87 lines
2.5 KiB
C++
87 lines
2.5 KiB
C++
//===- Hash.cpp - PDB Hash Functions --------------------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/DebugInfo/PDB/Native/Hash.h"
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#include "llvm/ADT/ArrayRef.h"
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#include "llvm/Support/Endian.h"
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#include "llvm/Support/JamCRC.h"
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#include <cstdint>
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using namespace llvm;
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using namespace llvm::support;
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// Corresponds to `Hasher::lhashPbCb` in PDB/include/misc.h.
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// Used for name hash table and TPI/IPI hashes.
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uint32_t pdb::hashStringV1(StringRef Str) {
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uint32_t Result = 0;
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uint32_t Size = Str.size();
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ArrayRef<ulittle32_t> Longs(reinterpret_cast<const ulittle32_t *>(Str.data()),
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Size / 4);
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for (auto Value : Longs)
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Result ^= Value;
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const uint8_t *Remainder = reinterpret_cast<const uint8_t *>(Longs.end());
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uint32_t RemainderSize = Size % 4;
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// Maximum of 3 bytes left. Hash a 2 byte word if possible, then hash the
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// possibly remaining 1 byte.
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if (RemainderSize >= 2) {
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uint16_t Value = *reinterpret_cast<const ulittle16_t *>(Remainder);
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Result ^= static_cast<uint32_t>(Value);
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Remainder += 2;
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RemainderSize -= 2;
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}
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// hash possible odd byte
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if (RemainderSize == 1) {
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Result ^= *(Remainder++);
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}
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const uint32_t toLowerMask = 0x20202020;
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Result |= toLowerMask;
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Result ^= (Result >> 11);
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return Result ^ (Result >> 16);
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}
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// Corresponds to `HasherV2::HashULONG` in PDB/include/misc.h.
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// Used for name hash table.
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uint32_t pdb::hashStringV2(StringRef Str) {
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uint32_t Hash = 0xb170a1bf;
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ArrayRef<char> Buffer(Str.begin(), Str.end());
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ArrayRef<ulittle32_t> Items(
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reinterpret_cast<const ulittle32_t *>(Buffer.data()),
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Buffer.size() / sizeof(ulittle32_t));
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for (ulittle32_t Item : Items) {
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Hash += Item;
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Hash += (Hash << 10);
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Hash ^= (Hash >> 6);
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}
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Buffer = Buffer.slice(Items.size() * sizeof(ulittle32_t));
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for (uint8_t Item : Buffer) {
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Hash += Item;
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Hash += (Hash << 10);
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Hash ^= (Hash >> 6);
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}
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return Hash * 1664525U + 1013904223U;
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}
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// Corresponds to `SigForPbCb` in langapi/shared/crc32.h.
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uint32_t pdb::hashBufferV8(ArrayRef<uint8_t> Buf) {
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JamCRC JC(/*Init=*/0U);
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JC.update(makeArrayRef<char>(reinterpret_cast<const char *>(Buf.data()),
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Buf.size()));
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return JC.getCRC();
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}
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