src/llvm-project/llvm/lib/DebugInfo/LogicalView/LVReaderHandler.cpp - toolchain/rustc - Git at Google

 //===-- LVReaderHandler.cpp -----------------------------------------------===//
 //
 // 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 class implements the Reader Handler.
 //
 //===----------------------------------------------------------------------===//

 #include "llvm/DebugInfo/LogicalView/LVReaderHandler.h"
 #include "llvm/DebugInfo/CodeView/LazyRandomTypeCollection.h"
 #include "llvm/DebugInfo/LogicalView/Core/LVCompare.h"
 #include "llvm/DebugInfo/LogicalView/Readers/LVCodeViewReader.h"
 #include "llvm/DebugInfo/LogicalView/Readers/LVELFReader.h"
 #include "llvm/DebugInfo/PDB/Native/NativeSession.h"
 #include "llvm/DebugInfo/PDB/PDB.h"
 #include "llvm/Object/COFF.h"

 using namespace llvm;
 using namespace llvm::object;
 using namespace llvm::pdb;
 using namespace llvm::logicalview;

 #define DEBUG_TYPE "ReaderHandler"

 Error LVReaderHandler::process() {
   if (Error Err = createReaders())
     return Err;
   if (Error Err = printReaders())
     return Err;
   if (Error Err = compareReaders())
     return Err;

   return Error::success();
 }

 Error LVReaderHandler::createReader(StringRef Filename, LVReaders &Readers,
                                     PdbOrObj &Input, StringRef FileFormatName,
                                     StringRef ExePath) {
   auto CreateOneReader = [&]() -> std::unique_ptr<LVReader> {
     if (isa<ObjectFile *>(Input)) {
       ObjectFile &Obj = *cast<ObjectFile *>(Input);
       if (Obj.isCOFF()) {
         COFFObjectFile *COFF = cast<COFFObjectFile>(&Obj);
         return std::make_unique<LVCodeViewReader>(Filename, FileFormatName,
                                                   *COFF, W, ExePath);
       }
       if (Obj.isELF() || Obj.isMachO())
         return std::make_unique<LVELFReader>(Filename, FileFormatName, Obj, W);
     }
     if (isa<PDBFile *>(Input)) {
       PDBFile &Pdb = *cast<PDBFile *>(Input);
       return std::make_unique<LVCodeViewReader>(Filename, FileFormatName, Pdb,
                                                 W, ExePath);
     }
     return nullptr;
   };

   std::unique_ptr<LVReader> ReaderObj = CreateOneReader();
   if (!ReaderObj)
     return createStringError(errc::invalid_argument,
                              "unable to create reader for: '%s'",
                              Filename.str().c_str());

   LVReader *Reader = ReaderObj.get();
   Readers.emplace_back(std::move(ReaderObj));
   return Reader->doLoad();
 }

 Error LVReaderHandler::handleArchive(LVReaders &Readers, StringRef Filename,
                                      Archive &Arch) {
   Error Err = Error::success();
   for (const Archive::Child &Child : Arch.children(Err)) {
     Expected<MemoryBufferRef> BuffOrErr = Child.getMemoryBufferRef();
     if (Error Err = BuffOrErr.takeError())
       return createStringError(errorToErrorCode(std::move(Err)), "%s",
                                Filename.str().c_str());
     Expected<StringRef> NameOrErr = Child.getName();
     if (Error Err = NameOrErr.takeError())
       return createStringError(errorToErrorCode(std::move(Err)), "%s",
                                Filename.str().c_str());
     std::string Name = (Filename + "(" + NameOrErr.get() + ")").str();
     if (Error Err = handleBuffer(Readers, Name, BuffOrErr.get()))
       return createStringError(errorToErrorCode(std::move(Err)), "%s",
                                Filename.str().c_str());
   }

   return Error::success();
 }

 // Search for a matching executable image for the given PDB path.
 static std::string searchForExe(const StringRef Path,
                                 const StringRef Extension) {
   SmallString<128> ExePath(Path);
   llvm::sys::path::replace_extension(ExePath, Extension);

   std::unique_ptr<IPDBSession> Session;
   if (Error Err = loadDataForEXE(PDB_ReaderType::Native, ExePath, Session)) {
     consumeError(std::move(Err));
     return {};
   }
   // We have a candidate for the executable image.
   Expected<std::string> PdbPathOrErr = NativeSession::searchForPdb({ExePath});
   if (!PdbPathOrErr) {
     consumeError(PdbPathOrErr.takeError());
     return {};
   }
   // Convert any Windows backslashes into forward slashes to get the path.
   std::string ConvertedPath = sys::path::convert_to_slash(
       PdbPathOrErr.get(), sys::path::Style::windows);
   if (ConvertedPath == Path)
     return std::string(ExePath);

   return {};
 }

 // Search for a matching object image for the given PDB path.
 static std::string searchForObj(const StringRef Path,
                                 const StringRef Extension) {
   SmallString<128> ObjPath(Path);
   llvm::sys::path::replace_extension(ObjPath, Extension);
   if (llvm::sys::fs::exists(ObjPath)) {
     ErrorOr<std::unique_ptr<MemoryBuffer>> BuffOrErr =
         MemoryBuffer::getFileOrSTDIN(ObjPath);
     if (!BuffOrErr)
       return {};
     return std::string(ObjPath);
   }

   return {};
 }

 Error LVReaderHandler::handleBuffer(LVReaders &Readers, StringRef Filename,
                                     MemoryBufferRef Buffer, StringRef ExePath) {
   // As PDB does not support the Binary interface, at this point we can check
   // if the buffer corresponds to a PDB or PE file.
   file_magic FileMagic = identify_magic(Buffer.getBuffer());
   if (FileMagic == file_magic::pdb) {
     if (!ExePath.empty())
       return handleObject(Readers, Filename, Buffer.getBuffer(), ExePath);

     // Search in the directory derived from the given 'Filename' for a
     // matching object file (.o, .obj, .lib) or a matching executable file
     // (.exe/.dll) and try to create the reader based on the matched file.
     // If no matching file is found then we load the original PDB file.
     std::vector<StringRef> ExecutableExtensions = {"exe", "dll"};
     for (StringRef Extension : ExecutableExtensions) {
       std::string ExecutableImage = searchForExe(Filename, Extension);
       if (ExecutableImage.empty())
         continue;
       if (Error Err = handleObject(Readers, Filename, Buffer.getBuffer(),
                                    ExecutableImage)) {
         consumeError(std::move(Err));
         continue;
       }
       return Error::success();
     }

     std::vector<StringRef> ObjectExtensions = {"o", "obj", "lib"};
     for (StringRef Extension : ObjectExtensions) {
       std::string ObjectImage = searchForObj(Filename, Extension);
       if (ObjectImage.empty())
         continue;
       if (Error Err = handleFile(Readers, ObjectImage)) {
         consumeError(std::move(Err));
         continue;
       }
       return Error::success();
     }

     // No matching executable/object image was found. Load the given PDB.
     return handleObject(Readers, Filename, Buffer.getBuffer(), ExePath);
   }
   if (FileMagic == file_magic::pecoff_executable) {
     // If we have a valid executable, try to find a matching PDB file.
     Expected<std::string> PdbPath = NativeSession::searchForPdb({Filename});
     if (errorToErrorCode(PdbPath.takeError())) {
       return createStringError(
           errc::not_supported,
           "Binary object format in '%s' does not have debug info.",
           Filename.str().c_str());
     }
     // Process the matching PDB file and pass the executable filename.
     return handleFile(Readers, PdbPath.get(), Filename);
   }

   Expected<std::unique_ptr<Binary>> BinOrErr = createBinary(Buffer);
   if (errorToErrorCode(BinOrErr.takeError())) {
     return createStringError(errc::not_supported,
                              "Binary object format in '%s' is not supported.",
                              Filename.str().c_str());
   }
   return handleObject(Readers, Filename, *BinOrErr.get());
 }

 Error LVReaderHandler::handleFile(LVReaders &Readers, StringRef Filename,
                                   StringRef ExePath) {
   // Convert any Windows backslashes into forward slashes to get the path.
   std::string ConvertedPath =
       sys::path::convert_to_slash(Filename, sys::path::Style::windows);
   ErrorOr<std::unique_ptr<MemoryBuffer>> BuffOrErr =
       MemoryBuffer::getFileOrSTDIN(ConvertedPath);
   if (BuffOrErr.getError()) {
     return createStringError(errc::bad_file_descriptor,
                              "File '%s' does not exist.",
                              ConvertedPath.c_str());
   }
   std::unique_ptr<MemoryBuffer> Buffer = std::move(BuffOrErr.get());
   return handleBuffer(Readers, ConvertedPath, *Buffer, ExePath);
 }

 Error LVReaderHandler::handleMach(LVReaders &Readers, StringRef Filename,
                                   MachOUniversalBinary &Mach) {
   for (const MachOUniversalBinary::ObjectForArch &ObjForArch : Mach.objects()) {
     std::string ObjName = (Twine(Filename) + Twine("(") +
                            Twine(ObjForArch.getArchFlagName()) + Twine(")"))
                               .str();
     if (Expected<std::unique_ptr<MachOObjectFile>> MachOOrErr =
             ObjForArch.getAsObjectFile()) {
       MachOObjectFile &Obj = **MachOOrErr;
       PdbOrObj Input = &Obj;
       if (Error Err =
               createReader(Filename, Readers, Input, Obj.getFileFormatName()))
         return Err;
       continue;
     } else
       consumeError(MachOOrErr.takeError());
     if (Expected<std::unique_ptr<Archive>> ArchiveOrErr =
             ObjForArch.getAsArchive()) {
       if (Error Err = handleArchive(Readers, ObjName, *ArchiveOrErr.get()))
         return Err;
       continue;
     } else
       consumeError(ArchiveOrErr.takeError());
   }
   return Error::success();
 }

 Error LVReaderHandler::handleObject(LVReaders &Readers, StringRef Filename,
                                     Binary &Binary) {
   if (PdbOrObj Input = dyn_cast<ObjectFile>(&Binary))
     return createReader(Filename, Readers, Input,
                         cast<ObjectFile *>(Input)->getFileFormatName());

   if (MachOUniversalBinary *Fat = dyn_cast<MachOUniversalBinary>(&Binary))
     return handleMach(Readers, Filename, *Fat);

   if (Archive *Arch = dyn_cast<Archive>(&Binary))
     return handleArchive(Readers, Filename, *Arch);

   return createStringError(errc::not_supported,
                            "Binary object format in '%s' is not supported.",
                            Filename.str().c_str());
 }

 Error LVReaderHandler::handleObject(LVReaders &Readers, StringRef Filename,
                                     StringRef Buffer, StringRef ExePath) {
   std::unique_ptr<IPDBSession> Session;
   if (Error Err = loadDataForPDB(PDB_ReaderType::Native, Filename, Session))
     return createStringError(errorToErrorCode(std::move(Err)), "%s",
                              Filename.str().c_str());

   std::unique_ptr<NativeSession> PdbSession;
   PdbSession.reset(static_cast<NativeSession *>(Session.release()));
   PdbOrObj Input = &PdbSession->getPDBFile();
   StringRef FileFormatName;
   size_t Pos = Buffer.find_first_of("\r\n");
   if (Pos)
     FileFormatName = Buffer.substr(0, Pos - 1);
   return createReader(Filename, Readers, Input, FileFormatName, ExePath);
 }

 Error LVReaderHandler::createReaders() {
   LLVM_DEBUG(dbgs() << "createReaders\n");
   for (std::string &Object : Objects) {
     LVReaders Readers;
     if (Error Err = createReader(Object, Readers))
       return Err;
     TheReaders.insert(TheReaders.end(),
                       std::make_move_iterator(Readers.begin()),
                       std::make_move_iterator(Readers.end()));
   }

   return Error::success();
 }

 Error LVReaderHandler::printReaders() {
   LLVM_DEBUG(dbgs() << "printReaders\n");
   if (options().getPrintExecute())
     for (const std::unique_ptr<LVReader> &Reader : TheReaders)
       if (Error Err = Reader->doPrint())
         return Err;

   return Error::success();
 }

 Error LVReaderHandler::compareReaders() {
   LLVM_DEBUG(dbgs() << "compareReaders\n");
   size_t ReadersCount = TheReaders.size();
   if (options().getCompareExecute() && ReadersCount >= 2) {
     // If we have more than 2 readers, compare them by pairs.
     size_t ViewPairs = ReadersCount / 2;
     LVCompare Compare(OS);
     for (size_t Pair = 0, Index = 0; Pair < ViewPairs; ++Pair) {
       if (Error Err = Compare.execute(TheReaders[Index].get(),
                                       TheReaders[Index + 1].get()))
         return Err;
       Index += 2;
     }
   }

   return Error::success();
 }

 void LVReaderHandler::print(raw_ostream &OS) const { OS << "ReaderHandler\n"; }
	//===-- LVReaderHandler.cpp -----------------------------------------------===//
	//
	// 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 class implements the Reader Handler.
	//
	//===----------------------------------------------------------------------===//

	#include "llvm/DebugInfo/LogicalView/LVReaderHandler.h"
	#include "llvm/DebugInfo/CodeView/LazyRandomTypeCollection.h"
	#include "llvm/DebugInfo/LogicalView/Core/LVCompare.h"
	#include "llvm/DebugInfo/LogicalView/Readers/LVCodeViewReader.h"
	#include "llvm/DebugInfo/LogicalView/Readers/LVELFReader.h"
	#include "llvm/DebugInfo/PDB/Native/NativeSession.h"
	#include "llvm/DebugInfo/PDB/PDB.h"
	#include "llvm/Object/COFF.h"

	using namespace llvm;
	using namespace llvm::object;
	using namespace llvm::pdb;
	using namespace llvm::logicalview;

	#define DEBUG_TYPE "ReaderHandler"

	Error LVReaderHandler::process() {
	if (Error Err = createReaders())
	return Err;
	if (Error Err = printReaders())
	return Err;
	if (Error Err = compareReaders())
	return Err;

	return Error::success();
	}

	Error LVReaderHandler::createReader(StringRef Filename, LVReaders &Readers,
	PdbOrObj &Input, StringRef FileFormatName,
	StringRef ExePath) {
	auto CreateOneReader = [&]() -> std::unique_ptr<LVReader> {
	if (isa<ObjectFile *>(Input)) {
	ObjectFile &Obj = cast<ObjectFile >(Input);
	if (Obj.isCOFF()) {
	COFFObjectFile *COFF = cast<COFFObjectFile>(&Obj);
	return std::make_unique<LVCodeViewReader>(Filename, FileFormatName,
	*COFF, W, ExePath);
	}
	if (Obj.isELF() \|\| Obj.isMachO())
	return std::make_unique<LVELFReader>(Filename, FileFormatName, Obj, W);
	}
	if (isa<PDBFile *>(Input)) {
	PDBFile &Pdb = cast<PDBFile >(Input);
	return std::make_unique<LVCodeViewReader>(Filename, FileFormatName, Pdb,
	W, ExePath);
	}
	return nullptr;
	};

	std::unique_ptr<LVReader> ReaderObj = CreateOneReader();
	if (!ReaderObj)
	return createStringError(errc::invalid_argument,
	"unable to create reader for: '%s'",
	Filename.str().c_str());

	LVReader *Reader = ReaderObj.get();
	Readers.emplace_back(std::move(ReaderObj));
	return Reader->doLoad();
	}

	Error LVReaderHandler::handleArchive(LVReaders &Readers, StringRef Filename,
	Archive &Arch) {
	Error Err = Error::success();
	for (const Archive::Child &Child : Arch.children(Err)) {
	Expected<MemoryBufferRef> BuffOrErr = Child.getMemoryBufferRef();
	if (Error Err = BuffOrErr.takeError())
	return createStringError(errorToErrorCode(std::move(Err)), "%s",
	Filename.str().c_str());
	Expected<StringRef> NameOrErr = Child.getName();
	if (Error Err = NameOrErr.takeError())
	return createStringError(errorToErrorCode(std::move(Err)), "%s",
	Filename.str().c_str());
	std::string Name = (Filename + "(" + NameOrErr.get() + ")").str();
	if (Error Err = handleBuffer(Readers, Name, BuffOrErr.get()))
	return createStringError(errorToErrorCode(std::move(Err)), "%s",
	Filename.str().c_str());
	}

	return Error::success();
	}

	// Search for a matching executable image for the given PDB path.
	static std::string searchForExe(const StringRef Path,
	const StringRef Extension) {
	SmallString<128> ExePath(Path);
	llvm::sys::path::replace_extension(ExePath, Extension);

	std::unique_ptr<IPDBSession> Session;
	if (Error Err = loadDataForEXE(PDB_ReaderType::Native, ExePath, Session)) {
	consumeError(std::move(Err));
	return {};
	}
	// We have a candidate for the executable image.
	Expected<std::string> PdbPathOrErr = NativeSession::searchForPdb({ExePath});
	if (!PdbPathOrErr) {
	consumeError(PdbPathOrErr.takeError());
	return {};
	}
	// Convert any Windows backslashes into forward slashes to get the path.
	std::string ConvertedPath = sys::path::convert_to_slash(
	PdbPathOrErr.get(), sys::path::Style::windows);
	if (ConvertedPath == Path)
	return std::string(ExePath);

	return {};
	}

	// Search for a matching object image for the given PDB path.
	static std::string searchForObj(const StringRef Path,
	const StringRef Extension) {
	SmallString<128> ObjPath(Path);
	llvm::sys::path::replace_extension(ObjPath, Extension);
	if (llvm::sys::fs::exists(ObjPath)) {
	ErrorOr<std::unique_ptr<MemoryBuffer>> BuffOrErr =
	MemoryBuffer::getFileOrSTDIN(ObjPath);
	if (!BuffOrErr)
	return {};
	return std::string(ObjPath);
	}

	return {};
	}

	Error LVReaderHandler::handleBuffer(LVReaders &Readers, StringRef Filename,
	MemoryBufferRef Buffer, StringRef ExePath) {
	// As PDB does not support the Binary interface, at this point we can check
	// if the buffer corresponds to a PDB or PE file.
	file_magic FileMagic = identify_magic(Buffer.getBuffer());
	if (FileMagic == file_magic::pdb) {
	if (!ExePath.empty())
	return handleObject(Readers, Filename, Buffer.getBuffer(), ExePath);

	// Search in the directory derived from the given 'Filename' for a
	// matching object file (.o, .obj, .lib) or a matching executable file
	// (.exe/.dll) and try to create the reader based on the matched file.
	// If no matching file is found then we load the original PDB file.
	std::vector<StringRef> ExecutableExtensions = {"exe", "dll"};
	for (StringRef Extension : ExecutableExtensions) {
	std::string ExecutableImage = searchForExe(Filename, Extension);
	if (ExecutableImage.empty())
	continue;
	if (Error Err = handleObject(Readers, Filename, Buffer.getBuffer(),
	ExecutableImage)) {
	consumeError(std::move(Err));
	continue;
	}
	return Error::success();
	}

	std::vector<StringRef> ObjectExtensions = {"o", "obj", "lib"};
	for (StringRef Extension : ObjectExtensions) {
	std::string ObjectImage = searchForObj(Filename, Extension);
	if (ObjectImage.empty())
	continue;
	if (Error Err = handleFile(Readers, ObjectImage)) {
	consumeError(std::move(Err));
	continue;
	}
	return Error::success();
	}

	// No matching executable/object image was found. Load the given PDB.
	return handleObject(Readers, Filename, Buffer.getBuffer(), ExePath);
	}
	if (FileMagic == file_magic::pecoff_executable) {
	// If we have a valid executable, try to find a matching PDB file.
	Expected<std::string> PdbPath = NativeSession::searchForPdb({Filename});
	if (errorToErrorCode(PdbPath.takeError())) {
	return createStringError(
	errc::not_supported,
	"Binary object format in '%s' does not have debug info.",
	Filename.str().c_str());
	}
	// Process the matching PDB file and pass the executable filename.
	return handleFile(Readers, PdbPath.get(), Filename);
	}

	Expected<std::unique_ptr<Binary>> BinOrErr = createBinary(Buffer);
	if (errorToErrorCode(BinOrErr.takeError())) {
	return createStringError(errc::not_supported,
	"Binary object format in '%s' is not supported.",
	Filename.str().c_str());
	}
	return handleObject(Readers, Filename, *BinOrErr.get());
	}

	Error LVReaderHandler::handleFile(LVReaders &Readers, StringRef Filename,
	StringRef ExePath) {
	// Convert any Windows backslashes into forward slashes to get the path.
	std::string ConvertedPath =
	sys::path::convert_to_slash(Filename, sys::path::Style::windows);
	ErrorOr<std::unique_ptr<MemoryBuffer>> BuffOrErr =
	MemoryBuffer::getFileOrSTDIN(ConvertedPath);
	if (BuffOrErr.getError()) {
	return createStringError(errc::bad_file_descriptor,
	"File '%s' does not exist.",
	ConvertedPath.c_str());
	}
	std::unique_ptr<MemoryBuffer> Buffer = std::move(BuffOrErr.get());
	return handleBuffer(Readers, ConvertedPath, *Buffer, ExePath);
	}

	Error LVReaderHandler::handleMach(LVReaders &Readers, StringRef Filename,
	MachOUniversalBinary &Mach) {
	for (const MachOUniversalBinary::ObjectForArch &ObjForArch : Mach.objects()) {
	std::string ObjName = (Twine(Filename) + Twine("(") +
	Twine(ObjForArch.getArchFlagName()) + Twine(")"))
	.str();
	if (Expected<std::unique_ptr<MachOObjectFile>> MachOOrErr =
	ObjForArch.getAsObjectFile()) {
	MachOObjectFile &Obj = **MachOOrErr;
	PdbOrObj Input = &Obj;
	if (Error Err =
	createReader(Filename, Readers, Input, Obj.getFileFormatName()))
	return Err;
	continue;
	} else
	consumeError(MachOOrErr.takeError());
	if (Expected<std::unique_ptr<Archive>> ArchiveOrErr =
	ObjForArch.getAsArchive()) {
	if (Error Err = handleArchive(Readers, ObjName, *ArchiveOrErr.get()))
	return Err;
	continue;
	} else
	consumeError(ArchiveOrErr.takeError());
	}
	return Error::success();
	}

	Error LVReaderHandler::handleObject(LVReaders &Readers, StringRef Filename,
	Binary &Binary) {
	if (PdbOrObj Input = dyn_cast<ObjectFile>(&Binary))
	return createReader(Filename, Readers, Input,
	cast<ObjectFile *>(Input)->getFileFormatName());

	if (MachOUniversalBinary *Fat = dyn_cast<MachOUniversalBinary>(&Binary))
	return handleMach(Readers, Filename, *Fat);

	if (Archive *Arch = dyn_cast<Archive>(&Binary))
	return handleArchive(Readers, Filename, *Arch);

	return createStringError(errc::not_supported,
	"Binary object format in '%s' is not supported.",
	Filename.str().c_str());
	}

	Error LVReaderHandler::handleObject(LVReaders &Readers, StringRef Filename,
	StringRef Buffer, StringRef ExePath) {
	std::unique_ptr<IPDBSession> Session;
	if (Error Err = loadDataForPDB(PDB_ReaderType::Native, Filename, Session))
	return createStringError(errorToErrorCode(std::move(Err)), "%s",
	Filename.str().c_str());

	std::unique_ptr<NativeSession> PdbSession;
	PdbSession.reset(static_cast<NativeSession *>(Session.release()));
	PdbOrObj Input = &PdbSession->getPDBFile();
	StringRef FileFormatName;
	size_t Pos = Buffer.find_first_of("\r\n");
	if (Pos)
	FileFormatName = Buffer.substr(0, Pos - 1);
	return createReader(Filename, Readers, Input, FileFormatName, ExePath);
	}

	Error LVReaderHandler::createReaders() {
	LLVM_DEBUG(dbgs() << "createReaders\n");
	for (std::string &Object : Objects) {
	LVReaders Readers;
	if (Error Err = createReader(Object, Readers))
	return Err;
	TheReaders.insert(TheReaders.end(),
	std::make_move_iterator(Readers.begin()),
	std::make_move_iterator(Readers.end()));
	}

	return Error::success();
	}

	Error LVReaderHandler::printReaders() {
	LLVM_DEBUG(dbgs() << "printReaders\n");
	if (options().getPrintExecute())
	for (const std::unique_ptr<LVReader> &Reader : TheReaders)
	if (Error Err = Reader->doPrint())
	return Err;

	return Error::success();
	}

	Error LVReaderHandler::compareReaders() {
	LLVM_DEBUG(dbgs() << "compareReaders\n");
	size_t ReadersCount = TheReaders.size();
	if (options().getCompareExecute() && ReadersCount >= 2) {
	// If we have more than 2 readers, compare them by pairs.
	size_t ViewPairs = ReadersCount / 2;
	LVCompare Compare(OS);
	for (size_t Pair = 0, Index = 0; Pair < ViewPairs; ++Pair) {
	if (Error Err = Compare.execute(TheReaders[Index].get(),
	TheReaders[Index + 1].get()))
	return Err;
	Index += 2;
	}
	}

	return Error::success();
	}

	void LVReaderHandler::print(raw_ostream &OS) const { OS << "ReaderHandler\n"; }