llvm-project/llvm/lib/Support/DebugCounter.cpp

#include "llvm/Support/DebugCounter.h"

#include "DebugOptions.h"

#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Format.h"
#include "llvm/Support/ManagedStatic.h"

using namespace llvm;

namespace llvm {

void DebugCounter::Chunk::print(llvm::raw_ostream &OS) {
  if (Begin == End)
    OS << Begin;
  else
    OS << Begin << "-" << End;
}

void DebugCounter::printChunks(raw_ostream &OS, ArrayRef<Chunk> Chunks) {
  if (Chunks.empty()) {
    OS << "empty";
  } else {
    bool IsFirst = true;
    for (auto E : Chunks) {
      if (!IsFirst)
        OS << ':';
      else
        IsFirst = false;
      E.print(OS);
    }
  }
}

bool DebugCounter::parseChunks(StringRef Str, SmallVector<Chunk> &Chunks) {
  StringRef Remaining = Str;

  auto ConsumeInt = [&]() -> int64_t {
    StringRef Number =
        Remaining.take_until([](char c) { return c < '0' || c > '9'; });
    int64_t Res;
    if (Number.getAsInteger(10, Res)) {
      errs() << "Failed to parse int at : " << Remaining << "\n";
      return -1;
    }
    Remaining = Remaining.drop_front(Number.size());
    return Res;
  };

  while (1) {
    int64_t Num = ConsumeInt();
    if (Num == -1)
      return true;
    if (!Chunks.empty() && Num <= Chunks[Chunks.size() - 1].End) {
      errs() << "Expected Chunks to be in increasing order " << Num
             << " <= " << Chunks[Chunks.size() - 1].End << "\n";
      return true;
    }
    if (Remaining.starts_with("-")) {
      Remaining = Remaining.drop_front();
      int64_t Num2 = ConsumeInt();
      if (Num2 == -1)
        return true;
      if (Num >= Num2) {
        errs() << "Expected " << Num << " < " << Num2 << " in " << Num << "-"
               << Num2 << "\n";
        return true;
      }

      Chunks.push_back({Num, Num2});
    } else {
      Chunks.push_back({Num, Num});
    }
    if (Remaining.starts_with(":")) {
      Remaining = Remaining.drop_front();
      continue;
    }
    if (Remaining.empty())
      break;
    errs() << "Failed to parse at : " << Remaining;
    return true;
  }
  return false;
}

} // namespace llvm

namespace {
// This class overrides the default list implementation of printing so we
// can pretty print the list of debug counter options.  This type of
// dynamic option is pretty rare (basically this and pass lists).
class DebugCounterList : public cl::list<std::string, DebugCounter> {
private:
  using Base = cl::list<std::string, DebugCounter>;

public:
  template <class... Mods>
  explicit DebugCounterList(Mods &&... Ms) : Base(std::forward<Mods>(Ms)...) {}

private:
  void printOptionInfo(size_t GlobalWidth) const override {
    // This is a variant of from generic_parser_base::printOptionInfo.  Sadly,
    // it's not easy to make it more usable.  We could get it to print these as
    // options if we were a cl::opt and registered them, but lists don't have
    // options, nor does the parser for std::string.  The other mechanisms for
    // options are global and would pollute the global namespace with our
    // counters.  Rather than go that route, we have just overridden the
    // printing, which only a few things call anyway.
    outs() << "  -" << ArgStr;
    // All of the other options in CommandLine.cpp use ArgStr.size() + 6 for
    // width, so we do the same.
    Option::printHelpStr(HelpStr, GlobalWidth, ArgStr.size() + 6);
    const auto &CounterInstance = DebugCounter::instance();
    for (const auto &Entry : CounterInstance) {
      const auto &[Name, Desc] = CounterInstance.getCounterDesc(Entry.second);
      size_t NumSpaces = GlobalWidth - Name.size() - 8;
      outs() << "    =" << Name;
      outs().indent(NumSpaces) << " -   " << Desc << '\n';
    }
  }
};

// All global objects associated to the DebugCounter, including the DebugCounter
// itself, are owned by a single global instance of the DebugCounterOwner
// struct. This makes it easier to control the order in which constructors and
// destructors are run.
struct DebugCounterOwner : DebugCounter {
  DebugCounterList DebugCounterOption{
      "debug-counter", cl::Hidden,
      cl::desc("Comma separated list of debug counter skip and count"),
      cl::CommaSeparated, cl::location<DebugCounter>(*this)};
  cl::opt<bool, true> PrintDebugCounter{
      "print-debug-counter",
      cl::Hidden,
      cl::Optional,
      cl::location(this->ShouldPrintCounter),
      cl::init(false),
      cl::desc("Print out debug counter info after all counters accumulated"),
      cl::callback([&](const bool &Value) {
        if (Value)
          activateAllCounters();
      })};
  cl::opt<bool, true> PrintDebugCounterQueries{
      "print-debug-counter-queries",
      cl::Hidden,
      cl::Optional,
      cl::location(this->ShouldPrintCounterQueries),
      cl::init(false),
      cl::desc("Print out each query of an enabled debug counter")};
  cl::opt<bool, true> BreakOnLastCount{
      "debug-counter-break-on-last",
      cl::Hidden,
      cl::Optional,
      cl::location(this->BreakOnLast),
      cl::init(false),
      cl::desc("Insert a break point on the last enabled count of a "
               "chunks list")};

  DebugCounterOwner() {
    // Our destructor uses the debug stream. By referencing it here, we
    // ensure that its destructor runs after our destructor.
    (void)dbgs();
  }

  // Print information when destroyed, iff command line option is specified.
  ~DebugCounterOwner() {
    if (ShouldPrintCounter)
      print(dbgs());
  }
};

} // anonymous namespace

// Use ManagedStatic instead of function-local static variable to ensure
// the destructor (which accesses counters and streams) runs during
// llvm_shutdown() rather than at some unspecified point.
static ManagedStatic<DebugCounterOwner> Owner;

void llvm::initDebugCounterOptions() { (void)DebugCounter::instance(); }

DebugCounter &DebugCounter::instance() { return *Owner; }

// This is called by the command line parser when it sees a value for the
// debug-counter option defined above.
void DebugCounter::push_back(const std::string &Val) {
  if (Val.empty())
    return;
#ifdef NDEBUG
  // isCountingEnabled is hardcoded to false in NDEBUG.
  errs() << "Requested --debug-counter in LLVM build without assertions. This "
            "is a no-op.\n";
#endif

  // The strings should come in as counter=chunk_list
  auto CounterPair = StringRef(Val).split('=');
  if (CounterPair.second.empty()) {
    errs() << "DebugCounter Error: " << Val << " does not have an = in it\n";
    return;
  }
  StringRef CounterName = CounterPair.first;
  SmallVector<Chunk> Chunks;

  if (parseChunks(CounterPair.second, Chunks)) {
    return;
  }

  CounterInfo *Counter = getCounterInfo(CounterName);
  if (!Counter) {
    errs() << "DebugCounter Error: " << CounterName
           << " is not a registered counter\n";
    return;
  }

  Counter->Active = Counter->IsSet = true;
  Counter->Chunks = std::move(Chunks);
}

void DebugCounter::print(raw_ostream &OS) const {
  SmallVector<StringRef, 16> CounterNames(Counters.keys());
  sort(CounterNames);

  OS << "Counters and values:\n";
  for (StringRef CounterName : CounterNames) {
    const CounterInfo *C = getCounterInfo(CounterName);
    OS << left_justify(C->Name, 32) << ": {" << C->Count << ",";
    printChunks(OS, C->Chunks);
    OS << "}\n";
  }
}

bool DebugCounter::handleCounterIncrement(CounterInfo &Info) {
  int64_t CurrCount = Info.Count++;
  uint64_t CurrIdx = Info.CurrChunkIdx;

  if (Info.Chunks.empty())
    return true;
  if (CurrIdx >= Info.Chunks.size())
    return false;

  bool Res = Info.Chunks[CurrIdx].contains(CurrCount);
  if (BreakOnLast && CurrIdx == (Info.Chunks.size() - 1) &&
      CurrCount == Info.Chunks[CurrIdx].End) {
    LLVM_BUILTIN_DEBUGTRAP;
  }
  if (CurrCount > Info.Chunks[CurrIdx].End) {
    Info.CurrChunkIdx++;

    /// Handle consecutive blocks.
    if (Info.CurrChunkIdx < Info.Chunks.size() &&
        CurrCount == Info.Chunks[Info.CurrChunkIdx].Begin)
      return true;
  }
  return Res;
}

bool DebugCounter::shouldExecuteImpl(CounterInfo &Counter) {
  auto &Us = instance();
  bool Res = Us.handleCounterIncrement(Counter);
  if (Us.ShouldPrintCounterQueries && Counter.IsSet) {
    dbgs() << "DebugCounter " << Counter.Name << "=" << (Counter.Count - 1)
           << (Res ? " execute" : " skip") << "\n";
  }
  return Res;
}

#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
LLVM_DUMP_METHOD void DebugCounter::dump() const {
  print(dbgs());
}
#endif