AMDGPU: Use lld as the linker again

Summary:
Now that LLVM is emitting version 2 of the AMD code object, we can
start using lld again for linking instead of our custom tool.

Reviewers: arsenm, kzhuravl

Subscribers: rafael, cfe-commits

Differential Revision: http://reviews.llvm.org/D19952

llvm-svn: 268648

clang/lib/Driver/Tools.cpp

@@ -6786,6 +6786,8 @@ void amdgpu::Linker::ConstructJob(Compilation &C, const JobAction &JA,
   std::string Linker = getToolChain().GetProgramPath(getShortName());
   ArgStringList CmdArgs;
   AddLinkerInputs(getToolChain(), Inputs, Args, CmdArgs);
+  CmdArgs.push_back("-shared");
+  CmdArgs.push_back("-o");
   CmdArgs.push_back(Output.getFilename());
   C.addCommand(llvm::make_unique<Command>(JA, *this, Args.MakeArgString(Linker),
                                           CmdArgs, Inputs));

clang/lib/Driver/Tools.h

@@ -242,7 +242,7 @@ namespace amdgpu {
 
 class LLVM_LIBRARY_VISIBILITY Linker : public GnuTool {
 public:
-  Linker(const ToolChain &TC) : GnuTool("amdgpu::Linker", "amdphdrs", TC) {}
+  Linker(const ToolChain &TC) : GnuTool("amdgpu::Linker", "ld.lld", TC) {}
   bool isLinkJob() const override { return true; }
   bool hasIntegratedCPP() const override { return false; }
   void ConstructJob(Compilation &C, const JobAction &JA,

clang/test/Driver/amdgpu-toolchain.c

@@ -1,3 +1,3 @@
 // RUN: %clang -### -target amdgcn--amdhsa -x assembler -mcpu=kaveri %s 2>&1 | FileCheck -check-prefix=AS_LINK %s
 // AS_LINK: clang{{.*}} "-cc1as"
-// AS_LINK: amdphdrs{{.*}}
+// AS_LINK: ld.lld{{.*}} "-shared"