lib/XRay/FDRTraceWriter.cpp

   1 //===- FDRTraceWriter.cpp - XRay FDR Trace Writer ---------------*- C++ -*-===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // Test a utility that can write out XRay FDR Mode formatted trace files.
  11 //
  12 //===----------------------------------------------------------------------===//
  13 #include "llvm/XRay/FDRTraceWriter.h"
  14 #include <tuple>
  15
  16 namespace llvm {
  17 namespace xray {
  18
  19 namespace {
  20
  21 template <size_t Index> struct IndexedWriter {
  22   template <
  23       class Tuple,
  24       typename std::enable_if<
  25           (Index <
  26            std::tuple_size<typename std::remove_reference<Tuple>::type>::value),
  27           int>::type = 0>
  28   static size_t write(support::endian::Writer &OS, Tuple &&T) {
  29     OS.write(std::get<Index>(T));
  30     return sizeof(std::get<Index>(T)) + IndexedWriter<Index + 1>::write(OS, T);
  31   }
  32
  33   template <
  34       class Tuple,
  35       typename std::enable_if<
  36           (Index >=
  37            std::tuple_size<typename std::remove_reference<Tuple>::type>::value),
  38           int>::type = 0>
  39   static size_t write(support::endian::Writer &OS, Tuple &&) {
  40     return 0;
  41   }
  42 };
  43
  44 template <uint8_t Kind, class... Values>
  45 Error writeMetadata(support::endian::Writer &OS, Values &&... Ds) {
  46   uint8_t FirstByte = (Kind << 1) | uint8_t{0x01};
  47   auto T = std::make_tuple(std::forward<Values>(std::move(Ds))...);
  48   // Write in field order.
  49   OS.write(FirstByte);
  50   auto Bytes = IndexedWriter<0>::write(OS, T);
  51   assert(Bytes <= 15 && "Must only ever write at most 16 byte metadata!");
  52   // Pad out with appropriate numbers of zero's.
  53   for (; Bytes < 15; ++Bytes)
  54     OS.write('\0');
  55   return Error::success();
  56 }
  57
  58 } // namespace
  59
  60 FDRTraceWriter::FDRTraceWriter(raw_ostream &O, const XRayFileHeader &H)
  61     : OS(O, support::endianness::native) {
  62   // We need to re-construct a header, by writing the fields we care about for
  63   // traces, in the format that the runtime would have written.
  64   uint32_t BitField =
  65       (H.ConstantTSC ? 0x01 : 0x0) | (H.NonstopTSC ? 0x02 : 0x0);
  66
  67   // For endian-correctness, we need to write these fields in the order they
  68   // appear and that we expect, instead of blasting bytes of the struct through.
  69   OS.write(H.Version);
  70   OS.write(H.Type);
  71   OS.write(BitField);
  72   OS.write(H.CycleFrequency);
  73   ArrayRef<char> FreeFormBytes(H.FreeFormData,
  74                                sizeof(XRayFileHeader::FreeFormData));
  75   OS.write(FreeFormBytes);
  76 }
  77
  78 FDRTraceWriter::~FDRTraceWriter() {}
  79
  80 Error FDRTraceWriter::visit(BufferExtents &R) {
  81   return writeMetadata<7u>(OS, R.size());
  82 }
  83
  84 Error FDRTraceWriter::visit(WallclockRecord &R) {
  85   return writeMetadata<4u>(OS, R.seconds(), R.nanos());
  86 }
  87
  88 Error FDRTraceWriter::visit(NewCPUIDRecord &R) {
  89   return writeMetadata<2u>(OS, R.cpuid(), R.tsc());
  90 }
  91
  92 Error FDRTraceWriter::visit(TSCWrapRecord &R) {
  93   return writeMetadata<3u>(OS, R.tsc());
  94 }
  95
  96 Error FDRTraceWriter::visit(CustomEventRecord &R) {
  97   if (auto E = writeMetadata<5u>(OS, R.size(), R.tsc()))
  98     return E;
  99   ArrayRef<char> Bytes(R.data().data(), R.data().size());
 100   OS.write(Bytes);
 101   return Error::success();
 102 }
 103
 104 Error FDRTraceWriter::visit(CallArgRecord &R) {
 105   return writeMetadata<6u>(OS, R.arg());
 106 }
 107
 108 Error FDRTraceWriter::visit(PIDRecord &R) {
 109   return writeMetadata<9u>(OS, R.pid());
 110 }
 111
 112 Error FDRTraceWriter::visit(NewBufferRecord &R) {
 113   return writeMetadata<0u>(OS, R.tid());
 114 }
 115
 116 Error FDRTraceWriter::visit(EndBufferRecord &R) {
 117   return writeMetadata<1u>(OS, 0);
 118 }
 119
 120 Error FDRTraceWriter::visit(FunctionRecord &R) {
 121   // Write out the data in "field" order, to be endian-aware.
 122   uint32_t TypeRecordFuncId = uint32_t{R.functionId() & ~uint32_t{0x0Fu << 28}};
 123   TypeRecordFuncId <<= 3;
 124   TypeRecordFuncId |= static_cast<uint32_t>(R.recordType());
 125   TypeRecordFuncId <<= 1;
 126   TypeRecordFuncId &= ~uint32_t{0x01};
 127   OS.write(TypeRecordFuncId);
 128   OS.write(R.delta());
 129   return Error::success();
 130 } // namespace xray
 131
 132 } // namespace xray
 133 } // namespace llvm