Implement the -fuse-ld= option.

Merge upstream Clang revision 211785:
  This commit implements the -fuse-ld= option, so that the user
  can specify -fuse-ld=bfd to use ld.bfd.

  This commit re-applies r194328 with some test case changes.
  It seems that r194328 was breaking macosx or mingw build
  because clang can't find ld.bfd or ld.gold in the given sysroot.
  We should use -B to specify the executable search path instead.

  Patch originally by David Chisnall.

This is a direct commit to stable/10 as this is change is already
included in Clang 3.5 in HEAD. The patch is also reworked slightly for
Clang 3.4.1.

Reviewed by:	dim
Sponsored by:	The FreeBSD Foundation

6 files changed, 42 insertions, 11 deletions

diff --git a/contrib/llvm/tools/clang/include/clang/Basic/DiagnosticDriverKinds.td b/contrib/llvm/tools/clang/include/clang/Basic/DiagnosticDriverKinds.td
index b489807..f7a575b 100644
--- a/contrib/llvm/tools/clang/include/clang/Basic/DiagnosticDriverKinds.td
+++ b/contrib/llvm/tools/clang/include/clang/Basic/DiagnosticDriverKinds.td
@@ -20,6 +20,8 @@ def err_drv_unknown_stdin_type : Error<
 def err_drv_unknown_language : Error<"language not recognized: '%0'">;
 def err_drv_invalid_arch_name : Error<
   "invalid arch name '%0'">;
+def err_drv_invalid_linker_name : Error<
+  "invalid linker name in argument '%0'">;
 def err_drv_invalid_rtlib_name : Error<
   "invalid runtime library name in argument '%0'">;
 def err_drv_unsupported_rtlib_for_platform : Error<
diff --git a/contrib/llvm/tools/clang/include/clang/Driver/Options.td b/contrib/llvm/tools/clang/include/clang/Driver/Options.td
index 5e7c76d..76a6d4d 100644
--- a/contrib/llvm/tools/clang/include/clang/Driver/Options.td
+++ b/contrib/llvm/tools/clang/include/clang/Driver/Options.td
@@ -1453,7 +1453,7 @@ def fprofile_dir : Joined<["-"], "fprofile-dir=">, Group<clang_ignored_f_Group>;
 
 defm profile_use : BooleanFFlag<"profile-use">, Group<clang_ignored_f_Group>;
 def fprofile_use_EQ : Joined<["-"], "fprofile-use=">, Group<clang_ignored_f_Group>;
-def fuse_ld_EQ : Joined<["-"], "fuse-ld=">, Group<clang_ignored_f_Group>;
+def fuse_ld_EQ : Joined<["-"], "fuse-ld=">, Group<f_Group>;
 
 defm align_functions : BooleanFFlag<"align-functions">, Group<clang_ignored_f_Group>;
 def falign_functions_EQ : Joined<["-"], "falign-functions=">, Group<clang_ignored_f_Group>;
diff --git a/contrib/llvm/tools/clang/include/clang/Driver/ToolChain.h b/contrib/llvm/tools/clang/include/clang/Driver/ToolChain.h
index c212a83..93c16c4 100644
--- a/contrib/llvm/tools/clang/include/clang/Driver/ToolChain.h
+++ b/contrib/llvm/tools/clang/include/clang/Driver/ToolChain.h
@@ -150,6 +150,10 @@ public:
   std::string GetFilePath(const char *Name) const;
   std::string GetProgramPath(const char *Name) const;
 
+  /// Returns the linker path, respecting the -fuse-ld= argument to determine
+  /// the linker suffix or name.
+  std::string GetLinkerPath() const;
+
   /// \brief Dispatch to the specific toolchain for verbose printing.
   ///
   /// This is used when handling the verbose option to print detailed,
diff --git a/contrib/llvm/tools/clang/lib/Driver/ToolChain.cpp b/contrib/llvm/tools/clang/lib/Driver/ToolChain.cpp
index 69b642e..003a362 100644
--- a/contrib/llvm/tools/clang/lib/Driver/ToolChain.cpp
+++ b/contrib/llvm/tools/clang/lib/Driver/ToolChain.cpp
@@ -15,6 +15,7 @@
 #include "clang/Driver/Options.h"
 #include "clang/Driver/SanitizerArgs.h"
 #include "clang/Driver/ToolChain.h"
+#include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/StringSwitch.h"
 #include "llvm/Option/Arg.h"
 #include "llvm/Option/ArgList.h"
@@ -146,6 +147,30 @@ std::string ToolChain::GetProgramPath(const char *Name) const {
   return D.GetProgramPath(Name, *this);
 }
 
+std::string ToolChain::GetLinkerPath() const {
+  if (Arg *A = Args.getLastArg(options::OPT_fuse_ld_EQ)) {
+    StringRef Suffix = A->getValue();
+
+    // If we're passed -fuse-ld= with no argument, or with the argument ld,
+    // then use whatever the default system linker is.
+    if (Suffix.empty() || Suffix == "ld")
+      return GetProgramPath("ld");
+
+    llvm::SmallString<8> LinkerName("ld.");
+    LinkerName.append(Suffix);
+
+    std::string LinkerPath(GetProgramPath(LinkerName.c_str()));
+    if (llvm::sys::fs::exists(LinkerPath))
+      return LinkerPath;
+
+    getDriver().Diag(diag::err_drv_invalid_linker_name) << A->getAsString(Args);
+    return "";
+  }
+
+  return GetProgramPath("ld");
+}
+
+
 types::ID ToolChain::LookupTypeForExtension(const char *Ext) const {
   return types::lookupTypeForExtension(Ext);
 }
diff --git a/contrib/llvm/tools/clang/lib/Driver/ToolChains.cpp b/contrib/llvm/tools/clang/lib/Driver/ToolChains.cpp
index f90ab69..5588941 100644
--- a/contrib/llvm/tools/clang/lib/Driver/ToolChains.cpp
+++ b/contrib/llvm/tools/clang/lib/Driver/ToolChains.cpp
@@ -2420,7 +2420,7 @@ Linux::Linux(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
   PPaths.push_back(Twine(GCCInstallation.getParentLibPath() + "/../" +
                          GCCInstallation.getTriple().str() + "/bin").str());
 
-  Linker = GetProgramPath("ld");
+  Linker = GetLinkerPath();
 
   Distro Distro = DetectDistro(Arch);
 
diff --git a/contrib/llvm/tools/clang/lib/Driver/Tools.cpp b/contrib/llvm/tools/clang/lib/Driver/Tools.cpp
index dc72085..86d046b 100644
--- a/contrib/llvm/tools/clang/lib/Driver/Tools.cpp
+++ b/contrib/llvm/tools/clang/lib/Driver/Tools.cpp
@@ -5088,7 +5088,7 @@ void darwin::Link::ConstructJob(Compilation &C, const JobAction &JA,
   Args.AddAllArgs(CmdArgs, options::OPT_F);
 
   const char *Exec =
-    Args.MakeArgString(getToolChain().GetProgramPath("ld"));
+    Args.MakeArgString(getToolChain().GetLinkerPath());
   C.addCommand(new Command(JA, *this, Exec, CmdArgs));
 }
 
@@ -5285,7 +5285,7 @@ void solaris::Link::ConstructJob(Compilation &C, const JobAction &JA,
   addProfileRT(getToolChain(), Args, CmdArgs, getToolChain().getTriple());
 
   const char *Exec =
-    Args.MakeArgString(getToolChain().GetProgramPath("ld"));
+    Args.MakeArgString(getToolChain().GetLinkerPath());
   C.addCommand(new Command(JA, *this, Exec, CmdArgs));
 }
 
@@ -5397,7 +5397,7 @@ void auroraux::Link::ConstructJob(Compilation &C, const JobAction &JA,
   addProfileRT(getToolChain(), Args, CmdArgs, getToolChain().getTriple());
 
   const char *Exec =
-    Args.MakeArgString(getToolChain().GetProgramPath("ld"));
+    Args.MakeArgString(getToolChain().GetLinkerPath());
   C.addCommand(new Command(JA, *this, Exec, CmdArgs));
 }
 
@@ -5587,7 +5587,7 @@ void openbsd::Link::ConstructJob(Compilation &C, const JobAction &JA,
   }
 
   const char *Exec =
-    Args.MakeArgString(getToolChain().GetProgramPath("ld"));
+    Args.MakeArgString(getToolChain().GetLinkerPath());
   C.addCommand(new Command(JA, *this, Exec, CmdArgs));
 }
 
@@ -5727,7 +5727,7 @@ void bitrig::Link::ConstructJob(Compilation &C, const JobAction &JA,
   }
 
   const char *Exec =
-    Args.MakeArgString(getToolChain().GetProgramPath("ld"));
+    Args.MakeArgString(getToolChain().GetLinkerPath());
   C.addCommand(new Command(JA, *this, Exec, CmdArgs));
 }
 
@@ -6016,7 +6016,7 @@ void freebsd::Link::ConstructJob(Compilation &C, const JobAction &JA,
   addProfileRT(ToolChain, Args, CmdArgs, ToolChain.getTriple());
 
   const char *Exec =
-    Args.MakeArgString(ToolChain.GetProgramPath("ld"));
+    Args.MakeArgString(ToolChain.GetLinkerPath());
   C.addCommand(new Command(JA, *this, Exec, CmdArgs));
 }
 
@@ -6204,7 +6204,7 @@ void netbsd::Link::ConstructJob(Compilation &C, const JobAction &JA,
 
   addProfileRT(getToolChain(), Args, CmdArgs, getToolChain().getTriple());
 
-  const char *Exec = Args.MakeArgString(getToolChain().GetProgramPath("ld"));
+  const char *Exec = Args.MakeArgString(getToolChain().GetLinkerPath());
   C.addCommand(new Command(JA, *this, Exec, CmdArgs));
 }
 
@@ -6749,7 +6749,7 @@ void minix::Link::ConstructJob(Compilation &C, const JobAction &JA,
          Args.MakeArgString(getToolChain().GetFilePath("crtend.o")));
   }
 
-  const char *Exec = Args.MakeArgString(getToolChain().GetProgramPath("ld"));
+  const char *Exec = Args.MakeArgString(getToolChain().GetLinkerPath());
   C.addCommand(new Command(JA, *this, Exec, CmdArgs));
 }
 
@@ -6933,7 +6933,7 @@ void dragonfly::Link::ConstructJob(Compilation &C, const JobAction &JA,
   addProfileRT(getToolChain(), Args, CmdArgs, getToolChain().getTriple());
 
   const char *Exec =
-    Args.MakeArgString(getToolChain().GetProgramPath("ld"));
+    Args.MakeArgString(getToolChain().GetLinkerPath());
   C.addCommand(new Command(JA, *this, Exec, CmdArgs));
 }