[SampleFDO] Add ExtBinary format to support extension of binary profile

[wmi]

Summary

This is a patch split from https://reviews.llvm.org/D66374. It tries to add a new format of profile called ExtBinary. The format adds a section header table to the profile and organize the profile in sections, so the future extension like adding a new section or extending an existing section will be easier while keeping backward compatiblity feasible.

[davidxl]

llvm-profdata should also have a round trip test:

text format --> ext-format-> text format --> compare text format before and after

text-format-> binary-format->ext-format-> text format --> compare text format.

Also for the the funcProfile section, should it also have a field (in the header) defining the profile kind, such as LBR samples, llc misses etc. Another question, is multiple such funcProfile section supported?

include/llvm/ProfileData/SampleProfReader.h

511

extend --> extended

521

why retiring the existing section? A natural way is to append a new section of a new type. The format of a new section can even be 'opaque' and the section reader plugin can be provided by the client.

lib/ProfileData/SampleProfWriter.cpp

89

I think it is better to explicit pass SectionStart as the parameter. It should also return a new offset.

101

let this function return an offset that can be passed to addNewSection

tools/llvm-profdata/llvm-profdata.cpp

40

is Compact_Ext_Binary also a choice?

[wmi]

In D66513#1639578, @davidxl wrote:

llvm-profdata should also have a round trip test:

text format --> ext-format-> text format --> compare text format before and after

text-format-> binary-format->ext-format-> text format --> compare text format.

I will add it.

Also for the the funcProfile section, should it also have a field (in the header) defining the profile kind, such as LBR samples, llc misses etc.

My plan was to use different section types to represent different funcProfile sections: secFuncProfile_LBR, secFuncProfile_LBR_LLCM, ... Each will have its own section reader.

Another question, is multiple such funcProfile section supported?

It is supported. Currently reader only read each section according to section tag. It can be multiple sections with the same type. As long as the section reader supports being called multiple times, there is no problem. (FunctionProfile section reader 'readFuncProfile' can be called multiple times)

include/llvm/ProfileData/SampleProfReader.h

511

Will fix.

521

If we want to append cache misses information, we need to express the parent symbol and line offset again in the form of [line offset: cache miss count], that will introduce redundency because we already express line offset in existing function profile. What we want is to append the information directly in the current format like: [line offset: lbr sample count, cache miss count]. That is why I say we may retire the current function profile section v1 and create a new function profile section v2. But the reader of function profile section v1 can be kept if backward compatibility is required.

The format of a new section can even be 'opaque' and the section reader plugin can be provided by the client.

Agreed.

lib/ProfileData/SampleProfWriter.cpp

89

will fix.

tools/llvm-profdata/llvm-profdata.cpp

40

Currently Compact_Binary uses md5 to represent string. Compact_Ext_Binary may confuse people to think the ext format also use md5 to represent string.

In the future, we can port the implementation of Compact_Binary to inherit from Ext_Binary too.

[wmi]

Address David's comment.
Add ExtBinaryBase class for the basics of extensible format and ExtBinary inherits from it, so we can add other types of profiles in extensible format separately.
Some refactoring and comment changes.

[davidxl]

LLC miss info should be very sparse, so mixing it with LBR may not bring a lot of benefit. Having mixure of different types of profile data can lead to combinatorial growth of the number of readers. As the number of profile types increases, it can cause the reader to be unmaintaintable. That is why I suggest making it clean -- one type per section.

Regarding compact format. Does it mean when LLC misses are included, there is no way to use the compact representation?

[wmi]

Address David's comment. Rename some section enums and reserve some enum values.

[davidxl]

lgtm

include/llvm/ProfileData/SampleProf.h

 namespace llvm {
 namespace sampleprof {
 
 enum SampleProfileFormat {
   SPF_None = 0,
   SPF_Text = 0x1,
   SPF_Compact_Binary = 0x2,
   SPF_GCC = 0x3,
+  SPF_Ext_Binary = 0x4,
   SPF_Binary = 0xff
 };
 
 static inline uint64_t SPMagic(SampleProfileFormat Format = SPF_Binary) {
   return uint64_t('S') << (64 - 8) | uint64_t('P') << (64 - 16) |
          uint64_t('R') << (64 - 24) | uint64_t('O') << (64 - 32) |
          uint64_t('F') << (64 - 40) | uint64_t('4') << (64 - 48) |
          uint64_t('2') << (64 - 56) | uint64_t(Format);
 }
 
 // Get the proper representation of a string in the input Format.
 static inline StringRef getRepInFormat(StringRef Name,
                                        SampleProfileFormat Format,
                                        std::string &GUIDBuf) {
   if (Name.empty())
     return Name;
   GUIDBuf = std::to_string(Function::getGUID(Name));
   return (Format == SPF_Compact_Binary) ? StringRef(GUIDBuf) : Name;
 }
 
 static inline uint64_t SPVersion() { return 103; }
 
+// Section Type used by SampleProfileExtBinaryBaseReader and
+// SampleProfileExtBinaryBaseWriter. Never change the existing
+// value of enum. Only append new ones.
+enum SecType {
+  SecInValid = 0,
+  SecProfSummary = 1,
+  SecNameTable = 2,
+  SecFuncProfile = 3
+};
+
+// Entry type of section header table used by SampleProfileExtBinaryBaseReader
+// and SampleProfileExtBinaryBaseWriter.
+struct SecHdrTableEntry {
+  SecType Type;
+  uint64_t Flag;
+  uint64_t Offset;
+  uint64_t Size;
+};
+
 /// Represents the relative location of an instruction.
 ///
 /// Instruction locations are specified by the line offset from the
 /// beginning of the function (marked by the line where the function
 /// header is) and the discriminator value within that line.
 ///
 /// The discriminator value is useful to distinguish instructions
 /// that are on the same line but belong to different basic blocks

include/llvm/ProfileData/SampleProfReader.h

protected:
   bool at_eof() const { return Data >= End; }
 
   /// Read the next function profile instance.
   std::error_code readFuncProfile();
 
   /// Read the contents of the given profile instance.
   std::error_code readProfile(FunctionSamples &FProfile);
 
+  /// Read the contents of Magic number and Version number.
+  std::error_code readMagicIdent();
+
+  /// Read profile summary.
+  std::error_code readSummary();
+
+  /// Read the whole name table.
+  virtual std::error_code readNameTable();
+
   /// Points to the current location in the buffer.
   const uint8_t *Data = nullptr;
 
   /// Points to the end of the buffer.
   const uint8_t *End = nullptr;
 
+  /// Function name table.
+  std::vector<StringRef> NameTable;
+
+  /// Read a string indirectly via the name table.
+  virtual ErrorOr<StringRef> readStringFromTable();
+
 private:
   std::error_code readSummaryEntry(std::vector<ProfileSummaryEntry> &Entries);
   virtual std::error_code verifySPMagic(uint64_t Magic) = 0;
+};
 
-  /// Read profile summary.
-  std::error_code readSummary();
+class SampleProfileReaderRawBinary : public SampleProfileReaderBinary {
+private:
+  virtual std::error_code verifySPMagic(uint64_t Magic) override;
 
-  /// Read the whole name table.
-  virtual std::error_code readNameTable() = 0;
+public:
+  SampleProfileReaderRawBinary(std::unique_ptr<MemoryBuffer> B, LLVMContext &C,
+                               SampleProfileFormat Format = SPF_Binary)
+      : SampleProfileReaderBinary(std::move(B), C, Format) {}
 
-  /// Read a string indirectly via the name table.
-  virtual ErrorOr<StringRef> readStringFromTable() = 0;
+  /// \brief Return true if \p Buffer is in the format supported by this class.
+  static bool hasFormat(const MemoryBuffer &Buffer);
 };
 
-class SampleProfileReaderRawBinary : public SampleProfileReaderBinary {
+/// SampleProfileReaderExtBinaryBase/SampleProfileWriterExtBinaryBase defines
+/// the basic structure of the extensible binary format.
+/// The format is organized in sections except the magic and version number
+/// at the beginning. There is a section table before all the sections, and
+/// each entry in the table describes the entry type, start, size and
+/// attributes. The format in each section is defined by the section itself.
+///
+/// It is easy to add a new section while maintaining the backward
+/// compatibility of the profile. Nothing extra needs to be done. If we want
+/// to extend an existing section, like add cache misses information in
+/// addition to the sample count in the profile body, we can add a new section
+/// with the extension and retire the existing section, and we could choose
+/// to keep the parser of the old section if we want the reader to be able
+/// to read both new and old format profile.
+///
+/// SampleProfileReaderExtBinary/SampleProfileWriterExtBinary define the
+/// commonly used sections of a profile in extensible binary format. It is
+/// possible to define other types of profile inherited from
+/// SampleProfileReaderExtBinaryBase/SampleProfileWriterExtBinaryBase.
+class SampleProfileReaderExtBinaryBase : public SampleProfileReaderBinary {
+protected:
+  std::vector<SecHdrTableEntry> SecHdrTable;
+  std::error_code readSecHdrTableEntry();
+  std::error_code readSecHdrTable();
+  virtual std::error_code readHeader() override;
+  virtual std::error_code verifySPMagic(uint64_t Magic) = 0;
+
+public:
+  SampleProfileReaderExtBinaryBase(std::unique_ptr<MemoryBuffer> B,
+                                   LLVMContext &C, SampleProfileFormat Format)
+      : SampleProfileReaderBinary(std::move(B), C, Format) {}
+
+  /// Read sample profiles in extensible format from the associated file.
+  std::error_code read() override;
+};
+
+class SampleProfileReaderExtBinary : public SampleProfileReaderExtBinaryBase {
 private:
-  /// Function name table.
-  std::vector<StringRef> NameTable;
   virtual std::error_code verifySPMagic(uint64_t Magic) override;
-  virtual std::error_code readNameTable() override;
-  /// Read a string indirectly via the name table.
-  virtual ErrorOr<StringRef> readStringFromTable() override;
 
 public:
-  SampleProfileReaderRawBinary(std::unique_ptr<MemoryBuffer> B, LLVMContext &C)
-      : SampleProfileReaderBinary(std::move(B), C, SPF_Binary) {}
+  SampleProfileReaderExtBinary(std::unique_ptr<MemoryBuffer> B, LLVMContext &C,
+                               SampleProfileFormat Format = SPF_Ext_Binary)
+      : SampleProfileReaderExtBinaryBase(std::move(B), C, Format) {}
 
   /// \brief Return true if \p Buffer is in the format supported by this class.
   static bool hasFormat(const MemoryBuffer &Buffer);
 };
 
 class SampleProfileReaderCompactBinary : public SampleProfileReaderBinary {
 private:
   /// Function name table.
   std::vector<std::string> NameTable;
   /// The table mapping from function name to the offset of its FunctionSample
   /// towards file start.
   DenseMap<StringRef, uint64_t> FuncOffsetTable;
   /// The set containing the functions to use when compiling a module.
   DenseSet<StringRef> FuncsToUse;
   /// Use all functions from the input profile.
   bool UseAllFuncs = true;
   virtual std::error_code verifySPMagic(uint64_t Magic) override;
   virtual std::error_code readNameTable() override;
   /// Read a string indirectly via the name table.
   virtual ErrorOr<StringRef> readStringFromTable() override;
   virtual std::error_code readHeader() override;
   std::error_code readFuncOffsetTable();
 
 public:
   SampleProfileReaderCompactBinary(std::unique_ptr<MemoryBuffer> B,
                                    LLVMContext &C)
       : SampleProfileReaderBinary(std::move(B), C, SPF_Compact_Binary) {}
 

include/llvm/ProfileData/SampleProfWriter.h

 /// Sample-based profile writer. Base class.
 class SampleProfileWriter {
 public:
   virtual ~SampleProfileWriter() = default;
 
   /// Write sample profiles in \p S.
   ///
   /// \returns status code of the file update operation.
-  virtual std::error_code write(const FunctionSamples &S) = 0;
+  virtual std::error_code writeSample(const FunctionSamples &S) = 0;
 
   /// Write all the sample profiles in the given map of samples.
   ///
   /// \returns status code of the file update operation.
   virtual std::error_code write(const StringMap<FunctionSamples> &ProfileMap);
 
   raw_ostream &getOutputStream() { return *OutputStream; }
 

 protected:
   SampleProfileWriter(std::unique_ptr<raw_ostream> &OS)
       : OutputStream(std::move(OS)) {}
 
   /// Write a file header for the profile file.
   virtual std::error_code
   writeHeader(const StringMap<FunctionSamples> &ProfileMap) = 0;
 
+  // Write function profiles to the profile file.
+  virtual std::error_code
+  writeFuncProfiles(const StringMap<FunctionSamples> &ProfileMap);
+
   /// Output stream where to emit the profile to.
   std::unique_ptr<raw_ostream> OutputStream;
 
   /// Profile summary.
   std::unique_ptr<ProfileSummary> Summary;
 
   /// Compute summary for this profile.
   void computeSummary(const StringMap<FunctionSamples> &ProfileMap);
+
+  /// Profile format.
+  SampleProfileFormat Format;
 };
 
 /// Sample-based profile writer (text format).
 class SampleProfileWriterText : public SampleProfileWriter {
 public:
-  std::error_code write(const FunctionSamples &S) override;
+  std::error_code writeSample(const FunctionSamples &S) override;
 
 protected:
   SampleProfileWriterText(std::unique_ptr<raw_ostream> &OS)
       : SampleProfileWriter(OS), Indent(0) {}
 
   std::error_code
   writeHeader(const StringMap<FunctionSamples> &ProfileMap) override {
     return sampleprof_error::success;
   }
 
 private:
   /// Indent level to use when writing.
   ///
   /// This is used when printing inlined callees.
   unsigned Indent;
 
   friend ErrorOr<std::unique_ptr<SampleProfileWriter>>
   SampleProfileWriter::create(std::unique_ptr<raw_ostream> &OS,
                               SampleProfileFormat Format);
 };
 
 /// Sample-based profile writer (binary format).
 class SampleProfileWriterBinary : public SampleProfileWriter {
 public:
-  virtual std::error_code write(const FunctionSamples &S) override;
+  virtual std::error_code writeSample(const FunctionSamples &S) override;
+
+protected:
   SampleProfileWriterBinary(std::unique_ptr<raw_ostream> &OS)
       : SampleProfileWriter(OS) {}
 
-protected:
-  virtual std::error_code writeNameTable() = 0;
-  virtual std::error_code writeMagicIdent() = 0;
+  virtual std::error_code writeMagicIdent(SampleProfileFormat Format);
+  virtual std::error_code writeNameTable();
   virtual std::error_code
   writeHeader(const StringMap<FunctionSamples> &ProfileMap) override;
   std::error_code writeSummary();
   std::error_code writeNameIdx(StringRef FName);
   std::error_code writeBody(const FunctionSamples &S);
   inline void stablizeNameTable(std::set<StringRef> &V);
 
   MapVector<StringRef, uint32_t> NameTable;
 
-private:
   void addName(StringRef FName);
   void addNames(const FunctionSamples &S);
 
+private:
   friend ErrorOr<std::unique_ptr<SampleProfileWriter>>
   SampleProfileWriter::create(std::unique_ptr<raw_ostream> &OS,
                               SampleProfileFormat Format);
 };
 
 class SampleProfileWriterRawBinary : public SampleProfileWriterBinary {
   using SampleProfileWriterBinary::SampleProfileWriterBinary;
+};
+
+class SampleProfileWriterExtBinaryBase : public SampleProfileWriterBinary {
+  using SampleProfileWriterBinary::SampleProfileWriterBinary;
+
+public:
+  virtual std::error_code
+  write(const StringMap<FunctionSamples> &ProfileMap) override;
 
 protected:
-  virtual std::error_code writeNameTable() override;
-  virtual std::error_code writeMagicIdent() override;
+  uint64_t markSectionStart();
+  uint64_t addNewSection(SecType Sec, uint64_t SectionStart);
+  virtual void initSectionLayout() = 0;
+  virtual std::error_code
+  writeSections(const StringMap<FunctionSamples> &ProfileMap) = 0;
+
+  // Specifiy the section layout in the profile. Note that the order in
+  // SecHdrTable (order to collect sections) may be different from the
+  // order in SectionLayout (order to write out sections into profile).
+  SmallVector<SecType, 8> SectionLayout;
+
+private:
+  void allocSecHdrTable();
+  std::error_code writeSecHdrTable();
+  virtual std::error_code
+  writeHeader(const StringMap<FunctionSamples> &ProfileMap) override;
+
+  // The location where the output stream starts.
+  uint64_t FileStart;
+  // The location in the output stream where the SecHdrTable should be
+  // written to.
+  uint64_t SecHdrTableOffset;
+  std::vector<SecHdrTableEntry> SecHdrTable;
+};
+
+class SampleProfileWriterExtBinary : public SampleProfileWriterExtBinaryBase {
+  using SampleProfileWriterExtBinaryBase::SampleProfileWriterExtBinaryBase;
+
+private:
+  virtual void initSectionLayout() {
+    SectionLayout = {SecProfSummary, SecNameTable, SecFuncProfile};
+  };
+  virtual std::error_code
+  writeSections(const StringMap<FunctionSamples> &ProfileMap) override;
 };
 
 // CompactBinary is a compact format of binary profile which both reduces
 // the profile size and the load time needed when compiling. It has two
 // major difference with Binary format.
 // 1. It represents all the strings in name table using md5 hash.
 // 2. It saves a function offset table which maps function name index to
 // the offset of its function profile to the start of the binary profile,

 //             function3 name index --> function3 profile start
 //
 // We need Part2 because profile reader can use it to find out and read
 // function offset table without reading Part3 first.
 class SampleProfileWriterCompactBinary : public SampleProfileWriterBinary {
   using SampleProfileWriterBinary::SampleProfileWriterBinary;
 
 public:
-  virtual std::error_code write(const FunctionSamples &S) override;
+  virtual std::error_code writeSample(const FunctionSamples &S) override;
   virtual std::error_code
   write(const StringMap<FunctionSamples> &ProfileMap) override;
 
 protected:
   /// The table mapping from function name to the offset of its FunctionSample
   /// towards profile start.
   MapVector<StringRef, uint64_t> FuncOffsetTable;
   /// The offset of the slot to be filled with the offset of FuncOffsetTable
   /// towards profile start.
   uint64_t TableOffset;
   virtual std::error_code writeNameTable() override;
-  virtual std::error_code writeMagicIdent() override;
   virtual std::error_code
   writeHeader(const StringMap<FunctionSamples> &ProfileMap) override;
   std::error_code writeFuncOffsetTable();
 };
 
 } // end namespace sampleprof
 } // end namespace llvm
 
 #endif // LLVM_PROFILEDATA_SAMPLEPROFWRITER_H

lib/ProfileData/SampleProfReader.cpp

inline ErrorOr<uint32_t> SampleProfileReaderBinary::readStringIndex(T &Table) {
   auto Idx = readNumber<uint32_t>();
   if (std::error_code EC = Idx.getError())
     return EC;
   if (*Idx >= Table.size())
     return sampleprof_error::truncated_name_table;
   return *Idx;
 }
 
-ErrorOr<StringRef> SampleProfileReaderRawBinary::readStringFromTable() {
+ErrorOr<StringRef> SampleProfileReaderBinary::readStringFromTable() {
   auto Idx = readStringIndex(NameTable);
   if (std::error_code EC = Idx.getError())
     return EC;
 
   return NameTable[*Idx];
 }
 
 ErrorOr<StringRef> SampleProfileReaderCompactBinary::readStringFromTable() {
std::error_code SampleProfileReaderBinary::read() {
   while (!at_eof()) {
     if (std::error_code EC = readFuncProfile())
       return EC;
   }
 
   return sampleprof_error::success;
 }
 
+std::error_code SampleProfileReaderExtBinaryBase::read() {
+  const uint8_t *BufStart =
+      reinterpret_cast<const uint8_t *>(Buffer->getBufferStart());
+
+  for (auto &Entry : SecHdrTable) {
+    // Skip empty section.
+    if (!Entry.Size)
+      continue;
+    Data = BufStart + Entry.Offset;
+    switch (Entry.Type) {
+    case SecProfSummary:
+      if (std::error_code EC = readSummary())
+        return EC;
+      break;
+    case SecNameTable:
+      if (std::error_code EC = readNameTable())
+        return EC;
+      break;
+    case SecFuncProfile:
+      while (Data < BufStart + Entry.Offset + Entry.Size) {
+        if (std::error_code EC = readFuncProfile())
+          return EC;
+      }
+      break;
+    default:
+      continue;
+    }
+    if (Data != BufStart + Entry.Offset + Entry.Size)
+      return sampleprof_error::malformed;
+  }
+
+  return sampleprof_error::success;
+}
+
 std::error_code SampleProfileReaderCompactBinary::read() {
   std::vector<uint64_t> OffsetsToUse;
   if (UseAllFuncs) {
     for (auto FuncEntry : FuncOffsetTable) {
       OffsetsToUse.push_back(FuncEntry.second);
     }
   }
   else {

 }
 
 std::error_code SampleProfileReaderRawBinary::verifySPMagic(uint64_t Magic) {
   if (Magic == SPMagic())
     return sampleprof_error::success;
   return sampleprof_error::bad_magic;
 }
 
+std::error_code SampleProfileReaderExtBinary::verifySPMagic(uint64_t Magic) {
+  if (Magic == SPMagic(SPF_Ext_Binary))
+    return sampleprof_error::success;
+  return sampleprof_error::bad_magic;
+}
+
 std::error_code
 SampleProfileReaderCompactBinary::verifySPMagic(uint64_t Magic) {
   if (Magic == SPMagic(SPF_Compact_Binary))
     return sampleprof_error::success;
   return sampleprof_error::bad_magic;
 }
 
-std::error_code SampleProfileReaderRawBinary::readNameTable() {
+std::error_code SampleProfileReaderBinary::readNameTable() {
   auto Size = readNumber<uint32_t>();
   if (std::error_code EC = Size.getError())
     return EC;
   NameTable.reserve(*Size);
   for (uint32_t I = 0; I < *Size; ++I) {
     auto Name(readString());
     if (std::error_code EC = Name.getError())
       return EC;
for (uint32_t I = 0; I < *Size; ++I) {
     auto FID = readNumber<uint64_t>();
     if (std::error_code EC = FID.getError())
       return EC;
     NameTable.push_back(std::to_string(*FID));
   }
   return sampleprof_error::success;
 }
 
-std::error_code SampleProfileReaderBinary::readHeader() {
-  Data = reinterpret_cast<const uint8_t *>(Buffer->getBufferStart());
-  End = Data + Buffer->getBufferSize();
+std::error_code SampleProfileReaderExtBinaryBase::readSecHdrTableEntry() {
+  SecHdrTableEntry Entry;
+  auto Type = readUnencodedNumber<uint64_t>();
+  if (std::error_code EC = Type.getError())
+    return EC;
+  Entry.Type = static_cast<SecType>(*Type);
+
+  auto Flag = readUnencodedNumber<uint64_t>();
+  if (std::error_code EC = Flag.getError())
+    return EC;
+  Entry.Flag = *Flag;
+
+  auto Offset = readUnencodedNumber<uint64_t>();
+  if (std::error_code EC = Offset.getError())
+    return EC;
+  Entry.Offset = *Offset;
+
+  auto Size = readUnencodedNumber<uint64_t>();
+  if (std::error_code EC = Size.getError())
+    return EC;
+  Entry.Size = *Size;
+
+  SecHdrTable.push_back(std::move(Entry));
+  return sampleprof_error::success;
+}
+
+std::error_code SampleProfileReaderExtBinaryBase::readSecHdrTable() {
+  auto EntryNum = readUnencodedNumber<uint64_t>();
+  if (std::error_code EC = EntryNum.getError())
+    return EC;
+
+  for (uint32_t i = 0; i < (*EntryNum); i++)
+    if (std::error_code EC = readSecHdrTableEntry())
+      return EC;
+
+  return sampleprof_error::success;
+}
+
+std::error_code SampleProfileReaderExtBinaryBase::readHeader() {
+  const uint8_t *BufStart =
+      reinterpret_cast<const uint8_t *>(Buffer->getBufferStart());
+  Data = BufStart;
+  End = BufStart + Buffer->getBufferSize();
+
+  if (std::error_code EC = readMagicIdent())
+    return EC;
+
+  if (std::error_code EC = readSecHdrTable())
+    return EC;
+
+  return sampleprof_error::success;
+}
 
+std::error_code SampleProfileReaderBinary::readMagicIdent() {
   // Read and check the magic identifier.
   auto Magic = readNumber<uint64_t>();
   if (std::error_code EC = Magic.getError())
     return EC;
   else if (std::error_code EC = verifySPMagic(*Magic))
     return EC;
 
   // Read the version number.
   auto Version = readNumber<uint64_t>();
   if (std::error_code EC = Version.getError())
     return EC;
   else if (*Version != SPVersion())
     return sampleprof_error::unsupported_version;
 
+  return sampleprof_error::success;
+}
+
+std::error_code SampleProfileReaderBinary::readHeader() {
+  Data = reinterpret_cast<const uint8_t *>(Buffer->getBufferStart());
+  End = Data + Buffer->getBufferSize();
+
+  if (std::error_code EC = readMagicIdent())
+    return EC;
+
   if (std::error_code EC = readSummary())
     return EC;
 
   if (std::error_code EC = readNameTable())
     return EC;
   return sampleprof_error::success;
 }
 

 
 bool SampleProfileReaderRawBinary::hasFormat(const MemoryBuffer &Buffer) {
   const uint8_t *Data =
       reinterpret_cast<const uint8_t *>(Buffer.getBufferStart());
   uint64_t Magic = decodeULEB128(Data);
   return Magic == SPMagic();
 }
 
+bool SampleProfileReaderExtBinary::hasFormat(const MemoryBuffer &Buffer) {
+  const uint8_t *Data =
+      reinterpret_cast<const uint8_t *>(Buffer.getBufferStart());
+  uint64_t Magic = decodeULEB128(Data);
+  return Magic == SPMagic(SPF_Ext_Binary);
+}
+
 bool SampleProfileReaderCompactBinary::hasFormat(const MemoryBuffer &Buffer) {
   const uint8_t *Data =
       reinterpret_cast<const uint8_t *>(Buffer.getBufferStart());
   uint64_t Magic = decodeULEB128(Data);
   return Magic == SPMagic(SPF_Compact_Binary);
 }
 
 std::error_code SampleProfileReaderGCC::skipNextWord() {

 /// \param C The LLVM context to use to emit diagnostics.
 ///
 /// \returns an error code indicating the status of the created reader.
 ErrorOr<std::unique_ptr<SampleProfileReader>>
 SampleProfileReader::create(std::unique_ptr<MemoryBuffer> &B, LLVMContext &C) {
   std::unique_ptr<SampleProfileReader> Reader;
   if (SampleProfileReaderRawBinary::hasFormat(*B))
     Reader.reset(new SampleProfileReaderRawBinary(std::move(B), C));
+  else if (SampleProfileReaderExtBinary::hasFormat(*B))
+    Reader.reset(new SampleProfileReaderExtBinary(std::move(B), C));
   else if (SampleProfileReaderCompactBinary::hasFormat(*B))
     Reader.reset(new SampleProfileReaderCompactBinary(std::move(B), C));
   else if (SampleProfileReaderGCC::hasFormat(*B))
     Reader.reset(new SampleProfileReaderGCC(std::move(B), C));
   else if (SampleProfileReaderText::hasFormat(*B))
     Reader.reset(new SampleProfileReaderText(std::move(B), C));
   else
     return sampleprof_error::unrecognized_format;
 
   FunctionSamples::Format = Reader->getFormat();
-  if (std::error_code EC = Reader->readHeader())
+  if (std::error_code EC = Reader->readHeader()) {
     return EC;
+  }
 
   return std::move(Reader);
 }
 
 // For text and GCC file formats, we compute the summary after reading the
 // profile. Binary format has the profile summary in its header.
 void SampleProfileReader::computeSummary() {
   SampleProfileSummaryBuilder Builder(ProfileSummaryBuilder::DefaultCutoffs);
   for (const auto &I : Profiles) {
     const FunctionSamples &Profile = I.second;
     Builder.addRecord(Profile);
   }
   Summary = Builder.getSummary();
 }

lib/ProfileData/SampleProfWriter.cpp

 #include <set>
 #include <system_error>
 #include <utility>
 #include <vector>
 
 using namespace llvm;
 using namespace sampleprof;
 
-std::error_code
-SampleProfileWriter::write(const StringMap<FunctionSamples> &ProfileMap) {
-  if (std::error_code EC = writeHeader(ProfileMap))
-    return EC;
-
+std::error_code SampleProfileWriter::writeFuncProfiles(
+    const StringMap<FunctionSamples> &ProfileMap) {
   // Sort the ProfileMap by total samples.
   typedef std::pair<StringRef, const FunctionSamples *> NameFunctionSamples;
   std::vector<NameFunctionSamples> V;
   for (const auto &I : ProfileMap)
     V.push_back(std::make_pair(I.getKey(), &I.second));
 
   llvm::stable_sort(
       V, [](const NameFunctionSamples &A, const NameFunctionSamples &B) {
         if (A.second->getTotalSamples() == B.second->getTotalSamples())
           return A.first > B.first;
         return A.second->getTotalSamples() > B.second->getTotalSamples();
       });
 
   for (const auto &I : V) {
-    if (std::error_code EC = write(*I.second))
-      return EC;
+    if (std::error_code EC = writeSample(*I.second))
+      return EC;
+  }
+  return sampleprof_error::success;
+}
+
+std::error_code
+SampleProfileWriter::write(const StringMap<FunctionSamples> &ProfileMap) {
+  if (std::error_code EC = writeHeader(ProfileMap))
+    return EC;
+
+  if (std::error_code EC = writeFuncProfiles(ProfileMap))
+    return EC;
+
+  return sampleprof_error::success;
+}
+
+/// Return the current position and prepare to use it as the start
+/// position of a section.
+uint64_t SampleProfileWriterExtBinaryBase::markSectionStart() {
+  return OutputStream->tell();
+}
+
+/// Add a new section into section header table. Return the position
+/// of SectionEnd.
+uint64_t
+SampleProfileWriterExtBinaryBase::addNewSection(SecType Sec,
+                                                uint64_t SectionStart) {
+  uint64_t SectionEnd = OutputStream->tell();
+  SecHdrTable.push_back(
+      {Sec, 0, SectionStart - FileStart, SectionEnd - SectionStart});
+  return SectionEnd;
+}
+
+std::error_code SampleProfileWriterExtBinaryBase::write(
+    const StringMap<FunctionSamples> &ProfileMap) {
+  if (std::error_code EC = writeHeader(ProfileMap))
+    return EC;
+
+  if (std::error_code EC = writeSections(ProfileMap))
+    return EC;
+
+  if (std::error_code EC = writeSecHdrTable())
+    return EC;
+
+  return sampleprof_error::success;
+}
+
+std::error_code SampleProfileWriterExtBinary::writeSections(
+    const StringMap<FunctionSamples> &ProfileMap) {
+  uint64_t SectionStart = markSectionStart();
+  computeSummary(ProfileMap);
+  if (auto EC = writeSummary())
+  SectionStart = addNewSection(SecProfSummary, SectionStart);
+
+  // Generate the name table for all the functions referenced in the profile.
+  for (const auto &I : ProfileMap) {
+    addName(I.first());
+    addNames(I.second);
   }
+  writeNameTable();
+  SectionStart = addNewSection(SecNameTable, SectionStart);
+
+  if (std::error_code EC = writeFuncProfiles(ProfileMap))
+    return EC;
+  addNewSection(SecFuncProfile, SectionStart);
+
   return sampleprof_error::success;
 }
 
 std::error_code SampleProfileWriterCompactBinary::write(
     const StringMap<FunctionSamples> &ProfileMap) {
   if (std::error_code EC = SampleProfileWriter::write(ProfileMap))
     return EC;
   if (std::error_code EC = writeFuncOffsetTable())
     return EC;
   return sampleprof_error::success;
 }
 
 /// Write samples to a text file.
 ///
 /// Note: it may be tempting to implement this in terms of
 /// FunctionSamples::print().  Please don't.  The dump functionality is intended
 /// for debugging and has no specified form.
 ///
 /// The format used here is more structured and deliberate because
 /// it needs to be parsed by the SampleProfileReaderText class.
-std::error_code SampleProfileWriterText::write(const FunctionSamples &S) {
+std::error_code SampleProfileWriterText::writeSample(const FunctionSamples &S) {
   auto &OS = *OutputStream;
   OS << S.getName() << ":" << S.getTotalSamples();
   if (Indent == 0)
     OS << ":" << S.getHeadSamples();
   OS << "\n";
 
   SampleSorter<LineLocation, SampleRecord> SortedSamples(S.getBodySamples());
   for (const auto &I : SortedSamples.get()) {
for (const auto &I : SortedCallsiteSamples.get())
     for (const auto &FS : I->second) {
       LineLocation Loc = I->first;
       const FunctionSamples &CalleeSamples = FS.second;
       OS.indent(Indent);
       if (Loc.Discriminator == 0)
         OS << Loc.LineOffset << ": ";
       else
         OS << Loc.LineOffset << "." << Loc.Discriminator << ": ";
-      if (std::error_code EC = write(CalleeSamples))
+      if (std::error_code EC = writeSample(CalleeSamples))
         return EC;
     }
   Indent -= 1;
 
   return sampleprof_error::success;
 }
 
 std::error_code SampleProfileWriterBinary::writeNameIdx(StringRef FName) {
void SampleProfileWriterBinary::stablizeNameTable(std::set<StringRef> &V) {
   // Sort the names to make NameTable deterministic.
   for (const auto &I : NameTable)
     V.insert(I.first);
   int i = 0;
   for (const StringRef &N : V)
     NameTable[N] = i++;
 }
 
-std::error_code SampleProfileWriterRawBinary::writeNameTable() {
+std::error_code SampleProfileWriterBinary::writeNameTable() {
   auto &OS = *OutputStream;
   std::set<StringRef> V;
   stablizeNameTable(V);
 
   // Write out the name table.
   encodeULEB128(NameTable.size(), OS);
   for (auto N : V) {
     OS << N;
std::error_code SampleProfileWriterCompactBinary::writeNameTable() {
   // Write out the name table.
   encodeULEB128(NameTable.size(), OS);
   for (auto N : V) {
     encodeULEB128(MD5Hash(N), OS);
   }
   return sampleprof_error::success;
 }
 
-std::error_code SampleProfileWriterRawBinary::writeMagicIdent() {
-  auto &OS = *OutputStream;
-  // Write file magic identifier.
-  encodeULEB128(SPMagic(), OS);
-  encodeULEB128(SPVersion(), OS);
-  return sampleprof_error::success;
-}
-
-std::error_code SampleProfileWriterCompactBinary::writeMagicIdent() {
+std::error_code
+SampleProfileWriterBinary::writeMagicIdent(SampleProfileFormat Format) {
   auto &OS = *OutputStream;
   // Write file magic identifier.
-  encodeULEB128(SPMagic(SPF_Compact_Binary), OS);
+  encodeULEB128(SPMagic(Format), OS);
   encodeULEB128(SPVersion(), OS);
   return sampleprof_error::success;
 }
 
 std::error_code SampleProfileWriterBinary::writeHeader(
     const StringMap<FunctionSamples> &ProfileMap) {
-  writeMagicIdent();
+  writeMagicIdent(Format);
 
   computeSummary(ProfileMap);
   if (auto EC = writeSummary())
     return EC;
 
   // Generate the name table for all the functions referenced in the profile.
   for (const auto &I : ProfileMap) {
     addName(I.first());
     addNames(I.second);
   }
 
   writeNameTable();
   return sampleprof_error::success;
 }
 
+void SampleProfileWriterExtBinaryBase::allocSecHdrTable() {
+  support::endian::Writer Writer(*OutputStream, support::little);
+
+  Writer.write(static_cast<uint64_t>(SectionLayout.size()));
+  SecHdrTableOffset = OutputStream->tell();
+  for (uint32_t i = 0; i < SectionLayout.size(); i++) {
+    Writer.write(static_cast<uint64_t>(-1));
+    Writer.write(static_cast<uint64_t>(-1));
+    Writer.write(static_cast<uint64_t>(-1));
+    Writer.write(static_cast<uint64_t>(-1));
+  }
+}
+
+std::error_code SampleProfileWriterExtBinaryBase::writeSecHdrTable() {
+  auto &OFS = static_cast<raw_fd_ostream &>(*OutputStream);
+  uint64_t Saved = OutputStream->tell();
+
+  // Set OutputStream to the location saved in SecHdrTableOffset.
+  if (OFS.seek(SecHdrTableOffset) == (uint64_t)-1)
+    return sampleprof_error::ostream_seek_unsupported;
+  support::endian::Writer Writer(*OutputStream, support::little);
+
+  DenseMap<uint32_t, uint32_t> IndexMap;
+  for (uint32_t i = 0; i < SecHdrTable.size(); i++) {
+    IndexMap.insert({static_cast<uint32_t>(SecHdrTable[i].Type), i});
+  }
+
+  // Write the sections in the order specified in SectionLayout.
+  // That is the sections order Reader will see. Note that the
+  // sections order in which Reader expects to read may be different
+  // from the order in which Writer is able to write, so we need
+  // to adjust the order in SecHdrTable to be consistent with
+  // SectionLayout when we write SecHdrTable to the memory.
+  for (uint32_t i = 0; i < SectionLayout.size(); i++) {
+    uint32_t idx = IndexMap[static_cast<uint32_t>(SectionLayout[i])];
+    Writer.write(static_cast<uint64_t>(SecHdrTable[idx].Type));
+    Writer.write(static_cast<uint64_t>(SecHdrTable[idx].Flag));
+    Writer.write(static_cast<uint64_t>(SecHdrTable[idx].Offset));
+    Writer.write(static_cast<uint64_t>(SecHdrTable[idx].Size));
+  }
+
+  // Reset OutputStream.
+  if (OFS.seek(Saved) == (uint64_t)-1)
+    return sampleprof_error::ostream_seek_unsupported;
+
+  return sampleprof_error::success;
+}
+
+std::error_code SampleProfileWriterExtBinaryBase::writeHeader(
+    const StringMap<FunctionSamples> &ProfileMap) {
+  auto &OS = *OutputStream;
+  FileStart = OS.tell();
+  writeMagicIdent(Format);
+
+  initSectionLayout();
+  allocSecHdrTable();
+  return sampleprof_error::success;
+}
+
 std::error_code SampleProfileWriterCompactBinary::writeHeader(
     const StringMap<FunctionSamples> &ProfileMap) {
   support::endian::Writer Writer(*OutputStream, support::little);
   if (auto EC = SampleProfileWriterBinary::writeHeader(ProfileMap))
     return EC;
 
   // Reserve a slot for the offset of function offset table. The slot will
   // be populated with the offset of FuncOffsetTable later.
for (const auto &J : S.getCallsiteSamples())
     }
 
   return sampleprof_error::success;
 }
 
 /// Write samples of a top-level function to a binary file.
 ///
 /// \returns true if the samples were written successfully, false otherwise.
-std::error_code SampleProfileWriterBinary::write(const FunctionSamples &S) {
+std::error_code
+SampleProfileWriterBinary::writeSample(const FunctionSamples &S) {
   encodeULEB128(S.getHeadSamples(), *OutputStream);
   return writeBody(S);
 }
 
 std::error_code
-SampleProfileWriterCompactBinary::write(const FunctionSamples &S) {
+SampleProfileWriterCompactBinary::writeSample(const FunctionSamples &S) {
   uint64_t Offset = OutputStream->tell();
   StringRef Name = S.getName();
   FuncOffsetTable[Name] = Offset;
   encodeULEB128(S.getHeadSamples(), *OutputStream);
   return writeBody(S);
 }
 
 /// Create a sample profile file writer based on the specified format.
 ///
 /// \param Filename The file to create.
 ///
 /// \param Format Encoding format for the profile file.
 ///
 /// \returns an error code indicating the status of the created writer.
 ErrorOr<std::unique_ptr<SampleProfileWriter>>
 SampleProfileWriter::create(StringRef Filename, SampleProfileFormat Format) {
   std::error_code EC;
   std::unique_ptr<raw_ostream> OS;
-  if (Format == SPF_Binary || Format == SPF_Compact_Binary)
+  if (Format == SPF_Binary || Format == SPF_Ext_Binary ||
+      Format == SPF_Compact_Binary)
     OS.reset(new raw_fd_ostream(Filename, EC, sys::fs::OF_None));
   else
     OS.reset(new raw_fd_ostream(Filename, EC, sys::fs::OF_Text));
   if (EC)
     return EC;
 
   return create(OS, Format);
 }
 
 /// Create a sample profile stream writer based on the specified format.
 ///
 /// \param OS The output stream to store the profile data to.
 ///
 /// \param Format Encoding format for the profile file.
 ///
 /// \returns an error code indicating the status of the created writer.
 ErrorOr<std::unique_ptr<SampleProfileWriter>>
 SampleProfileWriter::create(std::unique_ptr<raw_ostream> &OS,
                             SampleProfileFormat Format) {
   std::error_code EC;
   std::unique_ptr<SampleProfileWriter> Writer;
 
   if (Format == SPF_Binary)
     Writer.reset(new SampleProfileWriterRawBinary(OS));
+  else if (Format == SPF_Ext_Binary)
+    Writer.reset(new SampleProfileWriterExtBinary(OS));
   else if (Format == SPF_Compact_Binary)
     Writer.reset(new SampleProfileWriterCompactBinary(OS));
   else if (Format == SPF_Text)
     Writer.reset(new SampleProfileWriterText(OS));
   else if (Format == SPF_GCC)
     EC = sampleprof_error::unsupported_writing_format;
   else
     EC = sampleprof_error::unrecognized_format;
 
   if (EC)
     return EC;
 
+  Writer->Format = Format;
   return std::move(Writer);
 }
 
 void SampleProfileWriter::computeSummary(
     const StringMap<FunctionSamples> &ProfileMap) {
   SampleProfileSummaryBuilder Builder(ProfileSummaryBuilder::DefaultCutoffs);
   for (const auto &I : ProfileMap) {
     const FunctionSamples &Profile = I.second;
     Builder.addRecord(Profile);
   }
   Summary = Builder.getSummary();
 }

test/Transforms/SampleProfile/compact-binary-profile.ll

-; RUN: opt < %s -sample-profile -sample-profile-file=%S/Inputs/inline.prof -S | FileCheck %s
-; RUN: opt < %s -passes=sample-profile -sample-profile-file=%S/Inputs/inline.prof -S | FileCheck %s
-; RUN: opt < %s -sample-profile -sample-profile-file=%S/Inputs/inline.compactbinary.afdo -S | FileCheck %s
-; RUN: opt < %s -passes=sample-profile -sample-profile-file=%S/Inputs/inline.compactbinary.afdo -S | FileCheck %s
-
-; Original C++ test case
-;
-; #include <stdio.h>
-;
-; int sum(int x, int y) {
-;   return x + y;
-; }
-;
-; int main() {
-;   int s, i = 0;
-;   while (i++ < 20000 * 20000)
-;     if (i != 100) s = sum(i, s); else s = 30;
-;   printf("sum is %d\n", s);
-;   return 0;
-; }
-;
-@.str = private unnamed_addr constant [11 x i8] c"sum is %d\0A\00", align 1
-
-; Check sample-profile phase using compactbinary format profile will annotate
-; the IR with exactly the same result as using text format.
-; CHECK: br i1 %cmp, label %while.body, label %while.end{{.*}} !prof ![[IDX1:[0-9]*]]
-; CHECK: br i1 %cmp1, label %if.then, label %if.else{{.*}} !prof ![[IDX2:[0-9]*]]
-; CHECK: call i32 (i8*, ...) @printf{{.*}} !prof ![[IDX3:[0-9]*]]
-; CHECK: = !{!"TotalCount", i64 26781}
-; CHECK: = !{!"MaxCount", i64 5553}
-; CHECK: ![[IDX1]] = !{!"branch_weights", i32 5392, i32 163}
-; CHECK: ![[IDX2]] = !{!"branch_weights", i32 5280, i32 113}
-; CHECK: ![[IDX3]] = !{!"branch_weights", i32 1}
-
-; Function Attrs: nounwind uwtable
-define i32 @_Z3sumii(i32 %x, i32 %y) !dbg !4 {
-entry:
-  %x.addr = alloca i32, align 4
-  %y.addr = alloca i32, align 4
-  store i32 %x, i32* %x.addr, align 4
-  store i32 %y, i32* %y.addr, align 4
-  %0 = load i32, i32* %x.addr, align 4, !dbg !11
-  %1 = load i32, i32* %y.addr, align 4, !dbg !11
-  %add = add nsw i32 %0, %1, !dbg !11
-  ret i32 %add, !dbg !11
-}
-
-; Function Attrs: uwtable
-define i32 @main() !dbg !7 {
-entry:
-  %retval = alloca i32, align 4
-  %s = alloca i32, align 4
-  %i = alloca i32, align 4
-  store i32 0, i32* %retval
-  store i32 0, i32* %i, align 4, !dbg !12
-  br label %while.cond, !dbg !13
-
-while.cond:                                       ; preds = %if.end, %entry
-  %0 = load i32, i32* %i, align 4, !dbg !14
-  %inc = add nsw i32 %0, 1, !dbg !14
-  store i32 %inc, i32* %i, align 4, !dbg !14
-  %cmp = icmp slt i32 %0, 400000000, !dbg !14
-  br i1 %cmp, label %while.body, label %while.end, !dbg !14
-
-while.body:                                       ; preds = %while.cond
-  %1 = load i32, i32* %i, align 4, !dbg !16
-  %cmp1 = icmp ne i32 %1, 100, !dbg !16
-  br i1 %cmp1, label %if.then, label %if.else, !dbg !16
-
-
-if.then:                                          ; preds = %while.body
-  %2 = load i32, i32* %i, align 4, !dbg !18
-  %3 = load i32, i32* %s, align 4, !dbg !18
-  %call = call i32 @_Z3sumii(i32 %2, i32 %3), !dbg !18
-  store i32 %call, i32* %s, align 4, !dbg !18
-  br label %if.end, !dbg !18
-
-if.else:                                          ; preds = %while.body
-  store i32 30, i32* %s, align 4, !dbg !20
-  br label %if.end
-
-if.end:                                           ; preds = %if.else, %if.then
-  br label %while.cond, !dbg !22
-
-while.end:                                        ; preds = %while.cond
-  %4 = load i32, i32* %s, align 4, !dbg !24
-  %call2 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([11 x i8], [11 x i8]* @.str, i32 0, i32 0), i32 %4), !dbg !24
-  ret i32 0, !dbg !25
-}
-
-declare i32 @printf(i8*, ...) #2
-
-!llvm.dbg.cu = !{!0}
-!llvm.module.flags = !{!8, !9}
-!llvm.ident = !{!10}
-
-!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, producer: "clang version 3.5 ", isOptimized: false, emissionKind: NoDebug, file: !1, enums: !2, retainedTypes: !2, globals: !2, imports: !2)
-!1 = !DIFile(filename: "calls.cc", directory: ".")
-!2 = !{}
-!4 = distinct !DISubprogram(name: "sum", line: 3, isLocal: false, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: false, unit: !0, scopeLine: 3, file: !1, scope: !5, type: !6, retainedNodes: !2)
-!5 = !DIFile(filename: "calls.cc", directory: ".")
-!6 = !DISubroutineType(types: !2)
-!7 = distinct !DISubprogram(name: "main", line: 7, isLocal: false, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: false, unit: !0, scopeLine: 7, file: !1, scope: !5, type: !6, retainedNodes: !2)
-!8 = !{i32 2, !"Dwarf Version", i32 4}
-!9 = !{i32 1, !"Debug Info Version", i32 3}
-!10 = !{!"clang version 3.5 "}
-!11 = !DILocation(line: 4, scope: !4)
-!12 = !DILocation(line: 8, scope: !7)
-!13 = !DILocation(line: 9, scope: !7)
-!14 = !DILocation(line: 9, scope: !15)
-!15 = !DILexicalBlockFile(discriminator: 2, file: !1, scope: !7)
-!16 = !DILocation(line: 10, scope: !17)
-!17 = distinct !DILexicalBlock(line: 10, column: 0, file: !1, scope: !7)
-!18 = !DILocation(line: 10, scope: !19)
-!19 = !DILexicalBlockFile(discriminator: 2, file: !1, scope: !17)
-!20 = !DILocation(line: 10, scope: !21)
-!21 = !DILexicalBlockFile(discriminator: 4, file: !1, scope: !17)
-!22 = !DILocation(line: 10, scope: !23)
-!23 = !DILexicalBlockFile(discriminator: 6, file: !1, scope: !17)
-!24 = !DILocation(line: 11, scope: !7)
-!25 = !DILocation(line: 12, scope: !7)

test/tools/llvm-profdata/roundtrip.test

 RUN: llvm-profdata merge -o %t.0.profdata %S/Inputs/IR_profile.proftext
 RUN: llvm-profdata show -o %t.0.proftext -all-functions -text %t.0.profdata 
 RUN: diff %t.0.proftext %S/Inputs/IR_profile.proftext
 RUN: llvm-profdata merge -o %t.1.profdata %t.0.proftext
 RUN: llvm-profdata show -o %t.1.proftext -all-functions -text %t.1.profdata 
 RUN: diff %t.1.proftext %S/Inputs/IR_profile.proftext
 RUN: llvm-profdata merge --sample --binary -output=%t.2.profdata %S/Inputs/sample-profile.proftext
 RUN: llvm-profdata merge --sample --text -output=%t.2.proftext %t.2.profdata
-RUN: diff %t.2.proftext %S/Inputs/sample-profile.proftext
+RUN: diff %t.2.proftext %S/Inputs/sample-profile.proftext
+# Round trip from text --> extbinary --> text
+RUN: llvm-profdata merge --sample --extbinary -output=%t.3.profdata %S/Inputs/sample-profile.proftext
+RUN: llvm-profdata merge --sample --text -output=%t.3.proftext %t.3.profdata
+RUN: diff %t.3.proftext %S/Inputs/sample-profile.proftext
+# Round trip from text --> binary --> extbinary --> text
+RUN: llvm-profdata merge --sample --binary -output=%t.4.profdata %S/Inputs/sample-profile.proftext
+RUN: llvm-profdata merge --sample --extbinary -output=%t.5.profdata %t.4.profdata
+RUN: llvm-profdata merge --sample --text -output=%t.4.proftext %t.5.profdata
+RUN: diff %t.4.proftext %S/Inputs/sample-profile.proftext

tools/llvm-profdata/llvm-profdata.cpp

 #include <algorithm>
 
 using namespace llvm;
 
 enum ProfileFormat {
   PF_None = 0,
   PF_Text,
   PF_Compact_Binary,
+  PF_Ext_Binary,
   PF_GCC,
   PF_Binary
 };
 
 static void warn(Twine Message, std::string Whence = "",
                  std::string Hint = "") {
   WithColor::warning();
   if (!Whence.empty())
static void mergeInstrProfile(const WeightedFileVector &Inputs,
                               SymbolRemapper *Remapper,
                               StringRef OutputFilename,
                               ProfileFormat OutputFormat, bool OutputSparse,
                               unsigned NumThreads) {
   if (OutputFilename.compare("-") == 0)
     exitWithError("Cannot write indexed profdata format to stdout.");
 
   if (OutputFormat != PF_Binary && OutputFormat != PF_Compact_Binary &&
-      OutputFormat != PF_Text)
+      OutputFormat != PF_Ext_Binary && OutputFormat != PF_Text)
     exitWithError("Unknown format is specified.");
 
   std::mutex ErrorLock;
   SmallSet<instrprof_error, 4> WriterErrorCodes;
 
   // If NumThreads is not specified, auto-detect a good default.
   if (NumThreads == 0)
     NumThreads =
for (const auto &Callsite : CallsiteSamples.second) {
           remapSamples(Callsite.second, Remapper, Error);
       MergeResult(Error, Target[Remapped.getName()].merge(Remapped));
     }
   }
   return Result;
 }
 
 static sampleprof::SampleProfileFormat FormatMap[] = {
-    sampleprof::SPF_None, sampleprof::SPF_Text, sampleprof::SPF_Compact_Binary,
-    sampleprof::SPF_GCC, sampleprof::SPF_Binary};
+    sampleprof::SPF_None,
+    sampleprof::SPF_Text,
+    sampleprof::SPF_Compact_Binary,
+    sampleprof::SPF_Ext_Binary,
+    sampleprof::SPF_GCC,
+    sampleprof::SPF_Binary};
 
 static void mergeSampleProfile(const WeightedFileVector &Inputs,
                                SymbolRemapper *Remapper,
                                StringRef OutputFilename,
                                ProfileFormat OutputFormat) {
   using namespace sampleprof;
   StringMap<FunctionSamples> ProfileMap;
   SmallVector<std::unique_ptr<sampleprof::SampleProfileReader>, 5> Readers;
static int merge_main(int argc, const char *argv[]) {
   cl::alias OutputFilenameA("o", cl::desc("Alias for --output"),
                             cl::aliasopt(OutputFilename));
   cl::opt<ProfileKinds> ProfileKind(
       cl::desc("Profile kind:"), cl::init(instr),
       cl::values(clEnumVal(instr, "Instrumentation profile (default)"),
                  clEnumVal(sample, "Sample profile")));
   cl::opt<ProfileFormat> OutputFormat(
       cl::desc("Format of output profile"), cl::init(PF_Binary),
-      cl::values(clEnumValN(PF_Binary, "binary", "Binary encoding (default)"),
-                 clEnumValN(PF_Compact_Binary, "compbinary",
-                            "Compact binary encoding"),
-                 clEnumValN(PF_Text, "text", "Text encoding"),
-                 clEnumValN(PF_GCC, "gcc",
-                            "GCC encoding (only meaningful for -sample)")));
+      cl::values(
+          clEnumValN(PF_Binary, "binary", "Binary encoding (default)"),
+          clEnumValN(PF_Ext_Binary, "extbinary", "Extensible binary encoding"),
   cl::opt<bool> OutputSparse("sparse", cl::init(false),
       cl::desc("Generate a sparse profile (only meaningful for -instr)"));
   cl::opt<unsigned> NumThreads(
       "num-threads", cl::init(0),
       cl::desc("Number of merge threads to use (default: autodetect)"));
   cl::alias NumThreadsA("j", cl::desc("Alias for --num-threads"),
                         cl::aliasopt(NumThreads));
 

unittests/ProfileData/SampleProfTest.cpp

 TEST_F(SampleProfTest, roundtrip_raw_binary_profile) {
   testRoundTrip(SampleProfileFormat::SPF_Binary, false);
 }
 
 TEST_F(SampleProfTest, roundtrip_compact_binary_profile) {
   testRoundTrip(SampleProfileFormat::SPF_Compact_Binary, false);
 }
 
+TEST_F(SampleProfTest, roundtrip_ext_binary_profile) {
+  testRoundTrip(SampleProfileFormat::SPF_Ext_Binary, false);
+}
+
 TEST_F(SampleProfTest, remap_text_profile) {
   testRoundTrip(SampleProfileFormat::SPF_Text, true);
 }
 
 TEST_F(SampleProfTest, remap_raw_binary_profile) {
   testRoundTrip(SampleProfileFormat::SPF_Binary, true);
 }
 
+TEST_F(SampleProfTest, remap_ext_binary_profile) {
+  testRoundTrip(SampleProfileFormat::SPF_Ext_Binary, true);
+}
+
 TEST_F(SampleProfTest, sample_overflow_saturation) {
   const uint64_t Max = std::numeric_limits<uint64_t>::max();
   sampleprof_error Result;
 
   StringRef FooName("_Z3fooi");
   FunctionSamples FooSamples;
   Result = FooSamples.addTotalSamples(1);
   ASSERT_EQ(Result, sampleprof_error::success);