1 //===- DbiStreamBuilder.cpp - PDB Dbi Stream Creation -----------*- C++ -*-===//
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-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // The data structures defined in this file are based on the reference
10 // implementation which is available at
11 // https://github.com/Microsoft/microsoft-pdb/blob/master/PDB/dbi/gsi.cpp
12 //
13 //===----------------------------------------------------------------------===//
14
15 #include "llvm/DebugInfo/PDB/Native/GSIStreamBuilder.h"
16 #include "llvm/DebugInfo/CodeView/RecordName.h"
17 #include "llvm/DebugInfo/CodeView/RecordSerialization.h"
18 #include "llvm/DebugInfo/CodeView/SymbolRecord.h"
19 #include "llvm/DebugInfo/CodeView/SymbolSerializer.h"
20 #include "llvm/DebugInfo/MSF/MSFBuilder.h"
21 #include "llvm/DebugInfo/MSF/MSFCommon.h"
22 #include "llvm/DebugInfo/MSF/MappedBlockStream.h"
23 #include "llvm/DebugInfo/PDB/Native/GlobalsStream.h"
24 #include "llvm/DebugInfo/PDB/Native/Hash.h"
25 #include "llvm/DebugInfo/PDB/Native/RawTypes.h"
26 #include "llvm/Support/BinaryItemStream.h"
27 #include "llvm/Support/BinaryStreamWriter.h"
28 #include "llvm/Support/Parallel.h"
29 #include "llvm/Support/xxhash.h"
30 #include <algorithm>
31 #include <vector>
32
33 using namespace llvm;
34 using namespace llvm::msf;
35 using namespace llvm::pdb;
36 using namespace llvm::codeview;
37
38 // Helper class for building the public and global PDB hash table buckets.
39 struct llvm::pdb::GSIHashStreamBuilder {
40 // Sum of the size of all public or global records.
41 uint32_t RecordByteSize = 0;
42
43 std::vector<PSHashRecord> HashRecords;
44
45 // The hash bitmap has `ceil((IPHR_HASH + 1) / 32)` words in it. The
46 // reference implementation builds a hash table with IPHR_HASH buckets in it.
47 // The last bucket is used to link together free hash table cells in a linked
48 // list, but it is always empty in the compressed, on-disk format. However,
49 // the bitmap must have a bit for it.
50 std::array<support::ulittle32_t, (IPHR_HASH + 32) / 32> HashBitmap;
51
52 std::vector<support::ulittle32_t> HashBuckets;
53
54 uint32_t calculateSerializedLength() const;
55 Error commit(BinaryStreamWriter &Writer);
56
57 void finalizePublicBuckets();
58 void finalizeGlobalBuckets(uint32_t RecordZeroOffset);
59
60 // Assign public and global symbol records into hash table buckets.
61 // Modifies the list of records to store the bucket index, but does not
62 // change the order.
63 void finalizeBuckets(uint32_t RecordZeroOffset,
64 MutableArrayRef<BulkPublic> Globals);
65 };
66
67 // DenseMapInfo implementation for deduplicating symbol records.
68 struct llvm::pdb::SymbolDenseMapInfo {
getEmptyKeyllvm::pdb::SymbolDenseMapInfo69 static inline CVSymbol getEmptyKey() {
70 static CVSymbol Empty;
71 return Empty;
72 }
getTombstoneKeyllvm::pdb::SymbolDenseMapInfo73 static inline CVSymbol getTombstoneKey() {
74 static CVSymbol Tombstone(
75 DenseMapInfo<ArrayRef<uint8_t>>::getTombstoneKey());
76 return Tombstone;
77 }
getHashValuellvm::pdb::SymbolDenseMapInfo78 static unsigned getHashValue(const CVSymbol &Val) {
79 return xxHash64(Val.RecordData);
80 }
isEqualllvm::pdb::SymbolDenseMapInfo81 static bool isEqual(const CVSymbol &LHS, const CVSymbol &RHS) {
82 return LHS.RecordData == RHS.RecordData;
83 }
84 };
85
86 namespace {
87 LLVM_PACKED_START
88 struct PublicSym32Layout {
89 RecordPrefix Prefix;
90 PublicSym32Header Pub;
91 // char Name[];
92 };
93 LLVM_PACKED_END
94 } // namespace
95
96 // Calculate how much memory this public needs when serialized.
sizeOfPublic(const BulkPublic & Pub)97 static uint32_t sizeOfPublic(const BulkPublic &Pub) {
98 uint32_t NameLen = Pub.NameLen;
99 NameLen = std::min(NameLen,
100 uint32_t(MaxRecordLength - sizeof(PublicSym32Layout) - 1));
101 return alignTo(sizeof(PublicSym32Layout) + NameLen + 1, 4);
102 }
103
serializePublic(uint8_t * Mem,const BulkPublic & Pub)104 static CVSymbol serializePublic(uint8_t *Mem, const BulkPublic &Pub) {
105 // Assume the caller has allocated sizeOfPublic bytes.
106 uint32_t NameLen = std::min(
107 Pub.NameLen, uint32_t(MaxRecordLength - sizeof(PublicSym32Layout) - 1));
108 size_t Size = alignTo(sizeof(PublicSym32Layout) + NameLen + 1, 4);
109 assert(Size == sizeOfPublic(Pub));
110 auto *FixedMem = reinterpret_cast<PublicSym32Layout *>(Mem);
111 FixedMem->Prefix.RecordKind = static_cast<uint16_t>(codeview::S_PUB32);
112 FixedMem->Prefix.RecordLen = static_cast<uint16_t>(Size - 2);
113 FixedMem->Pub.Flags = Pub.Flags;
114 FixedMem->Pub.Offset = Pub.Offset;
115 FixedMem->Pub.Segment = Pub.Segment;
116 char *NameMem = reinterpret_cast<char *>(FixedMem + 1);
117 memcpy(NameMem, Pub.Name, NameLen);
118 // Zero the null terminator and remaining bytes.
119 memset(&NameMem[NameLen], 0, Size - sizeof(PublicSym32Layout) - NameLen);
120 return CVSymbol(ArrayRef(reinterpret_cast<uint8_t *>(Mem), Size));
121 }
122
calculateSerializedLength() const123 uint32_t GSIHashStreamBuilder::calculateSerializedLength() const {
124 uint32_t Size = sizeof(GSIHashHeader);
125 Size += HashRecords.size() * sizeof(PSHashRecord);
126 Size += HashBitmap.size() * sizeof(uint32_t);
127 Size += HashBuckets.size() * sizeof(uint32_t);
128 return Size;
129 }
130
commit(BinaryStreamWriter & Writer)131 Error GSIHashStreamBuilder::commit(BinaryStreamWriter &Writer) {
132 GSIHashHeader Header;
133 Header.VerSignature = GSIHashHeader::HdrSignature;
134 Header.VerHdr = GSIHashHeader::HdrVersion;
135 Header.HrSize = HashRecords.size() * sizeof(PSHashRecord);
136 Header.NumBuckets = HashBitmap.size() * 4 + HashBuckets.size() * 4;
137
138 if (auto EC = Writer.writeObject(Header))
139 return EC;
140
141 if (auto EC = Writer.writeArray(ArrayRef(HashRecords)))
142 return EC;
143 if (auto EC = Writer.writeArray(ArrayRef(HashBitmap)))
144 return EC;
145 if (auto EC = Writer.writeArray(ArrayRef(HashBuckets)))
146 return EC;
147 return Error::success();
148 }
149
isAsciiString(StringRef S)150 static bool isAsciiString(StringRef S) {
151 return llvm::all_of(S, [](char C) { return unsigned(C) < 0x80; });
152 }
153
154 // See `caseInsensitiveComparePchPchCchCch` in gsi.cpp
gsiRecordCmp(StringRef S1,StringRef S2)155 static int gsiRecordCmp(StringRef S1, StringRef S2) {
156 size_t LS = S1.size();
157 size_t RS = S2.size();
158 // Shorter strings always compare less than longer strings.
159 if (LS != RS)
160 return (LS > RS) - (LS < RS);
161
162 // If either string contains non ascii characters, memcmp them.
163 if (LLVM_UNLIKELY(!isAsciiString(S1) || !isAsciiString(S2)))
164 return memcmp(S1.data(), S2.data(), LS);
165
166 // Both strings are ascii, perform a case-insensitive comparison.
167 return S1.compare_insensitive(S2.data());
168 }
169
finalizePublicBuckets()170 void GSIStreamBuilder::finalizePublicBuckets() {
171 PSH->finalizeBuckets(0, Publics);
172 }
173
finalizeGlobalBuckets(uint32_t RecordZeroOffset)174 void GSIStreamBuilder::finalizeGlobalBuckets(uint32_t RecordZeroOffset) {
175 // Build up a list of globals to be bucketed. Use the BulkPublic data
176 // structure for this purpose, even though these are global records, not
177 // public records. Most of the same fields are required:
178 // - Name
179 // - NameLen
180 // - SymOffset
181 // - BucketIdx
182 // The dead fields are Offset, Segment, and Flags.
183 std::vector<BulkPublic> Records;
184 Records.resize(Globals.size());
185 uint32_t SymOffset = RecordZeroOffset;
186 for (size_t I = 0, E = Globals.size(); I < E; ++I) {
187 StringRef Name = getSymbolName(Globals[I]);
188 Records[I].Name = Name.data();
189 Records[I].NameLen = Name.size();
190 Records[I].SymOffset = SymOffset;
191 SymOffset += Globals[I].length();
192 }
193
194 GSH->finalizeBuckets(RecordZeroOffset, Records);
195 }
196
finalizeBuckets(uint32_t RecordZeroOffset,MutableArrayRef<BulkPublic> Records)197 void GSIHashStreamBuilder::finalizeBuckets(
198 uint32_t RecordZeroOffset, MutableArrayRef<BulkPublic> Records) {
199 // Hash every name in parallel.
200 parallelFor(0, Records.size(), [&](size_t I) {
201 Records[I].setBucketIdx(hashStringV1(Records[I].Name) % IPHR_HASH);
202 });
203
204 // Count up the size of each bucket. Then, use an exclusive prefix sum to
205 // calculate the bucket start offsets. This is C++17 std::exclusive_scan, but
206 // we can't use it yet.
207 uint32_t BucketStarts[IPHR_HASH] = {0};
208 for (const BulkPublic &P : Records)
209 ++BucketStarts[P.BucketIdx];
210 uint32_t Sum = 0;
211 for (uint32_t &B : BucketStarts) {
212 uint32_t Size = B;
213 B = Sum;
214 Sum += Size;
215 }
216
217 // Place globals into the hash table in bucket order. When placing a global,
218 // update the bucket start. Every hash table slot should be filled. Always use
219 // a refcount of one for now.
220 HashRecords.resize(Records.size());
221 uint32_t BucketCursors[IPHR_HASH];
222 memcpy(BucketCursors, BucketStarts, sizeof(BucketCursors));
223 for (int I = 0, E = Records.size(); I < E; ++I) {
224 uint32_t HashIdx = BucketCursors[Records[I].BucketIdx]++;
225 HashRecords[HashIdx].Off = I;
226 HashRecords[HashIdx].CRef = 1;
227 }
228
229 // Within the buckets, sort each bucket by memcmp of the symbol's name. It's
230 // important that we use the same sorting algorithm as is used by the
231 // reference implementation to ensure that the search for a record within a
232 // bucket can properly early-out when it detects the record won't be found.
233 // The algorithm used here corresponds to the function
234 // caseInsensitiveComparePchPchCchCch in the reference implementation.
235 parallelFor(0, IPHR_HASH, [&](size_t I) {
236 auto B = HashRecords.begin() + BucketStarts[I];
237 auto E = HashRecords.begin() + BucketCursors[I];
238 if (B == E)
239 return;
240 auto BucketCmp = [Records](const PSHashRecord &LHash,
241 const PSHashRecord &RHash) {
242 const BulkPublic &L = Records[uint32_t(LHash.Off)];
243 const BulkPublic &R = Records[uint32_t(RHash.Off)];
244 assert(L.BucketIdx == R.BucketIdx);
245 int Cmp = gsiRecordCmp(L.getName(), R.getName());
246 if (Cmp != 0)
247 return Cmp < 0;
248 // This comparison is necessary to make the sorting stable in the presence
249 // of two static globals with the same name. The easiest way to observe
250 // this is with S_LDATA32 records.
251 return L.SymOffset < R.SymOffset;
252 };
253 llvm::sort(B, E, BucketCmp);
254
255 // After we are done sorting, replace the global indices with the stream
256 // offsets of each global. Add one when writing symbol offsets to disk.
257 // See GSI1::fixSymRecs.
258 for (PSHashRecord &HRec : make_range(B, E))
259 HRec.Off = Records[uint32_t(HRec.Off)].SymOffset + 1;
260 });
261
262 // For each non-empty bucket, push the bucket start offset into HashBuckets
263 // and set a bit in the hash bitmap.
264 for (uint32_t I = 0; I < HashBitmap.size(); ++I) {
265 uint32_t Word = 0;
266 for (uint32_t J = 0; J < 32; ++J) {
267 // Skip empty buckets.
268 uint32_t BucketIdx = I * 32 + J;
269 if (BucketIdx >= IPHR_HASH ||
270 BucketStarts[BucketIdx] == BucketCursors[BucketIdx])
271 continue;
272 Word |= (1U << J);
273
274 // Calculate what the offset of the first hash record in the chain would
275 // be if it were inflated to contain 32-bit pointers. On a 32-bit system,
276 // each record would be 12 bytes. See HROffsetCalc in gsi.h.
277 const int SizeOfHROffsetCalc = 12;
278 ulittle32_t ChainStartOff =
279 ulittle32_t(BucketStarts[BucketIdx] * SizeOfHROffsetCalc);
280 HashBuckets.push_back(ChainStartOff);
281 }
282 HashBitmap[I] = Word;
283 }
284 }
285
GSIStreamBuilder(msf::MSFBuilder & Msf)286 GSIStreamBuilder::GSIStreamBuilder(msf::MSFBuilder &Msf)
287 : Msf(Msf), PSH(std::make_unique<GSIHashStreamBuilder>()),
288 GSH(std::make_unique<GSIHashStreamBuilder>()) {}
289
290 GSIStreamBuilder::~GSIStreamBuilder() = default;
291
calculatePublicsHashStreamSize() const292 uint32_t GSIStreamBuilder::calculatePublicsHashStreamSize() const {
293 uint32_t Size = 0;
294 Size += sizeof(PublicsStreamHeader);
295 Size += PSH->calculateSerializedLength();
296 Size += Publics.size() * sizeof(uint32_t); // AddrMap
297 // FIXME: Add thunk map and section offsets for incremental linking.
298
299 return Size;
300 }
301
calculateGlobalsHashStreamSize() const302 uint32_t GSIStreamBuilder::calculateGlobalsHashStreamSize() const {
303 return GSH->calculateSerializedLength();
304 }
305
finalizeMsfLayout()306 Error GSIStreamBuilder::finalizeMsfLayout() {
307 // First we write public symbol records, then we write global symbol records.
308 finalizePublicBuckets();
309 finalizeGlobalBuckets(PSH->RecordByteSize);
310
311 Expected<uint32_t> Idx = Msf.addStream(calculateGlobalsHashStreamSize());
312 if (!Idx)
313 return Idx.takeError();
314 GlobalsStreamIndex = *Idx;
315
316 Idx = Msf.addStream(calculatePublicsHashStreamSize());
317 if (!Idx)
318 return Idx.takeError();
319 PublicsStreamIndex = *Idx;
320
321 uint32_t RecordBytes = PSH->RecordByteSize + GSH->RecordByteSize;
322
323 Idx = Msf.addStream(RecordBytes);
324 if (!Idx)
325 return Idx.takeError();
326 RecordStreamIndex = *Idx;
327 return Error::success();
328 }
329
addPublicSymbols(std::vector<BulkPublic> && PublicsIn)330 void GSIStreamBuilder::addPublicSymbols(std::vector<BulkPublic> &&PublicsIn) {
331 assert(Publics.empty() && PSH->RecordByteSize == 0 &&
332 "publics can only be added once");
333 Publics = std::move(PublicsIn);
334
335 // Sort the symbols by name. PDBs contain lots of symbols, so use parallelism.
336 parallelSort(Publics, [](const BulkPublic &L, const BulkPublic &R) {
337 return L.getName() < R.getName();
338 });
339
340 // Assign offsets and calculate the length of the public symbol records.
341 uint32_t SymOffset = 0;
342 for (BulkPublic &Pub : Publics) {
343 Pub.SymOffset = SymOffset;
344 SymOffset += sizeOfPublic(Pub);
345 }
346
347 // Remember the length of the public stream records.
348 PSH->RecordByteSize = SymOffset;
349 }
350
addGlobalSymbol(const ProcRefSym & Sym)351 void GSIStreamBuilder::addGlobalSymbol(const ProcRefSym &Sym) {
352 serializeAndAddGlobal(Sym);
353 }
354
addGlobalSymbol(const DataSym & Sym)355 void GSIStreamBuilder::addGlobalSymbol(const DataSym &Sym) {
356 serializeAndAddGlobal(Sym);
357 }
358
addGlobalSymbol(const ConstantSym & Sym)359 void GSIStreamBuilder::addGlobalSymbol(const ConstantSym &Sym) {
360 serializeAndAddGlobal(Sym);
361 }
362
363 template <typename T>
serializeAndAddGlobal(const T & Symbol)364 void GSIStreamBuilder::serializeAndAddGlobal(const T &Symbol) {
365 T Copy(Symbol);
366 addGlobalSymbol(SymbolSerializer::writeOneSymbol(Copy, Msf.getAllocator(),
367 CodeViewContainer::Pdb));
368 }
369
addGlobalSymbol(const codeview::CVSymbol & Symbol)370 void GSIStreamBuilder::addGlobalSymbol(const codeview::CVSymbol &Symbol) {
371 // Ignore duplicate typedefs and constants.
372 if (Symbol.kind() == S_UDT || Symbol.kind() == S_CONSTANT) {
373 auto Iter = GlobalsSeen.insert(Symbol);
374 if (!Iter.second)
375 return;
376 }
377 GSH->RecordByteSize += Symbol.length();
378 Globals.push_back(Symbol);
379 }
380
381 // Serialize each public and write it.
writePublics(BinaryStreamWriter & Writer,ArrayRef<BulkPublic> Publics)382 static Error writePublics(BinaryStreamWriter &Writer,
383 ArrayRef<BulkPublic> Publics) {
384 std::vector<uint8_t> Storage;
385 for (const BulkPublic &Pub : Publics) {
386 Storage.resize(sizeOfPublic(Pub));
387 serializePublic(Storage.data(), Pub);
388 if (Error E = Writer.writeBytes(Storage))
389 return E;
390 }
391 return Error::success();
392 }
393
writeRecords(BinaryStreamWriter & Writer,ArrayRef<CVSymbol> Records)394 static Error writeRecords(BinaryStreamWriter &Writer,
395 ArrayRef<CVSymbol> Records) {
396 BinaryItemStream<CVSymbol> ItemStream(support::endianness::little);
397 ItemStream.setItems(Records);
398 BinaryStreamRef RecordsRef(ItemStream);
399 return Writer.writeStreamRef(RecordsRef);
400 }
401
commitSymbolRecordStream(WritableBinaryStreamRef Stream)402 Error GSIStreamBuilder::commitSymbolRecordStream(
403 WritableBinaryStreamRef Stream) {
404 BinaryStreamWriter Writer(Stream);
405
406 // Write public symbol records first, followed by global symbol records. This
407 // must match the order that we assume in finalizeMsfLayout when computing
408 // PSHZero and GSHZero.
409 if (auto EC = writePublics(Writer, Publics))
410 return EC;
411 if (auto EC = writeRecords(Writer, Globals))
412 return EC;
413
414 return Error::success();
415 }
416
417 static std::vector<support::ulittle32_t>
computeAddrMap(ArrayRef<BulkPublic> Publics)418 computeAddrMap(ArrayRef<BulkPublic> Publics) {
419 // Build a parallel vector of indices into the Publics vector, and sort it by
420 // address.
421 std::vector<ulittle32_t> PubAddrMap;
422 PubAddrMap.reserve(Publics.size());
423 for (int I = 0, E = Publics.size(); I < E; ++I)
424 PubAddrMap.push_back(ulittle32_t(I));
425
426 auto AddrCmp = [Publics](const ulittle32_t &LIdx, const ulittle32_t &RIdx) {
427 const BulkPublic &L = Publics[LIdx];
428 const BulkPublic &R = Publics[RIdx];
429 if (L.Segment != R.Segment)
430 return L.Segment < R.Segment;
431 if (L.Offset != R.Offset)
432 return L.Offset < R.Offset;
433 // parallelSort is unstable, so we have to do name comparison to ensure
434 // that two names for the same location come out in a deterministic order.
435 return L.getName() < R.getName();
436 };
437 parallelSort(PubAddrMap, AddrCmp);
438
439 // Rewrite the public symbol indices into symbol offsets.
440 for (ulittle32_t &Entry : PubAddrMap)
441 Entry = Publics[Entry].SymOffset;
442 return PubAddrMap;
443 }
444
commitPublicsHashStream(WritableBinaryStreamRef Stream)445 Error GSIStreamBuilder::commitPublicsHashStream(
446 WritableBinaryStreamRef Stream) {
447 BinaryStreamWriter Writer(Stream);
448 PublicsStreamHeader Header;
449
450 // FIXME: Fill these in. They are for incremental linking.
451 Header.SymHash = PSH->calculateSerializedLength();
452 Header.AddrMap = Publics.size() * 4;
453 Header.NumThunks = 0;
454 Header.SizeOfThunk = 0;
455 Header.ISectThunkTable = 0;
456 memset(Header.Padding, 0, sizeof(Header.Padding));
457 Header.OffThunkTable = 0;
458 Header.NumSections = 0;
459 if (auto EC = Writer.writeObject(Header))
460 return EC;
461
462 if (auto EC = PSH->commit(Writer))
463 return EC;
464
465 std::vector<support::ulittle32_t> PubAddrMap = computeAddrMap(Publics);
466 assert(PubAddrMap.size() == Publics.size());
467 if (auto EC = Writer.writeArray(ArrayRef(PubAddrMap)))
468 return EC;
469
470 return Error::success();
471 }
472
commitGlobalsHashStream(WritableBinaryStreamRef Stream)473 Error GSIStreamBuilder::commitGlobalsHashStream(
474 WritableBinaryStreamRef Stream) {
475 BinaryStreamWriter Writer(Stream);
476 return GSH->commit(Writer);
477 }
478
commit(const msf::MSFLayout & Layout,WritableBinaryStreamRef Buffer)479 Error GSIStreamBuilder::commit(const msf::MSFLayout &Layout,
480 WritableBinaryStreamRef Buffer) {
481 auto GS = WritableMappedBlockStream::createIndexedStream(
482 Layout, Buffer, getGlobalsStreamIndex(), Msf.getAllocator());
483 auto PS = WritableMappedBlockStream::createIndexedStream(
484 Layout, Buffer, getPublicsStreamIndex(), Msf.getAllocator());
485 auto PRS = WritableMappedBlockStream::createIndexedStream(
486 Layout, Buffer, getRecordStreamIndex(), Msf.getAllocator());
487
488 if (auto EC = commitSymbolRecordStream(*PRS))
489 return EC;
490 if (auto EC = commitGlobalsHashStream(*GS))
491 return EC;
492 if (auto EC = commitPublicsHashStream(*PS))
493 return EC;
494 return Error::success();
495 }
496