InstrProf.h   [plain text]

//=-- InstrProf.h - Instrumented profiling format support ---------*- C++ -*-=//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Instrumentation-based profiling data is generated by instrumented
// binaries through library functions in compiler-rt, and read by the clang
// frontend to feed PGO.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_PROFILEDATA_INSTRPROF_H_
#define LLVM_PROFILEDATA_INSTRPROF_H_

#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/StringSet.h"
#include "llvm/IR/GlobalValue.h"
#include "llvm/Support/Endian.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/ErrorOr.h"
#include "llvm/Support/MD5.h"
#include <cstdint>
#include <list>
#include <system_error>
#include <vector>

namespace llvm {

class Function;
class GlobalVariable;
class Module;

/// Return the name of data section containing profile counter variables.
inline StringRef getInstrProfCountersSectionName(bool AddSegment) {
  return AddSegment ? "__DATA,__llvm_prf_cnts" : "__llvm_prf_cnts";
}

/// Return the name of data section containing names of instrumented
/// functions.
inline StringRef getInstrProfNameSectionName(bool AddSegment) {
  return AddSegment ? "__DATA,__llvm_prf_names" : "__llvm_prf_names";
}

/// Return the name of the data section containing per-function control
/// data.
inline StringRef getInstrProfDataSectionName(bool AddSegment) {
  return AddSegment ? "__DATA,__llvm_prf_data" : "__llvm_prf_data";
}

/// Return the name of the section containing function coverage mapping
/// data.
inline StringRef getInstrProfCoverageSectionName(bool AddSegment) {
  return AddSegment ? "__DATA,__llvm_covmap" : "__llvm_covmap";
}

/// Return the name prefix of variables containing instrumented function names.
inline StringRef getInstrProfNameVarPrefix() { return "__llvm_profile_name_"; }

/// Return the name prefix of variables containing per-function control data.
inline StringRef getInstrProfDataVarPrefix() { return "__llvm_profile_data_"; }

/// Return the name prefix of profile counter variables.
inline StringRef getInstrProfCountersVarPrefix() {
  return "__llvm_profile_counters_";
}

/// Return the name prefix of the COMDAT group for instrumentation variables
/// associated with a COMDAT function.
inline StringRef getInstrProfComdatPrefix() { return "__llvm_profile_vars_"; }

/// Return the name of a covarage mapping variable (internal linkage) 
/// for each instrumented source module. Such variables are allocated
/// in the __llvm_covmap section.
inline StringRef getCoverageMappingVarName() {
  return "__llvm_coverage_mapping";
}

/// Return the name of function that registers all the per-function control
/// data at program startup time by calling __llvm_register_function. This
/// function has internal linkage and is called by  __llvm_profile_init
/// runtime method. This function is not generated for these platforms:
/// Darwin, Linux, and FreeBSD.
inline StringRef getInstrProfRegFuncsName() {
  return "__llvm_profile_register_functions";
}

/// Return the name of the runtime interface that registers per-function control
/// data for one instrumented function.
inline StringRef getInstrProfRegFuncName() {
  return "__llvm_profile_register_function";
}

/// Return the name of the runtime initialization method that is generated by
/// the compiler. The function calls __llvm_profile_register_functions and
/// __llvm_profile_override_default_filename functions if needed. This function
/// has internal linkage and invoked at startup time via init_array.
inline StringRef getInstrProfInitFuncName() { return "__llvm_profile_init"; }

/// Return the name of the hook variable defined in profile runtime library.
/// A reference to the variable causes the linker to link in the runtime
/// initialization module (which defines the hook variable).
inline StringRef getInstrProfRuntimeHookVarName() {
  return "__llvm_profile_runtime";
}

/// Return the name of the compiler generated function that references the
/// runtime hook variable. The function is a weak global.
inline StringRef getInstrProfRuntimeHookVarUseFuncName() {
  return "__llvm_profile_runtime_user";
}

/// Return the name of the profile runtime interface that overrides the default
/// profile data file name.
inline StringRef getInstrProfFileOverriderFuncName() {
  return "__llvm_profile_override_default_filename";
}

/// Return the modified name for function \c F suitable to be
/// used the key for profile lookup.
std::string getPGOFuncName(const Function &F);

/// Return the modified name for a function suitable to be
/// used the key for profile lookup. The function's original
/// name is \c RawFuncName and has linkage of type \c Linkage.
/// The function is defined in module \c FileName.
std::string getPGOFuncName(StringRef RawFuncName,
                           GlobalValue::LinkageTypes Linkage,
                           StringRef FileName);

/// Create and return the global variable for function name used in PGO
/// instrumentation. \c FuncName is the name of the function returned
/// by \c getPGOFuncName call.
GlobalVariable *createPGOFuncNameVar(Function &F, StringRef FuncName);

/// Create and return the global variable for function name used in PGO
/// instrumentation.  /// \c FuncName is the name of the function
/// returned by \c getPGOFuncName call, \c M is the owning module,
/// and \c Linkage is the linkage of the instrumented function.
GlobalVariable *createPGOFuncNameVar(Module &M,
                                     GlobalValue::LinkageTypes Linkage,
                                     StringRef FuncName);

const std::error_category &instrprof_category();

enum class instrprof_error {
  success = 0,
  eof,
  bad_magic,
  bad_header,
  unsupported_version,
  unsupported_hash_type,
  too_large,
  truncated,
  malformed,
  unknown_function,
  hash_mismatch,
  count_mismatch,
  counter_overflow,
  value_site_count_mismatch
};

inline std::error_code make_error_code(instrprof_error E) {
  return std::error_code(static_cast<int>(E), instrprof_category());
}

enum InstrProfValueKind : uint32_t {
  IPVK_IndirectCallTarget = 0,

  IPVK_First = IPVK_IndirectCallTarget,
  IPVK_Last = IPVK_IndirectCallTarget
};

struct InstrProfStringTable {
  // Set of string values in profiling data.
  StringSet<> StringValueSet;
  InstrProfStringTable() { StringValueSet.clear(); }
  // Get a pointer to internal storage of a string in set
  const char *getStringData(StringRef Str) {
    auto Result = StringValueSet.find(Str);
    return (Result == StringValueSet.end()) ? nullptr : Result->first().data();
  }
  // Insert a string to StringTable
  const char *insertString(StringRef Str) {
    auto Result = StringValueSet.insert(Str);
    return Result.first->first().data();
  }
};

struct InstrProfValueData {
  // Profiled value.
  uint64_t Value;
  // Number of times the value appears in the training run.
  uint64_t Count;
};

struct InstrProfValueSiteRecord {
  /// Value profiling data pairs at a given value site.
  std::list<InstrProfValueData> ValueData;

  InstrProfValueSiteRecord() { ValueData.clear(); }
  template <class InputIterator>
  InstrProfValueSiteRecord(InputIterator F, InputIterator L)
      : ValueData(F, L) {}

  /// Sort ValueData ascending by Value
  void sortByTargetValues() {
    ValueData.sort(
        [](const InstrProfValueData &left, const InstrProfValueData &right) {
          return left.Value < right.Value;
        });
  }

  /// Merge data from another InstrProfValueSiteRecord
  void mergeValueData(InstrProfValueSiteRecord &Input) {
    this->sortByTargetValues();
    Input.sortByTargetValues();
    auto I = ValueData.begin();
    auto IE = ValueData.end();
    for (auto J = Input.ValueData.begin(), JE = Input.ValueData.end(); J != JE;
         ++J) {
      while (I != IE && I->Value < J->Value)
        ++I;
      if (I != IE && I->Value == J->Value) {
        I->Count += J->Count;
        ++I;
        continue;
      }
      ValueData.insert(I, *J);
    }
  }
};

/// Profiling information for a single function.
struct InstrProfRecord {
  InstrProfRecord() {}
  InstrProfRecord(StringRef Name, uint64_t Hash, std::vector<uint64_t> Counts)
      : Name(Name), Hash(Hash), Counts(std::move(Counts)) {}
  StringRef Name;
  uint64_t Hash;
  std::vector<uint64_t> Counts;

  typedef std::vector<std::pair<uint64_t, const char *>> ValueMapType;

  /// Return the number of value profile kinds with non-zero number
  /// of profile sites.
  inline uint32_t getNumValueKinds() const;
  /// Return the number of instrumented sites for ValueKind.
  inline uint32_t getNumValueSites(uint32_t ValueKind) const;
  /// Return the total number of ValueData for ValueKind.
  inline uint32_t getNumValueData(uint32_t ValueKind) const;
  /// Return the number of value data collected for ValueKind at profiling
  /// site: Site.
  inline uint32_t getNumValueDataForSite(uint32_t ValueKind,
                                         uint32_t Site) const;
  inline std::unique_ptr<InstrProfValueData[]>
  getValueForSite(uint32_t ValueKind, uint32_t Site) const;
  /// Reserve space for NumValueSites sites.
  inline void reserveSites(uint32_t ValueKind, uint32_t NumValueSites);
  /// Add ValueData for ValueKind at value Site.
  inline void addValueData(uint32_t ValueKind, uint32_t Site,
                           InstrProfValueData *VData, uint32_t N,
                           ValueMapType *HashKeys);
  /// Merge Value Profile ddata from Src record to this record for ValueKind.
  inline instrprof_error mergeValueProfData(uint32_t ValueKind,
                                            InstrProfRecord &Src);

  /// Used by InstrProfWriter: update the value strings to commoned strings in
  /// the writer instance.
  inline void updateStrings(InstrProfStringTable *StrTab);

private:
  std::vector<InstrProfValueSiteRecord> IndirectCallSites;
  const std::vector<InstrProfValueSiteRecord> &
  getValueSitesForKind(uint32_t ValueKind) const {
    switch (ValueKind) {
    case IPVK_IndirectCallTarget:
      return IndirectCallSites;
    default:
      llvm_unreachable("Unknown value kind!");
    }
    return IndirectCallSites;
  }

  std::vector<InstrProfValueSiteRecord> &
  getValueSitesForKind(uint32_t ValueKind) {
    return const_cast<std::vector<InstrProfValueSiteRecord> &>(
        const_cast<const InstrProfRecord *>(this)
            ->getValueSitesForKind(ValueKind));
  }
  // Map indirect call target name hash to name string.
  uint64_t remapValue(uint64_t Value, uint32_t ValueKind,
                      ValueMapType *HashKeys) {
    if (!HashKeys)
      return Value;
    switch (ValueKind) {
    case IPVK_IndirectCallTarget: {
      auto Result =
          std::lower_bound(HashKeys->begin(), HashKeys->end(), Value,
                           [](const std::pair<uint64_t, const char *> &LHS,
                              uint64_t RHS) { return LHS.first < RHS; });
      assert(Result != HashKeys->end() &&
             "Hash does not match any known keys\n");
      Value = (uint64_t)Result->second;
      break;
    }
    }
    return Value;
  }
};

uint32_t InstrProfRecord::getNumValueKinds() const {
  uint32_t NumValueKinds = 0;
  for (uint32_t Kind = IPVK_First; Kind <= IPVK_Last; ++Kind)
    NumValueKinds += !(getValueSitesForKind(Kind).empty());
  return NumValueKinds;
}

uint32_t InstrProfRecord::getNumValueData(uint32_t ValueKind) const {
  uint32_t N = 0;
  const std::vector<InstrProfValueSiteRecord> &SiteRecords =
      getValueSitesForKind(ValueKind);
  for (auto &SR : SiteRecords) {
    N += SR.ValueData.size();
  }
  return N;
}

uint32_t InstrProfRecord::getNumValueSites(uint32_t ValueKind) const {
  return getValueSitesForKind(ValueKind).size();
}

uint32_t InstrProfRecord::getNumValueDataForSite(uint32_t ValueKind,
                                                 uint32_t Site) const {
  return getValueSitesForKind(ValueKind)[Site].ValueData.size();
}

std::unique_ptr<InstrProfValueData[]>
InstrProfRecord::getValueForSite(uint32_t ValueKind, uint32_t Site) const {
  uint32_t N = getNumValueDataForSite(ValueKind, Site);
  if (N == 0)
    return std::unique_ptr<InstrProfValueData[]>(nullptr);

  std::unique_ptr<InstrProfValueData[]> VD(new InstrProfValueData[N]);
  uint32_t I = 0;
  for (auto V : getValueSitesForKind(ValueKind)[Site].ValueData) {
    VD[I] = V;
    I++;
  }
  assert(I == N);

  return VD;
}

void InstrProfRecord::addValueData(uint32_t ValueKind, uint32_t Site,
                                   InstrProfValueData *VData, uint32_t N,
                                   ValueMapType *HashKeys) {
  for (uint32_t I = 0; I < N; I++) {
    VData[I].Value = remapValue(VData[I].Value, ValueKind, HashKeys);
  }
  std::vector<InstrProfValueSiteRecord> &ValueSites =
      getValueSitesForKind(ValueKind);
  if (N == 0)
    ValueSites.push_back(InstrProfValueSiteRecord());
  else
    ValueSites.emplace_back(VData, VData + N);
}

void InstrProfRecord::reserveSites(uint32_t ValueKind, uint32_t NumValueSites) {
  std::vector<InstrProfValueSiteRecord> &ValueSites =
      getValueSitesForKind(ValueKind);
  ValueSites.reserve(NumValueSites);
}

instrprof_error InstrProfRecord::mergeValueProfData(uint32_t ValueKind,
                                                    InstrProfRecord &Src) {
  uint32_t ThisNumValueSites = getNumValueSites(ValueKind);
  uint32_t OtherNumValueSites = Src.getNumValueSites(ValueKind);
  if (ThisNumValueSites != OtherNumValueSites)
    return instrprof_error::value_site_count_mismatch;
  std::vector<InstrProfValueSiteRecord> &ThisSiteRecords =
      getValueSitesForKind(ValueKind);
  std::vector<InstrProfValueSiteRecord> &OtherSiteRecords =
      Src.getValueSitesForKind(ValueKind);
  for (uint32_t I = 0; I < ThisNumValueSites; I++)
    ThisSiteRecords[I].mergeValueData(OtherSiteRecords[I]);
  return instrprof_error::success;
}

void InstrProfRecord::updateStrings(InstrProfStringTable *StrTab) {
  if (!StrTab)
    return;

  Name = StrTab->insertString(Name);
  for (auto &VSite : IndirectCallSites)
    for (auto &VData : VSite.ValueData)
      VData.Value = (uint64_t)StrTab->insertString((const char *)VData.Value);
}

namespace IndexedInstrProf {
enum class HashT : uint32_t {
  MD5,

  Last = MD5
};

static inline uint64_t MD5Hash(StringRef Str) {
  MD5 Hash;
  Hash.update(Str);
  llvm::MD5::MD5Result Result;
  Hash.final(Result);
  // Return the least significant 8 bytes. Our MD5 implementation returns the
  // result in little endian, so we may need to swap bytes.
  using namespace llvm::support;
  return endian::read<uint64_t, little, unaligned>(Result);
}

static inline uint64_t ComputeHash(HashT Type, StringRef K) {
  switch (Type) {
    case HashT::MD5:
      return IndexedInstrProf::MD5Hash(K);
  }
  llvm_unreachable("Unhandled hash type");
}

const uint64_t Magic = 0x8169666f72706cff;  // "\xfflprofi\x81"
const uint64_t Version = 3;
const HashT HashType = HashT::MD5;

// This structure defines the file header of the LLVM profile
// data file in indexed-format.
struct Header {
  uint64_t Magic;
  uint64_t Version;
  uint64_t MaxFunctionCount;
  uint64_t HashType;
  uint64_t HashOffset;
};

inline support::endianness getHostEndianness() {
  return sys::IsLittleEndianHost ? support::little : support::big;
}

/// This is the header of the data structure that defines the on-disk
/// layout of the value profile data of a particular kind for one function.
struct ValueProfRecord {
  // The kind of the value profile record.
  uint32_t Kind;
  // The number of value profile sites. It is guaranteed to be non-zero;
  // otherwise the record for this kind won't be emitted.
  uint32_t NumValueSites;
  // The first element of the array that stores the number of profiled
  // values for each value site. The size of the array is NumValueSites.
  // Since NumValueSites is greater than zero, there is at least one
  // element in the array.
  uint8_t SiteCountArray[1];

  // The fake declaration is for documentation purpose only.
  // Align the start of next field to be on 8 byte boundaries.
  // uint8_t Padding[X];

  // The array of value profile data. The size of the array is the sum
  // of all elements in SiteCountArray[].
  // InstrProfValueData ValueData[];

  /// Return the \c ValueProfRecord header size including the padding bytes.
  static uint32_t getHeaderSize(uint32_t NumValueSites);
  /// Return the total size of the value profile record including the
  /// header and the value data.
  static uint32_t getSize(uint32_t NumValueSites, uint32_t NumValueData);
  /// Return the total size of the value profile record including the
  /// header and the value data.
  uint32_t getSize() const { return getSize(NumValueSites, getNumValueData()); }
  /// Use this method to advance to the next \c ValueProfRecord.
  ValueProfRecord *getNext();
  /// Return the pointer to the first value profile data.
  InstrProfValueData *getValueData();
  /// Return the number of value sites.
  uint32_t getNumValueSites() const { return NumValueSites; }
  /// Return the number of value data.
  uint32_t getNumValueData() const;
  /// Read data from this record and save it to Record.
  void deserializeTo(InstrProfRecord &Record,
                     InstrProfRecord::ValueMapType *VMap);
  /// Extract data from \c Record and serialize into this instance.
  void serializeFrom(const InstrProfRecord &Record, uint32_t ValueKind,
                     uint32_t NumValueSites);
  /// In-place byte swap:
  /// Do byte swap for this instance. \c Old is the original order before
  /// the swap, and \c New is the New byte order.
  void swapBytes(support::endianness Old, support::endianness New);
};

/// Per-function header/control data structure for value profiling
/// data in indexed format.
struct ValueProfData {
  // Total size in bytes including this field. It must be a multiple
  // of sizeof(uint64_t).
  uint32_t TotalSize;
  // The number of value profile kinds that has value profile data.
  // In this implementation, a value profile kind is considered to
  // have profile data if the number of value profile sites for the
  // kind is not zero. More aggressively, the implemnetation can
  // choose to check the actual data value: if none of the value sites
  // has any profiled values, the kind can be skipped.
  uint32_t NumValueKinds;

  // Following are a sequence of variable length records. The prefix/header
  // of each record is defined by ValueProfRecord type. The number of
  // records is NumValueKinds.
  // ValueProfRecord Record_1;
  // ValueProfRecord Record_N;

  /// Return the total size in bytes of the on-disk value profile data
  /// given the data stored in Record.
  static uint32_t getSize(const InstrProfRecord &Record);
  /// Return a pointer to \c ValueProfData instance ready to be streamed.
  static std::unique_ptr<ValueProfData>
  serializeFrom(const InstrProfRecord &Record);
  /// Return a pointer to \c ValueProfileData instance ready to be read.
  /// All data in the instance are properly byte swapped. The input
  /// data is assumed to be in little endian order.
  static ErrorOr<std::unique_ptr<ValueProfData>>
  getValueProfData(const unsigned char *D, const unsigned char *const BufferEnd,
                   support::endianness SrcDataEndianness);
  /// Swap byte order from \c Endianness order to host byte order.
  void swapBytesToHost(support::endianness Endianness);
  /// Swap byte order from host byte order to \c Endianness order.
  void swapBytesFromHost(support::endianness Endianness);
  /// Return the total size of \c ValueProfileData.
  uint32_t getSize() const { return TotalSize; }
  /// Read data from this data and save it to \c Record.
  void deserializeTo(InstrProfRecord &Record,
                     InstrProfRecord::ValueMapType *VMap);
  /// Return the first \c ValueProfRecord instance.
  ValueProfRecord *getFirstValueProfRecord();
};

}  // end namespace IndexedInstrProf

namespace RawInstrProf {

const uint64_t Version = 1;

// Magic number to detect file format and endianness.
// Use 255 at one end, since no UTF-8 file can use that character.  Avoid 0,
// so that utilities, like strings, don't grab it as a string.  129 is also
// invalid UTF-8, and high enough to be interesting.
// Use "lprofr" in the centre to stand for "LLVM Profile Raw", or "lprofR"
// for 32-bit platforms.
// The magic and version need to be kept in sync with
// projects/compiler-rt/lib/profile/InstrProfiling.c

template <class IntPtrT>
inline uint64_t getMagic();
template <>
inline uint64_t getMagic<uint64_t>() {
  return uint64_t(255) << 56 | uint64_t('l') << 48 | uint64_t('p') << 40 |
         uint64_t('r') << 32 | uint64_t('o') << 24 | uint64_t('f') << 16 |
         uint64_t('r') << 8 | uint64_t(129);
}

template <>
inline uint64_t getMagic<uint32_t>() {
  return uint64_t(255) << 56 | uint64_t('l') << 48 | uint64_t('p') << 40 |
         uint64_t('r') << 32 | uint64_t('o') << 24 | uint64_t('f') << 16 |
         uint64_t('R') << 8 | uint64_t(129);
}

// Per-function profile data header/control structure.
// The definition should match the structure defined in
// compiler-rt/lib/profile/InstrProfiling.h.
// It should also match the synthesized type in
// Transforms/Instrumentation/InstrProfiling.cpp:getOrCreateRegionCounters.
template <class IntPtrT> struct ProfileData {
  #define INSTR_PROF_DATA(Type, LLVMType, Name, Init) Type Name;
  #include "llvm/ProfileData/InstrProfData.inc"
};

// File header structure of the LLVM profile data in raw format.
// The definition should match the header referenced in
// compiler-rt/lib/profile/InstrProfilingFile.c  and
// InstrProfilingBuffer.c.
struct Header {
  const uint64_t Magic;
  const uint64_t Version;
  const uint64_t DataSize;
  const uint64_t CountersSize;
  const uint64_t NamesSize;
  const uint64_t CountersDelta;
  const uint64_t NamesDelta;
};

}  // end namespace RawInstrProf

namespace coverage {

// Profile coverage map has the following layout:
// [CoverageMapFileHeader]
// [ArrayStart]
//  [CovMapFunctionRecord]
//  [CovMapFunctionRecord]
//  ...
// [ArrayEnd]
// [Encoded Region Mapping Data]
LLVM_PACKED_START
template <class IntPtrT> struct CovMapFunctionRecord {
  #define COVMAP_FUNC_RECORD(Type, LLVMType, Name, Init) Type Name;
  #include "llvm/ProfileData/InstrProfData.inc"
};
LLVM_PACKED_END

}

} // end namespace llvm

namespace std {
template <>
struct is_error_code_enum<llvm::instrprof_error> : std::true_type {};
}

#endif // LLVM_PROFILEDATA_INSTRPROF_H_