include/llvm/ProfileData/SampleProfWriter.h

   1 //===- SampleProfWriter.h - Write LLVM sample profile data ------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file contains definitions needed for writing sample profiles.
  10 //
  11 //===----------------------------------------------------------------------===//
  12 #ifndef LLVM_PROFILEDATA_SAMPLEPROFWRITER_H
  13 #define LLVM_PROFILEDATA_SAMPLEPROFWRITER_H
  14
  15 #include "llvm/ADT/MapVector.h"
  16 #include "llvm/ADT/StringMap.h"
  17 #include "llvm/ADT/StringRef.h"
  18 #include "llvm/IR/ProfileSummary.h"
  19 #include "llvm/ProfileData/SampleProf.h"
  20 #include "llvm/Support/ErrorOr.h"
  21 #include "llvm/Support/raw_ostream.h"
  22 #include <algorithm>
  23 #include <cstdint>
  24 #include <memory>
  25 #include <set>
  26 #include <system_error>
  27
  28 namespace llvm {
  29 namespace sampleprof {
  30
  31 /// Sample-based profile writer. Base class.
  32 class SampleProfileWriter {
  33 public:
  34   virtual ~SampleProfileWriter() = default;
  35
  36   /// Write sample profiles in \p S.
  37   ///
  38   /// \returns status code of the file update operation.
  39   virtual std::error_code writeSample(const FunctionSamples &S) = 0;
  40
  41   /// Write all the sample profiles in the given map of samples.
  42   ///
  43   /// \returns status code of the file update operation.
  44   virtual std::error_code write(const StringMap<FunctionSamples> &ProfileMap);
  45
  46   raw_ostream &getOutputStream() { return *OutputStream; }
  47
  48   /// Profile writer factory.
  49   ///
  50   /// Create a new file writer based on the value of \p Format.
  51   static ErrorOr<std::unique_ptr<SampleProfileWriter>>
  52   create(StringRef Filename, SampleProfileFormat Format);
  53
  54   /// Create a new stream writer based on the value of \p Format.
  55   /// For testing.
  56   static ErrorOr<std::unique_ptr<SampleProfileWriter>>
  57   create(std::unique_ptr<raw_ostream> &OS, SampleProfileFormat Format);
  58
  59   virtual void setProfileSymbolList(ProfileSymbolList *PSL) {}
  60
  61 protected:
  62   SampleProfileWriter(std::unique_ptr<raw_ostream> &OS)
  63       : OutputStream(std::move(OS)) {}
  64
  65   /// Write a file header for the profile file.
  66   virtual std::error_code
  67   writeHeader(const StringMap<FunctionSamples> &ProfileMap) = 0;
  68
  69   // Write function profiles to the profile file.
  70   virtual std::error_code
  71   writeFuncProfiles(const StringMap<FunctionSamples> &ProfileMap);
  72
  73   /// Output stream where to emit the profile to.
  74   std::unique_ptr<raw_ostream> OutputStream;
  75
  76   /// Profile summary.
  77   std::unique_ptr<ProfileSummary> Summary;
  78
  79   /// Compute summary for this profile.
  80   void computeSummary(const StringMap<FunctionSamples> &ProfileMap);
  81
  82   /// Profile format.
  83   SampleProfileFormat Format;
  84 };
  85
  86 /// Sample-based profile writer (text format).
  87 class SampleProfileWriterText : public SampleProfileWriter {
  88 public:
  89   std::error_code writeSample(const FunctionSamples &S) override;
  90
  91 protected:
  92   SampleProfileWriterText(std::unique_ptr<raw_ostream> &OS)
  93       : SampleProfileWriter(OS), Indent(0) {}
  94
  95   std::error_code
  96   writeHeader(const StringMap<FunctionSamples> &ProfileMap) override {
  97     return sampleprof_error::success;
  98   }
  99
 100 private:
 101   /// Indent level to use when writing.
 102   ///
 103   /// This is used when printing inlined callees.
 104   unsigned Indent;
 105
 106   friend ErrorOr<std::unique_ptr<SampleProfileWriter>>
 107   SampleProfileWriter::create(std::unique_ptr<raw_ostream> &OS,
 108                               SampleProfileFormat Format);
 109 };
 110
 111 /// Sample-based profile writer (binary format).
 112 class SampleProfileWriterBinary : public SampleProfileWriter {
 113 public:
 114   SampleProfileWriterBinary(std::unique_ptr<raw_ostream> &OS)
 115       : SampleProfileWriter(OS) {}
 116
 117   virtual std::error_code writeSample(const FunctionSamples &S) override;
 118
 119 protected:
 120   virtual std::error_code writeMagicIdent(SampleProfileFormat Format);
 121   virtual std::error_code writeNameTable();
 122   virtual std::error_code
 123   writeHeader(const StringMap<FunctionSamples> &ProfileMap) override;
 124   std::error_code writeSummary();
 125   std::error_code writeNameIdx(StringRef FName);
 126   std::error_code writeBody(const FunctionSamples &S);
 127   inline void stablizeNameTable(std::set<StringRef> &V);
 128
 129   MapVector<StringRef, uint32_t> NameTable;
 130
 131   void addName(StringRef FName);
 132   void addNames(const FunctionSamples &S);
 133
 134 private:
 135   friend ErrorOr<std::unique_ptr<SampleProfileWriter>>
 136   SampleProfileWriter::create(std::unique_ptr<raw_ostream> &OS,
 137                               SampleProfileFormat Format);
 138 };
 139
 140 class SampleProfileWriterRawBinary : public SampleProfileWriterBinary {
 141   using SampleProfileWriterBinary::SampleProfileWriterBinary;
 142 };
 143
 144 class SampleProfileWriterExtBinaryBase : public SampleProfileWriterBinary {
 145   using SampleProfileWriterBinary::SampleProfileWriterBinary;
 146 public:
 147   virtual std::error_code
 148   write(const StringMap<FunctionSamples> &ProfileMap) override;
 149
 150   void setToCompressAllSections();
 151   void setToCompressSection(SecType Type);
 152
 153 protected:
 154   uint64_t markSectionStart(SecType Type);
 155   std::error_code addNewSection(SecType Sec, uint64_t SectionStart);
 156   virtual void initSectionHdrLayout() = 0;
 157   virtual std::error_code
 158   writeSections(const StringMap<FunctionSamples> &ProfileMap) = 0;
 159
 160   // Specifiy the order of sections in section header table. Note
 161   // the order of sections in the profile may be different that the
 162   // order in SectionHdrLayout. sample Reader will follow the order
 163   // in SectionHdrLayout to read each section.
 164   SmallVector<SecHdrTableEntry, 8> SectionHdrLayout;
 165
 166 private:
 167   void allocSecHdrTable();
 168   std::error_code writeSecHdrTable();
 169   virtual std::error_code
 170   writeHeader(const StringMap<FunctionSamples> &ProfileMap) override;
 171   void addSectionFlags(SecType Type, SecFlags Flags);
 172   SecHdrTableEntry &getEntryInLayout(SecType Type);
 173   std::error_code compressAndOutput();
 174
 175   // We will swap the raw_ostream held by LocalBufStream and that
 176   // held by OutputStream if we try to add a section which needs
 177   // compression. After the swap, all the data written to output
 178   // will be temporarily buffered into the underlying raw_string_ostream
 179   // originally held by LocalBufStream. After the data writing for the
 180   // section is completed, compress the data in the local buffer,
 181   // swap the raw_ostream back and write the compressed data to the
 182   // real output.
 183   std::unique_ptr<raw_ostream> LocalBufStream;
 184   // The location where the output stream starts.
 185   uint64_t FileStart;
 186   // The location in the output stream where the SecHdrTable should be
 187   // written to.
 188   uint64_t SecHdrTableOffset;
 189   // Initial Section Flags setting.
 190   std::vector<SecHdrTableEntry> SecHdrTable;
 191 };
 192
 193 class SampleProfileWriterExtBinary : public SampleProfileWriterExtBinaryBase {
 194 public:
 195   SampleProfileWriterExtBinary(std::unique_ptr<raw_ostream> &OS)
 196       : SampleProfileWriterExtBinaryBase(OS) {
 197     initSectionHdrLayout();
 198   }
 199
 200   virtual std::error_code writeSample(const FunctionSamples &S) override;
 201   virtual void setProfileSymbolList(ProfileSymbolList *PSL) override {
 202     ProfSymList = PSL;
 203   };
 204
 205 private:
 206   virtual void initSectionHdrLayout() override {
 207     // Note that SecFuncOffsetTable section is written after SecLBRProfile
 208     // in the profile, but is put before SecLBRProfile in SectionHdrLayout.
 209     //
 210     // This is because sample reader follows the order of SectionHdrLayout to
 211     // read each section, to read function profiles on demand sample reader
 212     // need to get the offset of each function profile first.
 213     //
 214     // SecFuncOffsetTable section is written after SecLBRProfile in the
 215     // profile because FuncOffsetTable needs to be populated while section
 216     // SecLBRProfile is written.
 217     SectionHdrLayout = {{SecProfSummary, 0, 0, 0},
 218                         {SecNameTable, 0, 0, 0},
 219                         {SecFuncOffsetTable, 0, 0, 0},
 220                         {SecLBRProfile, 0, 0, 0},
 221                         {SecProfileSymbolList, 0, 0, 0}};
 222   };
 223   virtual std::error_code
 224   writeSections(const StringMap<FunctionSamples> &ProfileMap) override;
 225   ProfileSymbolList *ProfSymList = nullptr;
 226
 227   // Save the start of SecLBRProfile so we can compute the offset to the
 228   // start of SecLBRProfile for each Function's Profile and will keep it
 229   // in FuncOffsetTable.
 230   uint64_t SecLBRProfileStart;
 231   // FuncOffsetTable maps function name to its profile offset in SecLBRProfile
 232   // section. It is used to load function profile on demand.
 233   MapVector<StringRef, uint64_t> FuncOffsetTable;
 234   std::error_code writeFuncOffsetTable();
 235 };
 236
 237 // CompactBinary is a compact format of binary profile which both reduces
 238 // the profile size and the load time needed when compiling. It has two
 239 // major difference with Binary format.
 240 // 1. It represents all the strings in name table using md5 hash.
 241 // 2. It saves a function offset table which maps function name index to
 242 // the offset of its function profile to the start of the binary profile,
 243 // so by using the function offset table, for those function profiles which
 244 // will not be needed when compiling a module, the profile reader does't
 245 // have to read them and it saves compile time if the profile size is huge.
 246 // The layout of the compact format is shown as follows:
 247 //
 248 //    Part1: Profile header, the same as binary format, containing magic
 249 //           number, version, summary, name table...
 250 //    Part2: Function Offset Table Offset, which saves the position of
 251 //           Part4.
 252 //    Part3: Function profile collection
 253 //             function1 profile start
 254 //                 ....
 255 //             function2 profile start
 256 //                 ....
 257 //             function3 profile start
 258 //                 ....
 259 //                ......
 260 //    Part4: Function Offset Table
 261 //             function1 name index --> function1 profile start
 262 //             function2 name index --> function2 profile start
 263 //             function3 name index --> function3 profile start
 264 //
 265 // We need Part2 because profile reader can use it to find out and read
 266 // function offset table without reading Part3 first.
 267 class SampleProfileWriterCompactBinary : public SampleProfileWriterBinary {
 268   using SampleProfileWriterBinary::SampleProfileWriterBinary;
 269
 270 public:
 271   virtual std::error_code writeSample(const FunctionSamples &S) override;
 272   virtual std::error_code
 273   write(const StringMap<FunctionSamples> &ProfileMap) override;
 274
 275 protected:
 276   /// The table mapping from function name to the offset of its FunctionSample
 277   /// towards profile start.
 278   MapVector<StringRef, uint64_t> FuncOffsetTable;
 279   /// The offset of the slot to be filled with the offset of FuncOffsetTable
 280   /// towards profile start.
 281   uint64_t TableOffset;
 282   virtual std::error_code writeNameTable() override;
 283   virtual std::error_code
 284   writeHeader(const StringMap<FunctionSamples> &ProfileMap) override;
 285   std::error_code writeFuncOffsetTable();
 286 };
 287
 288 } // end namespace sampleprof
 289 } // end namespace llvm
 290
 291 #endif // LLVM_PROFILEDATA_SAMPLEPROFWRITER_H