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   // The first bit in the first byte of metadata records is always set to 1, so
47   // we ensure this is the case when we write out the first byte of the record.
48   uint8_t FirstByte = (static_cast<uint8_t>(Kind) << 1) | uint8_t{0x01u};
49   auto T = std::make_tuple(std::forward<Values>(std::move(Ds))...);
50   // Write in field order.
51   OS.write(FirstByte);
52   auto Bytes = IndexedWriter<0>::write(OS, T);
53   assert(Bytes <= 15 && "Must only ever write at most 16 byte metadata!");
54   // Pad out with appropriate numbers of zero's.
55   for (; Bytes < 15; ++Bytes)
56     OS.write('\0');
57   return Error::success();
58 }
59 
60 } // namespace
61 
62 FDRTraceWriter::FDRTraceWriter(raw_ostream &O, const XRayFileHeader &H)
63     : OS(O, support::endianness::native) {
64   // We need to re-construct a header, by writing the fields we care about for
65   // traces, in the format that the runtime would have written.
66   uint32_t BitField =
67       (H.ConstantTSC ? 0x01 : 0x0) | (H.NonstopTSC ? 0x02 : 0x0);
68 
69   // For endian-correctness, we need to write these fields in the order they
70   // appear and that we expect, instead of blasting bytes of the struct through.
71   OS.write(H.Version);
72   OS.write(H.Type);
73   OS.write(BitField);
74   OS.write(H.CycleFrequency);
75   ArrayRef<char> FreeFormBytes(H.FreeFormData,
76                                sizeof(XRayFileHeader::FreeFormData));
77   OS.write(FreeFormBytes);
78 }
79 
80 FDRTraceWriter::~FDRTraceWriter() {}
81 
82 Error FDRTraceWriter::visit(BufferExtents &R) {
83   return writeMetadata<7u>(OS, R.size());
84 }
85 
86 Error FDRTraceWriter::visit(WallclockRecord &R) {
87   return writeMetadata<4u>(OS, R.seconds(), R.nanos());
88 }
89 
90 Error FDRTraceWriter::visit(NewCPUIDRecord &R) {
91   return writeMetadata<2u>(OS, R.cpuid(), R.tsc());
92 }
93 
94 Error FDRTraceWriter::visit(TSCWrapRecord &R) {
95   return writeMetadata<3u>(OS, R.tsc());
96 }
97 
98 Error FDRTraceWriter::visit(CustomEventRecord &R) {
99   if (auto E = writeMetadata<5u>(OS, R.size(), R.tsc(), R.cpu()))
100     return E;
101   auto D = R.data();
102   ArrayRef<char> Bytes(D.data(), D.size());
103   OS.write(Bytes);
104   return Error::success();
105 }
106 
107 Error FDRTraceWriter::visit(CustomEventRecordV5 &R) {
108   if (auto E = writeMetadata<5u>(OS, R.size(), R.delta()))
109     return E;
110   auto D = R.data();
111   ArrayRef<char> Bytes(D.data(), D.size());
112   OS.write(Bytes);
113   return Error::success();
114 }
115 
116 Error FDRTraceWriter::visit(TypedEventRecord &R) {
117   if (auto E = writeMetadata<8u>(OS, R.size(), R.delta(), R.eventType()))
118     return E;
119   auto D = R.data();
120   ArrayRef<char> Bytes(D.data(), D.size());
121   OS.write(Bytes);
122   return Error::success();
123 }
124 
125 Error FDRTraceWriter::visit(CallArgRecord &R) {
126   return writeMetadata<6u>(OS, R.arg());
127 }
128 
129 Error FDRTraceWriter::visit(PIDRecord &R) {
130   return writeMetadata<9u>(OS, R.pid());
131 }
132 
133 Error FDRTraceWriter::visit(NewBufferRecord &R) {
134   return writeMetadata<0u>(OS, R.tid());
135 }
136 
137 Error FDRTraceWriter::visit(EndBufferRecord &R) {
138   return writeMetadata<1u>(OS, 0);
139 }
140 
141 Error FDRTraceWriter::visit(FunctionRecord &R) {
142   // Write out the data in "field" order, to be endian-aware.
143   uint32_t TypeRecordFuncId = uint32_t{R.functionId() & ~uint32_t{0x0Fu << 28}};
144   TypeRecordFuncId <<= 3;
145   TypeRecordFuncId |= static_cast<uint32_t>(R.recordType());
146   TypeRecordFuncId <<= 1;
147   TypeRecordFuncId &= ~uint32_t{0x01};
148   OS.write(TypeRecordFuncId);
149   OS.write(R.delta());
150   return Error::success();
151 }
152 
153 } // namespace xray
154 } // namespace llvm
155