lib/XRay/FDRTraceWriter.cpp

   1 //===- FDRTraceWriter.cpp - XRay FDR Trace Writer ---------------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // Test a utility that can write out XRay FDR Mode formatted trace files.
  10 //
  11 //===----------------------------------------------------------------------===//
  12 #include "llvm/XRay/FDRTraceWriter.h"
  13 #include <tuple>
  14
  15 namespace llvm {
  16 namespace xray {
  17
  18 namespace {
  19
  20 template <size_t Index> struct IndexedWriter {
  21   template <
  22       class Tuple,
  23       typename std::enable_if<
  24           (Index <
  25            std::tuple_size<typename std::remove_reference<Tuple>::type>::value),
  26           int>::type = 0>
  27   static size_t write(support::endian::Writer &OS, Tuple &&T) {
  28     OS.write(std::get<Index>(T));
  29     return sizeof(std::get<Index>(T)) + IndexedWriter<Index + 1>::write(OS, T);
  30   }
  31
  32   template <
  33       class Tuple,
  34       typename std::enable_if<
  35           (Index >=
  36            std::tuple_size<typename std::remove_reference<Tuple>::type>::value),
  37           int>::type = 0>
  38   static size_t write(support::endian::Writer &OS, Tuple &&) {
  39     return 0;
  40   }
  41 };
  42
  43 template <uint8_t Kind, class... Values>
  44 Error writeMetadata(support::endian::Writer &OS, Values &&... Ds) {
  45   // The first bit in the first byte of metadata records is always set to 1, so
  46   // we ensure this is the case when we write out the first byte of the record.
  47   uint8_t FirstByte = (static_cast<uint8_t>(Kind) << 1) | uint8_t{0x01u};
  48   auto T = std::make_tuple(std::forward<Values>(std::move(Ds))...);
  49   // Write in field order.
  50   OS.write(FirstByte);
  51   auto Bytes = IndexedWriter<0>::write(OS, T);
  52   assert(Bytes <= 15 && "Must only ever write at most 16 byte metadata!");
  53   // Pad out with appropriate numbers of zero's.
  54   for (; Bytes < 15; ++Bytes)
  55     OS.write('\0');
  56   return Error::success();
  57 }
  58
  59 } // namespace
  60
  61 FDRTraceWriter::FDRTraceWriter(raw_ostream &O, const XRayFileHeader &H)
  62     : OS(O, support::endianness::native) {
  63   // We need to re-construct a header, by writing the fields we care about for
  64   // traces, in the format that the runtime would have written.
  65   uint32_t BitField =
  66       (H.ConstantTSC ? 0x01 : 0x0) | (H.NonstopTSC ? 0x02 : 0x0);
  67
  68   // For endian-correctness, we need to write these fields in the order they
  69   // appear and that we expect, instead of blasting bytes of the struct through.
  70   OS.write(H.Version);
  71   OS.write(H.Type);
  72   OS.write(BitField);
  73   OS.write(H.CycleFrequency);
  74   ArrayRef<char> FreeFormBytes(H.FreeFormData,
  75                                sizeof(XRayFileHeader::FreeFormData));
  76   OS.write(FreeFormBytes);
  77 }
  78
  79 FDRTraceWriter::~FDRTraceWriter() {}
  80
  81 Error FDRTraceWriter::visit(BufferExtents &R) {
  82   return writeMetadata<7u>(OS, R.size());
  83 }
  84
  85 Error FDRTraceWriter::visit(WallclockRecord &R) {
  86   return writeMetadata<4u>(OS, R.seconds(), R.nanos());
  87 }
  88
  89 Error FDRTraceWriter::visit(NewCPUIDRecord &R) {
  90   return writeMetadata<2u>(OS, R.cpuid(), R.tsc());
  91 }
  92
  93 Error FDRTraceWriter::visit(TSCWrapRecord &R) {
  94   return writeMetadata<3u>(OS, R.tsc());
  95 }
  96
  97 Error FDRTraceWriter::visit(CustomEventRecord &R) {
  98   if (auto E = writeMetadata<5u>(OS, R.size(), R.tsc(), R.cpu()))
  99     return E;
 100   auto D = R.data();
 101   ArrayRef<char> Bytes(D.data(), D.size());
 102   OS.write(Bytes);
 103   return Error::success();
 104 }
 105
 106 Error FDRTraceWriter::visit(CustomEventRecordV5 &R) {
 107   if (auto E = writeMetadata<5u>(OS, R.size(), R.delta()))
 108     return E;
 109   auto D = R.data();
 110   ArrayRef<char> Bytes(D.data(), D.size());
 111   OS.write(Bytes);
 112   return Error::success();
 113 }
 114
 115 Error FDRTraceWriter::visit(TypedEventRecord &R) {
 116   if (auto E = writeMetadata<8u>(OS, R.size(), R.delta(), R.eventType()))
 117     return E;
 118   auto D = R.data();
 119   ArrayRef<char> Bytes(D.data(), D.size());
 120   OS.write(Bytes);
 121   return Error::success();
 122 }
 123
 124 Error FDRTraceWriter::visit(CallArgRecord &R) {
 125   return writeMetadata<6u>(OS, R.arg());
 126 }
 127
 128 Error FDRTraceWriter::visit(PIDRecord &R) {
 129   return writeMetadata<9u>(OS, R.pid());
 130 }
 131
 132 Error FDRTraceWriter::visit(NewBufferRecord &R) {
 133   return writeMetadata<0u>(OS, R.tid());
 134 }
 135
 136 Error FDRTraceWriter::visit(EndBufferRecord &R) {
 137   return writeMetadata<1u>(OS, 0);
 138 }
 139
 140 Error FDRTraceWriter::visit(FunctionRecord &R) {
 141   // Write out the data in "field" order, to be endian-aware.
 142   uint32_t TypeRecordFuncId = uint32_t{R.functionId() & ~uint32_t{0x0Fu << 28}};
 143   TypeRecordFuncId <<= 3;
 144   TypeRecordFuncId |= static_cast<uint32_t>(R.recordType());
 145   TypeRecordFuncId <<= 1;
 146   TypeRecordFuncId &= ~uint32_t{0x01};
 147   OS.write(TypeRecordFuncId);
 148   OS.write(R.delta());
 149   return Error::success();
 150 }
 151
 152 } // namespace xray
 153 } // namespace llvm