::support;17 18// Corresponds to `Hasher::lhashPbCb` in PDB/include/misc.h.19// Used for name hash table and TPI/IPI hashes.20uint32_t pdb::hashStringV1(StringRef Str) {21 uint32_t Result = 0;22 uint32_t Size = Str.size();23 24 ArrayRef<ulittle32_t> Longs(reinterpret_cast<const ulittle32_t *>(Str.data()),25 Size / 4);26 27 for (auto Value : Longs)28 Result ^= Value;29 30 const uint8_t *Remainder = reinterpret_cast<const uint8_t *>(Longs.end());31 uint32_t RemainderSize = Size % 4;32 33 // Maximum of 3 bytes left. Hash a 2 byte word if possible, then hash the34 // possibly remaining 1 byte.35 if (RemainderSize >= 2) {36 uint16_t Value = *reinterpret_cast<const ulittle16_t *>(Remainder);37 Result ^= static_cast<uint32_t>(Value);38 Remainder += 2;39 RemainderSize -= 2;40 }41 42 // hash possible odd byte43 if (RemainderSize == 1) {44 Result ^= *(Remainder++);45 }46 47 const uint32_t toLowerMask = 0x20202020;48 Result |= toLowerMask;49 Result ^= (Result >> 11);50 51 return Result ^ (Result >> 16);52}53 54// Corresponds to `HasherV2::HashULONG` in PDB/include/misc.h.55// Used for name hash table.56uint32_t pdb::hashStringV2(StringRef Str) {57 uint32_t Hash = 0xb170a1bf;58 59 ArrayRef<char> Buffer(Str.begin(), Str.end());60 61 ArrayRef<ulittle32_t> Items(62 reinterpret_cast<const ulittle32_t *>(Buffer.data()),63 Buffer.size() / sizeof(ulittle32_t));64 for (ulittle32_t Item : Items) {65 Hash += Item;66 Hash += (Hash << 10);67 Hash ^= (Hash >> 6);68 }69 Buffer = Buffer.slice(Items.size() * sizeof(ulittle32_t));70 for (uint8_t Item : Buffer) {71 Hash += Item;72 Hash += (Hash << 10);73 Hash ^= (Hash >> 6);74 }75 76 return Hash * 1664525U + 1013904223U;77}78 79// Corresponds to `SigForPbCb` in langapi/shared/crc32.h.80uint32_t pdb::hashBufferV8(ArrayRef<uint8_t> Buf) {81 JamCRC JC(/*Init=*/0U);82 JC.update(Buf);83 return JC.getCRC();84}85