lld/COFF/InputFiles.cpp - toolchain/llvm-project - Gitiles

 //===- InputFiles.cpp -----------------------------------------------------===//
 //
 //                             The LLVM Linker
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//

 #include "Chunks.h"
 #include "Error.h"
 #include "InputFiles.h"
 #include "Writer.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/LTO/LTOModule.h"
 #include "llvm/Object/COFF.h"
 #include "llvm/Support/COFF.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/raw_ostream.h"

 using namespace llvm::object;
 using namespace llvm::support::endian;
 using llvm::COFF::ImportHeader;
 using llvm::COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE;
 using llvm::RoundUpToAlignment;
 using llvm::sys::fs::identify_magic;
 using llvm::sys::fs::file_magic;

 namespace lld {
 namespace coff {

 // Returns the last element of a path, which is supposed to be a filename.
 static StringRef getBasename(StringRef Path) {
   size_t Pos = Path.find_last_of("\\/");
   if (Pos == StringRef::npos)
     return Path;
   return Path.substr(Pos + 1);
 }

 // Returns a string in the format of "foo.obj" or "foo.obj(bar.lib)".
 std::string InputFile::getShortName() {
   if (ParentName == "")
     return getName().lower();
   std::string Res = (getBasename(ParentName) + "(" +
                      getBasename(getName()) + ")").str();
   return StringRef(Res).lower();
 }

 std::error_code ArchiveFile::parse() {
   // Parse a MemoryBufferRef as an archive file.
   auto ArchiveOrErr = Archive::create(MB);
   if (auto EC = ArchiveOrErr.getError())
     return EC;
   File = std::move(ArchiveOrErr.get());

   // Allocate a buffer for Lazy objects.
   size_t BufSize = File->getNumberOfSymbols() * sizeof(Lazy);
   Lazy *Buf = (Lazy *)Alloc.Allocate(BufSize, llvm::alignOf<Lazy>());

   // Read the symbol table to construct Lazy objects.
   uint32_t I = 0;
   for (const Archive::Symbol &Sym : File->symbols()) {
     auto *B = new (&Buf[I++]) Lazy(this, Sym);
     // Skip special symbol exists in import library files.
     if (B->getName() != "__NULL_IMPORT_DESCRIPTOR")
       SymbolBodies.push_back(B);
   }
   return std::error_code();
 }

 // Returns a buffer pointing to a member file containing a given symbol.
 ErrorOr<MemoryBufferRef> ArchiveFile::getMember(const Archive::Symbol *Sym) {
   auto ItOrErr = Sym->getMember();
   if (auto EC = ItOrErr.getError())
     return EC;
   Archive::child_iterator It = ItOrErr.get();

   // Return an empty buffer if we have already returned the same buffer.
   const char *StartAddr = It->getBuffer().data();
   auto Pair = Seen.insert(StartAddr);
   if (!Pair.second)
     return MemoryBufferRef();
   return It->getMemoryBufferRef();
 }

 std::error_code ObjectFile::parse() {
   // Parse a memory buffer as a COFF file.
   auto BinOrErr = createBinary(MB);
   if (auto EC = BinOrErr.getError())
     return EC;
   std::unique_ptr<Binary> Bin = std::move(BinOrErr.get());

   if (auto *Obj = dyn_cast<COFFObjectFile>(Bin.get())) {
     Bin.release();
     COFFObj.reset(Obj);
   } else {
     llvm::errs() << getName() << " is not a COFF file.\n";
     return make_error_code(LLDError::InvalidFile);
   }

   // Read section and symbol tables.
   if (auto EC = initializeChunks())
     return EC;
   return initializeSymbols();
 }

 SymbolBody *ObjectFile::getSymbolBody(uint32_t SymbolIndex) {
   return SparseSymbolBodies[SymbolIndex]->getReplacement();
 }

 std::error_code ObjectFile::initializeChunks() {
   uint32_t NumSections = COFFObj->getNumberOfSections();
   Chunks.reserve(NumSections);
   SparseChunks.resize(NumSections + 1);
   for (uint32_t I = 1; I < NumSections + 1; ++I) {
     const coff_section *Sec;
     StringRef Name;
     if (auto EC = COFFObj->getSection(I, Sec)) {
       llvm::errs() << "getSection failed: " << Name << ": "
                    << EC.message() << "\n";
       return make_error_code(LLDError::BrokenFile);
     }
     if (auto EC = COFFObj->getSectionName(Sec, Name)) {
       llvm::errs() << "getSectionName failed: " << Name << ": "
                    << EC.message() << "\n";
       return make_error_code(LLDError::BrokenFile);
     }
     if (Name == ".drectve") {
       ArrayRef<uint8_t> Data;
       COFFObj->getSectionContents(Sec, Data);
       Directives = std::string((const char *)Data.data(), Data.size());
       continue;
     }
     if (Name.startswith(".debug"))
       continue;
     if (Sec->Characteristics & llvm::COFF::IMAGE_SCN_LNK_REMOVE)
       continue;
     auto *C = new (Alloc) SectionChunk(this, Sec, I);
     Chunks.push_back(C);
     SparseChunks[I] = C;
   }
   return std::error_code();
 }

 std::error_code ObjectFile::initializeSymbols() {
   uint32_t NumSymbols = COFFObj->getNumberOfSymbols();
   SymbolBodies.reserve(NumSymbols);
   SparseSymbolBodies.resize(NumSymbols);
   int32_t LastSectionNumber = 0;
   for (uint32_t I = 0; I < NumSymbols; ++I) {
     // Get a COFFSymbolRef object.
     auto SymOrErr = COFFObj->getSymbol(I);
     if (auto EC = SymOrErr.getError()) {
       llvm::errs() << "broken object file: " << getName() << ": "
                    << EC.message() << "\n";
       return make_error_code(LLDError::BrokenFile);
     }
     COFFSymbolRef Sym = SymOrErr.get();

     const void *AuxP = nullptr;
     if (Sym.getNumberOfAuxSymbols())
       AuxP = COFFObj->getSymbol(I + 1)->getRawPtr();
     bool IsFirst = (LastSectionNumber != Sym.getSectionNumber());

     SymbolBody *Body = createSymbolBody(Sym, AuxP, IsFirst);
     if (Body) {
       SymbolBodies.push_back(Body);
       SparseSymbolBodies[I] = Body;
     }
     I += Sym.getNumberOfAuxSymbols();
     LastSectionNumber = Sym.getSectionNumber();
   }
   return std::error_code();
 }

 SymbolBody *ObjectFile::createSymbolBody(COFFSymbolRef Sym, const void *AuxP,
                                          bool IsFirst) {
   StringRef Name;
   if (Sym.isUndefined()) {
     COFFObj->getSymbolName(Sym, Name);
     return new (Alloc) Undefined(Name);
   }
   if (Sym.isCommon()) {
     Chunk *C = new (Alloc) CommonChunk(Sym);
     Chunks.push_back(C);
     return new (Alloc) DefinedCommon(COFFObj.get(), Sym, C);
   }
   if (Sym.isAbsolute()) {
     COFFObj->getSymbolName(Sym, Name);
     // Skip special symbols.
     if (Name == "@comp.id" || Name == "@feat.00")
       return nullptr;
     return new (Alloc) DefinedAbsolute(Name, Sym.getValue());
   }
   // TODO: Handle IMAGE_WEAK_EXTERN_SEARCH_ALIAS
   if (Sym.isWeakExternal()) {
     COFFObj->getSymbolName(Sym, Name);
     auto *Aux = (const coff_aux_weak_external *)AuxP;
     return new (Alloc) Undefined(Name, &SparseSymbolBodies[Aux->TagIndex]);
   }
   // Handle associative sections
   if (IsFirst && AuxP) {
     if (Chunk *C = SparseChunks[Sym.getSectionNumber()]) {
       auto *Aux = reinterpret_cast<const coff_aux_section_definition *>(AuxP);
       if (Aux->Selection == IMAGE_COMDAT_SELECT_ASSOCIATIVE) {
         auto *Parent =
           (SectionChunk *)(SparseChunks[Aux->getNumber(Sym.isBigObj())]);
         if (Parent)
           Parent->addAssociative((SectionChunk *)C);
       }
     }
   }
   if (Chunk *C = SparseChunks[Sym.getSectionNumber()])
     return new (Alloc) DefinedRegular(COFFObj.get(), Sym, C);
   return nullptr;
 }

 std::error_code ImportFile::parse() {
   const char *Buf = MB.getBufferStart();
   const char *End = MB.getBufferEnd();
   const auto *Hdr = reinterpret_cast<const coff_import_header *>(Buf);

   // Check if the total size is valid.
   if ((size_t)(End - Buf) != (sizeof(*Hdr) + Hdr->SizeOfData)) {
     llvm::errs() << "broken import library\n";
     return make_error_code(LLDError::BrokenFile);
   }

   // Read names and create an __imp_ symbol.
   StringRef Name = StringAlloc.save(StringRef(Buf + sizeof(*Hdr)));
   StringRef ImpName = StringAlloc.save(Twine("__imp_") + Name);
   StringRef DLLName(Buf + sizeof(coff_import_header) + Name.size() + 1);
   StringRef ExternalName = Name;
   if (Hdr->getNameType() == llvm::COFF::IMPORT_ORDINAL)
     ExternalName = "";
   auto *ImpSym = new (Alloc) DefinedImportData(DLLName, ImpName, ExternalName,
                                                Hdr);
   SymbolBodies.push_back(ImpSym);

   // If type is function, we need to create a thunk which jump to an
   // address pointed by the __imp_ symbol. (This allows you to call
   // DLL functions just like regular non-DLL functions.)
   if (Hdr->getType() == llvm::COFF::IMPORT_CODE)
     SymbolBodies.push_back(new (Alloc) DefinedImportThunk(Name, ImpSym));
   return std::error_code();
 }

 std::error_code BitcodeFile::parse() {
   std::string Err;
   M.reset(LTOModule::createFromBuffer(MB.getBufferStart(),
                                       MB.getBufferSize(),
                                       llvm::TargetOptions(), Err));
   if (!Err.empty()) {
     llvm::errs() << Err << '\n';
     return make_error_code(LLDError::BrokenFile);
   }

   llvm::BumpPtrStringSaver Saver(Alloc);
   for (unsigned I = 0, E = M->getSymbolCount(); I != E; ++I) {
     lto_symbol_attributes Attrs = M->getSymbolAttributes(I);
     if ((Attrs & LTO_SYMBOL_SCOPE_MASK) == LTO_SYMBOL_SCOPE_INTERNAL)
       continue;

     StringRef SymName = Saver.save(M->getSymbolName(I));
     int SymbolDef = Attrs & LTO_SYMBOL_DEFINITION_MASK;
     if (SymbolDef == LTO_SYMBOL_DEFINITION_UNDEFINED) {
       SymbolBodies.push_back(new (Alloc) Undefined(SymName));
     } else {
       bool Replaceable = (SymbolDef == LTO_SYMBOL_DEFINITION_TENTATIVE ||
                           (Attrs & LTO_SYMBOL_COMDAT));
       SymbolBodies.push_back(new (Alloc) DefinedBitcode(SymName, Replaceable));

       const llvm::GlobalValue *GV = M->getSymbolGV(I);
       if (GV && GV->hasDLLExportStorageClass()) {
         Directives += " /export:";
         Directives += SymName;
         if (!GV->getValueType()->isFunctionTy())
           Directives += ",data";
       }
     }
   }

   // Extract any linker directives from the bitcode file, which are represented
   // as module flags with the key "Linker Options".
   llvm::SmallVector<llvm::Module::ModuleFlagEntry, 8> Flags;
   M->getModule().getModuleFlagsMetadata(Flags);
   for (auto &&Flag : Flags) {
     if (Flag.Key->getString() != "Linker Options")
       continue;

     for (llvm::Metadata *Op : cast<llvm::MDNode>(Flag.Val)->operands()) {
       for (llvm::Metadata *InnerOp : cast<llvm::MDNode>(Op)->operands()) {
         Directives += " ";
         Directives += cast<llvm::MDString>(InnerOp)->getString();
       }
     }
   }

   return std::error_code();
 }

 } // namespace coff
 } // namespace lld
	//===- InputFiles.cpp -----------------------------------------------------===//
	//
	// The LLVM Linker
	//
	// This file is distributed under the University of Illinois Open Source
	// License. See LICENSE.TXT for details.
	//
	//===----------------------------------------------------------------------===//

	#include "Chunks.h"
	#include "Error.h"
	#include "InputFiles.h"
	#include "Writer.h"
	#include "llvm/ADT/STLExtras.h"
	#include "llvm/LTO/LTOModule.h"
	#include "llvm/Object/COFF.h"
	#include "llvm/Support/COFF.h"
	#include "llvm/Support/Debug.h"
	#include "llvm/Support/Endian.h"
	#include "llvm/Support/raw_ostream.h"

	using namespace llvm::object;
	using namespace llvm::support::endian;
	using llvm::COFF::ImportHeader;
	using llvm::COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE;
	using llvm::RoundUpToAlignment;
	using llvm::sys::fs::identify_magic;
	using llvm::sys::fs::file_magic;

	namespace lld {
	namespace coff {

	// Returns the last element of a path, which is supposed to be a filename.
	static StringRef getBasename(StringRef Path) {
	size_t Pos = Path.find_last_of("\\/");
	if (Pos == StringRef::npos)
	return Path;
	return Path.substr(Pos + 1);
	}

	// Returns a string in the format of "foo.obj" or "foo.obj(bar.lib)".
	std::string InputFile::getShortName() {
	if (ParentName == "")
	return getName().lower();
	std::string Res = (getBasename(ParentName) + "(" +
	getBasename(getName()) + ")").str();
	return StringRef(Res).lower();
	}

	std::error_code ArchiveFile::parse() {
	// Parse a MemoryBufferRef as an archive file.
	auto ArchiveOrErr = Archive::create(MB);
	if (auto EC = ArchiveOrErr.getError())
	return EC;
	File = std::move(ArchiveOrErr.get());

	// Allocate a buffer for Lazy objects.
	size_t BufSize = File->getNumberOfSymbols() * sizeof(Lazy);
	Lazy Buf = (Lazy )Alloc.Allocate(BufSize, llvm::alignOf<Lazy>());

	// Read the symbol table to construct Lazy objects.
	uint32_t I = 0;
	for (const Archive::Symbol &Sym : File->symbols()) {
	auto *B = new (&Buf[I++]) Lazy(this, Sym);
	// Skip special symbol exists in import library files.
	if (B->getName() != "__NULL_IMPORT_DESCRIPTOR")
	SymbolBodies.push_back(B);
	}
	return std::error_code();
	}

	// Returns a buffer pointing to a member file containing a given symbol.
	ErrorOr<MemoryBufferRef> ArchiveFile::getMember(const Archive::Symbol *Sym) {
	auto ItOrErr = Sym->getMember();
	if (auto EC = ItOrErr.getError())
	return EC;
	Archive::child_iterator It = ItOrErr.get();

	// Return an empty buffer if we have already returned the same buffer.
	const char *StartAddr = It->getBuffer().data();
	auto Pair = Seen.insert(StartAddr);
	if (!Pair.second)
	return MemoryBufferRef();
	return It->getMemoryBufferRef();
	}

	std::error_code ObjectFile::parse() {
	// Parse a memory buffer as a COFF file.
	auto BinOrErr = createBinary(MB);
	if (auto EC = BinOrErr.getError())
	return EC;
	std::unique_ptr<Binary> Bin = std::move(BinOrErr.get());

	if (auto *Obj = dyn_cast<COFFObjectFile>(Bin.get())) {
	Bin.release();
	COFFObj.reset(Obj);
	} else {
	llvm::errs() << getName() << " is not a COFF file.\n";
	return make_error_code(LLDError::InvalidFile);
	}

	// Read section and symbol tables.
	if (auto EC = initializeChunks())
	return EC;
	return initializeSymbols();
	}

	SymbolBody *ObjectFile::getSymbolBody(uint32_t SymbolIndex) {
	return SparseSymbolBodies[SymbolIndex]->getReplacement();
	}

	std::error_code ObjectFile::initializeChunks() {
	uint32_t NumSections = COFFObj->getNumberOfSections();
	Chunks.reserve(NumSections);
	SparseChunks.resize(NumSections + 1);
	for (uint32_t I = 1; I < NumSections + 1; ++I) {
	const coff_section *Sec;
	StringRef Name;
	if (auto EC = COFFObj->getSection(I, Sec)) {
	llvm::errs() << "getSection failed: " << Name << ": "
	<< EC.message() << "\n";
	return make_error_code(LLDError::BrokenFile);
	}
	if (auto EC = COFFObj->getSectionName(Sec, Name)) {
	llvm::errs() << "getSectionName failed: " << Name << ": "
	<< EC.message() << "\n";
	return make_error_code(LLDError::BrokenFile);
	}
	if (Name == ".drectve") {
	ArrayRef<uint8_t> Data;
	COFFObj->getSectionContents(Sec, Data);
	Directives = std::string((const char *)Data.data(), Data.size());
	continue;
	}
	if (Name.startswith(".debug"))
	continue;
	if (Sec->Characteristics & llvm::COFF::IMAGE_SCN_LNK_REMOVE)
	continue;
	auto *C = new (Alloc) SectionChunk(this, Sec, I);
	Chunks.push_back(C);
	SparseChunks[I] = C;
	}
	return std::error_code();
	}

	std::error_code ObjectFile::initializeSymbols() {
	uint32_t NumSymbols = COFFObj->getNumberOfSymbols();
	SymbolBodies.reserve(NumSymbols);
	SparseSymbolBodies.resize(NumSymbols);
	int32_t LastSectionNumber = 0;
	for (uint32_t I = 0; I < NumSymbols; ++I) {
	// Get a COFFSymbolRef object.
	auto SymOrErr = COFFObj->getSymbol(I);
	if (auto EC = SymOrErr.getError()) {
	llvm::errs() << "broken object file: " << getName() << ": "
	<< EC.message() << "\n";
	return make_error_code(LLDError::BrokenFile);
	}
	COFFSymbolRef Sym = SymOrErr.get();

	const void *AuxP = nullptr;
	if (Sym.getNumberOfAuxSymbols())
	AuxP = COFFObj->getSymbol(I + 1)->getRawPtr();
	bool IsFirst = (LastSectionNumber != Sym.getSectionNumber());

	SymbolBody *Body = createSymbolBody(Sym, AuxP, IsFirst);
	if (Body) {
	SymbolBodies.push_back(Body);
	SparseSymbolBodies[I] = Body;
	}
	I += Sym.getNumberOfAuxSymbols();
	LastSectionNumber = Sym.getSectionNumber();
	}
	return std::error_code();
	}

	SymbolBody ObjectFile::createSymbolBody(COFFSymbolRef Sym, const void AuxP,
	bool IsFirst) {
	StringRef Name;
	if (Sym.isUndefined()) {
	COFFObj->getSymbolName(Sym, Name);
	return new (Alloc) Undefined(Name);
	}
	if (Sym.isCommon()) {
	Chunk *C = new (Alloc) CommonChunk(Sym);
	Chunks.push_back(C);
	return new (Alloc) DefinedCommon(COFFObj.get(), Sym, C);
	}
	if (Sym.isAbsolute()) {
	COFFObj->getSymbolName(Sym, Name);
	// Skip special symbols.
	if (Name == "@comp.id" \|\| Name == "@feat.00")
	return nullptr;
	return new (Alloc) DefinedAbsolute(Name, Sym.getValue());
	}
	// TODO: Handle IMAGE_WEAK_EXTERN_SEARCH_ALIAS
	if (Sym.isWeakExternal()) {
	COFFObj->getSymbolName(Sym, Name);
	auto Aux = (const coff_aux_weak_external )AuxP;
	return new (Alloc) Undefined(Name, &SparseSymbolBodies[Aux->TagIndex]);
	}
	// Handle associative sections
	if (IsFirst && AuxP) {
	if (Chunk *C = SparseChunks[Sym.getSectionNumber()]) {
	auto Aux = reinterpret_cast<const coff_aux_section_definition >(AuxP);
	if (Aux->Selection == IMAGE_COMDAT_SELECT_ASSOCIATIVE) {
	auto *Parent =
	(SectionChunk *)(SparseChunks[Aux->getNumber(Sym.isBigObj())]);
	if (Parent)
	Parent->addAssociative((SectionChunk *)C);
	}
	}
	}
	if (Chunk *C = SparseChunks[Sym.getSectionNumber()])
	return new (Alloc) DefinedRegular(COFFObj.get(), Sym, C);
	return nullptr;
	}

	std::error_code ImportFile::parse() {
	const char *Buf = MB.getBufferStart();
	const char *End = MB.getBufferEnd();
	const auto Hdr = reinterpret_cast<const coff_import_header >(Buf);

	// Check if the total size is valid.
	if ((size_t)(End - Buf) != (sizeof(*Hdr) + Hdr->SizeOfData)) {
	llvm::errs() << "broken import library\n";
	return make_error_code(LLDError::BrokenFile);
	}

	// Read names and create an __imp_ symbol.
	StringRef Name = StringAlloc.save(StringRef(Buf + sizeof(*Hdr)));
	StringRef ImpName = StringAlloc.save(Twine("__imp_") + Name);
	StringRef DLLName(Buf + sizeof(coff_import_header) + Name.size() + 1);
	StringRef ExternalName = Name;
	if (Hdr->getNameType() == llvm::COFF::IMPORT_ORDINAL)
	ExternalName = "";
	auto *ImpSym = new (Alloc) DefinedImportData(DLLName, ImpName, ExternalName,
	Hdr);
	SymbolBodies.push_back(ImpSym);

	// If type is function, we need to create a thunk which jump to an
	// address pointed by the __imp_ symbol. (This allows you to call
	// DLL functions just like regular non-DLL functions.)
	if (Hdr->getType() == llvm::COFF::IMPORT_CODE)
	SymbolBodies.push_back(new (Alloc) DefinedImportThunk(Name, ImpSym));
	return std::error_code();
	}

	std::error_code BitcodeFile::parse() {
	std::string Err;
	M.reset(LTOModule::createFromBuffer(MB.getBufferStart(),
	MB.getBufferSize(),
	llvm::TargetOptions(), Err));
	if (!Err.empty()) {
	llvm::errs() << Err << '\n';
	return make_error_code(LLDError::BrokenFile);
	}

	llvm::BumpPtrStringSaver Saver(Alloc);
	for (unsigned I = 0, E = M->getSymbolCount(); I != E; ++I) {
	lto_symbol_attributes Attrs = M->getSymbolAttributes(I);
	if ((Attrs & LTO_SYMBOL_SCOPE_MASK) == LTO_SYMBOL_SCOPE_INTERNAL)
	continue;

	StringRef SymName = Saver.save(M->getSymbolName(I));
	int SymbolDef = Attrs & LTO_SYMBOL_DEFINITION_MASK;
	if (SymbolDef == LTO_SYMBOL_DEFINITION_UNDEFINED) {
	SymbolBodies.push_back(new (Alloc) Undefined(SymName));
	} else {
	bool Replaceable = (SymbolDef == LTO_SYMBOL_DEFINITION_TENTATIVE \|\|
	(Attrs & LTO_SYMBOL_COMDAT));
	SymbolBodies.push_back(new (Alloc) DefinedBitcode(SymName, Replaceable));

	const llvm::GlobalValue *GV = M->getSymbolGV(I);
	if (GV && GV->hasDLLExportStorageClass()) {
	Directives += " /export:";
	Directives += SymName;
	if (!GV->getValueType()->isFunctionTy())
	Directives += ",data";
	}
	}
	}

	// Extract any linker directives from the bitcode file, which are represented
	// as module flags with the key "Linker Options".
	llvm::SmallVector<llvm::Module::ModuleFlagEntry, 8> Flags;
	M->getModule().getModuleFlagsMetadata(Flags);
	for (auto &&Flag : Flags) {
	if (Flag.Key->getString() != "Linker Options")
	continue;

	for (llvm::Metadata *Op : cast<llvm::MDNode>(Flag.Val)->operands()) {
	for (llvm::Metadata *InnerOp : cast<llvm::MDNode>(Op)->operands()) {
	Directives += " ";
	Directives += cast<llvm::MDString>(InnerOp)->getString();
	}
	}
	}

	return std::error_code();
	}

	} // namespace coff
	} // namespace lld