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llvm-mirror/lib/XRay/FileHeaderReader.cpp
Dean Michael Berris d9e9a38395 [XRay] Use TSC delta encoding for custom/typed events
Summary:
This change updates the version number for FDR logs to 5, and update the
trace processing to support changes in the custom event records.

In the runtime, since we're already writing down the record preamble to
handle CPU migrations and TSC wraparound, we can use the same TSC delta
encoding in the custom event and typed event records that we use in
function event records. We do the same change to typed events (which
were unsupported before this change in the trace processing) which now
show up in the trace.

Future changes should increase our testing coverage to make custom and
typed events as first class entities in the FDR mode log processing
tools.

This change is also a good example of how we end up supporting new
record types in the FDR mode implementation. This shows the places where
new record types are added and supported.

Depends on D54139.

Reviewers: mboerger

Subscribers: hiraditya, arphaman, jfb, llvm-commits

Differential Revision: https://reviews.llvm.org/D54140

llvm-svn: 346293
2018-11-07 04:37:42 +00:00

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C++

//===- FileHeaderReader.cpp - XRay File Header Reader --------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "llvm/XRay/FileHeaderReader.h"
namespace llvm {
namespace xray {
// Populates the FileHeader reference by reading the first 32 bytes of the file.
Expected<XRayFileHeader> readBinaryFormatHeader(DataExtractor &HeaderExtractor,
uint32_t &OffsetPtr) {
// FIXME: Maybe deduce whether the data is little or big-endian using some
// magic bytes in the beginning of the file?
// First 32 bytes of the file will always be the header. We assume a certain
// format here:
//
// (2) uint16 : version
// (2) uint16 : type
// (4) uint32 : bitfield
// (8) uint64 : cycle frequency
// (16) - : padding
XRayFileHeader FileHeader;
auto PreReadOffset = OffsetPtr;
FileHeader.Version = HeaderExtractor.getU16(&OffsetPtr);
if (OffsetPtr == PreReadOffset)
return createStringError(
std::make_error_code(std::errc::invalid_argument),
"Failed reading version from file header at offset %d.", OffsetPtr);
PreReadOffset = OffsetPtr;
FileHeader.Type = HeaderExtractor.getU16(&OffsetPtr);
if (OffsetPtr == PreReadOffset)
return createStringError(
std::make_error_code(std::errc::invalid_argument),
"Failed reading file type from file header at offset %d.", OffsetPtr);
PreReadOffset = OffsetPtr;
uint32_t Bitfield = HeaderExtractor.getU32(&OffsetPtr);
if (OffsetPtr == PreReadOffset)
return createStringError(
std::make_error_code(std::errc::invalid_argument),
"Failed reading flag bits from file header at offset %d.", OffsetPtr);
FileHeader.ConstantTSC = Bitfield & 1uL;
FileHeader.NonstopTSC = Bitfield & 1uL << 1;
PreReadOffset = OffsetPtr;
FileHeader.CycleFrequency = HeaderExtractor.getU64(&OffsetPtr);
if (OffsetPtr == PreReadOffset)
return createStringError(
std::make_error_code(std::errc::invalid_argument),
"Failed reading cycle frequency from file header at offset %d.",
OffsetPtr);
std::memcpy(&FileHeader.FreeFormData,
HeaderExtractor.getData().bytes_begin() + OffsetPtr, 16);
// Manually advance the offset pointer 16 bytes, after getting a raw memcpy
// from the underlying data.
OffsetPtr += 16;
return std::move(FileHeader);
}
} // namespace xray
} // namespace llvm