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llvm-mirror/lib/XRay/FileHeaderReader.cpp
Dean Michael Berris f9e1fbc647 [XRay] Refactor file header reading (NFC)
Summary:
This patch moves out the definition of the XRay log file header from
binary logs into its own header and implementation file.

This is one part of the refactoring being done in D50441.

Reviewers: eizan

Subscribers: mgorny, hiraditya, llvm-commits

Differential Revision: https://reviews.llvm.org/D51086

llvm-svn: 340389
2018-08-22 07:37:55 +00:00

76 lines
2.9 KiB
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;
if (FileHeader.Version != 1 && FileHeader.Version != 2 &&
FileHeader.Version != 3)
return createStringError(std::make_error_code(std::errc::invalid_argument),
"Unsupported XRay file version: %d at offset %d",
FileHeader.Version, OffsetPtr);
return std::move(FileHeader);
}
} // namespace xray
} // namespace llvm