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llvm-mirror/include/llvm/XRay/XRayRecord.h
Dean Michael Berris 37f9897224 [XRay] Update FDR log reader to be aware of buffer sizes per thread.
Summary:
It is problematic for this reader that it expects to read data from
several threads, but the header or message format does not define
framing. Since the buffers are reused, we can't rely on skipping
zeroed out data as a synchronization method either.

There is an argument that this is not version compatible with the format
the reader expected previously. I argue that since the writer wrote garbage
past the end of buffer record, there is no currently working reader to
compromise.

The corresponding writer change is posted to D31384.

Reviewers: dberris, pelikan

Reviewed By: dberris

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D31385

llvm-svn: 298983
2017-03-29 06:10:12 +00:00

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//===- XRayRecord.h - XRay Trace Record -----------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file replicates the record definition for XRay log entries. This should
// follow the evolution of the log record versions supported in the compiler-rt
// xray project.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_XRAY_XRAY_RECORD_H
#define LLVM_XRAY_XRAY_RECORD_H
#include <cstdint>
namespace llvm {
namespace xray {
/// XRay traces all have a header providing some top-matter information useful
/// to help tools determine how to interpret the information available in the
/// trace.
struct XRayFileHeader {
/// Version of the XRay implementation that produced this file.
uint16_t Version = 0;
/// A numeric identifier for the type of file this is. Best used in
/// combination with Version.
uint16_t Type = 0;
/// Whether the CPU that produced the timestamp counters (TSC) move at a
/// constant rate.
bool ConstantTSC;
/// Whether the CPU that produced the timestamp counters (TSC) do not stop.
bool NonstopTSC;
/// The number of cycles per second for the CPU that produced the timestamp
/// counter (TSC) values. Useful for estimating the amount of time that
/// elapsed between two TSCs on some platforms.
uint64_t CycleFrequency = 0;
// This is different depending on the type of xray record. The naive format
// stores a Wallclock timespec. FDR logging stores the size of a thread
// buffer.
char FreeFormData[16];
};
/// Determines the supported types of records that could be seen in XRay traces.
/// This may or may not correspond to actual record types in the raw trace (as
/// the loader implementation may synthesize this information in the process of
/// of loading).
enum class RecordTypes { ENTER, EXIT };
struct XRayRecord {
/// The type of record.
uint16_t RecordType;
/// The CPU where the thread is running. We assume number of CPUs <= 65536.
uint16_t CPU;
/// Identifies the type of record.
RecordTypes Type;
/// The function ID for the record.
int32_t FuncId;
/// Get the full 8 bytes of the TSC when we get the log record.
uint64_t TSC;
/// The thread ID for the currently running thread.
uint32_t TId;
};
} // namespace xray
} // namespace llvm
#endif // LLVM_XRAY_XRAY_RECORD_H