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//===- SampleProfWriter.h - Write LLVM sample profile data ------*- C++ -*-===//

//

// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.

// See https://llvm.org/LICENSE.txt for license information.

// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

//

//===----------------------------------------------------------------------===//

//

// This file contains definitions needed for writing sample profiles.

//

//===----------------------------------------------------------------------===//

#ifndef LLVM_PROFILEDATA_SAMPLEPROFWRITER_H

#define LLVM_PROFILEDATA_SAMPLEPROFWRITER_H

#include "llvm/ADT/MapVector.h"

#include "llvm/ADT/StringRef.h"

#include "llvm/IR/ProfileSummary.h"

#include "llvm/ProfileData/SampleProf.h"

#include "llvm/Support/ErrorOr.h"

#include "llvm/Support/raw_ostream.h"

#include <cstdint>

#include <memory>

#include <set>

#include <system_error>

namespace llvm {

namespace sampleprof {

enum SectionLayout {

  DefaultLayout,

  // The layout splits profile with context information from profile without

  // context information. When Thinlto is enabled, ThinLTO postlink phase only

  // has to load profile with context information and can skip the other part.

  CtxSplitLayout,

  NumOfLayout,

};

/// 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 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 SampleProfileMap &ProfileMap);

  raw_ostream &getOutputStream() { return *OutputStream; }

  /// Profile writer factory.

  ///

  /// Create a new file writer based on the value of \p Format.

  static ErrorOr<std::unique_ptr<SampleProfileWriter>>

  create(StringRef Filename, SampleProfileFormat Format);

  /// Create a new stream writer based on the value of \p Format.

  /// For testing.

  static ErrorOr<std::unique_ptr<SampleProfileWriter>>

  create(std::unique_ptr<raw_ostream> &OS, SampleProfileFormat Format);

  virtual void setProfileSymbolList(ProfileSymbolList *PSL) {}

  virtual void setToCompressAllSections() {}

  virtual void setUseMD5() {}

  virtual void setPartialProfile() {}

  virtual void resetSecLayout(SectionLayout SL) {}

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 SampleProfileMap &ProfileMap) = 0;

  // Write function profiles to the profile file.

  virtual std::error_code writeFuncProfiles(const SampleProfileMap &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 SampleProfileMap &ProfileMap);

  /// Profile format.

  SampleProfileFormat Format = SPF_None;

};

/// Sample-based profile writer (text format).

class SampleProfileWriterText : public SampleProfileWriter {

public:

  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 SampleProfileMap &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:

  SampleProfileWriterBinary(std::unique_ptr<raw_ostream> &OS)

      : SampleProfileWriter(OS) {}

  std::error_code writeSample(const FunctionSamples &S) override;

protected:

  virtual MapVector<StringRef, uint32_t> &getNameTable() { return NameTable; }

  virtual std::error_code writeMagicIdent(SampleProfileFormat Format);

  virtual std::error_code writeNameTable();

  std::error_code writeHeader(const SampleProfileMap &ProfileMap) override;

  std::error_code writeSummary();

  virtual std::error_code writeContextIdx(const SampleContext &Context);

  std::error_code writeNameIdx(StringRef FName);

  std::error_code writeBody(const FunctionSamples &S);

  inline void stablizeNameTable(MapVector<StringRef, uint32_t> &NameTable,

                                std::set<StringRef> &V);

  MapVector<StringRef, uint32_t> NameTable;

  void addName(StringRef FName);

  virtual void addContext(const SampleContext &Context);

  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;

};

const std::array<SmallVector<SecHdrTableEntry, 8>, NumOfLayout>

    ExtBinaryHdrLayoutTable = {

        // Note that SecFuncOffsetTable section is written after SecLBRProfile

        // in the profile, but is put before SecLBRProfile in SectionHdrLayout.

        // This is because sample reader follows the order in SectionHdrLayout

        // to read each section. To read function profiles on demand, sample

        // reader need to get the offset of each function profile first.

        //

        // DefaultLayout

        SmallVector<SecHdrTableEntry, 8>({{SecProfSummary, 0, 0, 0, 0},

                                          {SecNameTable, 0, 0, 0, 0},

                                          {SecCSNameTable, 0, 0, 0, 0},

                                          {SecFuncOffsetTable, 0, 0, 0, 0},

                                          {SecLBRProfile, 0, 0, 0, 0},

                                          {SecProfileSymbolList, 0, 0, 0, 0},

                                          {SecFuncMetadata, 0, 0, 0, 0}}),

        // CtxSplitLayout

        SmallVector<SecHdrTableEntry, 8>({{SecProfSummary, 0, 0, 0, 0},

                                          {SecNameTable, 0, 0, 0, 0},

                                          // profile with context

                                          // for next two sections

                                          {SecFuncOffsetTable, 0, 0, 0, 0},

                                          {SecLBRProfile, 0, 0, 0, 0},

                                          // profile without context

                                          // for next two sections

                                          {SecFuncOffsetTable, 0, 0, 0, 0},

                                          {SecLBRProfile, 0, 0, 0, 0},

                                          {SecProfileSymbolList, 0, 0, 0, 0},

                                          {SecFuncMetadata, 0, 0, 0, 0}}),

};

class SampleProfileWriterExtBinaryBase : public SampleProfileWriterBinary {

  using SampleProfileWriterBinary::SampleProfileWriterBinary;

public:

  std::error_code write(const SampleProfileMap &ProfileMap) override;

  void setToCompressAllSections() override;

  void setToCompressSection(SecType Type);

  std::error_code writeSample(const FunctionSamples &S) override;

  // Set to use MD5 to represent string in NameTable.

  void setUseMD5() override {

    UseMD5 = true;

    addSectionFlag(SecNameTable, SecNameTableFlags::SecFlagMD5Name);

    // MD5 will be stored as plain uint64_t instead of variable-length

    // quantity format in NameTable section.

    addSectionFlag(SecNameTable, SecNameTableFlags::SecFlagFixedLengthMD5);

  }

  // Set the profile to be partial. It means the profile is for

  // common/shared code. The common profile is usually merged from

  // profiles collected from running other targets.

  void setPartialProfile() override {

    addSectionFlag(SecProfSummary, SecProfSummaryFlags::SecFlagPartial);

  }

  void setProfileSymbolList(ProfileSymbolList *PSL) override {

    ProfSymList = PSL;

  };

  void resetSecLayout(SectionLayout SL) override {

    verifySecLayout(SL);

#ifndef NDEBUG

    // Make sure resetSecLayout is called before any flag setting.

    for (auto &Entry : SectionHdrLayout) {

      assert(Entry.Flags == 0 &&

             "resetSecLayout has to be called before any flag setting");

    }

#endif

    SecLayout = SL;

    SectionHdrLayout = ExtBinaryHdrLayoutTable[SL];

  }

protected:

  uint64_t markSectionStart(SecType Type, uint32_t LayoutIdx);

  std::error_code addNewSection(SecType Sec, uint32_t LayoutIdx,

                                uint64_t SectionStart);

  template <class SecFlagType>

  void addSectionFlag(SecType Type, SecFlagType Flag) {

    for (auto &Entry : SectionHdrLayout) {

      if (Entry.Type == Type)

        addSecFlag(Entry, Flag);

    }

  }

  template <class SecFlagType>

  void addSectionFlag(uint32_t SectionIdx, SecFlagType Flag) {

    addSecFlag(SectionHdrLayout[SectionIdx], Flag);

  }

  void addContext(const SampleContext &Context) override;

  // placeholder for subclasses to dispatch their own section writers.

  virtual std::error_code writeCustomSection(SecType Type) = 0;

  // Verify the SecLayout is supported by the format.

  virtual void verifySecLayout(SectionLayout SL) = 0;

  // specify the order to write sections.

  virtual std::error_code writeSections(const SampleProfileMap &ProfileMap) = 0;

  // Dispatch section writer for each section. \p LayoutIdx is the sequence

  // number indicating where the section is located in SectionHdrLayout.

  virtual std::error_code writeOneSection(SecType Type, uint32_t LayoutIdx,

                                          const SampleProfileMap &ProfileMap);

  // Helper function to write name table.

  std::error_code writeNameTable() override;

  std::error_code writeContextIdx(const SampleContext &Context) override;

  std::error_code writeCSNameIdx(const SampleContext &Context);

  std::error_code writeCSNameTableSection();

  std::error_code writeFuncMetadata(const SampleProfileMap &Profiles);

  std::error_code writeFuncMetadata(const FunctionSamples &Profile);

  // Functions to write various kinds of sections.

  std::error_code writeNameTableSection(const SampleProfileMap &ProfileMap);

  std::error_code writeFuncOffsetTable();

  std::error_code writeProfileSymbolListSection();

  SectionLayout SecLayout = DefaultLayout;

  // Specifiy the order of sections in section header table. Note

  // the order of sections in SecHdrTable may be different that the

  // order in SectionHdrLayout. sample Reader will follow the order

  // in SectionHdrLayout to read each section.

  SmallVector<SecHdrTableEntry, 8> SectionHdrLayout =

      ExtBinaryHdrLayoutTable[DefaultLayout];

  // Save the start of SecLBRProfile so we can compute the offset to the

  // start of SecLBRProfile for each Function's Profile and will keep it

  // in FuncOffsetTable.

  uint64_t SecLBRProfileStart = 0;

private:

  void allocSecHdrTable();

  std::error_code writeSecHdrTable();

  std::error_code writeHeader(const SampleProfileMap &ProfileMap) override;

  std::error_code compressAndOutput();

  // We will swap the raw_ostream held by LocalBufStream and that

  // held by OutputStream if we try to add a section which needs

  // compression. After the swap, all the data written to output

  // will be temporarily buffered into the underlying raw_string_ostream

  // originally held by LocalBufStream. After the data writing for the

  // section is completed, compress the data in the local buffer,

  // swap the raw_ostream back and write the compressed data to the

  // real output.

  std::unique_ptr<raw_ostream> LocalBufStream;

  // 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;

  // The table contains SecHdrTableEntry entries in order of how they are

  // populated in the writer. It may be different from the order in

  // SectionHdrLayout which specifies the sequence in which sections will

  // be read.

  std::vector<SecHdrTableEntry> SecHdrTable;

  // FuncOffsetTable maps function context to its profile offset in

  // SecLBRProfile section. It is used to load function profile on demand.

  MapVector<SampleContext, uint64_t> FuncOffsetTable;

  // Whether to use MD5 to represent string.

  bool UseMD5 = false;

  /// CSNameTable maps function context to its offset in SecCSNameTable section.

  /// The offset will be used everywhere where the context is referenced.

  MapVector<SampleContext, uint32_t> CSNameTable;

  ProfileSymbolList *ProfSymList = nullptr;

};

class SampleProfileWriterExtBinary : public SampleProfileWriterExtBinaryBase {

public:

  SampleProfileWriterExtBinary(std::unique_ptr<raw_ostream> &OS)

      : SampleProfileWriterExtBinaryBase(OS) {}

private:

  std::error_code writeDefaultLayout(const SampleProfileMap &ProfileMap);

  std::error_code writeCtxSplitLayout(const SampleProfileMap &ProfileMap);

  std::error_code writeSections(const SampleProfileMap &ProfileMap) override;

  std::error_code writeCustomSection(SecType Type) override {

    return sampleprof_error::success;

  };

  void verifySecLayout(SectionLayout SL) override {

    assert((SL == DefaultLayout || SL == CtxSplitLayout) &&

           "Unsupported layout");

  }

};

// 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,

// so by using the function offset table, for those function profiles which

// will not be needed when compiling a module, the profile reader does't

// have to read them and it saves compile time if the profile size is huge.

// The layout of the compact format is shown as follows:

//

//    Part1: Profile header, the same as binary format, containing magic

//           number, version, summary, name table...

//    Part2: Function Offset Table Offset, which saves the position of

//           Part4.

//    Part3: Function profile collection

//             function1 profile start

//                 ....

//             function2 profile start

//                 ....

//             function3 profile start

//                 ....

//                ......

//    Part4: Function Offset Table

//             function1 name index --> function1 profile start

//             function2 name index --> function2 profile start

//             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:

  std::error_code writeSample(const FunctionSamples &S) override;

  std::error_code write(const SampleProfileMap &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;

  std::error_code writeNameTable() override;

  std::error_code writeHeader(const SampleProfileMap &ProfileMap) override;

  std::error_code writeFuncOffsetTable();

};

} // end namespace sampleprof

} // end namespace llvm

#endif // LLVM_PROFILEDATA_SAMPLEPROFWRITER_H