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,
245                                  const std::string &InputStr) {
246     EncLen = encodeULEB128(CompressedLen, P);
247     P += EncLen;
248     char *HeaderStr = reinterpret_cast<char *>(&Header[0]);
249     unsigned HeaderLen = P - &Header[0];
250     Result.append(HeaderStr, HeaderLen);
251     Result += InputStr;
252     return Error::success();
253   };
254 
255   if (!doCompression) {
256     return WriteStringToResult(0, UncompressedNameStrings);
257   }
258 
259   SmallVector<char, 128> CompressedNameStrings;
260   zlib::Status Success =
261       zlib::compress(StringRef(UncompressedNameStrings), CompressedNameStrings,
262                      zlib::BestSizeCompression);
263 
264   if (Success != zlib::StatusOK)
265     return make_error<InstrProfError>(instrprof_error::compress_failed);
266 
267   return WriteStringToResult(
268       CompressedNameStrings.size(),
269       std::string(CompressedNameStrings.data(), CompressedNameStrings.size()));
270 }
271 
272 StringRef getPGOFuncNameVarInitializer(GlobalVariable *NameVar) {
273   auto *Arr = cast<ConstantDataArray>(NameVar->getInitializer());
274   StringRef NameStr =
275       Arr->isCString() ? Arr->getAsCString() : Arr->getAsString();
276   return NameStr;
277 }
278 
279 Error collectPGOFuncNameStrings(const std::vector<GlobalVariable *> &NameVars,
280                                 std::string &Result, bool doCompression) {
281   std::vector<std::string> NameStrs;
282   for (auto *NameVar : NameVars) {
283     NameStrs.push_back(getPGOFuncNameVarInitializer(NameVar));
284   }
285   return collectPGOFuncNameStrings(
286       NameStrs, zlib::isAvailable() && doCompression, Result);
287 }
288 
289 Error readPGOFuncNameStrings(StringRef NameStrings, InstrProfSymtab &Symtab) {
290   const uint8_t *P = reinterpret_cast<const uint8_t *>(NameStrings.data());
291   const uint8_t *EndP = reinterpret_cast<const uint8_t *>(NameStrings.data() +
292                                                           NameStrings.size());
293   while (P < EndP) {
294     uint32_t N;
295     uint64_t UncompressedSize = decodeULEB128(P, &N);
296     P += N;
297     uint64_t CompressedSize = decodeULEB128(P, &N);
298     P += N;
299     bool isCompressed = (CompressedSize != 0);
300     SmallString<128> UncompressedNameStrings;
301     StringRef NameStrings;
302     if (isCompressed) {
303       StringRef CompressedNameStrings(reinterpret_cast<const char *>(P),
304                                       CompressedSize);
305       if (zlib::uncompress(CompressedNameStrings, UncompressedNameStrings,
306                            UncompressedSize) != zlib::StatusOK)
307         return make_error<InstrProfError>(instrprof_error::uncompress_failed);
308       P += CompressedSize;
309       NameStrings = StringRef(UncompressedNameStrings.data(),
310                               UncompressedNameStrings.size());
311     } else {
312       NameStrings =
313           StringRef(reinterpret_cast<const char *>(P), UncompressedSize);
314       P += UncompressedSize;
315     }
316     // Now parse the name strings.
317     SmallVector<StringRef, 0> Names;
318     NameStrings.split(Names, getInstrProfNameSeparator());
319     for (StringRef &Name : Names)
320       Symtab.addFuncName(Name);
321 
322     while (P < EndP && *P == 0)
323       P++;
324   }
325   Symtab.finalizeSymtab();
326   return Error::success();
327 }
328 
329 void InstrProfValueSiteRecord::merge(SoftInstrProfErrors &SIPE,
330                                      InstrProfValueSiteRecord &Input,
331                                      uint64_t Weight) {
332   this->sortByTargetValues();
333   Input.sortByTargetValues();
334   auto I = ValueData.begin();
335   auto IE = ValueData.end();
336   for (auto J = Input.ValueData.begin(), JE = Input.ValueData.end(); J != JE;
337        ++J) {
338     while (I != IE && I->Value < J->Value)
339       ++I;
340     if (I != IE && I->Value == J->Value) {
341       bool Overflowed;
342       I->Count = SaturatingMultiplyAdd(J->Count, Weight, I->Count, &Overflowed);
343       if (Overflowed)
344         SIPE.addError(instrprof_error::counter_overflow);
345       ++I;
346       continue;
347     }
348     ValueData.insert(I, *J);
349   }
350 }
351 
352 void InstrProfValueSiteRecord::scale(SoftInstrProfErrors &SIPE,
353                                      uint64_t Weight) {
354   for (auto I = ValueData.begin(), IE = ValueData.end(); I != IE; ++I) {
355     bool Overflowed;
356     I->Count = SaturatingMultiply(I->Count, Weight, &Overflowed);
357     if (Overflowed)
358       SIPE.addError(instrprof_error::counter_overflow);
359   }
360 }
361 
362 // Merge Value Profile data from Src record to this record for ValueKind.
363 // Scale merged value counts by \p Weight.
364 void InstrProfRecord::mergeValueProfData(uint32_t ValueKind,
365                                          InstrProfRecord &Src,
366                                          uint64_t Weight) {
367   uint32_t ThisNumValueSites = getNumValueSites(ValueKind);
368   uint32_t OtherNumValueSites = Src.getNumValueSites(ValueKind);
369   if (ThisNumValueSites != OtherNumValueSites) {
370     SIPE.addError(instrprof_error::value_site_count_mismatch);
371     return;
372   }
373   std::vector<InstrProfValueSiteRecord> &ThisSiteRecords =
374       getValueSitesForKind(ValueKind);
375   std::vector<InstrProfValueSiteRecord> &OtherSiteRecords =
376       Src.getValueSitesForKind(ValueKind);
377   for (uint32_t I = 0; I < ThisNumValueSites; I++)
378     ThisSiteRecords[I].merge(SIPE, OtherSiteRecords[I], Weight);
379 }
380 
381 void InstrProfRecord::merge(InstrProfRecord &Other, uint64_t Weight) {
382   // If the number of counters doesn't match we either have bad data
383   // or a hash collision.
384   if (Counts.size() != Other.Counts.size()) {
385     SIPE.addError(instrprof_error::count_mismatch);
386     return;
387   }
388 
389   for (size_t I = 0, E = Other.Counts.size(); I < E; ++I) {
390     bool Overflowed;
391     Counts[I] =
392         SaturatingMultiplyAdd(Other.Counts[I], Weight, Counts[I], &Overflowed);
393     if (Overflowed)
394       SIPE.addError(instrprof_error::counter_overflow);
395   }
396 
397   for (uint32_t Kind = IPVK_First; Kind <= IPVK_Last; ++Kind)
398     mergeValueProfData(Kind, Other, Weight);
399 }
400 
401 void InstrProfRecord::scaleValueProfData(uint32_t ValueKind, uint64_t Weight) {
402   uint32_t ThisNumValueSites = getNumValueSites(ValueKind);
403   std::vector<InstrProfValueSiteRecord> &ThisSiteRecords =
404       getValueSitesForKind(ValueKind);
405   for (uint32_t I = 0; I < ThisNumValueSites; I++)
406     ThisSiteRecords[I].scale(SIPE, Weight);
407 }
408 
409 void InstrProfRecord::scale(uint64_t Weight) {
410   for (auto &Count : this->Counts) {
411     bool Overflowed;
412     Count = SaturatingMultiply(Count, Weight, &Overflowed);
413     if (Overflowed)
414       SIPE.addError(instrprof_error::counter_overflow);
415   }
416   for (uint32_t Kind = IPVK_First; Kind <= IPVK_Last; ++Kind)
417     scaleValueProfData(Kind, Weight);
418 }
419 
420 // Map indirect call target name hash to name string.
421 uint64_t InstrProfRecord::remapValue(uint64_t Value, uint32_t ValueKind,
422                                      ValueMapType *ValueMap) {
423   if (!ValueMap)
424     return Value;
425   switch (ValueKind) {
426   case IPVK_IndirectCallTarget: {
427     auto Result =
428         std::lower_bound(ValueMap->begin(), ValueMap->end(), Value,
429                          [](const std::pair<uint64_t, uint64_t> &LHS,
430                             uint64_t RHS) { return LHS.first < RHS; });
431    // Raw function pointer collected by value profiler may be from
432    // external functions that are not instrumented. They won't have
433    // mapping data to be used by the deserializer. Force the value to
434    // be 0 in this case.
435     if (Result != ValueMap->end() && Result->first == Value)
436       Value = (uint64_t)Result->second;
437     else
438       Value = 0;
439     break;
440   }
441   }
442   return Value;
443 }
444 
445 void InstrProfRecord::addValueData(uint32_t ValueKind, uint32_t Site,
446                                    InstrProfValueData *VData, uint32_t N,
447                                    ValueMapType *ValueMap) {
448   for (uint32_t I = 0; I < N; I++) {
449     VData[I].Value = remapValue(VData[I].Value, ValueKind, ValueMap);
450   }
451   std::vector<InstrProfValueSiteRecord> &ValueSites =
452       getValueSitesForKind(ValueKind);
453   if (N == 0)
454     ValueSites.emplace_back();
455   else
456     ValueSites.emplace_back(VData, VData + N);
457 }
458 
459 #define INSTR_PROF_COMMON_API_IMPL
460 #include "llvm/ProfileData/InstrProfData.inc"
461 
462 /*!
463  * \brief ValueProfRecordClosure Interface implementation for  InstrProfRecord
464  *  class. These C wrappers are used as adaptors so that C++ code can be
465  *  invoked as callbacks.
466  */
467 uint32_t getNumValueKindsInstrProf(const void *Record) {
468   return reinterpret_cast<const InstrProfRecord *>(Record)->getNumValueKinds();
469 }
470 
471 uint32_t getNumValueSitesInstrProf(const void *Record, uint32_t VKind) {
472   return reinterpret_cast<const InstrProfRecord *>(Record)
473       ->getNumValueSites(VKind);
474 }
475 
476 uint32_t getNumValueDataInstrProf(const void *Record, uint32_t VKind) {
477   return reinterpret_cast<const InstrProfRecord *>(Record)
478       ->getNumValueData(VKind);
479 }
480 
481 uint32_t getNumValueDataForSiteInstrProf(const void *R, uint32_t VK,
482                                          uint32_t S) {
483   return reinterpret_cast<const InstrProfRecord *>(R)
484       ->getNumValueDataForSite(VK, S);
485 }
486 
487 void getValueForSiteInstrProf(const void *R, InstrProfValueData *Dst,
488                               uint32_t K, uint32_t S) {
489   reinterpret_cast<const InstrProfRecord *>(R)->getValueForSite(Dst, K, S);
490 }
491 
492 ValueProfData *allocValueProfDataInstrProf(size_t TotalSizeInBytes) {
493   ValueProfData *VD =
494       (ValueProfData *)(new (::operator new(TotalSizeInBytes)) ValueProfData());
495   memset(VD, 0, TotalSizeInBytes);
496   return VD;
497 }
498 
499 static ValueProfRecordClosure InstrProfRecordClosure = {
500     nullptr,
501     getNumValueKindsInstrProf,
502     getNumValueSitesInstrProf,
503     getNumValueDataInstrProf,
504     getNumValueDataForSiteInstrProf,
505     nullptr,
506     getValueForSiteInstrProf,
507     allocValueProfDataInstrProf};
508 
509 // Wrapper implementation using the closure mechanism.
510 uint32_t ValueProfData::getSize(const InstrProfRecord &Record) {
511   InstrProfRecordClosure.Record = &Record;
512   return getValueProfDataSize(&InstrProfRecordClosure);
513 }
514 
515 // Wrapper implementation using the closure mechanism.
516 std::unique_ptr<ValueProfData>
517 ValueProfData::serializeFrom(const InstrProfRecord &Record) {
518   InstrProfRecordClosure.Record = &Record;
519 
520   std::unique_ptr<ValueProfData> VPD(
521       serializeValueProfDataFrom(&InstrProfRecordClosure, nullptr));
522   return VPD;
523 }
524 
525 void ValueProfRecord::deserializeTo(InstrProfRecord &Record,
526                                     InstrProfRecord::ValueMapType *VMap) {
527   Record.reserveSites(Kind, NumValueSites);
528 
529   InstrProfValueData *ValueData = getValueProfRecordValueData(this);
530   for (uint64_t VSite = 0; VSite < NumValueSites; ++VSite) {
531     uint8_t ValueDataCount = this->SiteCountArray[VSite];
532     Record.addValueData(Kind, VSite, ValueData, ValueDataCount, VMap);
533     ValueData += ValueDataCount;
534   }
535 }
536 
537 // For writing/serializing,  Old is the host endianness, and  New is
538 // byte order intended on disk. For Reading/deserialization, Old
539 // is the on-disk source endianness, and New is the host endianness.
540 void ValueProfRecord::swapBytes(support::endianness Old,
541                                 support::endianness New) {
542   using namespace support;
543   if (Old == New)
544     return;
545 
546   if (getHostEndianness() != Old) {
547     sys::swapByteOrder<uint32_t>(NumValueSites);
548     sys::swapByteOrder<uint32_t>(Kind);
549   }
550   uint32_t ND = getValueProfRecordNumValueData(this);
551   InstrProfValueData *VD = getValueProfRecordValueData(this);
552 
553   // No need to swap byte array: SiteCountArrray.
554   for (uint32_t I = 0; I < ND; I++) {
555     sys::swapByteOrder<uint64_t>(VD[I].Value);
556     sys::swapByteOrder<uint64_t>(VD[I].Count);
557   }
558   if (getHostEndianness() == Old) {
559     sys::swapByteOrder<uint32_t>(NumValueSites);
560     sys::swapByteOrder<uint32_t>(Kind);
561   }
562 }
563 
564 void ValueProfData::deserializeTo(InstrProfRecord &Record,
565                                   InstrProfRecord::ValueMapType *VMap) {
566   if (NumValueKinds == 0)
567     return;
568 
569   ValueProfRecord *VR = getFirstValueProfRecord(this);
570   for (uint32_t K = 0; K < NumValueKinds; K++) {
571     VR->deserializeTo(Record, VMap);
572     VR = getValueProfRecordNext(VR);
573   }
574 }
575 
576 template <class T>
577 static T swapToHostOrder(const unsigned char *&D, support::endianness Orig) {
578   using namespace support;
579   if (Orig == little)
580     return endian::readNext<T, little, unaligned>(D);
581   else
582     return endian::readNext<T, big, unaligned>(D);
583 }
584 
585 static std::unique_ptr<ValueProfData> allocValueProfData(uint32_t TotalSize) {
586   return std::unique_ptr<ValueProfData>(new (::operator new(TotalSize))
587                                             ValueProfData());
588 }
589 
590 Error ValueProfData::checkIntegrity() {
591   if (NumValueKinds > IPVK_Last + 1)
592     return make_error<InstrProfError>(instrprof_error::malformed);
593   // Total size needs to be mulltiple of quadword size.
594   if (TotalSize % sizeof(uint64_t))
595     return make_error<InstrProfError>(instrprof_error::malformed);
596 
597   ValueProfRecord *VR = getFirstValueProfRecord(this);
598   for (uint32_t K = 0; K < this->NumValueKinds; K++) {
599     if (VR->Kind > IPVK_Last)
600       return make_error<InstrProfError>(instrprof_error::malformed);
601     VR = getValueProfRecordNext(VR);
602     if ((char *)VR - (char *)this > (ptrdiff_t)TotalSize)
603       return make_error<InstrProfError>(instrprof_error::malformed);
604   }
605   return Error::success();
606 }
607 
608 Expected<std::unique_ptr<ValueProfData>>
609 ValueProfData::getValueProfData(const unsigned char *D,
610                                 const unsigned char *const BufferEnd,
611                                 support::endianness Endianness) {
612   using namespace support;
613   if (D + sizeof(ValueProfData) > BufferEnd)
614     return make_error<InstrProfError>(instrprof_error::truncated);
615 
616   const unsigned char *Header = D;
617   uint32_t TotalSize = swapToHostOrder<uint32_t>(Header, Endianness);
618   if (D + TotalSize > BufferEnd)
619     return make_error<InstrProfError>(instrprof_error::too_large);
620 
621   std::unique_ptr<ValueProfData> VPD = allocValueProfData(TotalSize);
622   memcpy(VPD.get(), D, TotalSize);
623   // Byte swap.
624   VPD->swapBytesToHost(Endianness);
625 
626   Error E = VPD->checkIntegrity();
627   if (E)
628     return std::move(E);
629 
630   return std::move(VPD);
631 }
632 
633 void ValueProfData::swapBytesToHost(support::endianness Endianness) {
634   using namespace support;
635   if (Endianness == getHostEndianness())
636     return;
637 
638   sys::swapByteOrder<uint32_t>(TotalSize);
639   sys::swapByteOrder<uint32_t>(NumValueKinds);
640 
641   ValueProfRecord *VR = getFirstValueProfRecord(this);
642   for (uint32_t K = 0; K < NumValueKinds; K++) {
643     VR->swapBytes(Endianness, getHostEndianness());
644     VR = getValueProfRecordNext(VR);
645   }
646 }
647 
648 void ValueProfData::swapBytesFromHost(support::endianness Endianness) {
649   using namespace support;
650   if (Endianness == getHostEndianness())
651     return;
652 
653   ValueProfRecord *VR = getFirstValueProfRecord(this);
654   for (uint32_t K = 0; K < NumValueKinds; K++) {
655     ValueProfRecord *NVR = getValueProfRecordNext(VR);
656     VR->swapBytes(getHostEndianness(), Endianness);
657     VR = NVR;
658   }
659   sys::swapByteOrder<uint32_t>(TotalSize);
660   sys::swapByteOrder<uint32_t>(NumValueKinds);
661 }
662 
663 void annotateValueSite(Module &M, Instruction &Inst,
664                        const InstrProfRecord &InstrProfR,
665                        InstrProfValueKind ValueKind, uint32_t SiteIdx,
666                        uint32_t MaxMDCount) {
667   uint32_t NV = InstrProfR.getNumValueDataForSite(ValueKind, SiteIdx);
668   if (!NV)
669     return;
670 
671   uint64_t Sum = 0;
672   std::unique_ptr<InstrProfValueData[]> VD =
673       InstrProfR.getValueForSite(ValueKind, SiteIdx, &Sum);
674 
675   ArrayRef<InstrProfValueData> VDs(VD.get(), NV);
676   annotateValueSite(M, Inst, VDs, Sum, ValueKind, MaxMDCount);
677 }
678 
679 void annotateValueSite(Module &M, Instruction &Inst,
680                        ArrayRef<InstrProfValueData> VDs,
681                        uint64_t Sum, InstrProfValueKind ValueKind,
682                        uint32_t MaxMDCount) {
683   LLVMContext &Ctx = M.getContext();
684   MDBuilder MDHelper(Ctx);
685   SmallVector<Metadata *, 3> Vals;
686   // Tag
687   Vals.push_back(MDHelper.createString("VP"));
688   // Value Kind
689   Vals.push_back(MDHelper.createConstant(
690       ConstantInt::get(Type::getInt32Ty(Ctx), ValueKind)));
691   // Total Count
692   Vals.push_back(
693       MDHelper.createConstant(ConstantInt::get(Type::getInt64Ty(Ctx), Sum)));
694 
695   // Value Profile Data
696   uint32_t MDCount = MaxMDCount;
697   for (auto &VD : VDs) {
698     Vals.push_back(MDHelper.createConstant(
699         ConstantInt::get(Type::getInt64Ty(Ctx), VD.Value)));
700     Vals.push_back(MDHelper.createConstant(
701         ConstantInt::get(Type::getInt64Ty(Ctx), VD.Count)));
702     if (--MDCount == 0)
703       break;
704   }
705   Inst.setMetadata(LLVMContext::MD_prof, MDNode::get(Ctx, Vals));
706 }
707 
708 bool getValueProfDataFromInst(const Instruction &Inst,
709                               InstrProfValueKind ValueKind,
710                               uint32_t MaxNumValueData,
711                               InstrProfValueData ValueData[],
712                               uint32_t &ActualNumValueData, uint64_t &TotalC) {
713   MDNode *MD = Inst.getMetadata(LLVMContext::MD_prof);
714   if (!MD)
715     return false;
716 
717   unsigned NOps = MD->getNumOperands();
718 
719   if (NOps < 5)
720     return false;
721 
722   // Operand 0 is a string tag "VP":
723   MDString *Tag = cast<MDString>(MD->getOperand(0));
724   if (!Tag)
725     return false;
726 
727   if (!Tag->getString().equals("VP"))
728     return false;
729 
730   // Now check kind:
731   ConstantInt *KindInt = mdconst::dyn_extract<ConstantInt>(MD->getOperand(1));
732   if (!KindInt)
733     return false;
734   if (KindInt->getZExtValue() != ValueKind)
735     return false;
736 
737   // Get total count
738   ConstantInt *TotalCInt = mdconst::dyn_extract<ConstantInt>(MD->getOperand(2));
739   if (!TotalCInt)
740     return false;
741   TotalC = TotalCInt->getZExtValue();
742 
743   ActualNumValueData = 0;
744 
745   for (unsigned I = 3; I < NOps; I += 2) {
746     if (ActualNumValueData >= MaxNumValueData)
747       break;
748     ConstantInt *Value = mdconst::dyn_extract<ConstantInt>(MD->getOperand(I));
749     ConstantInt *Count =
750         mdconst::dyn_extract<ConstantInt>(MD->getOperand(I + 1));
751     if (!Value || !Count)
752       return false;
753     ValueData[ActualNumValueData].Value = Value->getZExtValue();
754     ValueData[ActualNumValueData].Count = Count->getZExtValue();
755     ActualNumValueData++;
756   }
757   return true;
758 }
759 
760 MDNode *getPGOFuncNameMetadata(const Function &F) {
761   return F.getMetadata(getPGOFuncNameMetadataName());
762 }
763 
764 void createPGOFuncNameMetadata(Function &F, const std::string &PGOFuncName) {
765   // Only for internal linkage functions.
766   if (PGOFuncName == F.getName())
767       return;
768   // Don't create duplicated meta-data.
769   if (getPGOFuncNameMetadata(F))
770     return;
771   LLVMContext &C = F.getContext();
772   MDNode *N = MDNode::get(C, MDString::get(C, PGOFuncName.c_str()));
773   F.setMetadata(getPGOFuncNameMetadataName(), N);
774 }
775 
776 } // end namespace llvm
777