[XRay] Implement the `llvm-xray account` subcommand

Summary:
This is the third of a multi-part change to implement subcommands for
the `llvm-xray` tool.

Here we define the `account` subcommand which does simple function call
accounting, generating basic statistics on function calls we find in an
XRay log/trace. We support text output and csv output for this
subcommand.

This change also supports sorting, summing, and filtering the top N
results.

Part of this tool will later be turned into a library that could be used
for basic function call accounting.

Depends on D24376.

Reviewers: dblaikie, echristo

Subscribers: mehdi_amini, dberris, beanz, llvm-commits

Differential Revision: https://reviews.llvm.org/D24377

llvm-svn: 291749

4 files changed, 691 insertions, 0 deletions

diff --git a/llvm/tools/llvm-xray/CMakeLists.txt b/llvm/tools/llvm-xray/CMakeLists.txt
index e8cfe9f709e..abcd7d93211 100644
--- a/llvm/tools/llvm-xray/CMakeLists.txt
+++ b/llvm/tools/llvm-xray/CMakeLists.txt
@@ -8,6 +8,7 @@ set(LLVM_LINK_COMPONENTS
 
 set(LLVM_XRAY_TOOLS
   func-id-helper.cc
+  xray-account.cc
   xray-converter.cc
   xray-extract.cc
   xray-extract.cc
diff --git a/llvm/tools/llvm-xray/xray-account.cc b/llvm/tools/llvm-xray/xray-account.cc
new file mode 100644
index 00000000000..ceb8885cadb
--- /dev/null
+++ b/llvm/tools/llvm-xray/xray-account.cc
@@ -0,0 +1,484 @@
+//===- xray-account.h - XRay Function Call Accounting ---------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements basic function call accounting from an XRay trace.
+//
+//===----------------------------------------------------------------------===//
+
+#include <algorithm>
+#include <cassert>
+#include <system_error>
+#include <utility>
+
+#include "xray-account.h"
+#include "xray-extract.h"
+#include "xray-registry.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/FormatVariadic.h"
+#include "llvm/XRay/Trace.h"
+
+using namespace llvm;
+using namespace llvm::xray;
+
+static cl::SubCommand Account("account", "Function call accounting");
+static cl::opt<std::string> AccountInput(cl::Positional,
+                                         cl::desc("<xray log file>"),
+                                         cl::Required, cl::sub(Account));
+static cl::opt<bool>
+    AccountKeepGoing("keep-going", cl::desc("Keep going on errors encountered"),
+                     cl::sub(Account), cl::init(false));
+static cl::alias AccountKeepGoing2("k", cl::aliasopt(AccountKeepGoing),
+                                   cl::desc("Alias for -keep_going"),
+                                   cl::sub(Account));
+static cl::opt<bool> AccountDeduceSiblingCalls(
+    "deduce-sibling-calls",
+    cl::desc("Deduce sibling calls when unrolling function call stacks"),
+    cl::sub(Account), cl::init(false));
+static cl::alias
+    AccountDeduceSiblingCalls2("d", cl::aliasopt(AccountDeduceSiblingCalls),
+                               cl::desc("Alias for -deduce_sibling_calls"),
+                               cl::sub(Account));
+static cl::opt<std::string>
+    AccountOutput("output", cl::value_desc("output file"), cl::init("-"),
+                  cl::desc("output file; use '-' for stdout"),
+                  cl::sub(Account));
+static cl::alias AccountOutput2("o", cl::aliasopt(AccountOutput),
+                                cl::desc("Alias for -output"),
+                                cl::sub(Account));
+enum class AccountOutputFormats { TEXT, CSV };
+static cl::opt<AccountOutputFormats>
+    AccountOutputFormat("format", cl::desc("output format"),
+                        cl::values(clEnumValN(AccountOutputFormats::TEXT,
+                                              "text", "report stats in text"),
+                                   clEnumValN(AccountOutputFormats::CSV, "csv",
+                                              "report stats in csv")),
+                        cl::sub(Account));
+static cl::alias AccountOutputFormat2("f", cl::desc("Alias of -format"),
+                                      cl::aliasopt(AccountOutputFormat),
+                                      cl::sub(Account));
+
+enum class SortField {
+  FUNCID,
+  COUNT,
+  MIN,
+  MED,
+  PCT90,
+  PCT99,
+  MAX,
+  SUM,
+  FUNC,
+};
+
+static cl::opt<SortField> AccountSortOutput(
+    "sort", cl::desc("sort output by this field"), cl::value_desc("field"),
+    cl::sub(Account), cl::init(SortField::FUNCID),
+    cl::values(clEnumValN(SortField::FUNCID, "funcid", "function id"),
+               clEnumValN(SortField::COUNT, "count", "funciton call counts"),
+               clEnumValN(SortField::MIN, "min", "minimum function durations"),
+               clEnumValN(SortField::MED, "med", "median function durations"),
+               clEnumValN(SortField::PCT90, "90p", "90th percentile durations"),
+               clEnumValN(SortField::PCT99, "99p", "99th percentile durations"),
+               clEnumValN(SortField::MAX, "max", "maximum function durations"),
+               clEnumValN(SortField::SUM, "sum", "sum of call durations"),
+               clEnumValN(SortField::FUNC, "func", "function names")));
+static cl::alias AccountSortOutput2("s", cl::aliasopt(AccountSortOutput),
+                                    cl::desc("Alias for -sort"),
+                                    cl::sub(Account));
+
+enum class SortDirection {
+  ASCENDING,
+  DESCENDING,
+};
+static cl::opt<SortDirection> AccountSortOrder(
+    "sortorder", cl::desc("sort ordering"), cl::init(SortDirection::ASCENDING),
+    cl::values(clEnumValN(SortDirection::ASCENDING, "asc", "ascending"),
+               clEnumValN(SortDirection::DESCENDING, "dsc", "descending")),
+    cl::sub(Account));
+static cl::alias AccountSortOrder2("r", cl::aliasopt(AccountSortOrder),
+                                   cl::desc("Alias for -sortorder"),
+                                   cl::sub(Account));
+
+static cl::opt<int> AccountTop("top", cl::desc("only show the top N results"),
+                               cl::value_desc("N"), cl::sub(Account),
+                               cl::init(-1));
+static cl::alias AccountTop2("p", cl::desc("Alias for -top"),
+                             cl::aliasopt(AccountTop), cl::sub(Account));
+
+static cl::opt<std::string>
+    AccountInstrMap("instr_map",
+                    cl::desc("binary with the instrumentation map, or "
+                             "a separate instrumentation map"),
+                    cl::value_desc("binary with xray_instr_map"),
+                    cl::sub(Account), cl::init(""));
+static cl::alias AccountInstrMap2("m", cl::aliasopt(AccountInstrMap),
+                                  cl::desc("Alias for -instr_map"),
+                                  cl::sub(Account));
+static cl::opt<InstrumentationMapExtractor::InputFormats> InstrMapFormat(
+    "instr-map-format", cl::desc("format of instrumentation map"),
+    cl::values(clEnumValN(InstrumentationMapExtractor::InputFormats::ELF, "elf",
+                          "instrumentation map in an ELF header"),
+               clEnumValN(InstrumentationMapExtractor::InputFormats::YAML,
+                          "yaml", "instrumentation map in YAML")),
+    cl::sub(Account), cl::init(InstrumentationMapExtractor::InputFormats::ELF));
+static cl::alias InstrMapFormat2("t", cl::aliasopt(InstrMapFormat),
+                                 cl::desc("Alias for -instr-map-format"),
+                                 cl::sub(Account));
+
+namespace {
+
+template <class T, class U> void setMinMax(std::pair<T, T> &MM, U &&V) {
+  if (MM.first == 0 || MM.second == 0)
+    MM = std::make_pair(std::forward<U>(V), std::forward<U>(V));
+  else
+    MM = std::make_pair(std::min(MM.first, V), std::max(MM.second, V));
+}
+
+template <class T> T diff(T L, T R) { return std::max(L, R) - std::min(L, R); }
+
+} // namespace
+
+bool LatencyAccountant::accountRecord(const XRayRecord &Record) {
+  setMinMax(PerThreadMinMaxTSC[Record.TId], Record.TSC);
+  setMinMax(PerCPUMinMaxTSC[Record.CPU], Record.TSC);
+
+  if (CurrentMaxTSC == 0)
+    CurrentMaxTSC = Record.TSC;
+
+  if (Record.TSC < CurrentMaxTSC)
+    return false;
+
+  auto &ThreadStack = PerThreadFunctionStack[Record.TId];
+  switch (Record.Type) {
+  case RecordTypes::ENTER: {
+    // Function Enter
+    ThreadStack.emplace_back(Record.FuncId, Record.TSC);
+    break;
+  }
+  case RecordTypes::EXIT: {
+    // Function Exit
+    if (ThreadStack.back().first == Record.FuncId) {
+      const auto &Top = ThreadStack.back();
+      recordLatency(Top.first, diff(Top.second, Record.TSC));
+      ThreadStack.pop_back();
+      break;
+    }
+
+    if (!DeduceSiblingCalls)
+      return false;
+
+    // Look for the parent up the stack.
+    auto Parent =
+        std::find_if(ThreadStack.rbegin(), ThreadStack.rend(),
+                     [&](const std::pair<const int32_t, uint64_t> &E) {
+                       return E.first == Record.FuncId;
+                     });
+    if (Parent == ThreadStack.rend())
+      return false;
+
+    // Account time for this apparently sibling call exit up the stack.
+    // Considering the following case:
+    //
+    //   f()
+    //    g()
+    //      h()
+    //
+    // We might only ever see the following entries:
+    //
+    //   -> f()
+    //   -> g()
+    //   -> h()
+    //   <- h()
+    //   <- f()
+    //
+    // Now we don't see the exit to g() because some older version of the XRay
+    // runtime wasn't instrumenting tail exits. If we don't deduce tail calls,
+    // we may potentially never account time for g() -- and this code would have
+    // already bailed out, because `<- f()` doesn't match the current "top" of
+    // stack where we're waiting for the exit to `g()` instead. This is not
+    // ideal and brittle -- so instead we provide a potentially inaccurate
+    // accounting of g() instead, computing it from the exit of f().
+    //
+    // While it might be better that we account the time between `-> g()` and
+    // `-> h()` as the proper accounting of time for g() here, this introduces
+    // complexity to do correctly (need to backtrack, etc.).
+    //
+    // FIXME: Potentially implement the more complex deduction algorithm?
+    auto I = std::next(Parent).base();
+    for (auto &E : make_range(I, ThreadStack.end())) {
+      recordLatency(E.first, diff(E.second, Record.TSC));
+    }
+    ThreadStack.erase(I, ThreadStack.end());
+    break;
+  }
+  }
+
+  return true;
+}
+
+namespace {
+
+// We consolidate the data into a struct which we can output in various forms.
+struct ResultRow {
+  uint64_t Count;
+  double Min;
+  double Median;
+  double Pct90;
+  double Pct99;
+  double Max;
+  double Sum;
+  std::string DebugInfo;
+  std::string Function;
+};
+
+ResultRow getStats(std::vector<uint64_t> &Timings) {
+  assert(!Timings.empty());
+  ResultRow R;
+  R.Sum = std::accumulate(Timings.begin(), Timings.end(), 0.0);
+  auto MinMax = std::minmax_element(Timings.begin(), Timings.end());
+  R.Min = *MinMax.first;
+  R.Max = *MinMax.second;
+  auto MedianOff = Timings.size() / 2;
+  std::nth_element(Timings.begin(), Timings.begin() + MedianOff, Timings.end());
+  R.Median = Timings[MedianOff];
+  auto Pct90Off = std::floor(Timings.size() * 0.9);
+  std::nth_element(Timings.begin(), Timings.begin() + Pct90Off, Timings.end());
+  R.Pct90 = Timings[Pct90Off];
+  auto Pct99Off = std::floor(Timings.size() * 0.99);
+  std::nth_element(Timings.begin(), Timings.begin() + Pct90Off, Timings.end());
+  R.Pct99 = Timings[Pct99Off];
+  R.Count = Timings.size();
+  return R;
+}
+
+} // namespace
+
+template <class F>
+void LatencyAccountant::exportStats(const XRayFileHeader &Header, F Fn) const {
+  using TupleType = std::tuple<int32_t, uint64_t, ResultRow>;
+  std::vector<TupleType> Results;
+  Results.reserve(FunctionLatencies.size());
+  for (auto FT : FunctionLatencies) {
+    const auto &FuncId = FT.first;
+    auto &Timings = FT.second;
+    Results.emplace_back(FuncId, Timings.size(), getStats(Timings));
+    auto &Row = std::get<2>(Results.back());
+    if (Header.CycleFrequency) {
+      double CycleFrequency = Header.CycleFrequency;
+      Row.Min /= CycleFrequency;
+      Row.Median /= CycleFrequency;
+      Row.Pct90 /= CycleFrequency;
+      Row.Pct99 /= CycleFrequency;
+      Row.Max /= CycleFrequency;
+      Row.Sum /= CycleFrequency;
+    }
+
+    Row.Function = FuncIdHelper.SymbolOrNumber(FuncId);
+    Row.DebugInfo = FuncIdHelper.FileLineAndColumn(FuncId);
+  }
+
+  // Sort the data according to user-provided flags.
+  switch (AccountSortOutput) {
+  case SortField::FUNCID:
+    std::sort(Results.begin(), Results.end(),
+              [](const TupleType &L, const TupleType &R) {
+                if (AccountSortOrder == SortDirection::ASCENDING)
+                  return std::get<0>(L) < std::get<0>(R);
+                if (AccountSortOrder == SortDirection::DESCENDING)
+                  return std::get<0>(L) > std::get<0>(R);
+                llvm_unreachable("Unknown sort direction");
+              });
+    break;
+  case SortField::COUNT:
+    std::sort(Results.begin(), Results.end(),
+              [](const TupleType &L, const TupleType &R) {
+                if (AccountSortOrder == SortDirection::ASCENDING)
+                  return std::get<1>(L) < std::get<1>(R);
+                if (AccountSortOrder == SortDirection::DESCENDING)
+                  return std::get<1>(L) > std::get<1>(R);
+                llvm_unreachable("Unknown sort direction");
+              });
+    break;
+  default:
+    // Here we need to look into the ResultRow for the rest of the data that
+    // we want to sort by.
+    std::sort(Results.begin(), Results.end(),
+              [&](const TupleType &L, const TupleType &R) {
+                auto &LR = std::get<2>(L);
+                auto &RR = std::get<2>(R);
+                switch (AccountSortOutput) {
+                case SortField::COUNT:
+                  if (AccountSortOrder == SortDirection::ASCENDING)
+                    return LR.Count < RR.Count;
+                  if (AccountSortOrder == SortDirection::DESCENDING)
+                    return LR.Count > RR.Count;
+                  llvm_unreachable("Unknown sort direction");
+                case SortField::MIN:
+                  if (AccountSortOrder == SortDirection::ASCENDING)
+                    return LR.Min < RR.Min;
+                  if (AccountSortOrder == SortDirection::DESCENDING)
+                    return LR.Min > RR.Min;
+                  llvm_unreachable("Unknown sort direction");
+                case SortField::MED:
+                  if (AccountSortOrder == SortDirection::ASCENDING)
+                    return LR.Median < RR.Median;
+                  if (AccountSortOrder == SortDirection::DESCENDING)
+                    return LR.Median > RR.Median;
+                  llvm_unreachable("Unknown sort direction");
+                case SortField::PCT90:
+                  if (AccountSortOrder == SortDirection::ASCENDING)
+                    return LR.Pct90 < RR.Pct90;
+                  if (AccountSortOrder == SortDirection::DESCENDING)
+                    return LR.Pct90 > RR.Pct90;
+                  llvm_unreachable("Unknown sort direction");
+                case SortField::PCT99:
+                  if (AccountSortOrder == SortDirection::ASCENDING)
+                    return LR.Pct99 < RR.Pct99;
+                  if (AccountSortOrder == SortDirection::DESCENDING)
+                    return LR.Pct99 > RR.Pct99;
+                  llvm_unreachable("Unknown sort direction");
+                case SortField::MAX:
+                  if (AccountSortOrder == SortDirection::ASCENDING)
+                    return LR.Max < RR.Max;
+                  if (AccountSortOrder == SortDirection::DESCENDING)
+                    return LR.Max > RR.Max;
+                  llvm_unreachable("Unknown sort direction");
+                case SortField::SUM:
+                  if (AccountSortOrder == SortDirection::ASCENDING)
+                    return LR.Sum < RR.Sum;
+                  if (AccountSortOrder == SortDirection::DESCENDING)
+                    return LR.Sum > RR.Sum;
+                  llvm_unreachable("Unknown sort direction");
+                default:
+                  llvm_unreachable("Unsupported sort order");
+                }
+              });
+    break;
+  }
+
+  if (AccountTop > 0)
+    Results.erase(Results.begin() + AccountTop.getValue(), Results.end());
+
+  for (const auto &R : Results)
+    Fn(std::get<0>(R), std::get<1>(R), std::get<2>(R));
+}
+
+void LatencyAccountant::exportStatsAsText(raw_ostream &OS,
+                                          const XRayFileHeader &Header) const {
+  OS << "Functions with latencies: " << FunctionLatencies.size() << "\n";
+
+  // We spend some effort to make the text output more readable, so we do the
+  // following formatting decisions for each of the fields:
+  //
+  //   - funcid: 32-bit, but we can determine the largest number and be
+  //   between
+  //     a minimum of 5 characters, up to 9 characters, right aligned.
+  //   - count:  64-bit, but we can determine the largest number and be
+  //   between
+  //     a minimum of 5 characters, up to 9 characters, right aligned.
+  //   - min, median, 90pct, 99pct, max: double precision, but we want to keep
+  //     the values in seconds, with microsecond precision (0.000'001), so we
+  //     have at most 6 significant digits, with the whole number part to be
+  //     at
+  //     least 1 character. For readability we'll right-align, with full 9
+  //     characters each.
+  //   - debug info, function name: we format this as a concatenation of the
+  //     debug info and the function name.
+  //
+  static constexpr char StatsHeaderFormat[] =
+      "{0,+9} {1,+10} [{2,+9}, {3,+9}, {4,+9}, {5,+9}, {6,+9}] {7,+9}";
+  static constexpr char StatsFormat[] =
+      R"({0,+9} {1,+10} [{2,+9:f6}, {3,+9:f6}, {4,+9:f6}, {5,+9:f6}, {6,+9:f6}] {7,+9:f6})";
+  OS << llvm::formatv(StatsHeaderFormat, "funcid", "count", "min", "med", "90p",
+                      "99p", "max", "sum")
+     << llvm::formatv("  {0,-12}\n", "function");
+  exportStats(Header, [&](int32_t FuncId, size_t Count, const ResultRow &Row) {
+    OS << llvm::formatv(StatsFormat, FuncId, Count, Row.Min, Row.Median,
+                        Row.Pct90, Row.Pct99, Row.Max, Row.Sum)
+       << "  " << Row.DebugInfo << ": " << Row.Function << "\n";
+  });
+}
+
+void LatencyAccountant::exportStatsAsCSV(raw_ostream &OS,
+                                         const XRayFileHeader &Header) const {
+  OS << "funcid,count,min,median,90%ile,99%ile,max,sum,debug,function\n";
+  exportStats(Header, [&](int32_t FuncId, size_t Count, const ResultRow &Row) {
+    OS << FuncId << ',' << Count << ',' << Row.Min << ',' << Row.Median << ','
+       << Row.Pct90 << ',' << Row.Pct99 << ',' << Row.Max << "," << Row.Sum
+       << ",\"" << Row.DebugInfo << "\",\"" << Row.Function << "\"\n";
+  });
+}
+
+using namespace llvm::xray;
+
+static CommandRegistration Unused(&Account, []() -> Error {
+  int Fd;
+  auto EC = sys::fs::openFileForRead(AccountInput, Fd);
+  if (EC)
+    return make_error<StringError>(
+        Twine("Cannot open file '") + AccountInput + "'", EC);
+
+  Error Err = Error::success();
+  xray::InstrumentationMapExtractor Extractor(AccountInstrMap, InstrMapFormat,
+                                              Err);
+  if (auto E = handleErrors(
+          std::move(Err), [&](std::unique_ptr<StringError> E) -> Error {
+            if (E->convertToErrorCode() == std::errc::no_such_file_or_directory)
+              return Error::success();
+            return Error(std::move(E));
+          }))
+    return E;
+
+  raw_fd_ostream OS(AccountOutput, EC, sys::fs::OpenFlags::F_Text);
+  if (EC)
+    return make_error<StringError>(
+        Twine("Cannot open file '") + AccountOutput + "' for writing.", EC);
+
+  const auto &FunctionAddresses = Extractor.getFunctionAddresses();
+  symbolize::LLVMSymbolizer::Options Opts(
+      symbolize::FunctionNameKind::LinkageName, true, true, false, "");
+  symbolize::LLVMSymbolizer Symbolizer(Opts);
+  llvm::xray::FuncIdConversionHelper FuncIdHelper(AccountInstrMap, Symbolizer,
+                                                  FunctionAddresses);
+  xray::LatencyAccountant FCA(FuncIdHelper, AccountDeduceSiblingCalls);
+  if (auto TraceOrErr = loadTraceFile(AccountInput)) {
+    auto &T = *TraceOrErr;
+    for (const auto &Record : T) {
+      if (FCA.accountRecord(Record))
+        continue;
+      for (const auto &ThreadStack : FCA.getPerThreadFunctionStack()) {
+        errs() << "Thread ID: " << ThreadStack.first << "\n";
+        auto Level = ThreadStack.second.size();
+        for (const auto &Entry : llvm::reverse(ThreadStack.second))
+          errs() << "#" << Level-- << "\t"
+                 << FuncIdHelper.SymbolOrNumber(Entry.first) << '\n';
+      }
+      if (!AccountKeepGoing)
+        return make_error<StringError>(
+            Twine("Failed accounting function calls in file '") + AccountInput +
+                "'.",
+            std::make_error_code(std::errc::bad_message));
+    }
+    switch (AccountOutputFormat) {
+    case AccountOutputFormats::TEXT:
+      FCA.exportStatsAsText(OS, T.getFileHeader());
+      break;
+    case AccountOutputFormats::CSV:
+      FCA.exportStatsAsCSV(OS, T.getFileHeader());
+      break;
+    }
+  } else {
+    return joinErrors(
+        make_error<StringError>(
+            Twine("Failed loading input file '") + AccountInput + "'",
+            std::make_error_code(std::errc::protocol_error)),
+        TraceOrErr.takeError());
+  }
+
+  return Error::success();
+});
diff --git a/llvm/tools/llvm-xray/xray-account.h b/llvm/tools/llvm-xray/xray-account.h
new file mode 100644
index 00000000000..763ea011de0
--- /dev/null
+++ b/llvm/tools/llvm-xray/xray-account.h
@@ -0,0 +1,104 @@
+//===- xray-account.h - XRay Function Call Accounting ---------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the interface for performing some basic function call
+// accounting from an XRay trace.
+//
+//===----------------------------------------------------------------------===//
+#ifndef LLVM_TOOLS_LLVM_XRAY_XRAY_ACCOUNT_H
+#define LLVM_TOOLS_LLVM_XRAY_XRAY_ACCOUNT_H
+
+#include <map>
+#include <utility>
+#include <vector>
+
+#include "func-id-helper.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/XRay/XRayRecord.h"
+
+namespace llvm {
+namespace xray {
+
+class LatencyAccountant {
+public:
+  typedef std::map<int32_t, std::vector<uint64_t>> FunctionLatencyMap;
+  typedef std::map<pid_t, std::pair<uint64_t, uint64_t>> PerThreadMinMaxTSCMap;
+  typedef std::map<uint8_t, std::pair<uint64_t, uint64_t>> PerCPUMinMaxTSCMap;
+  typedef std::vector<std::pair<int32_t, uint64_t>> FunctionStack;
+  typedef std::map<pid_t, FunctionStack> PerThreadFunctionStackMap;
+
+private:
+  PerThreadFunctionStackMap PerThreadFunctionStack;
+  FunctionLatencyMap FunctionLatencies;
+  PerThreadMinMaxTSCMap PerThreadMinMaxTSC;
+  PerCPUMinMaxTSCMap PerCPUMinMaxTSC;
+  FuncIdConversionHelper &FuncIdHelper;
+
+  bool DeduceSiblingCalls = false;
+  uint64_t CurrentMaxTSC = 0;
+
+  void recordLatency(int32_t FuncId, uint64_t Latency) {
+    FunctionLatencies[FuncId].push_back(Latency);
+  }
+
+public:
+  explicit LatencyAccountant(FuncIdConversionHelper &FuncIdHelper,
+                             bool DeduceSiblingCalls)
+      : FuncIdHelper(FuncIdHelper), DeduceSiblingCalls(DeduceSiblingCalls) {}
+
+  const FunctionLatencyMap &getFunctionLatencies() const {
+    return FunctionLatencies;
+  }
+
+  const PerThreadMinMaxTSCMap &getPerThreadMinMaxTSC() const {
+    return PerThreadMinMaxTSC;
+  }
+
+  const PerCPUMinMaxTSCMap &getPerCPUMinMaxTSC() const {
+    return PerCPUMinMaxTSC;
+  }
+
+  /// Returns false in case we fail to account the provided record. This happens
+  /// in the following cases:
+  ///
+  ///   - An exit record does not match any entry records for the same function.
+  ///     If we've been set to deduce sibling calls, we try walking up the stack
+  ///     and recording times for the higher level functions.
+  ///   - A record has a TSC that's before the latest TSC that has been
+  ///     recorded. We still record the TSC for the min-max.
+  ///
+  bool accountRecord(const XRayRecord &Record);
+
+  const FunctionStack *getThreadFunctionStack(pid_t TId) const {
+    auto I = PerThreadFunctionStack.find(TId);
+    if (I == PerThreadFunctionStack.end())
+      return nullptr;
+    return &I->second;
+  }
+
+  const PerThreadFunctionStackMap &getPerThreadFunctionStack() const {
+    return PerThreadFunctionStack;
+  }
+
+  // Output Functions
+  // ================
+
+  void exportStatsAsText(raw_ostream &OS, const XRayFileHeader &Header) const;
+  void exportStatsAsCSV(raw_ostream &OS, const XRayFileHeader &Header) const;
+
+private:
+  // Internal helper to implement common parts of the exportStatsAs...
+  // functions.
+  template <class F> void exportStats(const XRayFileHeader &Header, F fn) const;
+};
+
+} // namespace xray
+} // namespace llvm
+
+#endif // LLVM_TOOLS_LLVM_XRAY_XRAY_ACCOUNT_H
diff --git a/llvm/tools/llvm-xray/xray-record-yaml.h b/llvm/tools/llvm-xray/xray-record-yaml.h
new file mode 100644
index 00000000000..abce8ff60a9
--- /dev/null
+++ b/llvm/tools/llvm-xray/xray-record-yaml.h
@@ -0,0 +1,102 @@
+//===- xray-record-yaml.h - XRay Record YAML Support Definitions ----------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Types and traits specialisations for YAML I/O of XRay log entries.
+//
+//===----------------------------------------------------------------------===//
+#ifndef LLVM_TOOLS_LLVM_XRAY_XRAY_RECORD_YAML_H
+#define LLVM_TOOLS_LLVM_XRAY_XRAY_RECORD_YAML_H
+
+#include <type_traits>
+
+#include "xray-record.h"
+#include "llvm/Support/YAMLTraits.h"
+
+namespace llvm {
+namespace xray {
+
+struct YAMLXRayFileHeader {
+  uint16_t Version;
+  uint16_t Type;
+  bool ConstantTSC;
+  bool NonstopTSC;
+  uint64_t CycleFrequency;
+};
+
+struct YAMLXRayRecord {
+  uint16_t RecordType;
+  uint8_t CPU;
+  RecordTypes Type;
+  int32_t FuncId;
+  std::string Function;
+  uint64_t TSC;
+  uint32_t TId;
+};
+
+struct YAMLXRayTrace {
+  YAMLXRayFileHeader Header;
+  std::vector<YAMLXRayRecord> Records;
+};
+
+using XRayRecordStorage =
+    std::aligned_storage<sizeof(XRayRecord), alignof(XRayRecord)>::type;
+
+} // namespace xray
+
+namespace yaml {
+
+// YAML Traits
+// -----------
+template <> struct ScalarEnumerationTraits<xray::RecordTypes> {
+  static void enumeration(IO &IO, xray::RecordTypes &Type) {
+    IO.enumCase(Type, "function-enter", xray::RecordTypes::ENTER);
+    IO.enumCase(Type, "function-exit", xray::RecordTypes::EXIT);
+  }
+};
+
+template <> struct MappingTraits<xray::YAMLXRayFileHeader> {
+  static void mapping(IO &IO, xray::YAMLXRayFileHeader &Header) {
+    IO.mapRequired("version", Header.Version);
+    IO.mapRequired("type", Header.Type);
+    IO.mapRequired("constant-tsc", Header.ConstantTSC);
+    IO.mapRequired("nonstop-tsc", Header.NonstopTSC);
+    IO.mapRequired("cycle-frequency", Header.CycleFrequency);
+  }
+};
+
+template <> struct MappingTraits<xray::YAMLXRayRecord> {
+  static void mapping(IO &IO, xray::YAMLXRayRecord &Record) {
+    // FIXME: Make this type actually be descriptive
+    IO.mapRequired("type", Record.RecordType);
+    IO.mapRequired("func-id", Record.FuncId);
+    IO.mapOptional("function", Record.Function);
+    IO.mapRequired("cpu", Record.CPU);
+    IO.mapRequired("thread", Record.TId);
+    IO.mapRequired("kind", Record.Type);
+    IO.mapRequired("tsc", Record.TSC);
+  }
+
+  static constexpr bool flow = true;
+};
+
+template <> struct MappingTraits<xray::YAMLXRayTrace> {
+  static void mapping(IO &IO, xray::YAMLXRayTrace &Trace) {
+    // A trace file contains two parts, the header and the list of all the
+    // trace records.
+    IO.mapRequired("header", Trace.Header);
+    IO.mapRequired("records", Trace.Records);
+  }
+};
+
+} // namespace yaml
+} // namespace llvm
+
+LLVM_YAML_IS_SEQUENCE_VECTOR(xray::YAMLXRayRecord) 
+
+#endif // LLVM_TOOLS_LLVM_XRAY_XRAY_RECORD_YAML_H