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/ADT/Triple.h"
18 #include "llvm/IR/Constants.h"
19 #include "llvm/IR/Function.h"
20 #include "llvm/IR/GlobalVariable.h"
21 #include "llvm/IR/MDBuilder.h"
22 #include "llvm/IR/Module.h"
23 #include "llvm/Support/Compression.h"
24 #include "llvm/Support/ErrorHandling.h"
25 #include "llvm/Support/LEB128.h"
26 #include "llvm/Support/ManagedStatic.h"
27 #include "llvm/Support/Path.h"
28 
29 using namespace llvm;
30 
31 static cl::opt<bool> StaticFuncFullModulePrefix(
32     "static-func-full-module-prefix", cl::init(false),
33     cl::desc("Use full module build paths in the profile counter names for "
34              "static functions."));
35 
36 namespace {
37 std::string getInstrProfErrString(instrprof_error Err) {
38   switch (Err) {
39   case instrprof_error::success:
40     return "Success";
41   case instrprof_error::eof:
42     return "End of File";
43   case instrprof_error::unrecognized_format:
44     return "Unrecognized instrumentation profile encoding format";
45   case instrprof_error::bad_magic:
46     return "Invalid instrumentation profile data (bad magic)";
47   case instrprof_error::bad_header:
48     return "Invalid instrumentation profile data (file header is corrupt)";
49   case instrprof_error::unsupported_version:
50     return "Unsupported instrumentation profile format version";
51   case instrprof_error::unsupported_hash_type:
52     return "Unsupported instrumentation profile hash type";
53   case instrprof_error::too_large:
54     return "Too much profile data";
55   case instrprof_error::truncated:
56     return "Truncated profile data";
57   case instrprof_error::malformed:
58     return "Malformed instrumentation profile data";
59   case instrprof_error::unknown_function:
60     return "No profile data available for function";
61   case instrprof_error::hash_mismatch:
62     return "Function control flow change detected (hash mismatch)";
63   case instrprof_error::count_mismatch:
64     return "Function basic block count change detected (counter mismatch)";
65   case instrprof_error::counter_overflow:
66     return "Counter overflow";
67   case instrprof_error::value_site_count_mismatch:
68     return "Function value site count change detected (counter mismatch)";
69   case instrprof_error::compress_failed:
70     return "Failed to compress data (zlib)";
71   case instrprof_error::uncompress_failed:
72     return "Failed to uncompress data (zlib)";
73   case instrprof_error::empty_raw_profile:
74     return "Empty raw profile file";
75   }
76   llvm_unreachable("A value of instrprof_error has no message.");
77 }
78 
79 // FIXME: This class is only here to support the transition to llvm::Error. It
80 // will be removed once this transition is complete. Clients should prefer to
81 // deal with the Error value directly, rather than converting to error_code.
82 class InstrProfErrorCategoryType : public std::error_category {
83   const char *name() const noexcept override { return "llvm.instrprof"; }
84   std::string message(int IE) const override {
85     return getInstrProfErrString(static_cast<instrprof_error>(IE));
86   }
87 };
88 } // end anonymous namespace
89 
90 static ManagedStatic<InstrProfErrorCategoryType> ErrorCategory;
91 
92 const std::error_category &llvm::instrprof_category() {
93   return *ErrorCategory;
94 }
95 
96 namespace llvm {
97 
98 void SoftInstrProfErrors::addError(instrprof_error IE) {
99   if (IE == instrprof_error::success)
100     return;
101 
102   if (FirstError == instrprof_error::success)
103     FirstError = IE;
104 
105   switch (IE) {
106   case instrprof_error::hash_mismatch:
107     ++NumHashMismatches;
108     break;
109   case instrprof_error::count_mismatch:
110     ++NumCountMismatches;
111     break;
112   case instrprof_error::counter_overflow:
113     ++NumCounterOverflows;
114     break;
115   case instrprof_error::value_site_count_mismatch:
116     ++NumValueSiteCountMismatches;
117     break;
118   default:
119     llvm_unreachable("Not a soft error");
120   }
121 }
122 
123 std::string InstrProfError::message() const {
124   return getInstrProfErrString(Err);
125 }
126 
127 char InstrProfError::ID = 0;
128 
129 std::string getPGOFuncName(StringRef RawFuncName,
130                            GlobalValue::LinkageTypes Linkage,
131                            StringRef FileName,
132                            uint64_t Version LLVM_ATTRIBUTE_UNUSED) {
133   return GlobalValue::getGlobalIdentifier(RawFuncName, Linkage, FileName);
134 }
135 
136 // Return the PGOFuncName. This function has some special handling when called
137 // in LTO optimization. The following only applies when calling in LTO passes
138 // (when \c InLTO is true): LTO's internalization privatizes many global linkage
139 // symbols. This happens after value profile annotation, but those internal
140 // linkage functions should not have a source prefix.
141 // Additionally, for ThinLTO mode, exported internal functions are promoted
142 // and renamed. We need to ensure that the original internal PGO name is
143 // used when computing the GUID that is compared against the profiled GUIDs.
144 // To differentiate compiler generated internal symbols from original ones,
145 // PGOFuncName meta data are created and attached to the original internal
146 // symbols in the value profile annotation step
147 // (PGOUseFunc::annotateIndirectCallSites). If a symbol does not have the meta
148 // data, its original linkage must be non-internal.
149 std::string getPGOFuncName(const Function &F, bool InLTO, uint64_t Version) {
150   if (!InLTO) {
151     StringRef FileName = (StaticFuncFullModulePrefix
152                               ? F.getParent()->getName()
153                               : sys::path::filename(F.getParent()->getName()));
154     return getPGOFuncName(F.getName(), F.getLinkage(), FileName, Version);
155   }
156 
157   // In LTO mode (when InLTO is true), first check if there is a meta data.
158   if (MDNode *MD = getPGOFuncNameMetadata(F)) {
159     StringRef S = cast<MDString>(MD->getOperand(0))->getString();
160     return S.str();
161   }
162 
163   // If there is no meta data, the function must be a global before the value
164   // profile annotation pass. Its current linkage may be internal if it is
165   // internalized in LTO mode.
166   return getPGOFuncName(F.getName(), GlobalValue::ExternalLinkage, "");
167 }
168 
169 StringRef getFuncNameWithoutPrefix(StringRef PGOFuncName, StringRef FileName) {
170   if (FileName.empty())
171     return PGOFuncName;
172   // Drop the file name including ':'. See also getPGOFuncName.
173   if (PGOFuncName.startswith(FileName))
174     PGOFuncName = PGOFuncName.drop_front(FileName.size() + 1);
175   return PGOFuncName;
176 }
177 
178 // \p FuncName is the string used as profile lookup key for the function. A
179 // symbol is created to hold the name. Return the legalized symbol name.
180 std::string getPGOFuncNameVarName(StringRef FuncName,
181                                   GlobalValue::LinkageTypes Linkage) {
182   std::string VarName = getInstrProfNameVarPrefix();
183   VarName += FuncName;
184 
185   if (!GlobalValue::isLocalLinkage(Linkage))
186     return VarName;
187 
188   // Now fix up illegal chars in local VarName that may upset the assembler.
189   const char *InvalidChars = "-:<>/\"'";
190   size_t found = VarName.find_first_of(InvalidChars);
191   while (found != std::string::npos) {
192     VarName[found] = '_';
193     found = VarName.find_first_of(InvalidChars, found + 1);
194   }
195   return VarName;
196 }
197 
198 GlobalVariable *createPGOFuncNameVar(Module &M,
199                                      GlobalValue::LinkageTypes Linkage,
200                                      StringRef PGOFuncName) {
201 
202   // We generally want to match the function's linkage, but available_externally
203   // and extern_weak both have the wrong semantics, and anything that doesn't
204   // need to link across compilation units doesn't need to be visible at all.
205   if (Linkage == GlobalValue::ExternalWeakLinkage)
206     Linkage = GlobalValue::LinkOnceAnyLinkage;
207   else if (Linkage == GlobalValue::AvailableExternallyLinkage)
208     Linkage = GlobalValue::LinkOnceODRLinkage;
209   else if (Linkage == GlobalValue::InternalLinkage ||
210            Linkage == GlobalValue::ExternalLinkage)
211     Linkage = GlobalValue::PrivateLinkage;
212 
213   auto *Value =
214       ConstantDataArray::getString(M.getContext(), PGOFuncName, false);
215   auto FuncNameVar =
216       new GlobalVariable(M, Value->getType(), true, Linkage, Value,
217                          getPGOFuncNameVarName(PGOFuncName, Linkage));
218 
219   // Hide the symbol so that we correctly get a copy for each executable.
220   if (!GlobalValue::isLocalLinkage(FuncNameVar->getLinkage()))
221     FuncNameVar->setVisibility(GlobalValue::HiddenVisibility);
222 
223   return FuncNameVar;
224 }
225 
226 GlobalVariable *createPGOFuncNameVar(Function &F, StringRef PGOFuncName) {
227   return createPGOFuncNameVar(*F.getParent(), F.getLinkage(), PGOFuncName);
228 }
229 
230 void InstrProfSymtab::create(Module &M, bool InLTO) {
231   for (Function &F : M) {
232     // Function may not have a name: like using asm("") to overwrite the name.
233     // Ignore in this case.
234     if (!F.hasName())
235       continue;
236     const std::string &PGOFuncName = getPGOFuncName(F, InLTO);
237     addFuncName(PGOFuncName);
238     MD5FuncMap.emplace_back(Function::getGUID(PGOFuncName), &F);
239   }
240 
241   finalizeSymtab();
242 }
243 
244 Error collectPGOFuncNameStrings(const std::vector<std::string> &NameStrs,
245                                 bool doCompression, std::string &Result) {
246   assert(NameStrs.size() && "No name data to emit");
247 
248   uint8_t Header[16], *P = Header;
249   std::string UncompressedNameStrings =
250       join(NameStrs.begin(), NameStrs.end(), getInstrProfNameSeparator());
251 
252   assert(StringRef(UncompressedNameStrings)
253                  .count(getInstrProfNameSeparator()) == (NameStrs.size() - 1) &&
254          "PGO name is invalid (contains separator token)");
255 
256   unsigned EncLen = encodeULEB128(UncompressedNameStrings.length(), P);
257   P += EncLen;
258 
259   auto WriteStringToResult = [&](size_t CompressedLen, StringRef InputStr) {
260     EncLen = encodeULEB128(CompressedLen, P);
261     P += EncLen;
262     char *HeaderStr = reinterpret_cast<char *>(&Header[0]);
263     unsigned HeaderLen = P - &Header[0];
264     Result.append(HeaderStr, HeaderLen);
265     Result += InputStr;
266     return Error::success();
267   };
268 
269   if (!doCompression) {
270     return WriteStringToResult(0, UncompressedNameStrings);
271   }
272 
273   SmallString<128> CompressedNameStrings;
274   Error E = zlib::compress(StringRef(UncompressedNameStrings),
275                            CompressedNameStrings, zlib::BestSizeCompression);
276   if (E) {
277     consumeError(std::move(E));
278     return make_error<InstrProfError>(instrprof_error::compress_failed);
279   }
280 
281   return WriteStringToResult(CompressedNameStrings.size(),
282                              CompressedNameStrings);
283 }
284 
285 StringRef getPGOFuncNameVarInitializer(GlobalVariable *NameVar) {
286   auto *Arr = cast<ConstantDataArray>(NameVar->getInitializer());
287   StringRef NameStr =
288       Arr->isCString() ? Arr->getAsCString() : Arr->getAsString();
289   return NameStr;
290 }
291 
292 Error collectPGOFuncNameStrings(const std::vector<GlobalVariable *> &NameVars,
293                                 std::string &Result, bool doCompression) {
294   std::vector<std::string> NameStrs;
295   for (auto *NameVar : NameVars) {
296     NameStrs.push_back(getPGOFuncNameVarInitializer(NameVar));
297   }
298   return collectPGOFuncNameStrings(
299       NameStrs, zlib::isAvailable() && doCompression, Result);
300 }
301 
302 Error readPGOFuncNameStrings(StringRef NameStrings, InstrProfSymtab &Symtab) {
303   const uint8_t *P = reinterpret_cast<const uint8_t *>(NameStrings.data());
304   const uint8_t *EndP = reinterpret_cast<const uint8_t *>(NameStrings.data() +
305                                                           NameStrings.size());
306   while (P < EndP) {
307     uint32_t N;
308     uint64_t UncompressedSize = decodeULEB128(P, &N);
309     P += N;
310     uint64_t CompressedSize = decodeULEB128(P, &N);
311     P += N;
312     bool isCompressed = (CompressedSize != 0);
313     SmallString<128> UncompressedNameStrings;
314     StringRef NameStrings;
315     if (isCompressed) {
316       StringRef CompressedNameStrings(reinterpret_cast<const char *>(P),
317                                       CompressedSize);
318       if (Error E =
319               zlib::uncompress(CompressedNameStrings, UncompressedNameStrings,
320                                UncompressedSize)) {
321         consumeError(std::move(E));
322         return make_error<InstrProfError>(instrprof_error::uncompress_failed);
323       }
324       P += CompressedSize;
325       NameStrings = StringRef(UncompressedNameStrings.data(),
326                               UncompressedNameStrings.size());
327     } else {
328       NameStrings =
329           StringRef(reinterpret_cast<const char *>(P), UncompressedSize);
330       P += UncompressedSize;
331     }
332     // Now parse the name strings.
333     SmallVector<StringRef, 0> Names;
334     NameStrings.split(Names, getInstrProfNameSeparator());
335     for (StringRef &Name : Names)
336       Symtab.addFuncName(Name);
337 
338     while (P < EndP && *P == 0)
339       P++;
340   }
341   Symtab.finalizeSymtab();
342   return Error::success();
343 }
344 
345 void InstrProfValueSiteRecord::merge(SoftInstrProfErrors &SIPE,
346                                      InstrProfValueSiteRecord &Input,
347                                      uint64_t Weight) {
348   this->sortByTargetValues();
349   Input.sortByTargetValues();
350   auto I = ValueData.begin();
351   auto IE = ValueData.end();
352   for (auto J = Input.ValueData.begin(), JE = Input.ValueData.end(); J != JE;
353        ++J) {
354     while (I != IE && I->Value < J->Value)
355       ++I;
356     if (I != IE && I->Value == J->Value) {
357       bool Overflowed;
358       I->Count = SaturatingMultiplyAdd(J->Count, Weight, I->Count, &Overflowed);
359       if (Overflowed)
360         SIPE.addError(instrprof_error::counter_overflow);
361       ++I;
362       continue;
363     }
364     ValueData.insert(I, *J);
365   }
366 }
367 
368 void InstrProfValueSiteRecord::scale(SoftInstrProfErrors &SIPE,
369                                      uint64_t Weight) {
370   for (auto I = ValueData.begin(), IE = ValueData.end(); I != IE; ++I) {
371     bool Overflowed;
372     I->Count = SaturatingMultiply(I->Count, Weight, &Overflowed);
373     if (Overflowed)
374       SIPE.addError(instrprof_error::counter_overflow);
375   }
376 }
377 
378 // Merge Value Profile data from Src record to this record for ValueKind.
379 // Scale merged value counts by \p Weight.
380 void InstrProfRecord::mergeValueProfData(uint32_t ValueKind,
381                                          InstrProfRecord &Src,
382                                          uint64_t Weight) {
383   uint32_t ThisNumValueSites = getNumValueSites(ValueKind);
384   uint32_t OtherNumValueSites = Src.getNumValueSites(ValueKind);
385   if (ThisNumValueSites != OtherNumValueSites) {
386     SIPE.addError(instrprof_error::value_site_count_mismatch);
387     return;
388   }
389   std::vector<InstrProfValueSiteRecord> &ThisSiteRecords =
390       getValueSitesForKind(ValueKind);
391   std::vector<InstrProfValueSiteRecord> &OtherSiteRecords =
392       Src.getValueSitesForKind(ValueKind);
393   for (uint32_t I = 0; I < ThisNumValueSites; I++)
394     ThisSiteRecords[I].merge(SIPE, OtherSiteRecords[I], Weight);
395 }
396 
397 void InstrProfRecord::merge(InstrProfRecord &Other, uint64_t Weight) {
398   // If the number of counters doesn't match we either have bad data
399   // or a hash collision.
400   if (Counts.size() != Other.Counts.size()) {
401     SIPE.addError(instrprof_error::count_mismatch);
402     return;
403   }
404 
405   for (size_t I = 0, E = Other.Counts.size(); I < E; ++I) {
406     bool Overflowed;
407     Counts[I] =
408         SaturatingMultiplyAdd(Other.Counts[I], Weight, Counts[I], &Overflowed);
409     if (Overflowed)
410       SIPE.addError(instrprof_error::counter_overflow);
411   }
412 
413   for (uint32_t Kind = IPVK_First; Kind <= IPVK_Last; ++Kind)
414     mergeValueProfData(Kind, Other, Weight);
415 }
416 
417 void InstrProfRecord::scaleValueProfData(uint32_t ValueKind, uint64_t Weight) {
418   uint32_t ThisNumValueSites = getNumValueSites(ValueKind);
419   std::vector<InstrProfValueSiteRecord> &ThisSiteRecords =
420       getValueSitesForKind(ValueKind);
421   for (uint32_t I = 0; I < ThisNumValueSites; I++)
422     ThisSiteRecords[I].scale(SIPE, Weight);
423 }
424 
425 void InstrProfRecord::scale(uint64_t Weight) {
426   for (auto &Count : this->Counts) {
427     bool Overflowed;
428     Count = SaturatingMultiply(Count, Weight, &Overflowed);
429     if (Overflowed)
430       SIPE.addError(instrprof_error::counter_overflow);
431   }
432   for (uint32_t Kind = IPVK_First; Kind <= IPVK_Last; ++Kind)
433     scaleValueProfData(Kind, Weight);
434 }
435 
436 // Map indirect call target name hash to name string.
437 uint64_t InstrProfRecord::remapValue(uint64_t Value, uint32_t ValueKind,
438                                      ValueMapType *ValueMap) {
439   if (!ValueMap)
440     return Value;
441   switch (ValueKind) {
442   case IPVK_IndirectCallTarget: {
443     auto Result =
444         std::lower_bound(ValueMap->begin(), ValueMap->end(), Value,
445                          [](const std::pair<uint64_t, uint64_t> &LHS,
446                             uint64_t RHS) { return LHS.first < RHS; });
447    // Raw function pointer collected by value profiler may be from
448    // external functions that are not instrumented. They won't have
449    // mapping data to be used by the deserializer. Force the value to
450    // be 0 in this case.
451     if (Result != ValueMap->end() && Result->first == Value)
452       Value = (uint64_t)Result->second;
453     else
454       Value = 0;
455     break;
456   }
457   }
458   return Value;
459 }
460 
461 void InstrProfRecord::addValueData(uint32_t ValueKind, uint32_t Site,
462                                    InstrProfValueData *VData, uint32_t N,
463                                    ValueMapType *ValueMap) {
464   for (uint32_t I = 0; I < N; I++) {
465     VData[I].Value = remapValue(VData[I].Value, ValueKind, ValueMap);
466   }
467   std::vector<InstrProfValueSiteRecord> &ValueSites =
468       getValueSitesForKind(ValueKind);
469   if (N == 0)
470     ValueSites.emplace_back();
471   else
472     ValueSites.emplace_back(VData, VData + N);
473 }
474 
475 #define INSTR_PROF_COMMON_API_IMPL
476 #include "llvm/ProfileData/InstrProfData.inc"
477 
478 /*!
479  * \brief ValueProfRecordClosure Interface implementation for  InstrProfRecord
480  *  class. These C wrappers are used as adaptors so that C++ code can be
481  *  invoked as callbacks.
482  */
483 uint32_t getNumValueKindsInstrProf(const void *Record) {
484   return reinterpret_cast<const InstrProfRecord *>(Record)->getNumValueKinds();
485 }
486 
487 uint32_t getNumValueSitesInstrProf(const void *Record, uint32_t VKind) {
488   return reinterpret_cast<const InstrProfRecord *>(Record)
489       ->getNumValueSites(VKind);
490 }
491 
492 uint32_t getNumValueDataInstrProf(const void *Record, uint32_t VKind) {
493   return reinterpret_cast<const InstrProfRecord *>(Record)
494       ->getNumValueData(VKind);
495 }
496 
497 uint32_t getNumValueDataForSiteInstrProf(const void *R, uint32_t VK,
498                                          uint32_t S) {
499   return reinterpret_cast<const InstrProfRecord *>(R)
500       ->getNumValueDataForSite(VK, S);
501 }
502 
503 void getValueForSiteInstrProf(const void *R, InstrProfValueData *Dst,
504                               uint32_t K, uint32_t S) {
505   reinterpret_cast<const InstrProfRecord *>(R)->getValueForSite(Dst, K, S);
506 }
507 
508 ValueProfData *allocValueProfDataInstrProf(size_t TotalSizeInBytes) {
509   ValueProfData *VD =
510       (ValueProfData *)(new (::operator new(TotalSizeInBytes)) ValueProfData());
511   memset(VD, 0, TotalSizeInBytes);
512   return VD;
513 }
514 
515 static ValueProfRecordClosure InstrProfRecordClosure = {
516     nullptr,
517     getNumValueKindsInstrProf,
518     getNumValueSitesInstrProf,
519     getNumValueDataInstrProf,
520     getNumValueDataForSiteInstrProf,
521     nullptr,
522     getValueForSiteInstrProf,
523     allocValueProfDataInstrProf};
524 
525 // Wrapper implementation using the closure mechanism.
526 uint32_t ValueProfData::getSize(const InstrProfRecord &Record) {
527   InstrProfRecordClosure.Record = &Record;
528   return getValueProfDataSize(&InstrProfRecordClosure);
529 }
530 
531 // Wrapper implementation using the closure mechanism.
532 std::unique_ptr<ValueProfData>
533 ValueProfData::serializeFrom(const InstrProfRecord &Record) {
534   InstrProfRecordClosure.Record = &Record;
535 
536   std::unique_ptr<ValueProfData> VPD(
537       serializeValueProfDataFrom(&InstrProfRecordClosure, nullptr));
538   return VPD;
539 }
540 
541 void ValueProfRecord::deserializeTo(InstrProfRecord &Record,
542                                     InstrProfRecord::ValueMapType *VMap) {
543   Record.reserveSites(Kind, NumValueSites);
544 
545   InstrProfValueData *ValueData = getValueProfRecordValueData(this);
546   for (uint64_t VSite = 0; VSite < NumValueSites; ++VSite) {
547     uint8_t ValueDataCount = this->SiteCountArray[VSite];
548     Record.addValueData(Kind, VSite, ValueData, ValueDataCount, VMap);
549     ValueData += ValueDataCount;
550   }
551 }
552 
553 // For writing/serializing,  Old is the host endianness, and  New is
554 // byte order intended on disk. For Reading/deserialization, Old
555 // is the on-disk source endianness, and New is the host endianness.
556 void ValueProfRecord::swapBytes(support::endianness Old,
557                                 support::endianness New) {
558   using namespace support;
559   if (Old == New)
560     return;
561 
562   if (getHostEndianness() != Old) {
563     sys::swapByteOrder<uint32_t>(NumValueSites);
564     sys::swapByteOrder<uint32_t>(Kind);
565   }
566   uint32_t ND = getValueProfRecordNumValueData(this);
567   InstrProfValueData *VD = getValueProfRecordValueData(this);
568 
569   // No need to swap byte array: SiteCountArrray.
570   for (uint32_t I = 0; I < ND; I++) {
571     sys::swapByteOrder<uint64_t>(VD[I].Value);
572     sys::swapByteOrder<uint64_t>(VD[I].Count);
573   }
574   if (getHostEndianness() == Old) {
575     sys::swapByteOrder<uint32_t>(NumValueSites);
576     sys::swapByteOrder<uint32_t>(Kind);
577   }
578 }
579 
580 void ValueProfData::deserializeTo(InstrProfRecord &Record,
581                                   InstrProfRecord::ValueMapType *VMap) {
582   if (NumValueKinds == 0)
583     return;
584 
585   ValueProfRecord *VR = getFirstValueProfRecord(this);
586   for (uint32_t K = 0; K < NumValueKinds; K++) {
587     VR->deserializeTo(Record, VMap);
588     VR = getValueProfRecordNext(VR);
589   }
590 }
591 
592 template <class T>
593 static T swapToHostOrder(const unsigned char *&D, support::endianness Orig) {
594   using namespace support;
595   if (Orig == little)
596     return endian::readNext<T, little, unaligned>(D);
597   else
598     return endian::readNext<T, big, unaligned>(D);
599 }
600 
601 static std::unique_ptr<ValueProfData> allocValueProfData(uint32_t TotalSize) {
602   return std::unique_ptr<ValueProfData>(new (::operator new(TotalSize))
603                                             ValueProfData());
604 }
605 
606 Error ValueProfData::checkIntegrity() {
607   if (NumValueKinds > IPVK_Last + 1)
608     return make_error<InstrProfError>(instrprof_error::malformed);
609   // Total size needs to be mulltiple of quadword size.
610   if (TotalSize % sizeof(uint64_t))
611     return make_error<InstrProfError>(instrprof_error::malformed);
612 
613   ValueProfRecord *VR = getFirstValueProfRecord(this);
614   for (uint32_t K = 0; K < this->NumValueKinds; K++) {
615     if (VR->Kind > IPVK_Last)
616       return make_error<InstrProfError>(instrprof_error::malformed);
617     VR = getValueProfRecordNext(VR);
618     if ((char *)VR - (char *)this > (ptrdiff_t)TotalSize)
619       return make_error<InstrProfError>(instrprof_error::malformed);
620   }
621   return Error::success();
622 }
623 
624 Expected<std::unique_ptr<ValueProfData>>
625 ValueProfData::getValueProfData(const unsigned char *D,
626                                 const unsigned char *const BufferEnd,
627                                 support::endianness Endianness) {
628   using namespace support;
629   if (D + sizeof(ValueProfData) > BufferEnd)
630     return make_error<InstrProfError>(instrprof_error::truncated);
631 
632   const unsigned char *Header = D;
633   uint32_t TotalSize = swapToHostOrder<uint32_t>(Header, Endianness);
634   if (D + TotalSize > BufferEnd)
635     return make_error<InstrProfError>(instrprof_error::too_large);
636 
637   std::unique_ptr<ValueProfData> VPD = allocValueProfData(TotalSize);
638   memcpy(VPD.get(), D, TotalSize);
639   // Byte swap.
640   VPD->swapBytesToHost(Endianness);
641 
642   Error E = VPD->checkIntegrity();
643   if (E)
644     return std::move(E);
645 
646   return std::move(VPD);
647 }
648 
649 void ValueProfData::swapBytesToHost(support::endianness Endianness) {
650   using namespace support;
651   if (Endianness == getHostEndianness())
652     return;
653 
654   sys::swapByteOrder<uint32_t>(TotalSize);
655   sys::swapByteOrder<uint32_t>(NumValueKinds);
656 
657   ValueProfRecord *VR = getFirstValueProfRecord(this);
658   for (uint32_t K = 0; K < NumValueKinds; K++) {
659     VR->swapBytes(Endianness, getHostEndianness());
660     VR = getValueProfRecordNext(VR);
661   }
662 }
663 
664 void ValueProfData::swapBytesFromHost(support::endianness Endianness) {
665   using namespace support;
666   if (Endianness == getHostEndianness())
667     return;
668 
669   ValueProfRecord *VR = getFirstValueProfRecord(this);
670   for (uint32_t K = 0; K < NumValueKinds; K++) {
671     ValueProfRecord *NVR = getValueProfRecordNext(VR);
672     VR->swapBytes(getHostEndianness(), Endianness);
673     VR = NVR;
674   }
675   sys::swapByteOrder<uint32_t>(TotalSize);
676   sys::swapByteOrder<uint32_t>(NumValueKinds);
677 }
678 
679 void annotateValueSite(Module &M, Instruction &Inst,
680                        const InstrProfRecord &InstrProfR,
681                        InstrProfValueKind ValueKind, uint32_t SiteIdx,
682                        uint32_t MaxMDCount) {
683   uint32_t NV = InstrProfR.getNumValueDataForSite(ValueKind, SiteIdx);
684   if (!NV)
685     return;
686 
687   uint64_t Sum = 0;
688   std::unique_ptr<InstrProfValueData[]> VD =
689       InstrProfR.getValueForSite(ValueKind, SiteIdx, &Sum);
690 
691   ArrayRef<InstrProfValueData> VDs(VD.get(), NV);
692   annotateValueSite(M, Inst, VDs, Sum, ValueKind, MaxMDCount);
693 }
694 
695 void annotateValueSite(Module &M, Instruction &Inst,
696                        ArrayRef<InstrProfValueData> VDs,
697                        uint64_t Sum, InstrProfValueKind ValueKind,
698                        uint32_t MaxMDCount) {
699   LLVMContext &Ctx = M.getContext();
700   MDBuilder MDHelper(Ctx);
701   SmallVector<Metadata *, 3> Vals;
702   // Tag
703   Vals.push_back(MDHelper.createString("VP"));
704   // Value Kind
705   Vals.push_back(MDHelper.createConstant(
706       ConstantInt::get(Type::getInt32Ty(Ctx), ValueKind)));
707   // Total Count
708   Vals.push_back(
709       MDHelper.createConstant(ConstantInt::get(Type::getInt64Ty(Ctx), Sum)));
710 
711   // Value Profile Data
712   uint32_t MDCount = MaxMDCount;
713   for (auto &VD : VDs) {
714     Vals.push_back(MDHelper.createConstant(
715         ConstantInt::get(Type::getInt64Ty(Ctx), VD.Value)));
716     Vals.push_back(MDHelper.createConstant(
717         ConstantInt::get(Type::getInt64Ty(Ctx), VD.Count)));
718     if (--MDCount == 0)
719       break;
720   }
721   Inst.setMetadata(LLVMContext::MD_prof, MDNode::get(Ctx, Vals));
722 }
723 
724 bool getValueProfDataFromInst(const Instruction &Inst,
725                               InstrProfValueKind ValueKind,
726                               uint32_t MaxNumValueData,
727                               InstrProfValueData ValueData[],
728                               uint32_t &ActualNumValueData, uint64_t &TotalC) {
729   MDNode *MD = Inst.getMetadata(LLVMContext::MD_prof);
730   if (!MD)
731     return false;
732 
733   unsigned NOps = MD->getNumOperands();
734 
735   if (NOps < 5)
736     return false;
737 
738   // Operand 0 is a string tag "VP":
739   MDString *Tag = cast<MDString>(MD->getOperand(0));
740   if (!Tag)
741     return false;
742 
743   if (!Tag->getString().equals("VP"))
744     return false;
745 
746   // Now check kind:
747   ConstantInt *KindInt = mdconst::dyn_extract<ConstantInt>(MD->getOperand(1));
748   if (!KindInt)
749     return false;
750   if (KindInt->getZExtValue() != ValueKind)
751     return false;
752 
753   // Get total count
754   ConstantInt *TotalCInt = mdconst::dyn_extract<ConstantInt>(MD->getOperand(2));
755   if (!TotalCInt)
756     return false;
757   TotalC = TotalCInt->getZExtValue();
758 
759   ActualNumValueData = 0;
760 
761   for (unsigned I = 3; I < NOps; I += 2) {
762     if (ActualNumValueData >= MaxNumValueData)
763       break;
764     ConstantInt *Value = mdconst::dyn_extract<ConstantInt>(MD->getOperand(I));
765     ConstantInt *Count =
766         mdconst::dyn_extract<ConstantInt>(MD->getOperand(I + 1));
767     if (!Value || !Count)
768       return false;
769     ValueData[ActualNumValueData].Value = Value->getZExtValue();
770     ValueData[ActualNumValueData].Count = Count->getZExtValue();
771     ActualNumValueData++;
772   }
773   return true;
774 }
775 
776 MDNode *getPGOFuncNameMetadata(const Function &F) {
777   return F.getMetadata(getPGOFuncNameMetadataName());
778 }
779 
780 void createPGOFuncNameMetadata(Function &F, StringRef PGOFuncName) {
781   // Only for internal linkage functions.
782   if (PGOFuncName == F.getName())
783       return;
784   // Don't create duplicated meta-data.
785   if (getPGOFuncNameMetadata(F))
786     return;
787   LLVMContext &C = F.getContext();
788   MDNode *N = MDNode::get(C, MDString::get(C, PGOFuncName));
789   F.setMetadata(getPGOFuncNameMetadataName(), N);
790 }
791 
792 bool needsComdatForCounter(const Function &F, const Module &M) {
793   if (F.hasComdat())
794     return true;
795 
796   Triple TT(M.getTargetTriple());
797   if (!TT.isOSBinFormatELF() && !TT.isOSBinFormatWasm())
798     return false;
799 
800   // See createPGOFuncNameVar for more details. To avoid link errors, profile
801   // counters for function with available_externally linkage needs to be changed
802   // to linkonce linkage. On ELF based systems, this leads to weak symbols to be
803   // created. Without using comdat, duplicate entries won't be removed by the
804   // linker leading to increased data segement size and raw profile size. Even
805   // worse, since the referenced counter from profile per-function data object
806   // will be resolved to the common strong definition, the profile counts for
807   // available_externally functions will end up being duplicated in raw profile
808   // data. This can result in distorted profile as the counts of those dups
809   // will be accumulated by the profile merger.
810   GlobalValue::LinkageTypes Linkage = F.getLinkage();
811   if (Linkage != GlobalValue::ExternalWeakLinkage &&
812       Linkage != GlobalValue::AvailableExternallyLinkage)
813     return false;
814 
815   return true;
816 }
817 
818 // Check if INSTR_PROF_RAW_VERSION_VAR is defined.
819 bool isIRPGOFlagSet(const Module *M) {
820   auto IRInstrVar =
821       M->getNamedGlobal(INSTR_PROF_QUOTE(INSTR_PROF_RAW_VERSION_VAR));
822   if (!IRInstrVar || IRInstrVar->isDeclaration() ||
823       IRInstrVar->hasLocalLinkage())
824     return false;
825 
826   // Check if the flag is set.
827   if (!IRInstrVar->hasInitializer())
828     return false;
829 
830   const Constant *InitVal = IRInstrVar->getInitializer();
831   if (!InitVal)
832     return false;
833 
834   return (dyn_cast<ConstantInt>(InitVal)->getZExtValue() &
835           VARIANT_MASK_IR_PROF) != 0;
836 }
837 
838 // Check if we can safely rename this Comdat function.
839 bool canRenameComdatFunc(const Function &F, bool CheckAddressTaken) {
840   if (F.getName().empty())
841     return false;
842   if (!needsComdatForCounter(F, *(F.getParent())))
843     return false;
844   // Unsafe to rename the address-taken function (which can be used in
845   // function comparison).
846   if (CheckAddressTaken && F.hasAddressTaken())
847     return false;
848   // Only safe to do if this function may be discarded if it is not used
849   // in the compilation unit.
850   if (!GlobalValue::isDiscardableIfUnused(F.getLinkage()))
851     return false;
852 
853   // For AvailableExternallyLinkage functions.
854   if (!F.hasComdat()) {
855     assert(F.getLinkage() == GlobalValue::AvailableExternallyLinkage);
856     return true;
857   }
858   return true;
859 }
860 } // end namespace llvm
861