Driver: Add AMDGPU toolchain

Summary:
This is a minimal toolchain, which sets the integrated assembler as default,
and uses lld for linking.

Reviewers: arsenm, mcrosier

Subscribers: cfe-commits

Differential Revision: http://reviews.llvm.org/D10700

llvm-svn: 242601
diff --git a/clang/lib/Driver/ToolChains.cpp b/clang/lib/Driver/ToolChains.cpp
index 15e36a1..685a51a 100644
--- a/clang/lib/Driver/ToolChains.cpp
+++ b/clang/lib/Driver/ToolChains.cpp
@@ -2293,6 +2293,16 @@
 }
 // End Hexagon
 
+/// AMDGPU Toolchain
+AMDGPUToolChain::AMDGPUToolChain(const Driver &D, const llvm::Triple &Triple,
+                                 const ArgList &Args)
+  : Generic_ELF(D, Triple, Args) { }
+
+Tool *AMDGPUToolChain::buildLinker() const {
+  return new tools::amdgpu::Linker(*this);
+}
+// End AMDGPU
+
 /// NaCl Toolchain
 NaCl_TC::NaCl_TC(const Driver &D, const llvm::Triple &Triple,
                  const ArgList &Args)