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