//===--- Statistic.h - Helpers for llvm::Statistic --------------*- C++ -*-===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2018 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//

#ifndef SWIFT_BASIC_STATISTIC_H
#define SWIFT_BASIC_STATISTIC_H

#include "swift/Basic/LLVM.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Support/Timer.h"
#include <optional>

#include <thread>
#include <tuple>

#define SWIFT_FUNC_STAT SWIFT_FUNC_STAT_NAMED(DEBUG_TYPE)

#define SWIFT_FUNC_STAT_NAMED(DEBUG_TYPE)                               \
  do {                                                                  \
    static llvm::Statistic FStat = {DEBUG_TYPE, __func__, __func__};    \
    ++FStat;                                                            \
  } while (0)

// Helper class designed to consolidate reporting of LLVM statistics and timers
// across swift compilations that typically invoke many drivers, each running
// many frontends. Additionally collects some cheap "always-on" statistics,
// beyond those that are (compile-time) parameterized by -DLLVM_ENABLE_STATS
// (LLVM's stats are global and involve some amount of locking and mfences).
//
// Assumes it's given a process name and target name (the latter used as
// decoration for its self-timer), and a directory to collect stats into, then:
//
//  - On construction:
//    - Calls llvm::EnableStatistics(/*PrintOnExit=*/false)
//    - Calls swift::enableCompilationTimers()
//    - Starts an llvm::NamedRegionTimer for this process
//
//  - On destruction:
//    - Add any standard always-enabled stats about the process as a whole
//    - Opens $dir/stats-$timestamp-$name-$random.json for writing
//    - Calls llvm::PrintStatisticsJSON(ostream) and/or its own writer
//
// Generally we make one of these per-process: either early in the life of the
// driver, or early in the life of the frontend.

namespace clang {
  class Decl;
  class SourceManager;
}

namespace swift {

class Decl;
class ProtocolConformance;
class Expr;
class SILFunction;
class FrontendStatsTracer;
class Pattern;
class SourceFile;
class SourceManager;
class Stmt;
class TypeRepr;
struct FingerprintAndMembers;

/// Get the number of instructions executed since this process was launched.
/// Returns 0 if the number of instructions executed could not be determined.
uint64_t getInstructionsExecuted();

// There are a handful of cases where the swift compiler can introduce
// counter-measurement noise via nondeterminism, especially via
// parallelism; inhibiting all such cases reliably using existing avenues
// is a bit tricky and depends both on delicate build-setting management
// and some build-system support that is still pending (see
// rdar://39528362); in the meantime we support an environment variable
// ourselves to request blanket suppression of parallelism (and anything
// else nondeterministic we find).
bool environmentVariableRequestedMaximumDeterminism();

class UnifiedStatsReporter {

public:
  struct AlwaysOnDriverCounters
  {
#define DRIVER_STATISTIC(ID) int64_t ID;
#include "Statistics.def"
#undef DRIVER_STATISTIC
  };

  struct AlwaysOnFrontendCounters
  {
#define FRONTEND_STATISTIC(NAME, ID) int64_t ID;
#include "Statistics.def"
#undef FRONTEND_STATISTIC
  };

  // To trace an entity, you have to provide a TraceFormatter for it. This is a
  // separate type since we do not have retroactive conformances in C++, and it
  // is a type that takes void* arguments since we do not have existentials
  // separate from objects in C++. Pity us.
  struct TraceFormatter {
    virtual void traceName(const void *Entity, raw_ostream &OS) const = 0;
    virtual void traceLoc(const void *Entity,
                          SourceManager *SourceMgr,
                          clang::SourceManager *ClangSourceMgr,
                          raw_ostream &OS) const = 0;
    virtual ~TraceFormatter();
  };

  struct FrontendStatsEvent
  {
    uint64_t TimeUSec;
    uint64_t LiveUSec;
    bool IsEntry;
    StringRef EventName;
    StringRef CounterName;
    int64_t CounterDelta;
    int64_t CounterValue;
    const void *Entity;
    const TraceFormatter *Formatter;
  };

  // We only write fine-grained trace entries when the user passed
  // -trace-stats-events, but we recycle the same FrontendStatsTracers to give
  // us some free recursion-save phase timings whenever -trace-stats-dir is
  // active at all. Reduces redundant machinery.
  class RecursionSafeTimers;

  // We also keep a few banks of optional hierarchical profilers for times and
  // statistics, activated with -profile-stats-events and
  // -profile-stats-entities, which are part way between the detail level of the
  // aggregate statistic JSON files and the fine-grained CSV traces. Naturally
  // these are written in yet a different file format: the input format for
  // flamegraphs.
  struct StatsProfilers;

private:
  bool currentProcessExitStatusSet;
  int currentProcessExitStatus;
  long maxChildRSS = 0;
  SmallString<128> StatsFilename;
  SmallString<128> TraceFilename;
  SmallString<128> ProfileDirname;
  llvm::TimeRecord StartedTime;
  std::thread::id MainThreadID;

  // This is unique_ptr because NamedRegionTimer is non-copy-constructable.
  std::unique_ptr<llvm::NamedRegionTimer> Timer;

  SourceManager *SourceMgr;
  clang::SourceManager *ClangSourceMgr;
  std::optional<AlwaysOnDriverCounters> DriverCounters;
  std::optional<AlwaysOnFrontendCounters> FrontendCounters;
  std::optional<AlwaysOnFrontendCounters> LastTracedFrontendCounters;
  std::optional<std::vector<FrontendStatsEvent>> FrontendStatsEvents;

  // These are unique_ptr so we can use incomplete types here.
  std::unique_ptr<RecursionSafeTimers> RecursiveTimers;
  std::unique_ptr<StatsProfilers> EventProfilers;
  std::unique_ptr<StatsProfilers> EntityProfilers;

  /// Whether fine-grained timers are enabled. In practice, this means request
  /// evaluator requests. This will have a runtime performance impact.
  bool FineGrainedTimers;

  /// Whether we are currently flushing statistics and should not therefore
  /// record any additional stats until we've finished.
  bool IsFlushingTracesAndProfiles;

  /// Whether we are printing all stats even if they are zero.
  bool IsPrintingZeroStats;

  void publishAlwaysOnStatsToLLVM();
  void printAlwaysOnStatsAndTimers(raw_ostream &OS);

  UnifiedStatsReporter(StringRef ProgramName,
                       StringRef AuxName,
                       StringRef Directory,
                       SourceManager *SM,
                       clang::SourceManager *CSM,
                       bool FineGrainedTimers,
                       bool TraceEvents,
                       bool ProfileEvents,
                       bool ProfileEntities,
                       bool PrintZeroStats);
public:
  UnifiedStatsReporter(StringRef ProgramName,
                       StringRef ModuleName,
                       StringRef InputName,
                       StringRef TripleName,
                       StringRef OutputType,
                       StringRef OptType,
                       StringRef Directory,
                       SourceManager *SM,
                       clang::SourceManager *CSM,
                       bool FineGrainedTimers,
                       bool TraceEvents,
                       bool ProfileEvents,
                       bool ProfileEntities,
                       bool PrintZeroStats);
  ~UnifiedStatsReporter();

  bool fineGrainedTimers() const { return FineGrainedTimers; }

  AlwaysOnDriverCounters &getDriverCounters();
  AlwaysOnFrontendCounters &getFrontendCounters();
  void flushTracesAndProfiles();
  void noteCurrentProcessExitStatus(int);
  void saveAnyFrontendStatsEvents(FrontendStatsTracer const &T, bool IsEntry);
  void recordJobMaxRSS(long rss);
  int64_t getChildrenMaxResidentSetSize();
};

// This is a non-nested type just to make it less work to write at call sites.
class FrontendStatsTracer
{
  FrontendStatsTracer(UnifiedStatsReporter *Reporter,
                      StringRef EventName,
                      const void *Entity,
                      const UnifiedStatsReporter::TraceFormatter *Formatter);

  // In the general case we do not know how to format an entity for tracing.
  template<typename T> static
  const UnifiedStatsReporter::TraceFormatter *getTraceFormatter() {
    return nullptr;
  }

public:
  UnifiedStatsReporter *Reporter;
  llvm::TimeRecord SavedTime;
  StringRef EventName;
  const void *Entity;
  const UnifiedStatsReporter::TraceFormatter *Formatter;
  FrontendStatsTracer();
  FrontendStatsTracer(FrontendStatsTracer&& other);
  FrontendStatsTracer& operator=(FrontendStatsTracer&&);
  ~FrontendStatsTracer();
  FrontendStatsTracer(const FrontendStatsTracer&) = delete;
  FrontendStatsTracer& operator=(const FrontendStatsTracer&) = delete;

  /// These are the convenience constructors you want to be calling throughout
  /// the compiler: they select an appropriate trace formatter for the provided
  /// entity type, and produce a tracer that's either active or inert depending
  /// on whether the provided \p Reporter is null (nullptr means "tracing is
  /// disabled").
  FrontendStatsTracer(UnifiedStatsReporter *Reporter, StringRef EventName);
  FrontendStatsTracer(UnifiedStatsReporter *Reporter, StringRef EventName,
                      const Decl *D);
  FrontendStatsTracer(UnifiedStatsReporter *Reporter, StringRef EventName,
                      const ProtocolConformance *P);
  FrontendStatsTracer(UnifiedStatsReporter *Reporter, StringRef EventName,
                      const clang::Decl *D);
  FrontendStatsTracer(UnifiedStatsReporter *Reporter, StringRef EventName,
                      const Expr *E);
  FrontendStatsTracer(UnifiedStatsReporter *Reporter, StringRef EventName,
                      const SILFunction *F);
  FrontendStatsTracer(UnifiedStatsReporter *Reporter, StringRef EventName,
                      const SourceFile *F);
  FrontendStatsTracer(UnifiedStatsReporter *Reporter, StringRef EventName,
                      const Stmt *S);
  FrontendStatsTracer(UnifiedStatsReporter *Reporter, StringRef EventName,
                      const Pattern *P);
  FrontendStatsTracer(UnifiedStatsReporter *Reporter, StringRef EventName,
                      const TypeRepr *TR);
};

// In particular cases, we do know how to format traced entities: we declare
// explicit specializations of getTraceFormatter() here, matching the overloaded
// constructors of FrontendStatsTracer above, where the _definitions_ live in
// the upper-level files (in libswiftAST or libswiftSIL), and provide tracing
// for those entity types. If you want to trace those types, it's assumed you're
// linking with the object files that define the tracer.

template <>
const UnifiedStatsReporter::TraceFormatter *
FrontendStatsTracer::getTraceFormatter<const Decl *>();

template <>
const UnifiedStatsReporter::TraceFormatter *
FrontendStatsTracer::getTraceFormatter<const ProtocolConformance *>();

template <>
const UnifiedStatsReporter::TraceFormatter *
FrontendStatsTracer::getTraceFormatter<const clang::Decl *>();

template <>
const UnifiedStatsReporter::TraceFormatter *
FrontendStatsTracer::getTraceFormatter<const Expr *>();

template <>
const UnifiedStatsReporter::TraceFormatter *
FrontendStatsTracer::getTraceFormatter<const SILFunction *>();

template<> const UnifiedStatsReporter::TraceFormatter*
FrontendStatsTracer::getTraceFormatter<const SourceFile *>();

template<> const UnifiedStatsReporter::TraceFormatter*
FrontendStatsTracer::getTraceFormatter<const Stmt *>();

template<> const UnifiedStatsReporter::TraceFormatter*
FrontendStatsTracer::getTraceFormatter<const Pattern *>();

template<> const UnifiedStatsReporter::TraceFormatter*
FrontendStatsTracer::getTraceFormatter<const TypeRepr *>();

// Provide inline definitions for the delegating constructors.  These avoid
// introducing a circular dependency between libParse and libSIL.  They are
// marked as `inline` explicitly to prevent ODR violations due to multiple
// emissions.  We cannot force the inlining by defining them in the declaration
// due to the explicit template specializations of the `getTraceFormatter`,
// which is declared in the `FrontendStatsTracer` scope (the nested name
// specifier scope cannot be used to declare them).

inline FrontendStatsTracer::FrontendStatsTracer(UnifiedStatsReporter *R,
                                                StringRef S)
    : FrontendStatsTracer(R, S, nullptr, nullptr) {}

inline FrontendStatsTracer::FrontendStatsTracer(UnifiedStatsReporter *R,
                                                StringRef S, const Decl *D)
    : FrontendStatsTracer(R, S, D, getTraceFormatter<const Decl *>()) {}

inline FrontendStatsTracer::FrontendStatsTracer(UnifiedStatsReporter *R,
                                                StringRef S,
                                                const ProtocolConformance *P)
    : FrontendStatsTracer(R, S, P,
                          getTraceFormatter<const ProtocolConformance *>()) {}

inline FrontendStatsTracer::FrontendStatsTracer(UnifiedStatsReporter *R,
                                                StringRef S,
                                                const clang::Decl *D)
    : FrontendStatsTracer(R, S, D, getTraceFormatter<const clang::Decl *>()) {}

inline FrontendStatsTracer::FrontendStatsTracer(UnifiedStatsReporter *R,
                                                StringRef S, const Expr *E)
    : FrontendStatsTracer(R, S, E, getTraceFormatter<const Expr *>()) {}

inline FrontendStatsTracer::FrontendStatsTracer(UnifiedStatsReporter *R,
                                                StringRef S,
                                                const SILFunction *F)
    : FrontendStatsTracer(R, S, F, getTraceFormatter<const SILFunction *>()) {}

inline FrontendStatsTracer::FrontendStatsTracer(UnifiedStatsReporter *R,
                                                StringRef S,
                                                const SourceFile *SF)
    : FrontendStatsTracer(R, S, SF, getTraceFormatter<const SourceFile *>()) {}

inline FrontendStatsTracer::FrontendStatsTracer(UnifiedStatsReporter *R,
                                                StringRef S,
                                                const Stmt *ST)
    : FrontendStatsTracer(R, S, ST, getTraceFormatter<const Stmt *>()) {}

inline FrontendStatsTracer::FrontendStatsTracer(UnifiedStatsReporter *R,
                                                StringRef S,
                                                const Pattern *P)
    : FrontendStatsTracer(R, S, P, getTraceFormatter<const Pattern *>()) {}

inline FrontendStatsTracer::FrontendStatsTracer(UnifiedStatsReporter *R,
                                                StringRef S,
                                                const TypeRepr *TR)
    : FrontendStatsTracer(R, S, TR, getTraceFormatter<const TypeRepr *>()) {}

/// Utilities for constructing TraceFormatters from entities in the request-evaluator:

template <typename T>
typename std::enable_if<
    std::is_constructible<FrontendStatsTracer, UnifiedStatsReporter *,
                          StringRef, const T *>::value,
    FrontendStatsTracer>::type
make_tracer_direct(UnifiedStatsReporter *Reporter, StringRef Name, T *Value) {
  return FrontendStatsTracer(Reporter, Name, static_cast<const T *>(Value));
}

template <typename T>
typename std::enable_if<
    std::is_constructible<FrontendStatsTracer, UnifiedStatsReporter *,
                          StringRef, const T *>::value,
    FrontendStatsTracer>::type
make_tracer_direct(UnifiedStatsReporter *Reporter, StringRef Name,
                   const T *Value) {
  return FrontendStatsTracer(Reporter, Name, Value);
}

template <typename T>
typename std::enable_if<
    !std::is_constructible<FrontendStatsTracer, UnifiedStatsReporter *,
                           StringRef, const T *>::value,
    FrontendStatsTracer>::type
make_tracer_direct(UnifiedStatsReporter *Reporter, StringRef Name, T *Value) {
  return FrontendStatsTracer(Reporter, Name);
}

template <typename T>
typename std::enable_if<!std::is_pointer<T>::value, FrontendStatsTracer>::type
make_tracer_direct(UnifiedStatsReporter *Reporter, StringRef Name, T Value) {
  return FrontendStatsTracer(Reporter, Name);
}

template <typename T> struct is_pointerunion : std::false_type {};
template <typename T, typename U>
struct is_pointerunion<llvm::PointerUnion<T, U>> : std::true_type {};

template <typename T, typename U>
FrontendStatsTracer make_tracer_pointerunion(UnifiedStatsReporter *Reporter,
                                             StringRef Name,
                                             llvm::PointerUnion<T, U> Value) {
  if (Value.template is<T>())
    return make_tracer_direct(Reporter, Name, Value.template get<T>());
  else
    return make_tracer_direct(Reporter, Name, Value.template get<U>());
}

template <typename T>
typename std::enable_if<!is_pointerunion<T>::value, FrontendStatsTracer>::type
make_tracer_pointerunion(UnifiedStatsReporter *Reporter, StringRef Name,
                         T Value) {
  return make_tracer_direct(Reporter, Name, Value);
}

template <typename First, typename... Rest>
FrontendStatsTracer make_tracer(UnifiedStatsReporter *Reporter, StringRef Name,
                                std::tuple<First, Rest...> Value) {
  return make_tracer_pointerunion(Reporter, Name, std::get<0>(Value));
}

} // namespace swift
#endif // SWIFT_BASIC_STATISTIC_H