[PECOFF] Create the import library file.

If the linker is instructed to create a DLL, it will also create an import
library (.lib file) to describe the symbols exported by the DLL. This patch is
to create the import library file.

There is a convenient command "lib.exe" which can create an import library
from a module definition file (.def file). The command is used in this patch.

llvm-svn: 197801

lld/lib/ReaderWriter/PECOFF/CMakeLists.txt

@@ -5,6 +5,7 @@ add_lld_library(lldPECOFF
   Pass.cpp
   ReaderCOFF.cpp
   ReaderImportHeader.cpp
+  WriterImportLibrary.cpp
   WriterPECOFF.cpp
   )
 

lld/lib/ReaderWriter/PECOFF/WriterImportLibrary.cpp

@@ -0,0 +1,76 @@
+//===- lib/ReaderWriter/PECOFF/WriterImportLibrary.cpp --------------------===//
+//
+//                             The LLVM Linker
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+///
+/// This file is reponsible for creating the Import Library file.
+///
+//===----------------------------------------------------------------------===//
+
+#include "lld/ReaderWriter/PECOFFLinkingContext.h"
+#include "llvm/Support/FileUtilities.h"
+#include "llvm/Support/Path.h"
+#include "llvm/Support/Program.h"
+#include "llvm/Support/raw_ostream.h"
+
+namespace lld {
+namespace pecoff {
+
+static std::string getOutputPath(const PECOFFLinkingContext &ctx) {
+  SmallString<128> path = ctx.outputPath();
+  llvm::sys::path::replace_extension(path, ".lib");
+  return path.str();
+}
+
+/// Creates a .def file containing the list of exported symbols.
+static std::string
+createModuleDefinitionFile(const PECOFFLinkingContext &ctx,
+                           llvm::FileRemover &fileRemover) {
+  SmallString<128> defFile;
+  int fd;
+  if (llvm::sys::fs::createTemporaryFile("tmp", "def", fd, defFile)) {
+    llvm::errs() << "Failed to create temporary file\n";
+    return "";
+  }
+
+  llvm::raw_fd_ostream os(fd, /*shouldClose*/ true);
+  os << "LIBRARY \"" << llvm::sys::path::filename(ctx.outputPath()) << "\"\n"
+     << "EXPORTS\n";
+
+  for (const PECOFFLinkingContext::ExportDesc &desc : ctx.getDllExports())
+    os << "  " << desc.name << " @" << desc.ordinal << "\n";
+  return defFile.str();
+}
+
+/// Creates a .def file and runs lib.exe on it to create an import library.
+void writeImportLibrary(const PECOFFLinkingContext &ctx) {
+  std::string program = "lib.exe";
+  std::string programPath = llvm::sys::FindProgramByName(program);
+  if (programPath.empty()) {
+    llvm::errs() << "Unable to find " << program << " in PATH\n";
+    return;
+  }
+
+  llvm::FileRemover tmpFile;
+  std::string defArg = "/def:";
+  defArg.append(createModuleDefinitionFile(ctx, tmpFile));
+  std::string outputArg = "/out:";
+  outputArg.append(getOutputPath(ctx));
+
+  std::vector<const char *> args;
+  args.push_back(programPath.c_str());
+  args.push_back("/nologo");
+  args.push_back("/machine:x86");
+  args.push_back(defArg.c_str());
+  args.push_back(outputArg.c_str());
+  args.push_back(nullptr);
+  if (llvm::sys::ExecuteAndWait(programPath.c_str(), &args[0]) != 0)
+    llvm::errs() << program << " failed\n";
+}
+
+} // end namespace pecoff
+} // end namespace lld

lld/lib/ReaderWriter/PECOFF/WriterImportLibrary.h

@@ -0,0 +1,23 @@
+//===- lib/ReaderWriter/PECOFF/WriterImportLibrary.h ----------------------===//
+//
+//                             The LLVM Linker
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLD_READER_WRITER_PE_COFF_WRITER_IMPORT_LIBRARY_H
+#define LLD_READER_WRITER_PE_COFF_WRITER_IMPORT_LIBRARY_H
+
+namespace lld {
+class PECOFFLinkingContext;
+
+namespace pecoff {
+
+void writeImportLibrary(const PECOFFLinkingContext &ctx);
+
+} // end namespace pecoff
+} // end namespace lld
+
+#endif

lld/lib/ReaderWriter/PECOFF/WriterPECOFF.cpp

@@ -27,6 +27,7 @@
 #include <vector>
 
 #include "Atoms.h"
+#include "WriterImportLibrary.h"
 
 #include "lld/Core/DefinedAtom.h"
 #include "lld/Core/File.h"
@@ -909,6 +910,10 @@ error_code PECOFFWriter::writeFile(const File &linkedFile, StringRef path) {
     chunk->write(buffer->getBufferStart() + chunk->fileOffset());
   applyAllRelocations(buffer->getBufferStart());
   DEBUG(printAllAtomAddresses());
+
+  if (_PECOFFLinkingContext.getImageType() == PECOFFLinkingContext::IMAGE_DLL)
+    writeImportLibrary(_PECOFFLinkingContext);
+
   return buffer->commit();
 }