1 //===- InstrProfReader.cpp - Instrumented profiling reader ----------------===//
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 // This file contains support for reading profiling data for clang's
10 // instrumentation based PGO and coverage.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "llvm/ProfileData/InstrProfReader.h"
15 #include "llvm/ADT/ArrayRef.h"
16 #include "llvm/ADT/DenseMap.h"
17 #include "llvm/ADT/STLExtras.h"
18 #include "llvm/ADT/StringExtras.h"
19 #include "llvm/ADT/StringRef.h"
20 #include "llvm/IR/ProfileSummary.h"
21 #include "llvm/ProfileData/InstrProf.h"
22 #include "llvm/ProfileData/ProfileCommon.h"
23 #include "llvm/Support/Endian.h"
24 #include "llvm/Support/Error.h"
25 #include "llvm/Support/ErrorOr.h"
26 #include "llvm/Support/MemoryBuffer.h"
27 #include "llvm/Support/SwapByteOrder.h"
28 #include "llvm/Support/SymbolRemappingReader.h"
29 #include <algorithm>
30 #include <cctype>
31 #include <cstddef>
32 #include <cstdint>
33 #include <limits>
34 #include <memory>
35 #include <system_error>
36 #include <utility>
37 #include <vector>
38 
39 using namespace llvm;
40 
41 static Expected<std::unique_ptr<MemoryBuffer>>
42 setupMemoryBuffer(const Twine &Path) {
43   ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOrErr =
44       MemoryBuffer::getFileOrSTDIN(Path, /*IsText=*/true);
45   if (std::error_code EC = BufferOrErr.getError())
46     return errorCodeToError(EC);
47   return std::move(BufferOrErr.get());
48 }
49 
50 static Error initializeReader(InstrProfReader &Reader) {
51   return Reader.readHeader();
52 }
53 
54 Expected<std::unique_ptr<InstrProfReader>>
55 InstrProfReader::create(const Twine &Path) {
56   // Set up the buffer to read.
57   auto BufferOrError = setupMemoryBuffer(Path);
58   if (Error E = BufferOrError.takeError())
59     return std::move(E);
60   return InstrProfReader::create(std::move(BufferOrError.get()));
61 }
62 
63 Expected<std::unique_ptr<InstrProfReader>>
64 InstrProfReader::create(std::unique_ptr<MemoryBuffer> Buffer) {
65   // Sanity check the buffer.
66   if (uint64_t(Buffer->getBufferSize()) > std::numeric_limits<uint64_t>::max())
67     return make_error<InstrProfError>(instrprof_error::too_large);
68 
69   if (Buffer->getBufferSize() == 0)
70     return make_error<InstrProfError>(instrprof_error::empty_raw_profile);
71 
72   std::unique_ptr<InstrProfReader> Result;
73   // Create the reader.
74   if (IndexedInstrProfReader::hasFormat(*Buffer))
75     Result.reset(new IndexedInstrProfReader(std::move(Buffer)));
76   else if (RawInstrProfReader64::hasFormat(*Buffer))
77     Result.reset(new RawInstrProfReader64(std::move(Buffer)));
78   else if (RawInstrProfReader32::hasFormat(*Buffer))
79     Result.reset(new RawInstrProfReader32(std::move(Buffer)));
80   else if (TextInstrProfReader::hasFormat(*Buffer))
81     Result.reset(new TextInstrProfReader(std::move(Buffer)));
82   else
83     return make_error<InstrProfError>(instrprof_error::unrecognized_format);
84 
85   // Initialize the reader and return the result.
86   if (Error E = initializeReader(*Result))
87     return std::move(E);
88 
89   return std::move(Result);
90 }
91 
92 Expected<std::unique_ptr<IndexedInstrProfReader>>
93 IndexedInstrProfReader::create(const Twine &Path, const Twine &RemappingPath) {
94   // Set up the buffer to read.
95   auto BufferOrError = setupMemoryBuffer(Path);
96   if (Error E = BufferOrError.takeError())
97     return std::move(E);
98 
99   // Set up the remapping buffer if requested.
100   std::unique_ptr<MemoryBuffer> RemappingBuffer;
101   std::string RemappingPathStr = RemappingPath.str();
102   if (!RemappingPathStr.empty()) {
103     auto RemappingBufferOrError = setupMemoryBuffer(RemappingPathStr);
104     if (Error E = RemappingBufferOrError.takeError())
105       return std::move(E);
106     RemappingBuffer = std::move(RemappingBufferOrError.get());
107   }
108 
109   return IndexedInstrProfReader::create(std::move(BufferOrError.get()),
110                                         std::move(RemappingBuffer));
111 }
112 
113 Expected<std::unique_ptr<IndexedInstrProfReader>>
114 IndexedInstrProfReader::create(std::unique_ptr<MemoryBuffer> Buffer,
115                                std::unique_ptr<MemoryBuffer> RemappingBuffer) {
116   // Sanity check the buffer.
117   if (uint64_t(Buffer->getBufferSize()) > std::numeric_limits<uint64_t>::max())
118     return make_error<InstrProfError>(instrprof_error::too_large);
119 
120   // Create the reader.
121   if (!IndexedInstrProfReader::hasFormat(*Buffer))
122     return make_error<InstrProfError>(instrprof_error::bad_magic);
123   auto Result = std::make_unique<IndexedInstrProfReader>(
124       std::move(Buffer), std::move(RemappingBuffer));
125 
126   // Initialize the reader and return the result.
127   if (Error E = initializeReader(*Result))
128     return std::move(E);
129 
130   return std::move(Result);
131 }
132 
133 void InstrProfIterator::Increment() {
134   if (auto E = Reader->readNextRecord(Record)) {
135     // Handle errors in the reader.
136     InstrProfError::take(std::move(E));
137     *this = InstrProfIterator();
138   }
139 }
140 
141 bool TextInstrProfReader::hasFormat(const MemoryBuffer &Buffer) {
142   // Verify that this really looks like plain ASCII text by checking a
143   // 'reasonable' number of characters (up to profile magic size).
144   size_t count = std::min(Buffer.getBufferSize(), sizeof(uint64_t));
145   StringRef buffer = Buffer.getBufferStart();
146   return count == 0 ||
147          std::all_of(buffer.begin(), buffer.begin() + count,
148                      [](char c) { return isPrint(c) || isSpace(c); });
149 }
150 
151 // Read the profile variant flag from the header: ":FE" means this is a FE
152 // generated profile. ":IR" means this is an IR level profile. Other strings
153 // with a leading ':' will be reported an error format.
154 Error TextInstrProfReader::readHeader() {
155   Symtab.reset(new InstrProfSymtab());
156   bool IsIRInstr = false;
157   bool IsEntryFirst = false;
158   bool IsCS = false;
159 
160   while (Line->startswith(":")) {
161     StringRef Str = Line->substr(1);
162     if (Str.equals_insensitive("ir"))
163       IsIRInstr = true;
164     else if (Str.equals_insensitive("fe"))
165       IsIRInstr = false;
166     else if (Str.equals_insensitive("csir")) {
167       IsIRInstr = true;
168       IsCS = true;
169     } else if (Str.equals_insensitive("entry_first"))
170       IsEntryFirst = true;
171     else if (Str.equals_insensitive("not_entry_first"))
172       IsEntryFirst = false;
173     else
174       return error(instrprof_error::bad_header);
175     ++Line;
176   }
177   IsIRLevelProfile = IsIRInstr;
178   InstrEntryBBEnabled = IsEntryFirst;
179   HasCSIRLevelProfile = IsCS;
180   return success();
181 }
182 
183 Error
184 TextInstrProfReader::readValueProfileData(InstrProfRecord &Record) {
185 
186 #define CHECK_LINE_END(Line)                                                   \
187   if (Line.is_at_end())                                                        \
188     return error(instrprof_error::truncated);
189 #define READ_NUM(Str, Dst)                                                     \
190   if ((Str).getAsInteger(10, (Dst)))                                           \
191     return error(instrprof_error::malformed);
192 #define VP_READ_ADVANCE(Val)                                                   \
193   CHECK_LINE_END(Line);                                                        \
194   uint32_t Val;                                                                \
195   READ_NUM((*Line), (Val));                                                    \
196   Line++;
197 
198   if (Line.is_at_end())
199     return success();
200 
201   uint32_t NumValueKinds;
202   if (Line->getAsInteger(10, NumValueKinds)) {
203     // No value profile data
204     return success();
205   }
206   if (NumValueKinds == 0 || NumValueKinds > IPVK_Last + 1)
207     return error(instrprof_error::malformed);
208   Line++;
209 
210   for (uint32_t VK = 0; VK < NumValueKinds; VK++) {
211     VP_READ_ADVANCE(ValueKind);
212     if (ValueKind > IPVK_Last)
213       return error(instrprof_error::malformed);
214     VP_READ_ADVANCE(NumValueSites);
215     if (!NumValueSites)
216       continue;
217 
218     Record.reserveSites(VK, NumValueSites);
219     for (uint32_t S = 0; S < NumValueSites; S++) {
220       VP_READ_ADVANCE(NumValueData);
221 
222       std::vector<InstrProfValueData> CurrentValues;
223       for (uint32_t V = 0; V < NumValueData; V++) {
224         CHECK_LINE_END(Line);
225         std::pair<StringRef, StringRef> VD = Line->rsplit(':');
226         uint64_t TakenCount, Value;
227         if (ValueKind == IPVK_IndirectCallTarget) {
228           if (InstrProfSymtab::isExternalSymbol(VD.first)) {
229             Value = 0;
230           } else {
231             if (Error E = Symtab->addFuncName(VD.first))
232               return E;
233             Value = IndexedInstrProf::ComputeHash(VD.first);
234           }
235         } else {
236           READ_NUM(VD.first, Value);
237         }
238         READ_NUM(VD.second, TakenCount);
239         CurrentValues.push_back({Value, TakenCount});
240         Line++;
241       }
242       Record.addValueData(ValueKind, S, CurrentValues.data(), NumValueData,
243                           nullptr);
244     }
245   }
246   return success();
247 
248 #undef CHECK_LINE_END
249 #undef READ_NUM
250 #undef VP_READ_ADVANCE
251 }
252 
253 Error TextInstrProfReader::readNextRecord(NamedInstrProfRecord &Record) {
254   // Skip empty lines and comments.
255   while (!Line.is_at_end() && (Line->empty() || Line->startswith("#")))
256     ++Line;
257   // If we hit EOF while looking for a name, we're done.
258   if (Line.is_at_end()) {
259     return error(instrprof_error::eof);
260   }
261 
262   // Read the function name.
263   Record.Name = *Line++;
264   if (Error E = Symtab->addFuncName(Record.Name))
265     return error(std::move(E));
266 
267   // Read the function hash.
268   if (Line.is_at_end())
269     return error(instrprof_error::truncated);
270   if ((Line++)->getAsInteger(0, Record.Hash))
271     return error(instrprof_error::malformed);
272 
273   // Read the number of counters.
274   uint64_t NumCounters;
275   if (Line.is_at_end())
276     return error(instrprof_error::truncated);
277   if ((Line++)->getAsInteger(10, NumCounters))
278     return error(instrprof_error::malformed);
279   if (NumCounters == 0)
280     return error(instrprof_error::malformed);
281 
282   // Read each counter and fill our internal storage with the values.
283   Record.Clear();
284   Record.Counts.reserve(NumCounters);
285   for (uint64_t I = 0; I < NumCounters; ++I) {
286     if (Line.is_at_end())
287       return error(instrprof_error::truncated);
288     uint64_t Count;
289     if ((Line++)->getAsInteger(10, Count))
290       return error(instrprof_error::malformed);
291     Record.Counts.push_back(Count);
292   }
293 
294   // Check if value profile data exists and read it if so.
295   if (Error E = readValueProfileData(Record))
296     return error(std::move(E));
297 
298   return success();
299 }
300 
301 template <class IntPtrT>
302 bool RawInstrProfReader<IntPtrT>::hasFormat(const MemoryBuffer &DataBuffer) {
303   if (DataBuffer.getBufferSize() < sizeof(uint64_t))
304     return false;
305   uint64_t Magic =
306     *reinterpret_cast<const uint64_t *>(DataBuffer.getBufferStart());
307   return RawInstrProf::getMagic<IntPtrT>() == Magic ||
308          sys::getSwappedBytes(RawInstrProf::getMagic<IntPtrT>()) == Magic;
309 }
310 
311 template <class IntPtrT>
312 Error RawInstrProfReader<IntPtrT>::readHeader() {
313   if (!hasFormat(*DataBuffer))
314     return error(instrprof_error::bad_magic);
315   if (DataBuffer->getBufferSize() < sizeof(RawInstrProf::Header))
316     return error(instrprof_error::bad_header);
317   auto *Header = reinterpret_cast<const RawInstrProf::Header *>(
318       DataBuffer->getBufferStart());
319   ShouldSwapBytes = Header->Magic != RawInstrProf::getMagic<IntPtrT>();
320   return readHeader(*Header);
321 }
322 
323 template <class IntPtrT>
324 Error RawInstrProfReader<IntPtrT>::readNextHeader(const char *CurrentPos) {
325   const char *End = DataBuffer->getBufferEnd();
326   // Skip zero padding between profiles.
327   while (CurrentPos != End && *CurrentPos == 0)
328     ++CurrentPos;
329   // If there's nothing left, we're done.
330   if (CurrentPos == End)
331     return make_error<InstrProfError>(instrprof_error::eof);
332   // If there isn't enough space for another header, this is probably just
333   // garbage at the end of the file.
334   if (CurrentPos + sizeof(RawInstrProf::Header) > End)
335     return make_error<InstrProfError>(instrprof_error::malformed);
336   // The writer ensures each profile is padded to start at an aligned address.
337   if (reinterpret_cast<size_t>(CurrentPos) % alignof(uint64_t))
338     return make_error<InstrProfError>(instrprof_error::malformed);
339   // The magic should have the same byte order as in the previous header.
340   uint64_t Magic = *reinterpret_cast<const uint64_t *>(CurrentPos);
341   if (Magic != swap(RawInstrProf::getMagic<IntPtrT>()))
342     return make_error<InstrProfError>(instrprof_error::bad_magic);
343 
344   // There's another profile to read, so we need to process the header.
345   auto *Header = reinterpret_cast<const RawInstrProf::Header *>(CurrentPos);
346   return readHeader(*Header);
347 }
348 
349 template <class IntPtrT>
350 Error RawInstrProfReader<IntPtrT>::createSymtab(InstrProfSymtab &Symtab) {
351   if (Error E = Symtab.create(StringRef(NamesStart, NamesSize)))
352     return error(std::move(E));
353   for (const RawInstrProf::ProfileData<IntPtrT> *I = Data; I != DataEnd; ++I) {
354     const IntPtrT FPtr = swap(I->FunctionPointer);
355     if (!FPtr)
356       continue;
357     Symtab.mapAddress(FPtr, I->NameRef);
358   }
359   return success();
360 }
361 
362 template <class IntPtrT>
363 Error RawInstrProfReader<IntPtrT>::readHeader(
364     const RawInstrProf::Header &Header) {
365   Version = swap(Header.Version);
366   if (GET_VERSION(Version) != RawInstrProf::Version)
367     return error(instrprof_error::unsupported_version);
368 
369   BinaryIdsSize = swap(Header.BinaryIdsSize);
370   CountersDelta = swap(Header.CountersDelta);
371   NamesDelta = swap(Header.NamesDelta);
372   auto DataSize = swap(Header.DataSize);
373   auto PaddingBytesBeforeCounters = swap(Header.PaddingBytesBeforeCounters);
374   auto CountersSize = swap(Header.CountersSize);
375   auto PaddingBytesAfterCounters = swap(Header.PaddingBytesAfterCounters);
376   NamesSize = swap(Header.NamesSize);
377   ValueKindLast = swap(Header.ValueKindLast);
378 
379   auto DataSizeInBytes = DataSize * sizeof(RawInstrProf::ProfileData<IntPtrT>);
380   auto PaddingSize = getNumPaddingBytes(NamesSize);
381 
382   // Profile data starts after profile header and binary ids if exist.
383   ptrdiff_t DataOffset = sizeof(RawInstrProf::Header) + BinaryIdsSize;
384   ptrdiff_t CountersOffset =
385       DataOffset + DataSizeInBytes + PaddingBytesBeforeCounters;
386   ptrdiff_t NamesOffset = CountersOffset + (sizeof(uint64_t) * CountersSize) +
387                           PaddingBytesAfterCounters;
388   ptrdiff_t ValueDataOffset = NamesOffset + NamesSize + PaddingSize;
389 
390   auto *Start = reinterpret_cast<const char *>(&Header);
391   if (Start + ValueDataOffset > DataBuffer->getBufferEnd())
392     return error(instrprof_error::bad_header);
393 
394   Data = reinterpret_cast<const RawInstrProf::ProfileData<IntPtrT> *>(
395       Start + DataOffset);
396   DataEnd = Data + DataSize;
397 
398   // Binary ids start just after the header.
399   BinaryIdsStart =
400       reinterpret_cast<const uint8_t *>(&Header) + sizeof(RawInstrProf::Header);
401   CountersStart = reinterpret_cast<const uint64_t *>(Start + CountersOffset);
402   NamesStart = Start + NamesOffset;
403   ValueDataStart = reinterpret_cast<const uint8_t *>(Start + ValueDataOffset);
404 
405   std::unique_ptr<InstrProfSymtab> NewSymtab = std::make_unique<InstrProfSymtab>();
406   if (Error E = createSymtab(*NewSymtab.get()))
407     return E;
408 
409   Symtab = std::move(NewSymtab);
410   return success();
411 }
412 
413 template <class IntPtrT>
414 Error RawInstrProfReader<IntPtrT>::readName(NamedInstrProfRecord &Record) {
415   Record.Name = getName(Data->NameRef);
416   return success();
417 }
418 
419 template <class IntPtrT>
420 Error RawInstrProfReader<IntPtrT>::readFuncHash(NamedInstrProfRecord &Record) {
421   Record.Hash = swap(Data->FuncHash);
422   return success();
423 }
424 
425 template <class IntPtrT>
426 Error RawInstrProfReader<IntPtrT>::readRawCounts(
427     InstrProfRecord &Record) {
428   uint32_t NumCounters = swap(Data->NumCounters);
429   IntPtrT CounterPtr = Data->CounterPtr;
430   if (NumCounters == 0)
431     return error(instrprof_error::malformed);
432 
433   auto *NamesStartAsCounter = reinterpret_cast<const uint64_t *>(NamesStart);
434   ptrdiff_t MaxNumCounters = NamesStartAsCounter - CountersStart;
435 
436   // Check bounds. Note that the counter pointer embedded in the data record
437   // may itself be corrupt.
438   if (MaxNumCounters < 0 || NumCounters > (uint32_t)MaxNumCounters)
439     return error(instrprof_error::malformed);
440 
441   // We need to compute the in-buffer counter offset from the in-memory address
442   // distance. The initial CountersDelta is the in-memory address difference
443   // start(__llvm_prf_cnts)-start(__llvm_prf_data), so SrcData->CounterPtr -
444   // CountersDelta computes the offset into the in-buffer counter section.
445   //
446   // CountersDelta decreases as we advance to the next data record.
447   ptrdiff_t CounterOffset = getCounterOffset(CounterPtr);
448   CountersDelta -= sizeof(*Data);
449   if (CounterOffset < 0 || CounterOffset > MaxNumCounters ||
450       ((uint32_t)CounterOffset + NumCounters) > (uint32_t)MaxNumCounters)
451     return error(instrprof_error::malformed);
452 
453   auto RawCounts = makeArrayRef(getCounter(CounterOffset), NumCounters);
454 
455   if (ShouldSwapBytes) {
456     Record.Counts.clear();
457     Record.Counts.reserve(RawCounts.size());
458     for (uint64_t Count : RawCounts)
459       Record.Counts.push_back(swap(Count));
460   } else
461     Record.Counts = RawCounts;
462 
463   return success();
464 }
465 
466 template <class IntPtrT>
467 Error RawInstrProfReader<IntPtrT>::readValueProfilingData(
468     InstrProfRecord &Record) {
469   Record.clearValueData();
470   CurValueDataSize = 0;
471   // Need to match the logic in value profile dumper code in compiler-rt:
472   uint32_t NumValueKinds = 0;
473   for (uint32_t I = 0; I < IPVK_Last + 1; I++)
474     NumValueKinds += (Data->NumValueSites[I] != 0);
475 
476   if (!NumValueKinds)
477     return success();
478 
479   Expected<std::unique_ptr<ValueProfData>> VDataPtrOrErr =
480       ValueProfData::getValueProfData(
481           ValueDataStart, (const unsigned char *)DataBuffer->getBufferEnd(),
482           getDataEndianness());
483 
484   if (Error E = VDataPtrOrErr.takeError())
485     return E;
486 
487   // Note that besides deserialization, this also performs the conversion for
488   // indirect call targets.  The function pointers from the raw profile are
489   // remapped into function name hashes.
490   VDataPtrOrErr.get()->deserializeTo(Record, Symtab.get());
491   CurValueDataSize = VDataPtrOrErr.get()->getSize();
492   return success();
493 }
494 
495 template <class IntPtrT>
496 Error RawInstrProfReader<IntPtrT>::readNextRecord(NamedInstrProfRecord &Record) {
497   if (atEnd())
498     // At this point, ValueDataStart field points to the next header.
499     if (Error E = readNextHeader(getNextHeaderPos()))
500       return error(std::move(E));
501 
502   // Read name ad set it in Record.
503   if (Error E = readName(Record))
504     return error(std::move(E));
505 
506   // Read FuncHash and set it in Record.
507   if (Error E = readFuncHash(Record))
508     return error(std::move(E));
509 
510   // Read raw counts and set Record.
511   if (Error E = readRawCounts(Record))
512     return error(std::move(E));
513 
514   // Read value data and set Record.
515   if (Error E = readValueProfilingData(Record))
516     return error(std::move(E));
517 
518   // Iterate.
519   advanceData();
520   return success();
521 }
522 
523 template <class IntPtrT>
524 Error RawInstrProfReader<IntPtrT>::printBinaryIds(raw_ostream &OS) {
525   if (BinaryIdsSize == 0)
526     return success();
527 
528   OS << "Binary IDs: \n";
529   const uint8_t *BI = BinaryIdsStart;
530   while (BI < BinaryIdsStart + BinaryIdsSize) {
531     uint64_t BinaryIdLen = swap(*reinterpret_cast<const uint64_t *>(BI));
532     // Increment by binary id length data type size.
533     BI += sizeof(BinaryIdLen);
534     if (BI > (const uint8_t *)DataBuffer->getBufferEnd())
535       return make_error<InstrProfError>(instrprof_error::malformed);
536 
537     for (uint64_t I = 0; I < BinaryIdLen; I++)
538       OS << format("%02x", BI[I]);
539     OS << "\n";
540 
541     // Increment by binary id data length.
542     BI += BinaryIdLen;
543     if (BI > (const uint8_t *)DataBuffer->getBufferEnd())
544       return make_error<InstrProfError>(instrprof_error::malformed);
545   }
546 
547   return success();
548 }
549 
550 namespace llvm {
551 
552 template class RawInstrProfReader<uint32_t>;
553 template class RawInstrProfReader<uint64_t>;
554 
555 } // end namespace llvm
556 
557 InstrProfLookupTrait::hash_value_type
558 InstrProfLookupTrait::ComputeHash(StringRef K) {
559   return IndexedInstrProf::ComputeHash(HashType, K);
560 }
561 
562 using data_type = InstrProfLookupTrait::data_type;
563 using offset_type = InstrProfLookupTrait::offset_type;
564 
565 bool InstrProfLookupTrait::readValueProfilingData(
566     const unsigned char *&D, const unsigned char *const End) {
567   Expected<std::unique_ptr<ValueProfData>> VDataPtrOrErr =
568       ValueProfData::getValueProfData(D, End, ValueProfDataEndianness);
569 
570   if (VDataPtrOrErr.takeError())
571     return false;
572 
573   VDataPtrOrErr.get()->deserializeTo(DataBuffer.back(), nullptr);
574   D += VDataPtrOrErr.get()->TotalSize;
575 
576   return true;
577 }
578 
579 data_type InstrProfLookupTrait::ReadData(StringRef K, const unsigned char *D,
580                                          offset_type N) {
581   using namespace support;
582 
583   // Check if the data is corrupt. If so, don't try to read it.
584   if (N % sizeof(uint64_t))
585     return data_type();
586 
587   DataBuffer.clear();
588   std::vector<uint64_t> CounterBuffer;
589 
590   const unsigned char *End = D + N;
591   while (D < End) {
592     // Read hash.
593     if (D + sizeof(uint64_t) >= End)
594       return data_type();
595     uint64_t Hash = endian::readNext<uint64_t, little, unaligned>(D);
596 
597     // Initialize number of counters for GET_VERSION(FormatVersion) == 1.
598     uint64_t CountsSize = N / sizeof(uint64_t) - 1;
599     // If format version is different then read the number of counters.
600     if (GET_VERSION(FormatVersion) != IndexedInstrProf::ProfVersion::Version1) {
601       if (D + sizeof(uint64_t) > End)
602         return data_type();
603       CountsSize = endian::readNext<uint64_t, little, unaligned>(D);
604     }
605     // Read counter values.
606     if (D + CountsSize * sizeof(uint64_t) > End)
607       return data_type();
608 
609     CounterBuffer.clear();
610     CounterBuffer.reserve(CountsSize);
611     for (uint64_t J = 0; J < CountsSize; ++J)
612       CounterBuffer.push_back(endian::readNext<uint64_t, little, unaligned>(D));
613 
614     DataBuffer.emplace_back(K, Hash, std::move(CounterBuffer));
615 
616     // Read value profiling data.
617     if (GET_VERSION(FormatVersion) > IndexedInstrProf::ProfVersion::Version2 &&
618         !readValueProfilingData(D, End)) {
619       DataBuffer.clear();
620       return data_type();
621     }
622   }
623   return DataBuffer;
624 }
625 
626 template <typename HashTableImpl>
627 Error InstrProfReaderIndex<HashTableImpl>::getRecords(
628     StringRef FuncName, ArrayRef<NamedInstrProfRecord> &Data) {
629   auto Iter = HashTable->find(FuncName);
630   if (Iter == HashTable->end())
631     return make_error<InstrProfError>(instrprof_error::unknown_function);
632 
633   Data = (*Iter);
634   if (Data.empty())
635     return make_error<InstrProfError>(instrprof_error::malformed);
636 
637   return Error::success();
638 }
639 
640 template <typename HashTableImpl>
641 Error InstrProfReaderIndex<HashTableImpl>::getRecords(
642     ArrayRef<NamedInstrProfRecord> &Data) {
643   if (atEnd())
644     return make_error<InstrProfError>(instrprof_error::eof);
645 
646   Data = *RecordIterator;
647 
648   if (Data.empty())
649     return make_error<InstrProfError>(instrprof_error::malformed);
650 
651   return Error::success();
652 }
653 
654 template <typename HashTableImpl>
655 InstrProfReaderIndex<HashTableImpl>::InstrProfReaderIndex(
656     const unsigned char *Buckets, const unsigned char *const Payload,
657     const unsigned char *const Base, IndexedInstrProf::HashT HashType,
658     uint64_t Version) {
659   FormatVersion = Version;
660   HashTable.reset(HashTableImpl::Create(
661       Buckets, Payload, Base,
662       typename HashTableImpl::InfoType(HashType, Version)));
663   RecordIterator = HashTable->data_begin();
664 }
665 
666 namespace {
667 /// A remapper that does not apply any remappings.
668 class InstrProfReaderNullRemapper : public InstrProfReaderRemapper {
669   InstrProfReaderIndexBase &Underlying;
670 
671 public:
672   InstrProfReaderNullRemapper(InstrProfReaderIndexBase &Underlying)
673       : Underlying(Underlying) {}
674 
675   Error getRecords(StringRef FuncName,
676                    ArrayRef<NamedInstrProfRecord> &Data) override {
677     return Underlying.getRecords(FuncName, Data);
678   }
679 };
680 }
681 
682 /// A remapper that applies remappings based on a symbol remapping file.
683 template <typename HashTableImpl>
684 class llvm::InstrProfReaderItaniumRemapper
685     : public InstrProfReaderRemapper {
686 public:
687   InstrProfReaderItaniumRemapper(
688       std::unique_ptr<MemoryBuffer> RemapBuffer,
689       InstrProfReaderIndex<HashTableImpl> &Underlying)
690       : RemapBuffer(std::move(RemapBuffer)), Underlying(Underlying) {
691   }
692 
693   /// Extract the original function name from a PGO function name.
694   static StringRef extractName(StringRef Name) {
695     // We can have multiple :-separated pieces; there can be pieces both
696     // before and after the mangled name. Find the first part that starts
697     // with '_Z'; we'll assume that's the mangled name we want.
698     std::pair<StringRef, StringRef> Parts = {StringRef(), Name};
699     while (true) {
700       Parts = Parts.second.split(':');
701       if (Parts.first.startswith("_Z"))
702         return Parts.first;
703       if (Parts.second.empty())
704         return Name;
705     }
706   }
707 
708   /// Given a mangled name extracted from a PGO function name, and a new
709   /// form for that mangled name, reconstitute the name.
710   static void reconstituteName(StringRef OrigName, StringRef ExtractedName,
711                                StringRef Replacement,
712                                SmallVectorImpl<char> &Out) {
713     Out.reserve(OrigName.size() + Replacement.size() - ExtractedName.size());
714     Out.insert(Out.end(), OrigName.begin(), ExtractedName.begin());
715     Out.insert(Out.end(), Replacement.begin(), Replacement.end());
716     Out.insert(Out.end(), ExtractedName.end(), OrigName.end());
717   }
718 
719   Error populateRemappings() override {
720     if (Error E = Remappings.read(*RemapBuffer))
721       return E;
722     for (StringRef Name : Underlying.HashTable->keys()) {
723       StringRef RealName = extractName(Name);
724       if (auto Key = Remappings.insert(RealName)) {
725         // FIXME: We could theoretically map the same equivalence class to
726         // multiple names in the profile data. If that happens, we should
727         // return NamedInstrProfRecords from all of them.
728         MappedNames.insert({Key, RealName});
729       }
730     }
731     return Error::success();
732   }
733 
734   Error getRecords(StringRef FuncName,
735                    ArrayRef<NamedInstrProfRecord> &Data) override {
736     StringRef RealName = extractName(FuncName);
737     if (auto Key = Remappings.lookup(RealName)) {
738       StringRef Remapped = MappedNames.lookup(Key);
739       if (!Remapped.empty()) {
740         if (RealName.begin() == FuncName.begin() &&
741             RealName.end() == FuncName.end())
742           FuncName = Remapped;
743         else {
744           // Try rebuilding the name from the given remapping.
745           SmallString<256> Reconstituted;
746           reconstituteName(FuncName, RealName, Remapped, Reconstituted);
747           Error E = Underlying.getRecords(Reconstituted, Data);
748           if (!E)
749             return E;
750 
751           // If we failed because the name doesn't exist, fall back to asking
752           // about the original name.
753           if (Error Unhandled = handleErrors(
754                   std::move(E), [](std::unique_ptr<InstrProfError> Err) {
755                     return Err->get() == instrprof_error::unknown_function
756                                ? Error::success()
757                                : Error(std::move(Err));
758                   }))
759             return Unhandled;
760         }
761       }
762     }
763     return Underlying.getRecords(FuncName, Data);
764   }
765 
766 private:
767   /// The memory buffer containing the remapping configuration. Remappings
768   /// holds pointers into this buffer.
769   std::unique_ptr<MemoryBuffer> RemapBuffer;
770 
771   /// The mangling remapper.
772   SymbolRemappingReader Remappings;
773 
774   /// Mapping from mangled name keys to the name used for the key in the
775   /// profile data.
776   /// FIXME: Can we store a location within the on-disk hash table instead of
777   /// redoing lookup?
778   DenseMap<SymbolRemappingReader::Key, StringRef> MappedNames;
779 
780   /// The real profile data reader.
781   InstrProfReaderIndex<HashTableImpl> &Underlying;
782 };
783 
784 bool IndexedInstrProfReader::hasFormat(const MemoryBuffer &DataBuffer) {
785   using namespace support;
786 
787   if (DataBuffer.getBufferSize() < 8)
788     return false;
789   uint64_t Magic =
790       endian::read<uint64_t, little, aligned>(DataBuffer.getBufferStart());
791   // Verify that it's magical.
792   return Magic == IndexedInstrProf::Magic;
793 }
794 
795 const unsigned char *
796 IndexedInstrProfReader::readSummary(IndexedInstrProf::ProfVersion Version,
797                                     const unsigned char *Cur, bool UseCS) {
798   using namespace IndexedInstrProf;
799   using namespace support;
800 
801   if (Version >= IndexedInstrProf::Version4) {
802     const IndexedInstrProf::Summary *SummaryInLE =
803         reinterpret_cast<const IndexedInstrProf::Summary *>(Cur);
804     uint64_t NFields =
805         endian::byte_swap<uint64_t, little>(SummaryInLE->NumSummaryFields);
806     uint64_t NEntries =
807         endian::byte_swap<uint64_t, little>(SummaryInLE->NumCutoffEntries);
808     uint32_t SummarySize =
809         IndexedInstrProf::Summary::getSize(NFields, NEntries);
810     std::unique_ptr<IndexedInstrProf::Summary> SummaryData =
811         IndexedInstrProf::allocSummary(SummarySize);
812 
813     const uint64_t *Src = reinterpret_cast<const uint64_t *>(SummaryInLE);
814     uint64_t *Dst = reinterpret_cast<uint64_t *>(SummaryData.get());
815     for (unsigned I = 0; I < SummarySize / sizeof(uint64_t); I++)
816       Dst[I] = endian::byte_swap<uint64_t, little>(Src[I]);
817 
818     SummaryEntryVector DetailedSummary;
819     for (unsigned I = 0; I < SummaryData->NumCutoffEntries; I++) {
820       const IndexedInstrProf::Summary::Entry &Ent = SummaryData->getEntry(I);
821       DetailedSummary.emplace_back((uint32_t)Ent.Cutoff, Ent.MinBlockCount,
822                                    Ent.NumBlocks);
823     }
824     std::unique_ptr<llvm::ProfileSummary> &Summary =
825         UseCS ? this->CS_Summary : this->Summary;
826 
827     // initialize InstrProfSummary using the SummaryData from disk.
828     Summary = std::make_unique<ProfileSummary>(
829         UseCS ? ProfileSummary::PSK_CSInstr : ProfileSummary::PSK_Instr,
830         DetailedSummary, SummaryData->get(Summary::TotalBlockCount),
831         SummaryData->get(Summary::MaxBlockCount),
832         SummaryData->get(Summary::MaxInternalBlockCount),
833         SummaryData->get(Summary::MaxFunctionCount),
834         SummaryData->get(Summary::TotalNumBlocks),
835         SummaryData->get(Summary::TotalNumFunctions));
836     return Cur + SummarySize;
837   } else {
838     // The older versions do not support a profile summary. This just computes
839     // an empty summary, which will not result in accurate hot/cold detection.
840     // We would need to call addRecord for all NamedInstrProfRecords to get the
841     // correct summary. However, this version is old (prior to early 2016) and
842     // has not been supporting an accurate summary for several years.
843     InstrProfSummaryBuilder Builder(ProfileSummaryBuilder::DefaultCutoffs);
844     Summary = Builder.getSummary();
845     return Cur;
846   }
847 }
848 
849 Error IndexedInstrProfReader::readHeader() {
850   using namespace support;
851 
852   const unsigned char *Start =
853       (const unsigned char *)DataBuffer->getBufferStart();
854   const unsigned char *Cur = Start;
855   if ((const unsigned char *)DataBuffer->getBufferEnd() - Cur < 24)
856     return error(instrprof_error::truncated);
857 
858   auto *Header = reinterpret_cast<const IndexedInstrProf::Header *>(Cur);
859   Cur += sizeof(IndexedInstrProf::Header);
860 
861   // Check the magic number.
862   uint64_t Magic = endian::byte_swap<uint64_t, little>(Header->Magic);
863   if (Magic != IndexedInstrProf::Magic)
864     return error(instrprof_error::bad_magic);
865 
866   // Read the version.
867   uint64_t FormatVersion = endian::byte_swap<uint64_t, little>(Header->Version);
868   if (GET_VERSION(FormatVersion) >
869       IndexedInstrProf::ProfVersion::CurrentVersion)
870     return error(instrprof_error::unsupported_version);
871 
872   Cur = readSummary((IndexedInstrProf::ProfVersion)FormatVersion, Cur,
873                     /* UseCS */ false);
874   if (FormatVersion & VARIANT_MASK_CSIR_PROF)
875     Cur = readSummary((IndexedInstrProf::ProfVersion)FormatVersion, Cur,
876                       /* UseCS */ true);
877 
878   // Read the hash type and start offset.
879   IndexedInstrProf::HashT HashType = static_cast<IndexedInstrProf::HashT>(
880       endian::byte_swap<uint64_t, little>(Header->HashType));
881   if (HashType > IndexedInstrProf::HashT::Last)
882     return error(instrprof_error::unsupported_hash_type);
883 
884   uint64_t HashOffset = endian::byte_swap<uint64_t, little>(Header->HashOffset);
885 
886   // The rest of the file is an on disk hash table.
887   auto IndexPtr =
888       std::make_unique<InstrProfReaderIndex<OnDiskHashTableImplV3>>(
889           Start + HashOffset, Cur, Start, HashType, FormatVersion);
890 
891   // Load the remapping table now if requested.
892   if (RemappingBuffer) {
893     Remapper = std::make_unique<
894         InstrProfReaderItaniumRemapper<OnDiskHashTableImplV3>>(
895         std::move(RemappingBuffer), *IndexPtr);
896     if (Error E = Remapper->populateRemappings())
897       return E;
898   } else {
899     Remapper = std::make_unique<InstrProfReaderNullRemapper>(*IndexPtr);
900   }
901   Index = std::move(IndexPtr);
902 
903   return success();
904 }
905 
906 InstrProfSymtab &IndexedInstrProfReader::getSymtab() {
907   if (Symtab.get())
908     return *Symtab.get();
909 
910   std::unique_ptr<InstrProfSymtab> NewSymtab = std::make_unique<InstrProfSymtab>();
911   if (Error E = Index->populateSymtab(*NewSymtab.get())) {
912     consumeError(error(InstrProfError::take(std::move(E))));
913   }
914 
915   Symtab = std::move(NewSymtab);
916   return *Symtab.get();
917 }
918 
919 Expected<InstrProfRecord>
920 IndexedInstrProfReader::getInstrProfRecord(StringRef FuncName,
921                                            uint64_t FuncHash) {
922   ArrayRef<NamedInstrProfRecord> Data;
923   Error Err = Remapper->getRecords(FuncName, Data);
924   if (Err)
925     return std::move(Err);
926   // Found it. Look for counters with the right hash.
927   for (unsigned I = 0, E = Data.size(); I < E; ++I) {
928     // Check for a match and fill the vector if there is one.
929     if (Data[I].Hash == FuncHash) {
930       return std::move(Data[I]);
931     }
932   }
933   return error(instrprof_error::hash_mismatch);
934 }
935 
936 Error IndexedInstrProfReader::getFunctionCounts(StringRef FuncName,
937                                                 uint64_t FuncHash,
938                                                 std::vector<uint64_t> &Counts) {
939   Expected<InstrProfRecord> Record = getInstrProfRecord(FuncName, FuncHash);
940   if (Error E = Record.takeError())
941     return error(std::move(E));
942 
943   Counts = Record.get().Counts;
944   return success();
945 }
946 
947 Error IndexedInstrProfReader::readNextRecord(NamedInstrProfRecord &Record) {
948   ArrayRef<NamedInstrProfRecord> Data;
949 
950   Error E = Index->getRecords(Data);
951   if (E)
952     return error(std::move(E));
953 
954   Record = Data[RecordIndex++];
955   if (RecordIndex >= Data.size()) {
956     Index->advanceToNextKey();
957     RecordIndex = 0;
958   }
959   return success();
960 }
961 
962 void InstrProfReader::accumulateCounts(CountSumOrPercent &Sum, bool IsCS) {
963   uint64_t NumFuncs = 0;
964   for (const auto &Func : *this) {
965     if (isIRLevelProfile()) {
966       bool FuncIsCS = NamedInstrProfRecord::hasCSFlagInHash(Func.Hash);
967       if (FuncIsCS != IsCS)
968         continue;
969     }
970     Func.accumulateCounts(Sum);
971     ++NumFuncs;
972   }
973   Sum.NumEntries = NumFuncs;
974 }
975