Support -rdynamic option in the new driver

lib/Driver/Tools.cpp

 //===--- Tools.cpp - Tools Implementations --------------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
 #include "Tools.h"
@@ skipping 8205 matching lines @@
   // handled somewhere else.
   Args.ClaimAllArgs(options::OPT_w);
   // Silence warning for libgcc since we only support compiler-rt.
   Args.ClaimAllArgs(options::OPT_shared_libgcc);
   Args.ClaimAllArgs(options::OPT_static_libgcc);
 
   if (!D.SysRoot.empty())
     CmdArgs.push_back(Args.MakeArgString("--sysroot=" + D.SysRoot));
 
   if (Arg *A = Args.getLastArg(options::OPT_shared,
-                               options::OPT_dynamic,
-                               options::OPT_rdynamic))
+                               options::OPT_dynamic))
     D.Diag(diag::err_drv_unsupported_opt) << A->getOption().getName();
 
+  // This option does not currently have any effect for bitcode linking,
+  // but we support it for backwards compatibility with the legacy driver
+  // and existing software packages.
+  if (Args.hasArg(options::OPT_rdynamic))
+    CmdArgs.push_back("-export-dynamic");
+
   std::string TripleStr = ToolChain.ComputeEffectiveClangTriple(Args);
   if (ToolChain.getArch() != llvm::Triple::le32)
     D.Diag(diag::err_target_unsupported_arch) << ToolChain.getArchName()
                                               << TripleStr;
 
   Args.AddAllArgs(CmdArgs, options::OPT_static);
   if (!Args.hasArg(options::OPT_static))
     CmdArgs.push_back("-static");
 
   bool EH = exceptionSettings(Args, ToolChain.getTriple());
@@ skipping 882 matching lines @@
       CmdArgs.push_back("-lmsvcrt");
       AddRunTimeLibs(TC, D, CmdArgs, Args);
     }
   }
 
   const std::string Linker = TC.GetProgramPath("ld");
   Exec = Args.MakeArgString(Linker);
 
   C.addCommand(llvm::make_unique<Command>(JA, *this, Exec, CmdArgs));
 }