Commit 1e1e3ba2 authored by Hans Wennborg's avatar Hans Wennborg
Browse files

Unify the two CRC implementations 

David added the JamCRC implementation in r246590. More recently, Eugene
added a CRC-32 implementation in r357901, which falls back to zlib's
crc32 function if present.

These checksums are essentially the same, so having multiple
implementations seems unnecessary. This replaces the CRC-32
implementation with the simpler one from JamCRC, and implements the
JamCRC interface in terms of CRC-32 since this means it can use zlib's
implementation when available, saving a few bytes and potentially making
it faster.

JamCRC took an ArrayRef<char> argument, and CRC-32 took a StringRef.
This patch changes it to ArrayRef<uint8_t> which I think is the best
choice, and simplifies a few of the callers nicely.

Differential revision: https://reviews.llvm.org/D68570

llvm-svn: 374148
parent f8d482c0

clang/lib/AST/MicrosoftMangle.cpp

+2 −2
Original line number Diff line number Diff line
@@ -27,11 +27,11 @@ 
#include "clang/Basic/DiagnosticOptions.h"

#include "clang/Basic/TargetInfo.h"

#include "llvm/ADT/StringExtras.h"

#include "llvm/Support/JamCRC.h"

#include "llvm/Support/xxhash.h"

#include "llvm/Support/CRC.h"

#include "llvm/Support/MD5.h"

#include "llvm/Support/MathExtras.h"

#include "llvm/Support/StringSaver.h"

#include "llvm/Support/xxhash.h"



using namespace clang;

lld/COFF/PDB.cpp

+2 −4
Original line number Diff line number Diff line
@@ -51,10 +51,10 @@ 
#include "llvm/Object/COFF.h"

#include "llvm/Object/CVDebugRecord.h"

#include "llvm/Support/BinaryByteStream.h"

#include "llvm/Support/CRC.h"

#include "llvm/Support/Endian.h"

#include "llvm/Support/Errc.h"

#include "llvm/Support/FormatVariadic.h"

#include "llvm/Support/JamCRC.h"

#include "llvm/Support/Path.h"

#include "llvm/Support/ScopedPrinter.h"

#include <memory>
@@ -965,9 +965,7 @@ static pdb::SectionContrib createSectionContrib(const Chunk *c, uint32_t modi) { 
    sc.Imod = secChunk->file->moduleDBI->getModuleIndex();

    ArrayRef<uint8_t> contents = secChunk->getContents();

    JamCRC crc(0);

    ArrayRef<char> charContents = makeArrayRef(

        reinterpret_cast<const char *>(contents.data()), contents.size());

    crc.update(charContents);

    crc.update(contents);

    sc.DataCrc = crc.getCRC();

  } else {

    sc.Characteristics = os ? os->header.Characteristics : 0;

lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp

+3 −5
Original line number Diff line number Diff line
@@ -36,7 +36,7 @@ 
#include "llvm/BinaryFormat/ELF.h"

#include "llvm/Object/Decompressor.h"

#include "llvm/Support/ARMBuildAttributes.h"

#include "llvm/Support/JamCRC.h"

#include "llvm/Support/CRC.h"

#include "llvm/Support/MathExtras.h"

#include "llvm/Support/MemoryBuffer.h"

#include "llvm/Support/MipsABIFlags.h"
@@ -398,10 +398,8 @@ bool ObjectFileELF::MagicBytesMatch(DataBufferSP &data_sp, 
}



static uint32_t calc_crc32(uint32_t init, const DataExtractor &data) {

  llvm::JamCRC crc(~init);

  crc.update(llvm::makeArrayRef(

      reinterpret_cast<const char *>(data.GetDataStart()), data.GetByteSize()));

  return ~crc.getCRC();

  return llvm::crc32(

      init, llvm::makeArrayRef(data.GetDataStart(), data.GetByteSize()));

}



uint32_t ObjectFileELF::CalculateELFNotesSegmentsCRC32(

llvm/include/llvm/Support/CRC.h

+40 −5
Original line number Diff line number Diff line
@@ -6,20 +6,55 @@ 
//

//===----------------------------------------------------------------------===//

//

// This file contains basic functions for calculating Cyclic Redundancy Check

// or CRC.

// This file contains implementations of CRC functions.

//

//===----------------------------------------------------------------------===//



#ifndef LLVM_SUPPORT_CRC_H

#define LLVM_SUPPORT_CRC_H



#include "llvm/ADT/StringRef.h"

#include "llvm/Support/DataTypes.h"



namespace llvm {

/// zlib independent CRC32 calculation.

uint32_t crc32(uint32_t CRC, StringRef S);

template <typename T> class ArrayRef;



// Compute the CRC-32 of Data.

uint32_t crc32(ArrayRef<uint8_t> Data);



// Compute the running CRC-32 of Data, with CRC being the previous value of the

// checksum.

uint32_t crc32(uint32_t CRC, ArrayRef<uint8_t> Data);



// Class for computing the JamCRC.

//

// We will use the "Rocksoft^tm Model CRC Algorithm" to describe the properties

// of this CRC:

//   Width  : 32

//   Poly   : 04C11DB7

//   Init   : FFFFFFFF

//   RefIn  : True

//   RefOut : True

//   XorOut : 00000000

//   Check  : 340BC6D9 (result of CRC for "123456789")

//

// In other words, this is the same as CRC-32, except that XorOut is 0 instead

// of FFFFFFFF.

//

// N.B.  We permit flexibility of the "Init" value.  Some consumers of this need

//       it to be zero.

class JamCRC {

public:

  JamCRC(uint32_t Init = 0xFFFFFFFFU) : CRC(Init) {}



  // Update the CRC calculation with Data.

  void update(ArrayRef<uint8_t> Data);



  uint32_t getCRC() const { return CRC; }



private:

  uint32_t CRC;

};



} // end namespace llvm



#endif

llvm/include/llvm/Support/JamCRC.h

deleted100644 → 0
+0 −48
Original line number Diff line number Diff line 
//===-- llvm/Support/JamCRC.h - Cyclic Redundancy Check ---------*- C++ -*-===//

//

// 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

//

//===----------------------------------------------------------------------===//

//

// This file contains an implementation of JamCRC.

//

// We will use the "Rocksoft^tm Model CRC Algorithm" to describe the properties

// of this CRC:

//   Width  : 32

//   Poly   : 04C11DB7

//   Init   : FFFFFFFF

//   RefIn  : True

//   RefOut : True

//   XorOut : 00000000

//   Check  : 340BC6D9 (result of CRC for "123456789")

//

// N.B.  We permit flexibility of the "Init" value.  Some consumers of this need

//       it to be zero.

//

//===----------------------------------------------------------------------===//



#ifndef LLVM_SUPPORT_JAMCRC_H

#define LLVM_SUPPORT_JAMCRC_H



#include "llvm/Support/DataTypes.h"



namespace llvm {

template <typename T> class ArrayRef;



class JamCRC {

public:

  JamCRC(uint32_t Init = 0xFFFFFFFFU) : CRC(Init) {}



  // Update the CRC calculation with Data.

  void update(ArrayRef<char> Data);



  uint32_t getCRC() const { return CRC; }



private:

  uint32_t CRC;

};

} // End of namespace llvm



#endif