1//===-- xray_fdr_log_records.h  -------------------------------------------===//
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// This file is a part of XRay, a function call tracing system.
11//
12//===----------------------------------------------------------------------===//
13#ifndef XRAY_XRAY_FDR_LOG_RECORDS_H
14#define XRAY_XRAY_FDR_LOG_RECORDS_H
15#include <cstdint>
16
17namespace __xray {
18
19enum class RecordType : uint8_t { Function, Metadata };
20
21// A MetadataRecord encodes the kind of record in its first byte, and have 15
22// additional bytes in the end to hold free-form data.
23struct alignas(16) MetadataRecord {
24  // A MetadataRecord must always have a type of 1.
25  /* RecordType */ uint8_t Type : 1;
26
27  // Each kind of record is represented as a 7-bit value (even though we use an
28  // unsigned 8-bit enum class to do so).
29  enum class RecordKinds : uint8_t {
30    NewBuffer,
31    EndOfBuffer,
32    NewCPUId,
33    TSCWrap,
34    WalltimeMarker,
35    CustomEventMarker,
36    CallArgument,
37    BufferExtents,
38    TypedEventMarker,
39    Pid,
40  };
41
42  // Use 7 bits to identify this record type.
43  /* RecordKinds */ uint8_t RecordKind : 7;
44  char Data[15];
45} __attribute__((packed));
46
47static_assert(sizeof(MetadataRecord) == 16, "Wrong size for MetadataRecord.");
48
49struct alignas(8) FunctionRecord {
50  // A FunctionRecord must always have a type of 0.
51  /* RecordType */ uint8_t Type : 1;
52  enum class RecordKinds {
53    FunctionEnter = 0x00,
54    FunctionExit = 0x01,
55    FunctionTailExit = 0x02,
56  };
57  /* RecordKinds */ uint8_t RecordKind : 3;
58
59  // We only use 28 bits of the function ID, so that we can use as few bytes as
60  // possible. This means we only support 2^28 (268,435,456) unique function ids
61  // in a single binary.
62  int FuncId : 28;
63
64  // We use another 4 bytes to hold the delta between the previous entry's TSC.
65  // In case we've found that the distance is greater than the allowable 32 bits
66  // (either because we are running in a different CPU and the TSC might be
67  // different then), we should use a MetadataRecord before this FunctionRecord
68  // that will contain the full TSC for that CPU, and keep this to 0.
69  uint32_t TSCDelta;
70} __attribute__((packed));
71
72static_assert(sizeof(FunctionRecord) == 8, "Wrong size for FunctionRecord.");
73
74} // namespace __xray
75
76#endif // XRAY_XRAY_FDR_LOG_RECORDS_H
77