[openmp] - Cherry pick changes for CUDA_ARCH and libclang-cpp.so.

38e2804
[openmp] - Remove linking of libclang-cpp.so with libomptarget.so.

Now that libomptarget is a LLVM library we
no longer need to link in libclang-cpp.so.

be30280
[openmp] - undef __CUDA_ARCH__

When -fcuda-is-device is passed on the clang device pass,
__CUDA_ARCH__ is defined. When __AMDGCN__ is defined,
ensure __CUDA_ARCH__ is undefined.

Change-Id: Icc0a8675b085b670d314b08cf4bfca04b6037ef1

clang/lib/Headers/openmp_wrappers/__clang_openmp_device_functions.h

@@ -42,6 +42,8 @@ extern "C" {
 #pragma omp end declare variant
 
 #ifdef __AMDGCN__
+// -fcuda-is-device defines __CUDA_ARCH__
+#undef __CUDA_ARCH__
 #pragma omp begin declare variant match(device = {arch(amdgcn)})
 
 // __NO_INLINE__ prevents some x86 optimized macro definitions in system headers

openmp/libomptarget/src/CMakeLists.txt

@@ -48,16 +48,7 @@ endif()
 
 find_library(LLVM_OFFLOAD_ARCH LLVMOffloadArch HINTS ${LLVM_LIBRARY_DIR} REQUIRED)
 
-target_include_directories(omptarget PRIVATE
-  ${LIBOMPTARGET_INCLUDE_DIR})
-
-# If LLVM DYLIB is off we need to link in libclang-cpp.
-find_library(LLVM_DYLIB LLVM HINTS ${LLVM_LIBRARY_DIR})
-if(NOT LLVM_DYLIB)
-  libomptarget_say("LLVM_DYLIB off: linking libclang-cpp with libomptarget.so")
-  find_library(CLANG_CPP clang-cpp HINTS ${LLVM_LIBRARY_DIR} REQUIRED)
-  target_link_libraries(omptarget PRIVATE ${CLANG_CPP})
-endif()
+target_include_directories(omptarget PRIVATE ${LIBOMPTARGET_INCLUDE_DIR})
 
 target_link_libraries(omptarget PRIVATE
   ${CMAKE_DL_LIBS}