Pull in r211785 from upstream clang trunk (by Logan Chien):

  Implement the -fuse-ld= option.

  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.

Pull in r211786 from upstream clang trunk (by Logan Chien):

  Propset the executables for GetProgramPath().

Introduced here: http://svnweb.freebsd.org/changeset/base/279302

Index: tools/clang/include/clang/Basic/DiagnosticDriverKinds.td
===================================================================
--- tools/clang/include/clang/Basic/DiagnosticDriverKinds.td
+++ 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<
Index: tools/clang/include/clang/Driver/Options.td
===================================================================
--- tools/clang/include/clang/Driver/Options.td
+++ tools/clang/include/clang/Driver/Options.td
@@ -1453,7 +1453,7 @@ def fprofile_dir : Joined<["-"], "fprofile-dir=">,
 
 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>;
Index: tools/clang/include/clang/Driver/ToolChain.h
===================================================================
--- tools/clang/include/clang/Driver/ToolChain.h
+++ tools/clang/include/clang/Driver/ToolChain.h
@@ -150,6 +150,10 @@ class ToolChain {
   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,
Index: tools/clang/lib/Driver/ToolChain.cpp
===================================================================
--- tools/clang/lib/Driver/ToolChain.cpp
+++ 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 *
   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);
 }
Index: tools/clang/lib/Driver/ToolChains.cpp
===================================================================
--- tools/clang/lib/Driver/ToolChains.cpp
+++ tools/clang/lib/Driver/ToolChains.cpp
@@ -2420,7 +2420,7 @@ Linux::Linux(const Driver &D, const llvm::Triple &
   PPaths.push_back(Twine(GCCInstallation.getParentLibPath() + "/../" +
                          GCCInstallation.getTriple().str() + "/bin").str());
 
-  Linker = GetProgramPath("ld");
+  Linker = GetLinkerPath();
 
   Distro Distro = DetectDistro(Arch);
 
Index: tools/clang/lib/Driver/Tools.cpp
===================================================================
--- tools/clang/lib/Driver/Tools.cpp
+++ tools/clang/lib/Driver/Tools.cpp
@@ -5088,7 +5088,7 @@ void darwin::Link::ConstructJob(Compilation &C, co
   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, c
   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,
   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, c
   }
 
   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, co
   }
 
   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, c
   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, co
 
   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, con
          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,
   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));
 }
 
Index: tools/clang/test/Driver/Inputs/basic_android_tree/arm-linux-androideabi/bin/ld
===================================================================

Property changes on: tools/clang/test/Driver/Inputs/basic_android_tree/arm-linux-androideabi/bin/ld
___________________________________________________________________
Added: svn:executable
## -0,0 +1 ##
+*
\ No newline at end of property
Index: tools/clang/test/Driver/Inputs/basic_android_tree/arm-linux-androideabi/bin/ld.bfd
===================================================================

Property changes on: tools/clang/test/Driver/Inputs/basic_android_tree/arm-linux-androideabi/bin/ld.bfd
___________________________________________________________________
Added: svn:executable
## -0,0 +1 ##
+*
\ No newline at end of property
Index: tools/clang/test/Driver/Inputs/basic_android_tree/arm-linux-androideabi/bin/ld.gold
===================================================================

Property changes on: tools/clang/test/Driver/Inputs/basic_android_tree/arm-linux-androideabi/bin/ld.gold
___________________________________________________________________
Added: svn:executable
## -0,0 +1 ##
+*
\ No newline at end of property
Index: tools/clang/test/Driver/Inputs/basic_android_tree/bin/arm-linux-androideabi-ld
===================================================================

Property changes on: tools/clang/test/Driver/Inputs/basic_android_tree/bin/arm-linux-androideabi-ld
___________________________________________________________________
Added: svn:executable
## -0,0 +1 ##
+*
\ No newline at end of property
Index: tools/clang/test/Driver/Inputs/basic_android_tree/bin/arm-linux-androideabi-ld.bfd
===================================================================

Property changes on: tools/clang/test/Driver/Inputs/basic_android_tree/bin/arm-linux-androideabi-ld.bfd
___________________________________________________________________
Added: svn:executable
## -0,0 +1 ##
+*
\ No newline at end of property
Index: tools/clang/test/Driver/Inputs/basic_android_tree/bin/arm-linux-androideabi-ld.gold
===================================================================

Property changes on: tools/clang/test/Driver/Inputs/basic_android_tree/bin/arm-linux-androideabi-ld.gold
___________________________________________________________________
Added: svn:executable
## -0,0 +1 ##
+*
\ No newline at end of property
Index: tools/clang/test/Driver/Inputs/basic_freebsd_tree/usr/bin/ld.bfd
===================================================================

Property changes on: tools/clang/test/Driver/Inputs/basic_freebsd_tree/usr/bin/ld.bfd
___________________________________________________________________
Added: svn:executable
## -0,0 +1 ##
+*
\ No newline at end of property
Index: tools/clang/test/Driver/Inputs/basic_freebsd_tree/usr/bin/ld.gold
===================================================================

Property changes on: tools/clang/test/Driver/Inputs/basic_freebsd_tree/usr/bin/ld.gold
___________________________________________________________________
Added: svn:executable
## -0,0 +1 ##
+*
\ No newline at end of property
Index: tools/clang/test/Driver/fuse-ld.c
===================================================================
--- tools/clang/test/Driver/fuse-ld.c
+++ tools/clang/test/Driver/fuse-ld.c
@@ -0,0 +1,63 @@
+// RUN: %clang %s -### \
+// RUN:     -target x86_64-unknown-freebsd 2>&1 \
+// RUN:   | FileCheck %s --check-prefix=CHECK-FREEBSD-LD
+// CHECK-FREEBSD-LD: ld
+
+// RUN: %clang %s -### -fuse-ld=bfd \
+// RUN:     --sysroot=%S/Inputs/basic_freebsd_tree \
+// RUN:     -target x86_64-unknown-freebsd \
+// RUN:     -B%S/Inputs/basic_freebsd_tree/usr/bin 2>&1 \
+// RUN:   | FileCheck %s -check-prefix=CHECK-FREEBSD-BFD
+// CHECK-FREEBSD-BFD: Inputs/basic_freebsd_tree/usr/bin/ld.bfd
+
+// RUN: %clang %s -### -fuse-ld=gold \
+// RUN:     --sysroot=%S/Inputs/basic_freebsd_tree \
+// RUN:     -target x86_64-unknown-freebsd \
+// RUN:     -B%S/Inputs/basic_freebsd_tree/usr/bin 2>&1 \
+// RUN:   | FileCheck %s -check-prefix=CHECK-FREEBSD-GOLD
+// CHECK-FREEBSD-GOLD: Inputs/basic_freebsd_tree/usr/bin/ld.gold
+
+// RUN: %clang %s -### -fuse-ld=plib \
+// RUN:     --sysroot=%S/Inputs/basic_freebsd_tree \
+// RUN:     -target x86_64-unknown-freebsd \
+// RUN:     -B%S/Inputs/basic_freebsd_tree/usr/bin 2>&1 \
+// RUN:   | FileCheck %s -check-prefix=CHECK-FREEBSD-PLIB
+// CHECK-FREEBSD-PLIB: error: invalid linker name
+
+
+
+// RUN: %clang %s -### \
+// RUN:     -target arm-linux-androideabi \
+// RUN:     -B%S/Inputs/basic_android_tree/bin 2>&1 \
+// RUN:   | FileCheck %s --check-prefix=CHECK-ANDROID-ARM-LD
+// CHECK-ANDROID-ARM-LD: Inputs/basic_android_tree/bin/arm-linux-androideabi-ld
+
+// RUN: %clang %s -### -fuse-ld=bfd \
+// RUN:     -target arm-linux-androideabi \
+// RUN:     -B%S/Inputs/basic_android_tree/bin 2>&1 \
+// RUN:   | FileCheck %s -check-prefix=CHECK-ANDROID-ARM-BFD
+// CHECK-ANDROID-ARM-BFD: Inputs/basic_android_tree/bin/arm-linux-androideabi-ld.bfd
+
+// RUN: %clang %s -### -fuse-ld=gold \
+// RUN:     -target arm-linux-androideabi \
+// RUN:     -B%S/Inputs/basic_android_tree/bin 2>&1 \
+// RUN:   | FileCheck %s -check-prefix=CHECK-ANDROID-ARM-GOLD
+// CHECK-ANDROID-ARM-GOLD: Inputs/basic_android_tree/bin/arm-linux-androideabi-ld.gold
+
+// RUN: %clang %s -### \
+// RUN:     -target arm-linux-androideabi \
+// RUN:     -gcc-toolchain %S/Inputs/basic_android_tree 2>&1 \
+// RUN:   | FileCheck %s --check-prefix=CHECK-ANDROID-ARM-LD-TC
+// CHECK-ANDROID-ARM-LD-TC: Inputs/basic_android_tree/lib/gcc/arm-linux-androideabi/4.4.3/../../../../arm-linux-androideabi/bin/ld
+
+// RUN: %clang %s -### -fuse-ld=bfd \
+// RUN:     -target arm-linux-androideabi \
+// RUN:     -gcc-toolchain %S/Inputs/basic_android_tree 2>&1 \
+// RUN:   | FileCheck %s -check-prefix=CHECK-ANDROID-ARM-BFD-TC
+// CHECK-ANDROID-ARM-BFD-TC: Inputs/basic_android_tree/lib/gcc/arm-linux-androideabi/4.4.3/../../../../arm-linux-androideabi/bin/ld.bfd
+
+// RUN: %clang %s -### -fuse-ld=gold \
+// RUN:     -target arm-linux-androideabi \
+// RUN:     -gcc-toolchain %S/Inputs/basic_android_tree 2>&1 \
+// RUN:   | FileCheck %s -check-prefix=CHECK-ANDROID-ARM-GOLD-TC
+// CHECK-ANDROID-ARM-GOLD-TC: Inputs/basic_android_tree/lib/gcc/arm-linux-androideabi/4.4.3/../../../../arm-linux-androideabi/bin/ld.gold