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1//===-- xray_fdr_log_records.h -------------------------------------------===//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-exception6//7//===----------------------------------------------------------------------===//8//9// This file is a part of XRay, a function call tracing system.10//11//===----------------------------------------------------------------------===//12#ifndef XRAY_XRAY_FDR_LOG_RECORDS_H13#define XRAY_XRAY_FDR_LOG_RECORDS_H14#include <cstdint>15 16namespace __xray {17 18enum class RecordType : uint8_t { Function, Metadata };19 20// A MetadataRecord encodes the kind of record in its first byte, and have 1521// additional bytes in the end to hold free-form data.22struct alignas(16) MetadataRecord {23 // A MetadataRecord must always have a type of 1.24 /* RecordType */ uint8_t Type : 1;25 26 // Each kind of record is represented as a 7-bit value (even though we use an27 // unsigned 8-bit enum class to do so).28 enum class RecordKinds : uint8_t {29 NewBuffer,30 EndOfBuffer,31 NewCPUId,32 TSCWrap,33 WalltimeMarker,34 CustomEventMarker,35 CallArgument,36 BufferExtents,37 TypedEventMarker,38 Pid,39 };40 41 // Use 7 bits to identify this record type.42 /* RecordKinds */ uint8_t RecordKind : 7;43 char Data[15];44} __attribute__((packed));45 46static_assert(sizeof(MetadataRecord) == 16, "Wrong size for MetadataRecord.");47 48struct alignas(8) FunctionRecord {49 // A FunctionRecord must always have a type of 0.50 /* RecordType */ uint8_t Type : 1;51 enum class RecordKinds {52 FunctionEnter = 0x00,53 FunctionExit = 0x01,54 FunctionTailExit = 0x02,55 };56 /* RecordKinds */ uint8_t RecordKind : 3;57 58 // We only use 28 bits of the function ID, so that we can use as few bytes as59 // possible. This means we only support 2^28 (268,435,456) unique function ids60 // in a single binary.61 int FuncId : 28;62 63 // We use another 4 bytes to hold the delta between the previous entry's TSC.64 // In case we've found that the distance is greater than the allowable 32 bits65 // (either because we are running in a different CPU and the TSC might be66 // different then), we should use a MetadataRecord before this FunctionRecord67 // that will contain the full TSC for that CPU, and keep this to 0.68 uint32_t TSCDelta;69} __attribute__((packed));70 71static_assert(sizeof(FunctionRecord) == 8, "Wrong size for FunctionRecord.");72 73} // namespace __xray74 75#endif // XRAY_XRAY_FDR_LOG_RECORDS_H76