xray_fdr_log_records.h revision 327952
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 16enum class RecordType : uint8_t { Function, Metadata }; 17 18// A MetadataRecord encodes the kind of record in its first byte, and have 15 19// additional bytes in the end to hold free-form data. 20struct alignas(16) MetadataRecord { 21 // A MetadataRecord must always have a type of 1. 22 /* RecordType */ uint8_t Type : 1; 23 24 // Each kind of record is represented as a 7-bit value (even though we use an 25 // unsigned 8-bit enum class to do so). 26 enum class RecordKinds : uint8_t { 27 NewBuffer, 28 EndOfBuffer, 29 NewCPUId, 30 TSCWrap, 31 WalltimeMarker, 32 CustomEventMarker, 33 CallArgument, 34 BufferExtents, 35 }; 36 37 // Use 7 bits to identify this record type. 38 /* RecordKinds */ uint8_t RecordKind : 7; 39 char Data[15]; 40} __attribute__((packed)); 41 42static_assert(sizeof(MetadataRecord) == 16, "Wrong size for MetadataRecord."); 43 44struct alignas(8) FunctionRecord { 45 // A FunctionRecord must always have a type of 0. 46 /* RecordType */ uint8_t Type : 1; 47 enum class RecordKinds { 48 FunctionEnter = 0x00, 49 FunctionExit = 0x01, 50 FunctionTailExit = 0x02, 51 }; 52 /* RecordKinds */ uint8_t RecordKind : 3; 53 54 // We only use 28 bits of the function ID, so that we can use as few bytes as 55 // possible. This means we only support 2^28 (268,435,456) unique function ids 56 // in a single binary. 57 int FuncId : 28; 58 59 // We use another 4 bytes to hold the delta between the previous entry's TSC. 60 // In case we've found that the distance is greater than the allowable 32 bits 61 // (either because we are running in a different CPU and the TSC might be 62 // different then), we should use a MetadataRecord before this FunctionRecord 63 // that will contain the full TSC for that CPU, and keep this to 0. 64 uint32_t TSCDelta; 65} __attribute__((packed)); 66 67static_assert(sizeof(FunctionRecord) == 8, "Wrong size for FunctionRecord."); 68 69#endif // XRAY_XRAY_FDR_LOG_RECORDS_H 70