forked from OSchip/llvm-project
410 lines
13 KiB
C++
410 lines
13 KiB
C++
//===- InputFiles.cpp -----------------------------------------------------===//
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//
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// The LLVM Linker
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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 "InputFiles.h"
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#include "Chunks.h"
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#include "Config.h"
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#include "Driver.h"
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#include "Error.h"
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#include "Memory.h"
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#include "SymbolTable.h"
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#include "Symbols.h"
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#include "llvm-c/lto.h"
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/ADT/Triple.h"
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#include "llvm/ADT/Twine.h"
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#include "llvm/BinaryFormat/COFF.h"
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#include "llvm/Object/Binary.h"
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#include "llvm/Object/COFF.h"
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#include "llvm/Support/Casting.h"
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#include "llvm/Support/Endian.h"
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#include "llvm/Support/Error.h"
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#include "llvm/Support/ErrorOr.h"
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#include "llvm/Support/FileSystem.h"
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#include "llvm/Target/TargetOptions.h"
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#include <cstring>
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#include <system_error>
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#include <utility>
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using namespace llvm;
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using namespace llvm::COFF;
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using namespace llvm::object;
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using namespace llvm::support::endian;
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using llvm::Triple;
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using llvm::support::ulittle32_t;
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namespace lld {
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namespace coff {
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/// Checks that Source is compatible with being a weak alias to Target.
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/// If Source is Undefined and has no weak alias set, makes it a weak
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/// alias to Target.
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static void checkAndSetWeakAlias(SymbolTable *Symtab, InputFile *F,
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SymbolBody *Source, SymbolBody *Target) {
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if (auto *U = dyn_cast<Undefined>(Source)) {
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if (U->WeakAlias && U->WeakAlias != Target)
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Symtab->reportDuplicate(Source->symbol(), F);
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U->WeakAlias = Target;
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}
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}
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ArchiveFile::ArchiveFile(MemoryBufferRef M) : InputFile(ArchiveKind, M) {}
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void ArchiveFile::parse() {
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// Parse a MemoryBufferRef as an archive file.
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File = check(Archive::create(MB), toString(this));
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// Read the symbol table to construct Lazy objects.
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for (const Archive::Symbol &Sym : File->symbols())
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Symtab->addLazy(this, Sym);
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}
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// Returns a buffer pointing to a member file containing a given symbol.
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void ArchiveFile::addMember(const Archive::Symbol *Sym) {
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const Archive::Child &C =
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check(Sym->getMember(),
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"could not get the member for symbol " + Sym->getName());
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// Return an empty buffer if we have already returned the same buffer.
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if (!Seen.insert(C.getChildOffset()).second)
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return;
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Driver->enqueueArchiveMember(C, Sym->getName(), getName());
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}
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void ObjectFile::parse() {
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// Parse a memory buffer as a COFF file.
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std::unique_ptr<Binary> Bin = check(createBinary(MB), toString(this));
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if (auto *Obj = dyn_cast<COFFObjectFile>(Bin.get())) {
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Bin.release();
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COFFObj.reset(Obj);
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} else {
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fatal(toString(this) + " is not a COFF file");
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}
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// Read section and symbol tables.
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initializeChunks();
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initializeSymbols();
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initializeSEH();
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}
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void ObjectFile::initializeChunks() {
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uint32_t NumSections = COFFObj->getNumberOfSections();
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Chunks.reserve(NumSections);
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SparseChunks.resize(NumSections + 1);
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for (uint32_t I = 1; I < NumSections + 1; ++I) {
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const coff_section *Sec;
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StringRef Name;
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if (auto EC = COFFObj->getSection(I, Sec))
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fatal(EC, "getSection failed: #" + Twine(I));
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if (auto EC = COFFObj->getSectionName(Sec, Name))
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fatal(EC, "getSectionName failed: #" + Twine(I));
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if (Name == ".sxdata") {
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SXData = Sec;
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continue;
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}
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if (Name == ".drectve") {
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ArrayRef<uint8_t> Data;
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COFFObj->getSectionContents(Sec, Data);
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Directives = std::string((const char *)Data.data(), Data.size());
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continue;
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}
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// Object files may have DWARF debug info or MS CodeView debug info
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// (or both).
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//
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// DWARF sections don't need any special handling from the perspective
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// of the linker; they are just a data section containing relocations.
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// We can just link them to complete debug info.
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//
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// CodeView needs a linker support. We need to interpret and debug
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// info, and then write it to a separate .pdb file.
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// Ignore debug info unless /debug is given.
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if (!Config->Debug && Name.startswith(".debug"))
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continue;
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if (Sec->Characteristics & llvm::COFF::IMAGE_SCN_LNK_REMOVE)
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continue;
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auto *C = make<SectionChunk>(this, Sec);
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// CodeView sections are stored to a different vector because they are not
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// linked in the regular manner.
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if (C->isCodeView())
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DebugChunks.push_back(C);
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else
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Chunks.push_back(C);
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SparseChunks[I] = C;
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}
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}
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void ObjectFile::initializeSymbols() {
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uint32_t NumSymbols = COFFObj->getNumberOfSymbols();
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SymbolBodies.reserve(NumSymbols);
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SparseSymbolBodies.resize(NumSymbols);
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SmallVector<std::pair<SymbolBody *, uint32_t>, 8> WeakAliases;
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int32_t LastSectionNumber = 0;
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for (uint32_t I = 0; I < NumSymbols; ++I) {
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// Get a COFFSymbolRef object.
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ErrorOr<COFFSymbolRef> SymOrErr = COFFObj->getSymbol(I);
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if (!SymOrErr)
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fatal(SymOrErr.getError(), "broken object file: " + toString(this));
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COFFSymbolRef Sym = *SymOrErr;
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const void *AuxP = nullptr;
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if (Sym.getNumberOfAuxSymbols())
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AuxP = COFFObj->getSymbol(I + 1)->getRawPtr();
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bool IsFirst = (LastSectionNumber != Sym.getSectionNumber());
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SymbolBody *Body = nullptr;
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if (Sym.isUndefined()) {
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Body = createUndefined(Sym);
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} else if (Sym.isWeakExternal()) {
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Body = createUndefined(Sym);
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uint32_t TagIndex =
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static_cast<const coff_aux_weak_external *>(AuxP)->TagIndex;
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WeakAliases.emplace_back(Body, TagIndex);
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} else {
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Body = createDefined(Sym, AuxP, IsFirst);
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}
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if (Body) {
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SymbolBodies.push_back(Body);
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SparseSymbolBodies[I] = Body;
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}
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I += Sym.getNumberOfAuxSymbols();
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LastSectionNumber = Sym.getSectionNumber();
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}
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for (auto &KV : WeakAliases) {
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SymbolBody *Sym = KV.first;
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uint32_t Idx = KV.second;
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checkAndSetWeakAlias(Symtab, this, Sym, SparseSymbolBodies[Idx]);
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}
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}
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SymbolBody *ObjectFile::createUndefined(COFFSymbolRef Sym) {
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StringRef Name;
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COFFObj->getSymbolName(Sym, Name);
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return Symtab->addUndefined(Name, this, Sym.isWeakExternal())->body();
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}
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SymbolBody *ObjectFile::createDefined(COFFSymbolRef Sym, const void *AuxP,
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bool IsFirst) {
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StringRef Name;
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if (Sym.isCommon()) {
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auto *C = make<CommonChunk>(Sym);
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Chunks.push_back(C);
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COFFObj->getSymbolName(Sym, Name);
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Symbol *S =
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Symtab->addCommon(this, Name, Sym.getValue(), Sym.getGeneric(), C);
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return S->body();
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}
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if (Sym.isAbsolute()) {
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COFFObj->getSymbolName(Sym, Name);
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// Skip special symbols.
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if (Name == "@comp.id")
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return nullptr;
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// COFF spec 5.10.1. The .sxdata section.
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if (Name == "@feat.00") {
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if (Sym.getValue() & 1)
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SEHCompat = true;
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return nullptr;
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}
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if (Sym.isExternal())
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return Symtab->addAbsolute(Name, Sym)->body();
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else
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return make<DefinedAbsolute>(Name, Sym);
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}
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int32_t SectionNumber = Sym.getSectionNumber();
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if (SectionNumber == llvm::COFF::IMAGE_SYM_DEBUG)
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return nullptr;
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// Reserved sections numbers don't have contents.
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if (llvm::COFF::isReservedSectionNumber(SectionNumber))
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fatal("broken object file: " + toString(this));
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// This symbol references a section which is not present in the section
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// header.
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if ((uint32_t)SectionNumber >= SparseChunks.size())
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fatal("broken object file: " + toString(this));
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// Nothing else to do without a section chunk.
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auto *SC = cast_or_null<SectionChunk>(SparseChunks[SectionNumber]);
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if (!SC)
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return nullptr;
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// Handle section definitions
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if (IsFirst && AuxP) {
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auto *Aux = reinterpret_cast<const coff_aux_section_definition *>(AuxP);
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if (Aux->Selection == IMAGE_COMDAT_SELECT_ASSOCIATIVE)
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if (auto *ParentSC = cast_or_null<SectionChunk>(
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SparseChunks[Aux->getNumber(Sym.isBigObj())])) {
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ParentSC->addAssociative(SC);
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// If we already discarded the parent, discard the child.
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if (ParentSC->isDiscarded())
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SC->markDiscarded();
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}
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SC->Checksum = Aux->CheckSum;
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}
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DefinedRegular *B;
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if (Sym.isExternal()) {
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COFFObj->getSymbolName(Sym, Name);
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Symbol *S =
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Symtab->addRegular(this, Name, SC->isCOMDAT(), Sym.getGeneric(), SC);
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B = cast<DefinedRegular>(S->body());
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} else
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B = make<DefinedRegular>(this, /*Name*/ "", SC->isCOMDAT(),
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/*IsExternal*/ false, Sym.getGeneric(), SC);
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if (SC->isCOMDAT() && Sym.getValue() == 0 && !AuxP)
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SC->setSymbol(B);
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return B;
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}
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void ObjectFile::initializeSEH() {
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if (!SEHCompat || !SXData)
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return;
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ArrayRef<uint8_t> A;
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COFFObj->getSectionContents(SXData, A);
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if (A.size() % 4 != 0)
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fatal(".sxdata must be an array of symbol table indices");
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auto *I = reinterpret_cast<const ulittle32_t *>(A.data());
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auto *E = reinterpret_cast<const ulittle32_t *>(A.data() + A.size());
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for (; I != E; ++I)
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SEHandlers.insert(SparseSymbolBodies[*I]);
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}
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MachineTypes ObjectFile::getMachineType() {
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if (COFFObj)
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return static_cast<MachineTypes>(COFFObj->getMachine());
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return IMAGE_FILE_MACHINE_UNKNOWN;
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}
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StringRef ltrim1(StringRef S, const char *Chars) {
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if (!S.empty() && strchr(Chars, S[0]))
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return S.substr(1);
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return S;
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}
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void ImportFile::parse() {
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const char *Buf = MB.getBufferStart();
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const char *End = MB.getBufferEnd();
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const auto *Hdr = reinterpret_cast<const coff_import_header *>(Buf);
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// Check if the total size is valid.
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if ((size_t)(End - Buf) != (sizeof(*Hdr) + Hdr->SizeOfData))
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fatal("broken import library");
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// Read names and create an __imp_ symbol.
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StringRef Name = Saver.save(StringRef(Buf + sizeof(*Hdr)));
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StringRef ImpName = Saver.save("__imp_" + Name);
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const char *NameStart = Buf + sizeof(coff_import_header) + Name.size() + 1;
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DLLName = StringRef(NameStart);
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StringRef ExtName;
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switch (Hdr->getNameType()) {
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case IMPORT_ORDINAL:
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ExtName = "";
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break;
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case IMPORT_NAME:
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ExtName = Name;
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break;
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case IMPORT_NAME_NOPREFIX:
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ExtName = ltrim1(Name, "?@_");
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break;
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case IMPORT_NAME_UNDECORATE:
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ExtName = ltrim1(Name, "?@_");
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ExtName = ExtName.substr(0, ExtName.find('@'));
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break;
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}
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this->Hdr = Hdr;
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ExternalName = ExtName;
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ImpSym = cast<DefinedImportData>(
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Symtab->addImportData(ImpName, this)->body());
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if (Hdr->getType() == llvm::COFF::IMPORT_CONST)
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ConstSym =
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cast<DefinedImportData>(Symtab->addImportData(Name, this)->body());
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// If type is function, we need to create a thunk which jump to an
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// address pointed by the __imp_ symbol. (This allows you to call
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// DLL functions just like regular non-DLL functions.)
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if (Hdr->getType() != llvm::COFF::IMPORT_CODE)
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return;
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ThunkSym = cast<DefinedImportThunk>(
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Symtab->addImportThunk(Name, ImpSym, Hdr->Machine)->body());
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}
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void BitcodeFile::parse() {
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Obj = check(lto::InputFile::create(MemoryBufferRef(
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MB.getBuffer(), Saver.save(ParentName + MB.getBufferIdentifier()))));
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for (const lto::InputFile::Symbol &ObjSym : Obj->symbols()) {
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StringRef SymName = Saver.save(ObjSym.getName());
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Symbol *Sym;
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if (ObjSym.isUndefined()) {
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Sym = Symtab->addUndefined(SymName, this, false);
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} else if (ObjSym.isCommon()) {
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Sym = Symtab->addCommon(this, SymName, ObjSym.getCommonSize());
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} else if (ObjSym.isWeak() && ObjSym.isIndirect()) {
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// Weak external.
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Sym = Symtab->addUndefined(SymName, this, true);
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std::string Fallback = ObjSym.getCOFFWeakExternalFallback();
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SymbolBody *Alias = Symtab->addUndefined(Saver.save(Fallback));
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checkAndSetWeakAlias(Symtab, this, Sym->body(), Alias);
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} else {
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bool IsCOMDAT = ObjSym.getComdatIndex() != -1;
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Sym = Symtab->addRegular(this, SymName, IsCOMDAT);
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}
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SymbolBodies.push_back(Sym->body());
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}
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Directives = Obj->getCOFFLinkerOpts();
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}
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MachineTypes BitcodeFile::getMachineType() {
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switch (Triple(Obj->getTargetTriple()).getArch()) {
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case Triple::x86_64:
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return AMD64;
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case Triple::x86:
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return I386;
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case Triple::arm:
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return ARMNT;
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default:
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return IMAGE_FILE_MACHINE_UNKNOWN;
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}
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}
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} // namespace coff
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} // namespace lld
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// Returns the last element of a path, which is supposed to be a filename.
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static StringRef getBasename(StringRef Path) {
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size_t Pos = Path.find_last_of("\\/");
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if (Pos == StringRef::npos)
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return Path;
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return Path.substr(Pos + 1);
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}
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// Returns a string in the format of "foo.obj" or "foo.obj(bar.lib)".
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std::string lld::toString(coff::InputFile *File) {
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if (!File)
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return "(internal)";
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if (File->ParentName.empty())
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return File->getName().lower();
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std::string Res =
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(getBasename(File->ParentName) + "(" + getBasename(File->getName()) + ")")
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.str();
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return StringRef(Res).lower();
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}
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