Vendor import of lld trunk r256633:vendor/lld/lld-trunk-r256633

https://llvm.org/svn/llvm-project/lld/trunk@256633

1 files changed, 367 insertions, 0 deletions

diff --git a/COFF/InputFiles.cpp b/COFF/InputFiles.cpp
new file mode 100644
index 000000000000..23fc2a085122
--- /dev/null
+++ b/COFF/InputFiles.cpp
@@ -0,0 +1,367 @@
+//===- 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 "Symbols.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/IR/LLVMContext.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::COFF;
+using namespace llvm::object;
+using namespace llvm::support::endian;
+using llvm::RoundUpToAlignment;
+using llvm::Triple;
+using llvm::support::ulittle32_t;
+using llvm::sys::fs::file_magic;
+using llvm::sys::fs::identify_magic;
+
+namespace lld {
+namespace coff {
+
+int InputFile::NextIndex = 0;
+
+// 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();
+}
+
+void ArchiveFile::parse() {
+  // Parse a MemoryBufferRef as an archive file.
+  auto ArchiveOrErr = Archive::create(MB);
+  error(ArchiveOrErr, "Failed to parse static library");
+  File = std::move(*ArchiveOrErr);
+
+  // Allocate a buffer for Lazy objects.
+  size_t NumSyms = File->getNumberOfSymbols();
+  LazySymbols.reserve(NumSyms);
+
+  // Read the symbol table to construct Lazy objects.
+  for (const Archive::Symbol &Sym : File->symbols())
+    LazySymbols.emplace_back(this, Sym);
+
+  // Seen is a map from member files to boolean values. Initially
+  // all members are mapped to false, which indicates all these files
+  // are not read yet.
+  for (auto &ChildOrErr : File->children()) {
+    error(ChildOrErr, "Failed to parse static library");
+    const Archive::Child &Child = *ChildOrErr;
+    Seen[Child.getChildOffset()].clear();
+  }
+}
+
+// Returns a buffer pointing to a member file containing a given symbol.
+// This function is thread-safe.
+MemoryBufferRef ArchiveFile::getMember(const Archive::Symbol *Sym) {
+  auto COrErr = Sym->getMember();
+  error(COrErr, Twine("Could not get the member for symbol ") + Sym->getName());
+  const Archive::Child &C = *COrErr;
+
+  // Return an empty buffer if we have already returned the same buffer.
+  if (Seen[C.getChildOffset()].test_and_set())
+    return MemoryBufferRef();
+  ErrorOr<MemoryBufferRef> Ret = C.getMemoryBufferRef();
+  error(Ret, Twine("Could not get the buffer for the member defining symbol ") +
+                 Sym->getName());
+  return *Ret;
+}
+
+void ObjectFile::parse() {
+  // Parse a memory buffer as a COFF file.
+  auto BinOrErr = createBinary(MB);
+  error(BinOrErr, "Failed to parse object file");
+  std::unique_ptr<Binary> Bin = std::move(*BinOrErr);
+
+  if (auto *Obj = dyn_cast<COFFObjectFile>(Bin.get())) {
+    Bin.release();
+    COFFObj.reset(Obj);
+  } else {
+    error(Twine(getName()) + " is not a COFF file.");
+  }
+
+  // Read section and symbol tables.
+  initializeChunks();
+  initializeSymbols();
+  initializeSEH();
+}
+
+void 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;
+    std::error_code EC = COFFObj->getSection(I, Sec);
+    error(EC, Twine("getSection failed: #") + Twine(I));
+    EC = COFFObj->getSectionName(Sec, Name);
+    error(EC, Twine("getSectionName failed: #") + Twine(I));
+    if (Name == ".sxdata") {
+      SXData = Sec;
+      continue;
+    }
+    if (Name == ".drectve") {
+      ArrayRef<uint8_t> Data;
+      COFFObj->getSectionContents(Sec, Data);
+      Directives = std::string((const char *)Data.data(), Data.size());
+      continue;
+    }
+    // Skip non-DWARF debug info. MSVC linker converts the sections into
+    // a PDB file, but we don't support that.
+    if (Name == ".debug" || Name.startswith(".debug$"))
+      continue;
+    // We want to preserve DWARF debug sections only when /debug is on.
+    if (!Config->Debug && Name.startswith(".debug"))
+      continue;
+    if (Sec->Characteristics & llvm::COFF::IMAGE_SCN_LNK_REMOVE)
+      continue;
+    auto *C = new (Alloc) SectionChunk(this, Sec);
+    Chunks.push_back(C);
+    SparseChunks[I] = C;
+  }
+}
+
+void ObjectFile::initializeSymbols() {
+  uint32_t NumSymbols = COFFObj->getNumberOfSymbols();
+  SymbolBodies.reserve(NumSymbols);
+  SparseSymbolBodies.resize(NumSymbols);
+  llvm::SmallVector<Undefined *, 8> WeakAliases;
+  int32_t LastSectionNumber = 0;
+  for (uint32_t I = 0; I < NumSymbols; ++I) {
+    // Get a COFFSymbolRef object.
+    auto SymOrErr = COFFObj->getSymbol(I);
+    error(SymOrErr, Twine("broken object file: ") + getName());
+
+    COFFSymbolRef Sym = *SymOrErr;
+
+    const void *AuxP = nullptr;
+    if (Sym.getNumberOfAuxSymbols())
+      AuxP = COFFObj->getSymbol(I + 1)->getRawPtr();
+    bool IsFirst = (LastSectionNumber != Sym.getSectionNumber());
+
+    SymbolBody *Body = nullptr;
+    if (Sym.isUndefined()) {
+      Body = createUndefined(Sym);
+    } else if (Sym.isWeakExternal()) {
+      Body = createWeakExternal(Sym, AuxP);
+      WeakAliases.push_back((Undefined *)Body);
+    } else {
+      Body = createDefined(Sym, AuxP, IsFirst);
+    }
+    if (Body) {
+      SymbolBodies.push_back(Body);
+      SparseSymbolBodies[I] = Body;
+    }
+    I += Sym.getNumberOfAuxSymbols();
+    LastSectionNumber = Sym.getSectionNumber();
+  }
+  for (Undefined *U : WeakAliases)
+    U->WeakAlias = SparseSymbolBodies[(uintptr_t)U->WeakAlias];
+}
+
+Undefined *ObjectFile::createUndefined(COFFSymbolRef Sym) {
+  StringRef Name;
+  COFFObj->getSymbolName(Sym, Name);
+  return new (Alloc) Undefined(Name);
+}
+
+Undefined *ObjectFile::createWeakExternal(COFFSymbolRef Sym, const void *AuxP) {
+  StringRef Name;
+  COFFObj->getSymbolName(Sym, Name);
+  auto *U = new (Alloc) Undefined(Name);
+  auto *Aux = (const coff_aux_weak_external *)AuxP;
+  U->WeakAlias = (Undefined *)(uintptr_t)Aux->TagIndex;
+  return U;
+}
+
+Defined *ObjectFile::createDefined(COFFSymbolRef Sym, const void *AuxP,
+                                   bool IsFirst) {
+  StringRef Name;
+  if (Sym.isCommon()) {
+    auto *C = new (Alloc) CommonChunk(Sym);
+    Chunks.push_back(C);
+    return new (Alloc) DefinedCommon(this, Sym, C);
+  }
+  if (Sym.isAbsolute()) {
+    COFFObj->getSymbolName(Sym, Name);
+    // Skip special symbols.
+    if (Name == "@comp.id")
+      return nullptr;
+    // COFF spec 5.10.1. The .sxdata section.
+    if (Name == "@feat.00") {
+      if (Sym.getValue() & 1)
+        SEHCompat = true;
+      return nullptr;
+    }
+    return new (Alloc) DefinedAbsolute(Name, Sym);
+  }
+  if (Sym.getSectionNumber() == llvm::COFF::IMAGE_SYM_DEBUG)
+    return nullptr;
+
+  // Nothing else to do without a section chunk.
+  auto *SC = cast_or_null<SectionChunk>(SparseChunks[Sym.getSectionNumber()]);
+  if (!SC)
+    return nullptr;
+
+  // Handle section definitions
+  if (IsFirst && AuxP) {
+    auto *Aux = reinterpret_cast<const coff_aux_section_definition *>(AuxP);
+    if (Aux->Selection == IMAGE_COMDAT_SELECT_ASSOCIATIVE)
+      if (auto *ParentSC = cast_or_null<SectionChunk>(
+              SparseChunks[Aux->getNumber(Sym.isBigObj())]))
+        ParentSC->addAssociative(SC);
+    SC->Checksum = Aux->CheckSum;
+  }
+
+  auto *B = new (Alloc) DefinedRegular(this, Sym, SC);
+  if (SC->isCOMDAT() && Sym.getValue() == 0 && !AuxP)
+    SC->setSymbol(B);
+
+  return B;
+}
+
+void ObjectFile::initializeSEH() {
+  if (!SEHCompat || !SXData)
+    return;
+  ArrayRef<uint8_t> A;
+  COFFObj->getSectionContents(SXData, A);
+  if (A.size() % 4 != 0)
+    error(".sxdata must be an array of symbol table indices");
+  auto *I = reinterpret_cast<const ulittle32_t *>(A.data());
+  auto *E = reinterpret_cast<const ulittle32_t *>(A.data() + A.size());
+  for (; I != E; ++I)
+    SEHandlers.insert(SparseSymbolBodies[*I]);
+}
+
+MachineTypes ObjectFile::getMachineType() {
+  if (COFFObj)
+    return static_cast<MachineTypes>(COFFObj->getMachine());
+  return IMAGE_FILE_MACHINE_UNKNOWN;
+}
+
+StringRef ltrim1(StringRef S, const char *Chars) {
+  if (!S.empty() && strchr(Chars, S[0]))
+    return S.substr(1);
+  return S;
+}
+
+void 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))
+    error("broken import library");
+
+  // Read names and create an __imp_ symbol.
+  StringRef Name = StringAlloc.save(StringRef(Buf + sizeof(*Hdr)));
+  StringRef ImpName = StringAlloc.save(Twine("__imp_") + Name);
+  const char *NameStart = Buf + sizeof(coff_import_header) + Name.size() + 1;
+  DLLName = StringRef(NameStart);
+  StringRef ExtName;
+  switch (Hdr->getNameType()) {
+  case IMPORT_ORDINAL:
+    ExtName = "";
+    break;
+  case IMPORT_NAME:
+    ExtName = Name;
+    break;
+  case IMPORT_NAME_NOPREFIX:
+    ExtName = ltrim1(Name, "?@_");
+    break;
+  case IMPORT_NAME_UNDECORATE:
+    ExtName = ltrim1(Name, "?@_");
+    ExtName = ExtName.substr(0, ExtName.find('@'));
+    break;
+  }
+  ImpSym = new (Alloc) DefinedImportData(DLLName, ImpName, ExtName, 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)
+    return;
+  ThunkSym = new (Alloc) DefinedImportThunk(Name, ImpSym, Hdr->Machine);
+  SymbolBodies.push_back(ThunkSym);
+}
+
+void BitcodeFile::parse() {
+  // Usually parse() is thread-safe, but bitcode file is an exception.
+  std::lock_guard<std::mutex> Lock(Mu);
+
+  ErrorOr<std::unique_ptr<LTOModule>> ModOrErr =
+      LTOModule::createFromBuffer(llvm::getGlobalContext(), MB.getBufferStart(),
+                                  MB.getBufferSize(), llvm::TargetOptions());
+  error(ModOrErr, "Could not create lto module");
+  M = std::move(*ModOrErr);
+
+  llvm::StringSaver 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 || // common
+           (Attrs & LTO_SYMBOL_COMDAT) ||                  // comdat
+           (SymbolDef == LTO_SYMBOL_DEFINITION_WEAK &&     // weak external
+            (Attrs & LTO_SYMBOL_ALIAS)));
+      SymbolBodies.push_back(new (Alloc) DefinedBitcode(this, SymName,
+                                                        Replaceable));
+    }
+  }
+
+  Directives = M->getLinkerOpts();
+}
+
+MachineTypes BitcodeFile::getMachineType() {
+  if (!M)
+    return IMAGE_FILE_MACHINE_UNKNOWN;
+  switch (Triple(M->getTargetTriple()).getArch()) {
+  case Triple::x86_64:
+    return AMD64;
+  case Triple::x86:
+    return I386;
+  case Triple::arm:
+    return ARMNT;
+  default:
+    return IMAGE_FILE_MACHINE_UNKNOWN;
+  }
+}
+
+std::mutex BitcodeFile::Mu;
+
+} // namespace coff
+} // namespace lld