[CODEGEN LLVM GPU] Initialize llvm before lookup for the target (#2683)

python/tvm/contrib/nvcc.py

@@ -151,7 +151,7 @@ def find_libdevice_path(arch):
     selected_ver = 0
     selected_path = None
     cuda_ver = get_cuda_version(cuda_path)
-    if cuda_ver in (9.0, 9.1):
+    if cuda_ver in (9.0, 9.1, 10.0):
         path = os.path.join(lib_path, "libdevice.10.bc")
     else:
         for fn in os.listdir(lib_path):

src/codegen/llvm/codegen_amdgpu.cc

@@ -156,6 +156,7 @@ inline int DetectROCMComputeVersion(const std::string& target) {
 }
 
 runtime::Module BuildAMDGPU(Array<LoweredFunc> funcs, std::string target) {
+  InitializeLLVM();
   CHECK(target.length() >= 4 &&
         target.substr(0, 4) == "rocm");
   std::ostringstream config;

src/codegen/llvm/codegen_nvptx.cc

@@ -166,6 +166,7 @@ inline int DetectCUDAComputeVersion() {
 }
 
 runtime::Module BuildNVPTX(Array<LoweredFunc> funcs, std::string target) {
+  InitializeLLVM();
   CHECK(target.length() >= 5 &&
         target.substr(0, 5) == "nvptx");
   int compute_ver = DetectCUDAComputeVersion();