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
15namespace llvm {
16namespace xray {
17
18namespace {
19
20template <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
43template <uint8_t Kind, class... Values>
44Error 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
61FDRTraceWriter::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
79FDRTraceWriter::~FDRTraceWriter() {}
80
81Error FDRTraceWriter::visit(BufferExtents &R) {
82  return writeMetadata<7u>(OS, R.size());
83}
84
85Error FDRTraceWriter::visit(WallclockRecord &R) {
86  return writeMetadata<4u>(OS, R.seconds(), R.nanos());
87}
88
89Error FDRTraceWriter::visit(NewCPUIDRecord &R) {
90  return writeMetadata<2u>(OS, R.cpuid(), R.tsc());
91}
92
93Error FDRTraceWriter::visit(TSCWrapRecord &R) {
94  return writeMetadata<3u>(OS, R.tsc());
95}
96
97Error 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
106Error 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
115Error 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
124Error FDRTraceWriter::visit(CallArgRecord &R) {
125  return writeMetadata<6u>(OS, R.arg());
126}
127
128Error FDRTraceWriter::visit(PIDRecord &R) {
129  return writeMetadata<9u>(OS, R.pid());
130}
131
132Error FDRTraceWriter::visit(NewBufferRecord &R) {
133  return writeMetadata<0u>(OS, R.tid());
134}
135
136Error FDRTraceWriter::visit(EndBufferRecord &R) {
137  return writeMetadata<1u>(OS, 0);
138}
139
140Error 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
154