1 //=-- InstrProf.cpp - Instrumented profiling format support -----------------=//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file contains support for clang's instrumentation based PGO and
11 // coverage.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "llvm/ProfileData/InstrProf.h"
16 #include "llvm/ADT/StringExtras.h"
17 #include "llvm/IR/Constants.h"
18 #include "llvm/IR/Function.h"
19 #include "llvm/IR/GlobalVariable.h"
20 #include "llvm/IR/MDBuilder.h"
21 #include "llvm/IR/Module.h"
22 #include "llvm/Support/Compression.h"
23 #include "llvm/Support/ErrorHandling.h"
24 #include "llvm/Support/LEB128.h"
25 #include "llvm/Support/ManagedStatic.h"
26 
27 using namespace llvm;
28 
29 namespace {
30 std::string getInstrProfErrString(instrprof_error Err) {
31   switch (Err) {
32   case instrprof_error::success:
33     return "Success";
34   case instrprof_error::eof:
35     return "End of File";
36   case instrprof_error::unrecognized_format:
37     return "Unrecognized instrumentation profile encoding format";
38   case instrprof_error::bad_magic:
39     return "Invalid instrumentation profile data (bad magic)";
40   case instrprof_error::bad_header:
41     return "Invalid instrumentation profile data (file header is corrupt)";
42   case instrprof_error::unsupported_version:
43     return "Unsupported instrumentation profile format version";
44   case instrprof_error::unsupported_hash_type:
45     return "Unsupported instrumentation profile hash type";
46   case instrprof_error::too_large:
47     return "Too much profile data";
48   case instrprof_error::truncated:
49     return "Truncated profile data";
50   case instrprof_error::malformed:
51     return "Malformed instrumentation profile data";
52   case instrprof_error::unknown_function:
53     return "No profile data available for function";
54   case instrprof_error::hash_mismatch:
55     return "Function control flow change detected (hash mismatch)";
56   case instrprof_error::count_mismatch:
57     return "Function basic block count change detected (counter mismatch)";
58   case instrprof_error::counter_overflow:
59     return "Counter overflow";
60   case instrprof_error::value_site_count_mismatch:
61     return "Function value site count change detected (counter mismatch)";
62   case instrprof_error::compress_failed:
63     return "Failed to compress data (zlib)";
64   case instrprof_error::uncompress_failed:
65     return "Failed to uncompress data (zlib)";
66   }
67   llvm_unreachable("A value of instrprof_error has no message.");
68 }
69 
70 // FIXME: This class is only here to support the transition to llvm::Error. It
71 // will be removed once this transition is complete. Clients should prefer to
72 // deal with the Error value directly, rather than converting to error_code.
73 class InstrProfErrorCategoryType : public std::error_category {
74   const char *name() const LLVM_NOEXCEPT override { return "llvm.instrprof"; }
75   std::string message(int IE) const override {
76     return getInstrProfErrString(static_cast<instrprof_error>(IE));
77   }
78 };
79 } // end anonymous namespace
80 
81 static ManagedStatic<InstrProfErrorCategoryType> ErrorCategory;
82 
83 const std::error_category &llvm::instrprof_category() {
84   return *ErrorCategory;
85 }
86 
87 namespace llvm {
88 
89 void SoftInstrProfErrors::addError(instrprof_error IE) {
90   if (IE == instrprof_error::success)
91     return;
92 
93   if (FirstError == instrprof_error::success)
94     FirstError = IE;
95 
96   switch (IE) {
97   case instrprof_error::hash_mismatch:
98     ++NumHashMismatches;
99     break;
100   case instrprof_error::count_mismatch:
101     ++NumCountMismatches;
102     break;
103   case instrprof_error::counter_overflow:
104     ++NumCounterOverflows;
105     break;
106   case instrprof_error::value_site_count_mismatch:
107     ++NumValueSiteCountMismatches;
108     break;
109   default:
110     llvm_unreachable("Not a soft error");
111   }
112 }
113 
114 std::string InstrProfError::message() const {
115   return getInstrProfErrString(Err);
116 }
117 
118 char InstrProfError::ID = 0;
119 
120 std::string getPGOFuncName(StringRef RawFuncName,
121                            GlobalValue::LinkageTypes Linkage,
122                            StringRef FileName,
123                            uint64_t Version LLVM_ATTRIBUTE_UNUSED) {
124   return GlobalValue::getGlobalIdentifier(RawFuncName, Linkage, FileName);
125 }
126 
127 // Return the PGOFuncName. This function has some special handling when called
128 // in LTO optimization. The following only applies when calling in LTO passes
129 // (when \c InLTO is true): LTO's internalization privatizes many global linkage
130 // symbols. This happens after value profile annotation, but those internal
131 // linkage functions should not have a source prefix.
132 // To differentiate compiler generated internal symbols from original ones,
133 // PGOFuncName meta data are created and attached to the original internal
134 // symbols in the value profile annotation step
135 // (PGOUseFunc::annotateIndirectCallSites). If a symbol does not have the meta
136 // data, its original linkage must be non-internal.
137 std::string getPGOFuncName(const Function &F, bool InLTO, uint64_t Version) {
138   if (!InLTO)
139     return getPGOFuncName(F.getName(), F.getLinkage(), F.getParent()->getName(),
140                           Version);
141 
142   // In LTO mode (when InLTO is true), first check if there is a meta data.
143   if (MDNode *MD = getPGOFuncNameMetadata(F)) {
144     StringRef S = cast<MDString>(MD->getOperand(0))->getString();
145     return S.str();
146   }
147 
148   // If there is no meta data, the function must be a global before the value
149   // profile annotation pass. Its current linkage may be internal if it is
150   // internalized in LTO mode.
151   return getPGOFuncName(F.getName(), GlobalValue::ExternalLinkage, "");
152 }
153 
154 StringRef getFuncNameWithoutPrefix(StringRef PGOFuncName, StringRef FileName) {
155   if (FileName.empty())
156     return PGOFuncName;
157   // Drop the file name including ':'. See also getPGOFuncName.
158   if (PGOFuncName.startswith(FileName))
159     PGOFuncName = PGOFuncName.drop_front(FileName.size() + 1);
160   return PGOFuncName;
161 }
162 
163 // \p FuncName is the string used as profile lookup key for the function. A
164 // symbol is created to hold the name. Return the legalized symbol name.
165 std::string getPGOFuncNameVarName(StringRef FuncName,
166                                   GlobalValue::LinkageTypes Linkage) {
167   std::string VarName = getInstrProfNameVarPrefix();
168   VarName += FuncName;
169 
170   if (!GlobalValue::isLocalLinkage(Linkage))
171     return VarName;
172 
173   // Now fix up illegal chars in local VarName that may upset the assembler.
174   const char *InvalidChars = "-:<>\"'";
175   size_t found = VarName.find_first_of(InvalidChars);
176   while (found != std::string::npos) {
177     VarName[found] = '_';
178     found = VarName.find_first_of(InvalidChars, found + 1);
179   }
180   return VarName;
181 }
182 
183 GlobalVariable *createPGOFuncNameVar(Module &M,
184                                      GlobalValue::LinkageTypes Linkage,
185                                      StringRef PGOFuncName) {
186 
187   // We generally want to match the function's linkage, but available_externally
188   // and extern_weak both have the wrong semantics, and anything that doesn't
189   // need to link across compilation units doesn't need to be visible at all.
190   if (Linkage == GlobalValue::ExternalWeakLinkage)
191     Linkage = GlobalValue::LinkOnceAnyLinkage;
192   else if (Linkage == GlobalValue::AvailableExternallyLinkage)
193     Linkage = GlobalValue::LinkOnceODRLinkage;
194   else if (Linkage == GlobalValue::InternalLinkage ||
195            Linkage == GlobalValue::ExternalLinkage)
196     Linkage = GlobalValue::PrivateLinkage;
197 
198   auto *Value =
199       ConstantDataArray::getString(M.getContext(), PGOFuncName, false);
200   auto FuncNameVar =
201       new GlobalVariable(M, Value->getType(), true, Linkage, Value,
202                          getPGOFuncNameVarName(PGOFuncName, Linkage));
203 
204   // Hide the symbol so that we correctly get a copy for each executable.
205   if (!GlobalValue::isLocalLinkage(FuncNameVar->getLinkage()))
206     FuncNameVar->setVisibility(GlobalValue::HiddenVisibility);
207 
208   return FuncNameVar;
209 }
210 
211 GlobalVariable *createPGOFuncNameVar(Function &F, StringRef PGOFuncName) {
212   return createPGOFuncNameVar(*F.getParent(), F.getLinkage(), PGOFuncName);
213 }
214 
215 void InstrProfSymtab::create(Module &M, bool InLTO) {
216   for (Function &F : M) {
217     // Function may not have a name: like using asm("") to overwrite the name.
218     // Ignore in this case.
219     if (!F.hasName())
220       continue;
221     const std::string &PGOFuncName = getPGOFuncName(F, InLTO);
222     addFuncName(PGOFuncName);
223     MD5FuncMap.emplace_back(Function::getGUID(PGOFuncName), &F);
224   }
225 
226   finalizeSymtab();
227 }
228 
229 Error collectPGOFuncNameStrings(const std::vector<std::string> &NameStrs,
230                                 bool doCompression, std::string &Result) {
231   assert(NameStrs.size() && "No name data to emit");
232 
233   uint8_t Header[16], *P = Header;
234   std::string UncompressedNameStrings =
235       join(NameStrs.begin(), NameStrs.end(), getInstrProfNameSeparator());
236 
237   assert(StringRef(UncompressedNameStrings)
238                  .count(getInstrProfNameSeparator()) == (NameStrs.size() - 1) &&
239          "PGO name is invalid (contains separator token)");
240 
241   unsigned EncLen = encodeULEB128(UncompressedNameStrings.length(), P);
242   P += EncLen;
243 
244   auto WriteStringToResult = [&](size_t CompressedLen, StringRef InputStr) {
245     EncLen = encodeULEB128(CompressedLen, P);
246     P += EncLen;
247     char *HeaderStr = reinterpret_cast<char *>(&Header[0]);
248     unsigned HeaderLen = P - &Header[0];
249     Result.append(HeaderStr, HeaderLen);
250     Result += InputStr;
251     return Error::success();
252   };
253 
254   if (!doCompression) {
255     return WriteStringToResult(0, UncompressedNameStrings);
256   }
257 
258   SmallString<128> CompressedNameStrings;
259   zlib::Status Success =
260       zlib::compress(StringRef(UncompressedNameStrings), CompressedNameStrings,
261                      zlib::BestSizeCompression);
262 
263   if (Success != zlib::StatusOK)
264     return make_error<InstrProfError>(instrprof_error::compress_failed);
265 
266   return WriteStringToResult(CompressedNameStrings.size(),
267                              CompressedNameStrings);
268 }
269 
270 StringRef getPGOFuncNameVarInitializer(GlobalVariable *NameVar) {
271   auto *Arr = cast<ConstantDataArray>(NameVar->getInitializer());
272   StringRef NameStr =
273       Arr->isCString() ? Arr->getAsCString() : Arr->getAsString();
274   return NameStr;
275 }
276 
277 Error collectPGOFuncNameStrings(const std::vector<GlobalVariable *> &NameVars,
278                                 std::string &Result, bool doCompression) {
279   std::vector<std::string> NameStrs;
280   for (auto *NameVar : NameVars) {
281     NameStrs.push_back(getPGOFuncNameVarInitializer(NameVar));
282   }
283   return collectPGOFuncNameStrings(
284       NameStrs, zlib::isAvailable() && doCompression, Result);
285 }
286 
287 Error readPGOFuncNameStrings(StringRef NameStrings, InstrProfSymtab &Symtab) {
288   const uint8_t *P = reinterpret_cast<const uint8_t *>(NameStrings.data());
289   const uint8_t *EndP = reinterpret_cast<const uint8_t *>(NameStrings.data() +
290                                                           NameStrings.size());
291   while (P < EndP) {
292     uint32_t N;
293     uint64_t UncompressedSize = decodeULEB128(P, &N);
294     P += N;
295     uint64_t CompressedSize = decodeULEB128(P, &N);
296     P += N;
297     bool isCompressed = (CompressedSize != 0);
298     SmallString<128> UncompressedNameStrings;
299     StringRef NameStrings;
300     if (isCompressed) {
301       StringRef CompressedNameStrings(reinterpret_cast<const char *>(P),
302                                       CompressedSize);
303       if (zlib::uncompress(CompressedNameStrings, UncompressedNameStrings,
304                            UncompressedSize) != zlib::StatusOK)
305         return make_error<InstrProfError>(instrprof_error::uncompress_failed);
306       P += CompressedSize;
307       NameStrings = StringRef(UncompressedNameStrings.data(),
308                               UncompressedNameStrings.size());
309     } else {
310       NameStrings =
311           StringRef(reinterpret_cast<const char *>(P), UncompressedSize);
312       P += UncompressedSize;
313     }
314     // Now parse the name strings.
315     SmallVector<StringRef, 0> Names;
316     NameStrings.split(Names, getInstrProfNameSeparator());
317     for (StringRef &Name : Names)
318       Symtab.addFuncName(Name);
319 
320     while (P < EndP && *P == 0)
321       P++;
322   }
323   Symtab.finalizeSymtab();
324   return Error::success();
325 }
326 
327 void InstrProfValueSiteRecord::merge(SoftInstrProfErrors &SIPE,
328                                      InstrProfValueSiteRecord &Input,
329                                      uint64_t Weight) {
330   this->sortByTargetValues();
331   Input.sortByTargetValues();
332   auto I = ValueData.begin();
333   auto IE = ValueData.end();
334   for (auto J = Input.ValueData.begin(), JE = Input.ValueData.end(); J != JE;
335        ++J) {
336     while (I != IE && I->Value < J->Value)
337       ++I;
338     if (I != IE && I->Value == J->Value) {
339       bool Overflowed;
340       I->Count = SaturatingMultiplyAdd(J->Count, Weight, I->Count, &Overflowed);
341       if (Overflowed)
342         SIPE.addError(instrprof_error::counter_overflow);
343       ++I;
344       continue;
345     }
346     ValueData.insert(I, *J);
347   }
348 }
349 
350 void InstrProfValueSiteRecord::scale(SoftInstrProfErrors &SIPE,
351                                      uint64_t Weight) {
352   for (auto I = ValueData.begin(), IE = ValueData.end(); I != IE; ++I) {
353     bool Overflowed;
354     I->Count = SaturatingMultiply(I->Count, Weight, &Overflowed);
355     if (Overflowed)
356       SIPE.addError(instrprof_error::counter_overflow);
357   }
358 }
359 
360 // Merge Value Profile data from Src record to this record for ValueKind.
361 // Scale merged value counts by \p Weight.
362 void InstrProfRecord::mergeValueProfData(uint32_t ValueKind,
363                                          InstrProfRecord &Src,
364                                          uint64_t Weight) {
365   uint32_t ThisNumValueSites = getNumValueSites(ValueKind);
366   uint32_t OtherNumValueSites = Src.getNumValueSites(ValueKind);
367   if (ThisNumValueSites != OtherNumValueSites) {
368     SIPE.addError(instrprof_error::value_site_count_mismatch);
369     return;
370   }
371   std::vector<InstrProfValueSiteRecord> &ThisSiteRecords =
372       getValueSitesForKind(ValueKind);
373   std::vector<InstrProfValueSiteRecord> &OtherSiteRecords =
374       Src.getValueSitesForKind(ValueKind);
375   for (uint32_t I = 0; I < ThisNumValueSites; I++)
376     ThisSiteRecords[I].merge(SIPE, OtherSiteRecords[I], Weight);
377 }
378 
379 void InstrProfRecord::merge(InstrProfRecord &Other, uint64_t Weight) {
380   // If the number of counters doesn't match we either have bad data
381   // or a hash collision.
382   if (Counts.size() != Other.Counts.size()) {
383     SIPE.addError(instrprof_error::count_mismatch);
384     return;
385   }
386 
387   for (size_t I = 0, E = Other.Counts.size(); I < E; ++I) {
388     bool Overflowed;
389     Counts[I] =
390         SaturatingMultiplyAdd(Other.Counts[I], Weight, Counts[I], &Overflowed);
391     if (Overflowed)
392       SIPE.addError(instrprof_error::counter_overflow);
393   }
394 
395   for (uint32_t Kind = IPVK_First; Kind <= IPVK_Last; ++Kind)
396     mergeValueProfData(Kind, Other, Weight);
397 }
398 
399 void InstrProfRecord::scaleValueProfData(uint32_t ValueKind, uint64_t Weight) {
400   uint32_t ThisNumValueSites = getNumValueSites(ValueKind);
401   std::vector<InstrProfValueSiteRecord> &ThisSiteRecords =
402       getValueSitesForKind(ValueKind);
403   for (uint32_t I = 0; I < ThisNumValueSites; I++)
404     ThisSiteRecords[I].scale(SIPE, Weight);
405 }
406 
407 void InstrProfRecord::scale(uint64_t Weight) {
408   for (auto &Count : this->Counts) {
409     bool Overflowed;
410     Count = SaturatingMultiply(Count, Weight, &Overflowed);
411     if (Overflowed)
412       SIPE.addError(instrprof_error::counter_overflow);
413   }
414   for (uint32_t Kind = IPVK_First; Kind <= IPVK_Last; ++Kind)
415     scaleValueProfData(Kind, Weight);
416 }
417 
418 // Map indirect call target name hash to name string.
419 uint64_t InstrProfRecord::remapValue(uint64_t Value, uint32_t ValueKind,
420                                      ValueMapType *ValueMap) {
421   if (!ValueMap)
422     return Value;
423   switch (ValueKind) {
424   case IPVK_IndirectCallTarget: {
425     auto Result =
426         std::lower_bound(ValueMap->begin(), ValueMap->end(), Value,
427                          [](const std::pair<uint64_t, uint64_t> &LHS,
428                             uint64_t RHS) { return LHS.first < RHS; });
429    // Raw function pointer collected by value profiler may be from
430    // external functions that are not instrumented. They won't have
431    // mapping data to be used by the deserializer. Force the value to
432    // be 0 in this case.
433     if (Result != ValueMap->end() && Result->first == Value)
434       Value = (uint64_t)Result->second;
435     else
436       Value = 0;
437     break;
438   }
439   }
440   return Value;
441 }
442 
443 void InstrProfRecord::addValueData(uint32_t ValueKind, uint32_t Site,
444                                    InstrProfValueData *VData, uint32_t N,
445                                    ValueMapType *ValueMap) {
446   for (uint32_t I = 0; I < N; I++) {
447     VData[I].Value = remapValue(VData[I].Value, ValueKind, ValueMap);
448   }
449   std::vector<InstrProfValueSiteRecord> &ValueSites =
450       getValueSitesForKind(ValueKind);
451   if (N == 0)
452     ValueSites.emplace_back();
453   else
454     ValueSites.emplace_back(VData, VData + N);
455 }
456 
457 #define INSTR_PROF_COMMON_API_IMPL
458 #include "llvm/ProfileData/InstrProfData.inc"
459 
460 /*!
461  * \brief ValueProfRecordClosure Interface implementation for  InstrProfRecord
462  *  class. These C wrappers are used as adaptors so that C++ code can be
463  *  invoked as callbacks.
464  */
465 uint32_t getNumValueKindsInstrProf(const void *Record) {
466   return reinterpret_cast<const InstrProfRecord *>(Record)->getNumValueKinds();
467 }
468 
469 uint32_t getNumValueSitesInstrProf(const void *Record, uint32_t VKind) {
470   return reinterpret_cast<const InstrProfRecord *>(Record)
471       ->getNumValueSites(VKind);
472 }
473 
474 uint32_t getNumValueDataInstrProf(const void *Record, uint32_t VKind) {
475   return reinterpret_cast<const InstrProfRecord *>(Record)
476       ->getNumValueData(VKind);
477 }
478 
479 uint32_t getNumValueDataForSiteInstrProf(const void *R, uint32_t VK,
480                                          uint32_t S) {
481   return reinterpret_cast<const InstrProfRecord *>(R)
482       ->getNumValueDataForSite(VK, S);
483 }
484 
485 void getValueForSiteInstrProf(const void *R, InstrProfValueData *Dst,
486                               uint32_t K, uint32_t S) {
487   reinterpret_cast<const InstrProfRecord *>(R)->getValueForSite(Dst, K, S);
488 }
489 
490 ValueProfData *allocValueProfDataInstrProf(size_t TotalSizeInBytes) {
491   ValueProfData *VD =
492       (ValueProfData *)(new (::operator new(TotalSizeInBytes)) ValueProfData());
493   memset(VD, 0, TotalSizeInBytes);
494   return VD;
495 }
496 
497 static ValueProfRecordClosure InstrProfRecordClosure = {
498     nullptr,
499     getNumValueKindsInstrProf,
500     getNumValueSitesInstrProf,
501     getNumValueDataInstrProf,
502     getNumValueDataForSiteInstrProf,
503     nullptr,
504     getValueForSiteInstrProf,
505     allocValueProfDataInstrProf};
506 
507 // Wrapper implementation using the closure mechanism.
508 uint32_t ValueProfData::getSize(const InstrProfRecord &Record) {
509   InstrProfRecordClosure.Record = &Record;
510   return getValueProfDataSize(&InstrProfRecordClosure);
511 }
512 
513 // Wrapper implementation using the closure mechanism.
514 std::unique_ptr<ValueProfData>
515 ValueProfData::serializeFrom(const InstrProfRecord &Record) {
516   InstrProfRecordClosure.Record = &Record;
517 
518   std::unique_ptr<ValueProfData> VPD(
519       serializeValueProfDataFrom(&InstrProfRecordClosure, nullptr));
520   return VPD;
521 }
522 
523 void ValueProfRecord::deserializeTo(InstrProfRecord &Record,
524                                     InstrProfRecord::ValueMapType *VMap) {
525   Record.reserveSites(Kind, NumValueSites);
526 
527   InstrProfValueData *ValueData = getValueProfRecordValueData(this);
528   for (uint64_t VSite = 0; VSite < NumValueSites; ++VSite) {
529     uint8_t ValueDataCount = this->SiteCountArray[VSite];
530     Record.addValueData(Kind, VSite, ValueData, ValueDataCount, VMap);
531     ValueData += ValueDataCount;
532   }
533 }
534 
535 // For writing/serializing,  Old is the host endianness, and  New is
536 // byte order intended on disk. For Reading/deserialization, Old
537 // is the on-disk source endianness, and New is the host endianness.
538 void ValueProfRecord::swapBytes(support::endianness Old,
539                                 support::endianness New) {
540   using namespace support;
541   if (Old == New)
542     return;
543 
544   if (getHostEndianness() != Old) {
545     sys::swapByteOrder<uint32_t>(NumValueSites);
546     sys::swapByteOrder<uint32_t>(Kind);
547   }
548   uint32_t ND = getValueProfRecordNumValueData(this);
549   InstrProfValueData *VD = getValueProfRecordValueData(this);
550 
551   // No need to swap byte array: SiteCountArrray.
552   for (uint32_t I = 0; I < ND; I++) {
553     sys::swapByteOrder<uint64_t>(VD[I].Value);
554     sys::swapByteOrder<uint64_t>(VD[I].Count);
555   }
556   if (getHostEndianness() == Old) {
557     sys::swapByteOrder<uint32_t>(NumValueSites);
558     sys::swapByteOrder<uint32_t>(Kind);
559   }
560 }
561 
562 void ValueProfData::deserializeTo(InstrProfRecord &Record,
563                                   InstrProfRecord::ValueMapType *VMap) {
564   if (NumValueKinds == 0)
565     return;
566 
567   ValueProfRecord *VR = getFirstValueProfRecord(this);
568   for (uint32_t K = 0; K < NumValueKinds; K++) {
569     VR->deserializeTo(Record, VMap);
570     VR = getValueProfRecordNext(VR);
571   }
572 }
573 
574 template <class T>
575 static T swapToHostOrder(const unsigned char *&D, support::endianness Orig) {
576   using namespace support;
577   if (Orig == little)
578     return endian::readNext<T, little, unaligned>(D);
579   else
580     return endian::readNext<T, big, unaligned>(D);
581 }
582 
583 static std::unique_ptr<ValueProfData> allocValueProfData(uint32_t TotalSize) {
584   return std::unique_ptr<ValueProfData>(new (::operator new(TotalSize))
585                                             ValueProfData());
586 }
587 
588 Error ValueProfData::checkIntegrity() {
589   if (NumValueKinds > IPVK_Last + 1)
590     return make_error<InstrProfError>(instrprof_error::malformed);
591   // Total size needs to be mulltiple of quadword size.
592   if (TotalSize % sizeof(uint64_t))
593     return make_error<InstrProfError>(instrprof_error::malformed);
594 
595   ValueProfRecord *VR = getFirstValueProfRecord(this);
596   for (uint32_t K = 0; K < this->NumValueKinds; K++) {
597     if (VR->Kind > IPVK_Last)
598       return make_error<InstrProfError>(instrprof_error::malformed);
599     VR = getValueProfRecordNext(VR);
600     if ((char *)VR - (char *)this > (ptrdiff_t)TotalSize)
601       return make_error<InstrProfError>(instrprof_error::malformed);
602   }
603   return Error::success();
604 }
605 
606 Expected<std::unique_ptr<ValueProfData>>
607 ValueProfData::getValueProfData(const unsigned char *D,
608                                 const unsigned char *const BufferEnd,
609                                 support::endianness Endianness) {
610   using namespace support;
611   if (D + sizeof(ValueProfData) > BufferEnd)
612     return make_error<InstrProfError>(instrprof_error::truncated);
613 
614   const unsigned char *Header = D;
615   uint32_t TotalSize = swapToHostOrder<uint32_t>(Header, Endianness);
616   if (D + TotalSize > BufferEnd)
617     return make_error<InstrProfError>(instrprof_error::too_large);
618 
619   std::unique_ptr<ValueProfData> VPD = allocValueProfData(TotalSize);
620   memcpy(VPD.get(), D, TotalSize);
621   // Byte swap.
622   VPD->swapBytesToHost(Endianness);
623 
624   Error E = VPD->checkIntegrity();
625   if (E)
626     return std::move(E);
627 
628   return std::move(VPD);
629 }
630 
631 void ValueProfData::swapBytesToHost(support::endianness Endianness) {
632   using namespace support;
633   if (Endianness == getHostEndianness())
634     return;
635 
636   sys::swapByteOrder<uint32_t>(TotalSize);
637   sys::swapByteOrder<uint32_t>(NumValueKinds);
638 
639   ValueProfRecord *VR = getFirstValueProfRecord(this);
640   for (uint32_t K = 0; K < NumValueKinds; K++) {
641     VR->swapBytes(Endianness, getHostEndianness());
642     VR = getValueProfRecordNext(VR);
643   }
644 }
645 
646 void ValueProfData::swapBytesFromHost(support::endianness Endianness) {
647   using namespace support;
648   if (Endianness == getHostEndianness())
649     return;
650 
651   ValueProfRecord *VR = getFirstValueProfRecord(this);
652   for (uint32_t K = 0; K < NumValueKinds; K++) {
653     ValueProfRecord *NVR = getValueProfRecordNext(VR);
654     VR->swapBytes(getHostEndianness(), Endianness);
655     VR = NVR;
656   }
657   sys::swapByteOrder<uint32_t>(TotalSize);
658   sys::swapByteOrder<uint32_t>(NumValueKinds);
659 }
660 
661 void annotateValueSite(Module &M, Instruction &Inst,
662                        const InstrProfRecord &InstrProfR,
663                        InstrProfValueKind ValueKind, uint32_t SiteIdx,
664                        uint32_t MaxMDCount) {
665   uint32_t NV = InstrProfR.getNumValueDataForSite(ValueKind, SiteIdx);
666   if (!NV)
667     return;
668 
669   uint64_t Sum = 0;
670   std::unique_ptr<InstrProfValueData[]> VD =
671       InstrProfR.getValueForSite(ValueKind, SiteIdx, &Sum);
672 
673   ArrayRef<InstrProfValueData> VDs(VD.get(), NV);
674   annotateValueSite(M, Inst, VDs, Sum, ValueKind, MaxMDCount);
675 }
676 
677 void annotateValueSite(Module &M, Instruction &Inst,
678                        ArrayRef<InstrProfValueData> VDs,
679                        uint64_t Sum, InstrProfValueKind ValueKind,
680                        uint32_t MaxMDCount) {
681   LLVMContext &Ctx = M.getContext();
682   MDBuilder MDHelper(Ctx);
683   SmallVector<Metadata *, 3> Vals;
684   // Tag
685   Vals.push_back(MDHelper.createString("VP"));
686   // Value Kind
687   Vals.push_back(MDHelper.createConstant(
688       ConstantInt::get(Type::getInt32Ty(Ctx), ValueKind)));
689   // Total Count
690   Vals.push_back(
691       MDHelper.createConstant(ConstantInt::get(Type::getInt64Ty(Ctx), Sum)));
692 
693   // Value Profile Data
694   uint32_t MDCount = MaxMDCount;
695   for (auto &VD : VDs) {
696     Vals.push_back(MDHelper.createConstant(
697         ConstantInt::get(Type::getInt64Ty(Ctx), VD.Value)));
698     Vals.push_back(MDHelper.createConstant(
699         ConstantInt::get(Type::getInt64Ty(Ctx), VD.Count)));
700     if (--MDCount == 0)
701       break;
702   }
703   Inst.setMetadata(LLVMContext::MD_prof, MDNode::get(Ctx, Vals));
704 }
705 
706 bool getValueProfDataFromInst(const Instruction &Inst,
707                               InstrProfValueKind ValueKind,
708                               uint32_t MaxNumValueData,
709                               InstrProfValueData ValueData[],
710                               uint32_t &ActualNumValueData, uint64_t &TotalC) {
711   MDNode *MD = Inst.getMetadata(LLVMContext::MD_prof);
712   if (!MD)
713     return false;
714 
715   unsigned NOps = MD->getNumOperands();
716 
717   if (NOps < 5)
718     return false;
719 
720   // Operand 0 is a string tag "VP":
721   MDString *Tag = cast<MDString>(MD->getOperand(0));
722   if (!Tag)
723     return false;
724 
725   if (!Tag->getString().equals("VP"))
726     return false;
727 
728   // Now check kind:
729   ConstantInt *KindInt = mdconst::dyn_extract<ConstantInt>(MD->getOperand(1));
730   if (!KindInt)
731     return false;
732   if (KindInt->getZExtValue() != ValueKind)
733     return false;
734 
735   // Get total count
736   ConstantInt *TotalCInt = mdconst::dyn_extract<ConstantInt>(MD->getOperand(2));
737   if (!TotalCInt)
738     return false;
739   TotalC = TotalCInt->getZExtValue();
740 
741   ActualNumValueData = 0;
742 
743   for (unsigned I = 3; I < NOps; I += 2) {
744     if (ActualNumValueData >= MaxNumValueData)
745       break;
746     ConstantInt *Value = mdconst::dyn_extract<ConstantInt>(MD->getOperand(I));
747     ConstantInt *Count =
748         mdconst::dyn_extract<ConstantInt>(MD->getOperand(I + 1));
749     if (!Value || !Count)
750       return false;
751     ValueData[ActualNumValueData].Value = Value->getZExtValue();
752     ValueData[ActualNumValueData].Count = Count->getZExtValue();
753     ActualNumValueData++;
754   }
755   return true;
756 }
757 
758 MDNode *getPGOFuncNameMetadata(const Function &F) {
759   return F.getMetadata(getPGOFuncNameMetadataName());
760 }
761 
762 void createPGOFuncNameMetadata(Function &F, StringRef PGOFuncName) {
763   // Only for internal linkage functions.
764   if (PGOFuncName == F.getName())
765       return;
766   // Don't create duplicated meta-data.
767   if (getPGOFuncNameMetadata(F))
768     return;
769   LLVMContext &C = F.getContext();
770   MDNode *N = MDNode::get(C, MDString::get(C, PGOFuncName));
771   F.setMetadata(getPGOFuncNameMetadataName(), N);
772 }
773 
774 } // end namespace llvm
775