Re-apply r246276 - Object: Teach llvm-ar to create symbol table for COFF short import files

This patch includes a fix for a llvm-readobj test. With this patch, 
the tool does no longer print out COFF headers for the short import
file, but that's probably desirable because the header for the short
import file is dummy.

llvm-svn: 246283

llvm/include/llvm/Object/Binary.h

@@ -41,6 +41,7 @@ protected:
   enum {
     ID_Archive,
     ID_MachOUniversalBinary,
+    ID_COFFImportFile,
     ID_IR, // LLVM IR
 
     // Object and children.
@@ -113,6 +114,10 @@ public:
     return TypeID == ID_COFF;
   }
 
+  bool isCOFFImportFile() const {
+    return TypeID == ID_COFFImportFile;
+  }
+
   bool isIR() const {
     return TypeID == ID_IR;
   }

llvm/include/llvm/Object/COFFImportFile.h

@@ -0,0 +1,70 @@
+//===- COFFImportFile.h - COFF short import file implementation -*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// COFF short import file is a special kind of file which contains
+// only symbol names for DLL-exported symbols. This class implements
+// SymbolicFile interface for the file.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_OBJECT_COFF_IMPORT_FILE_H
+#define LLVM_OBJECT_COFF_IMPORT_FILE_H
+
+#include "llvm/Object/COFF.h"
+#include "llvm/Object/IRObjectFile.h"
+#include "llvm/Object/ObjectFile.h"
+#include "llvm/Object/SymbolicFile.h"
+#include "llvm/Support/MemoryBuffer.h"
+
+namespace llvm {
+namespace object {
+
+class COFFImportFile : public SymbolicFile {
+public:
+  COFFImportFile(MemoryBufferRef Source)
+      : SymbolicFile(ID_COFFImportFile, Source) {}
+
+  static inline bool classof(Binary const *V) { return V->isCOFFImportFile(); }
+
+  void moveSymbolNext(DataRefImpl &Symb) const override { ++Symb.p; }
+
+  std::error_code printSymbolName(raw_ostream &OS,
+                                  DataRefImpl Symb) const override {
+    if (Symb.p == 1)
+      OS << "__imp_";
+    OS << StringRef(Data.getBufferStart() + sizeof(coff_import_header));
+    return std::error_code();
+  }
+
+  uint32_t getSymbolFlags(DataRefImpl Symb) const override {
+    return SymbolRef::SF_Global;
+  }
+
+  basic_symbol_iterator symbol_begin_impl() const override {
+    return BasicSymbolRef(DataRefImpl(), this);
+  }
+
+  basic_symbol_iterator symbol_end_impl() const override {
+    DataRefImpl Symb;
+    Symb.p = isCode() ? 2 : 1;
+    return BasicSymbolRef(Symb, this);
+  }
+
+private:
+  bool isCode() const {
+    auto *Import = reinterpret_cast<const object::coff_import_header *>(
+        Data.getBufferStart());
+    return Import->getType() == COFF::IMPORT_CODE;
+  }
+};
+
+} // namespace object
+} // namespace llvm
+
+#endif

llvm/lib/Object/SymbolicFile.cpp

@@ -11,6 +11,8 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "llvm/Object/COFF.h"
+#include "llvm/Object/COFFImportFile.h"
 #include "llvm/Object/IRObjectFile.h"
 #include "llvm/Object/ObjectFile.h"
 #include "llvm/Object/SymbolicFile.h"
@@ -54,9 +56,10 @@ ErrorOr<std::unique_ptr<SymbolicFile>> SymbolicFile::createSymbolicFile(
   case sys::fs::file_magic::macho_dynamically_linked_shared_lib_stub:
   case sys::fs::file_magic::macho_dsym_companion:
   case sys::fs::file_magic::macho_kext_bundle:
-  case sys::fs::file_magic::coff_import_library:
   case sys::fs::file_magic::pecoff_executable:
     return ObjectFile::createObjectFile(Object, Type);
+  case sys::fs::file_magic::coff_import_library:
+    return std::unique_ptr<SymbolicFile>(new COFFImportFile(Object));
   case sys::fs::file_magic::elf_relocatable:
   case sys::fs::file_magic::macho_object:
   case sys::fs::file_magic::coff_object: {

llvm/test/Object/archive-symtab.test

@@ -99,6 +99,16 @@ MACHO-NEXT: 0000000000000000 t _bar
 MACHO-NEXT: 0000000000000001 T _foo
 MACHO-NEXT: 0000000000000002 T _main
 
+RUN: rm -f %t.a
+RUN: llvm-ar --format=gnu rcsU %t.a %p/Inputs/coff-short-import-code %p/Inputs/coff-short-import-data
+RUN: llvm-nm -M %t.a | FileCheck --check-prefix=COFF-SHORT-IMPORT %s
+
+COFF-SHORT-IMPORT:      Archive map
+COFF-SHORT-IMPORT-NEXT: _foo in coff-short-import-code
+COFF-SHORT-IMPORT-NEXT: __imp__foo in coff-short-import-code
+COFF-SHORT-IMPORT-NEXT: _bar in coff-short-import-data
+COFF-SHORT-IMPORT-NOT:  __imp__bar in coff-short-import-data
+
 Test that we pad the symbol table so that it ends in a multiple of 4 bytes:
 8 + 60 + 36 == 104
 RUN: rm -f %t.a

llvm/test/tools/llvm-readobj/file-headers.test

@@ -330,16 +330,4 @@ COFF-UNKNOWN-NEXT:   Characteristics [ (0x0)
 COFF-UNKNOWN-NEXT:   ]
 COFF-UNKNOWN-NEXT: }
 
-COFF-IMPORTLIB:      Format: COFF-<unknown arch>
-COFF-IMPORTLIB-NEXT: Arch: unknown
-COFF-IMPORTLIB-NEXT: AddressSize: 32bit
-COFF-IMPORTLIB-NEXT: ImageFileHeader {
-COFF-IMPORTLIB-NEXT:   Machine: IMAGE_FILE_MACHINE_UNKNOWN (0x0)
-COFF-IMPORTLIB-NEXT:   SectionCount: 0
-COFF-IMPORTLIB-NEXT:   TimeDateStamp: 1970-09-09 19:52:32 (0x14C0000)
-COFF-IMPORTLIB-NEXT:   PointerToSymbolTable: 0x0
-COFF-IMPORTLIB-NEXT:   SymbolCount: 0
-COFF-IMPORTLIB-NEXT:   OptionalHeaderSize: 0
-COFF-IMPORTLIB-NEXT:   Characteristics [ (0x0)
-COFF-IMPORTLIB-NEXT:   ]
-COFF-IMPORTLIB-NEXT: }
+COFF-IMPORTLIB: Format: COFF-import-file

llvm/tools/llvm-readobj/llvm-readobj.cpp

@@ -24,6 +24,7 @@
 #include "ObjDumper.h"
 #include "StreamWriter.h"
 #include "llvm/Object/Archive.h"
+#include "llvm/Object/COFFImportFile.h"
 #include "llvm/Object/ELFObjectFile.h"
 #include "llvm/Object/MachOUniversal.h"
 #include "llvm/Object/ObjectFile.h"
@@ -330,6 +331,12 @@ static void dumpObject(const ObjectFile *Obj) {
     Dumper->printStackMap();
 }
 
+static void dumpCOFFImportFile(const COFFImportFile *File) {
+  outs() << '\n';
+  outs() << "File: " << File->getFileName() << "\n";
+  outs() << "Format: COFF-import-file\n";
+}
+
 /// @brief Dumps each object file in \a Arc;
 static void dumpArchive(const Archive *Arc) {
   for (const auto &Child : Arc->children()) {
@@ -384,6 +391,8 @@ static void dumpInput(StringRef File) {
     dumpMachOUniversalBinary(UBinary);
   else if (ObjectFile *Obj = dyn_cast<ObjectFile>(&Binary))
     dumpObject(Obj);
+  else if (COFFImportFile *Import = dyn_cast<COFFImportFile>(&Binary))
+    dumpCOFFImportFile(Import);
   else
     reportError(File, readobj_error::unrecognized_file_format);
 }