1 //===- Hash.cpp - PDB Hash Functions --------------------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 #include "llvm/DebugInfo/PDB/Native/Hash.h"
11 #include "llvm/ADT/ArrayRef.h"
12 #include "llvm/Support/Endian.h"
13 #include "llvm/Support/JamCRC.h"
17 using namespace llvm::support;
19 // Corresponds to `Hasher::lhashPbCb` in PDB/include/misc.h.
20 // Used for name hash table and TPI/IPI hashes.
21 uint32_t pdb::hashStringV1(StringRef Str) {
23 uint32_t Size = Str.size();
25 ArrayRef<ulittle32_t> Longs(reinterpret_cast<const ulittle32_t *>(Str.data()),
28 for (auto Value : Longs)
31 const uint8_t *Remainder = reinterpret_cast<const uint8_t *>(Longs.end());
32 uint32_t RemainderSize = Size % 4;
34 // Maximum of 3 bytes left. Hash a 2 byte word if possible, then hash the
35 // possibly remaining 1 byte.
36 if (RemainderSize >= 2) {
37 uint16_t Value = *reinterpret_cast<const ulittle16_t *>(Remainder);
38 Result ^= static_cast<uint32_t>(Value);
43 // hash possible odd byte
44 if (RemainderSize == 1) {
45 Result ^= *(Remainder++);
48 const uint32_t toLowerMask = 0x20202020;
49 Result |= toLowerMask;
50 Result ^= (Result >> 11);
52 return Result ^ (Result >> 16);
55 // Corresponds to `HasherV2::HashULONG` in PDB/include/misc.h.
56 // Used for name hash table.
57 uint32_t pdb::hashStringV2(StringRef Str) {
58 uint32_t Hash = 0xb170a1bf;
60 ArrayRef<char> Buffer(Str.begin(), Str.end());
62 ArrayRef<ulittle32_t> Items(
63 reinterpret_cast<const ulittle32_t *>(Buffer.data()),
64 Buffer.size() / sizeof(ulittle32_t));
65 for (ulittle32_t Item : Items) {
70 Buffer = Buffer.slice(Items.size() * sizeof(ulittle32_t));
71 for (uint8_t Item : Buffer) {
77 return Hash * 1664525U + 1013904223U;
80 // Corresponds to `SigForPbCb` in langapi/shared/crc32.h.
81 uint32_t pdb::hashBufferV8(ArrayRef<uint8_t> Buf) {
82 JamCRC JC(/*Init=*/0U);
83 JC.update(makeArrayRef<char>(reinterpret_cast<const char *>(Buf.data()),