[llvm-dlltool] Remove support for implying output name

I don't see GNU dlltool supporting doing this; with only a -d option
and no -l option, GNU dlltool runs successfully but doesn't write any
output file.

Differential Revision: https://reviews.llvm.org/D65645

llvm-svn: 370655

Author: mstorsjo

llvm/lib/ToolDrivers/llvm-dlltool/DlltoolDriver.cpp

@@ -74,13 +74,6 @@ static MachineTypes getEmulation(StringRef S) {
       .Default(IMAGE_FILE_MACHINE_UNKNOWN);
 }
 
-static std::string getImplibPath(StringRef Path) {
-  SmallString<128> Out = StringRef("lib");
-  Out.append(Path);
-  sys::path::replace_extension(Out, ".a");
-  return Out.str();
-}
-
 int llvm::dlltoolDriverMain(llvm::ArrayRef<const char *> ArgsArr) {
   DllOptTable Table;
   unsigned MissingIndex;
@@ -154,8 +147,6 @@ int llvm::dlltoolDriverMain(llvm::ArrayRef<const char *> ArgsArr) {
   }
 
   std::string Path = Args.getLastArgValue(OPT_l);
-  if (Path.empty())
-    Path = getImplibPath(Def->OutputFile);
 
   if (Machine == IMAGE_FILE_MACHINE_I386 && Args.getLastArg(OPT_k)) {
     for (COFFShortExport& E : Def->Exports) {
@@ -175,7 +166,8 @@ int llvm::dlltoolDriverMain(llvm::ArrayRef<const char *> ArgsArr) {
     }
   }
 
-  if (writeImportLibrary(Def->OutputFile, Path, Def->Exports, Machine, true))
+  if (!Path.empty() &&
+      writeImportLibrary(Def->OutputFile, Path, Def->Exports, Machine, true))
     return 1;
   return 0;
 }