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
154