76 lines
2.9 KiB
C++
76 lines
2.9 KiB
C++
//===- FileHeaderReader.cpp - XRay File Header Reader --------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/XRay/FileHeaderReader.h"
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namespace llvm {
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namespace xray {
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// Populates the FileHeader reference by reading the first 32 bytes of the file.
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Expected<XRayFileHeader> readBinaryFormatHeader(DataExtractor &HeaderExtractor,
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uint32_t &OffsetPtr) {
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// FIXME: Maybe deduce whether the data is little or big-endian using some
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// magic bytes in the beginning of the file?
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// First 32 bytes of the file will always be the header. We assume a certain
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// format here:
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//
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// (2) uint16 : version
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// (2) uint16 : type
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// (4) uint32 : bitfield
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// (8) uint64 : cycle frequency
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// (16) - : padding
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XRayFileHeader FileHeader;
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auto PreReadOffset = OffsetPtr;
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FileHeader.Version = HeaderExtractor.getU16(&OffsetPtr);
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if (OffsetPtr == PreReadOffset)
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return createStringError(
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std::make_error_code(std::errc::invalid_argument),
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"Failed reading version from file header at offset %d.", OffsetPtr);
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PreReadOffset = OffsetPtr;
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FileHeader.Type = HeaderExtractor.getU16(&OffsetPtr);
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if (OffsetPtr == PreReadOffset)
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return createStringError(
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std::make_error_code(std::errc::invalid_argument),
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"Failed reading file type from file header at offset %d.", OffsetPtr);
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PreReadOffset = OffsetPtr;
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uint32_t Bitfield = HeaderExtractor.getU32(&OffsetPtr);
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if (OffsetPtr == PreReadOffset)
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return createStringError(
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std::make_error_code(std::errc::invalid_argument),
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"Failed reading flag bits from file header at offset %d.", OffsetPtr);
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FileHeader.ConstantTSC = Bitfield & 1uL;
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FileHeader.NonstopTSC = Bitfield & 1uL << 1;
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PreReadOffset = OffsetPtr;
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FileHeader.CycleFrequency = HeaderExtractor.getU64(&OffsetPtr);
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if (OffsetPtr == PreReadOffset)
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return createStringError(
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std::make_error_code(std::errc::invalid_argument),
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"Failed reading cycle frequency from file header at offset %d.",
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OffsetPtr);
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std::memcpy(&FileHeader.FreeFormData,
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HeaderExtractor.getData().bytes_begin() + OffsetPtr, 16);
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// Manually advance the offset pointer 16 bytes, after getting a raw memcpy
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// from the underlying data.
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OffsetPtr += 16;
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if (FileHeader.Version != 1 && FileHeader.Version != 2 &&
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FileHeader.Version != 3)
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return createStringError(std::make_error_code(std::errc::invalid_argument),
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"Unsupported XRay file version: %d at offset %d",
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FileHeader.Version, OffsetPtr);
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return std::move(FileHeader);
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}
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} // namespace xray
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} // namespace llvm
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