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llvm-mirror/lib/XRay/FileHeaderReader.cpp
Igor Kudrin 2f7af9b01c Switch LLVM to use 64-bit offsets (2/5)
This updates all libraries and tools in LLVM Core to use 64-bit offsets
which directly or indirectly come to DataExtractor.

Differential Revision: https://reviews.llvm.org/D65638

llvm-svn: 368014
2019-08-06 10:49:40 +00:00

74 lines
2.7 KiB
C++

//===- FileHeaderReader.cpp - XRay File Header Reader --------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#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,
uint64_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 %" PRId64 ".",
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 %" PRId64 ".",
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 %" PRId64 ".",
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 %" PRId64
".",
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