[LLD][COFF] Create COFFObjectFile instance when constructing ObjFile (NFC) (#120144)

This change moves the creation of COFFObjectFile to the construction of
ObjFile, instead of delaying it until parsing.

Author: cjacek

lld/COFF/Driver.cpp

@@ -229,7 +229,7 @@ void LinkerDriver::addBuffer(std::unique_ptr<MemoryBuffer> mb,
     break;
   case file_magic::coff_object:
   case file_magic::coff_import_library:
-    ctx.symtab.addFile(make<ObjFile>(ctx, mbref, lazy));
+    ctx.symtab.addFile(ObjFile::create(ctx, mbref, lazy));
     break;
   case file_magic::pdb:
     ctx.symtab.addFile(make<PDBInputFile>(ctx, mbref));
@@ -312,7 +312,7 @@ void LinkerDriver::addArchiveBuffer(MemoryBufferRef mb, StringRef symName,
 
   InputFile *obj;
   if (magic == file_magic::coff_object) {
-    obj = make<ObjFile>(ctx, mb);
+    obj = ObjFile::create(ctx, mb);
   } else if (magic == file_magic::bitcode) {
     obj =
         make<BitcodeFile>(ctx, mb, parentName, offsetInArchive, /*lazy=*/false);
@@ -1389,7 +1389,7 @@ void LinkerDriver::convertResources() {
     return;
   }
   ObjFile *f =
-      make<ObjFile>(ctx, convertResToCOFF(resources, resourceObjFiles));
+      ObjFile::create(ctx, convertResToCOFF(resources, resourceObjFiles));
   ctx.symtab.addFile(f);
   f->includeResourceChunks();
 }

lld/COFF/InputFiles.cpp

@@ -162,13 +162,26 @@ lld::coff::getArchiveMembers(COFFLinkerContext &ctx, Archive *file) {
   return v;
 }
 
-ObjFile::ObjFile(COFFLinkerContext &ctx, MemoryBufferRef m, bool lazy)
-    : InputFile(ctx.symtab, ObjectKind, m, lazy) {}
+ObjFile::ObjFile(SymbolTable &symtab, COFFObjectFile *coffObj, bool lazy)
+    : InputFile(symtab, ObjectKind, coffObj->getMemoryBufferRef(), lazy),
+      coffObj(coffObj) {}
+
+ObjFile *ObjFile::create(COFFLinkerContext &ctx, MemoryBufferRef m, bool lazy) {
+  // Parse a memory buffer as a COFF file.
+  Expected<std::unique_ptr<Binary>> bin = createBinary(m);
+  if (!bin)
+    Fatal(ctx) << "Could not parse " << m.getBufferIdentifier();
+
+  auto *obj = dyn_cast<COFFObjectFile>(bin->get());
+  if (!obj)
+    Fatal(ctx) << m.getBufferIdentifier() << " is not a COFF file";
+
+  bin->release();
+  return make<ObjFile>(ctx.symtab, obj, lazy);
+}
 
 void ObjFile::parseLazy() {
   // Native object file.
-  std::unique_ptr<Binary> coffObjPtr = CHECK(createBinary(mb), this);
-  COFFObjectFile *coffObj = cast<COFFObjectFile>(coffObjPtr.get());
   uint32_t numSymbols = coffObj->getNumberOfSymbols();
   for (uint32_t i = 0; i < numSymbols; ++i) {
     COFFSymbolRef coffSym = check(coffObj->getSymbol(i));
@@ -219,16 +232,6 @@ void ObjFile::initializeECThunks() {
 }
 
 void ObjFile::parse() {
-  // Parse a memory buffer as a COFF file.
-  std::unique_ptr<Binary> bin = CHECK(createBinary(mb), this);
-
-  if (auto *obj = dyn_cast<COFFObjectFile>(bin.get())) {
-    bin.release();
-    coffObj.reset(obj);
-  } else {
-    Fatal(symtab.ctx) << toString(this) << " is not a COFF file";
-  }
-
   // Read section and symbol tables.
   initializeChunks();
   initializeSymbols();
@@ -807,9 +810,7 @@ std::optional<Symbol *> ObjFile::createDefined(
 }
 
 MachineTypes ObjFile::getMachineType() const {
-  if (coffObj)
-    return static_cast<MachineTypes>(coffObj->getMachine());
-  return IMAGE_FILE_MACHINE_UNKNOWN;
+  return static_cast<MachineTypes>(coffObj->getMachine());
 }
 
 ArrayRef<uint8_t> ObjFile::getDebugSection(StringRef secName) {

lld/COFF/InputFiles.h

@@ -136,8 +136,10 @@ class ArchiveFile : public InputFile {
 // .obj or .o file. This may be a member of an archive file.
 class ObjFile : public InputFile {
 public:
-  explicit ObjFile(COFFLinkerContext &ctx, MemoryBufferRef m,
-                   bool lazy = false);
+  static ObjFile *create(COFFLinkerContext &ctx, MemoryBufferRef mb,
+                         bool lazy = false);
+  explicit ObjFile(SymbolTable &symtab, COFFObjectFile *coffObj, bool lazy);
+
   static bool classof(const InputFile *f) { return f->kind() == ObjectKind; }
   void parse() override;
   void parseLazy();

lld/COFF/LTO.cpp

@@ -259,7 +259,7 @@ std::vector<InputFile *> BitcodeCompiler::compile() {
     if (llvm::is_contained(ctx.config.saveTempsArgs, "prelink") || emitASM)
       saveBuffer(buf[i].second, ltoObjName);
     if (!emitASM)
-      ret.push_back(make<ObjFile>(ctx, MemoryBufferRef(objBuf, ltoObjName)));
+      ret.push_back(ObjFile::create(ctx, MemoryBufferRef(objBuf, ltoObjName)));
   }
 
   return ret;