[CUDA] Only allow NVIDIA offload-arch during CUDA compilation.

Otherwise, if someone specifies a valid AMD arch, we may end up triggering an
assertion on unexpected arch later on.

Differential Revision: https://reviews.llvm.org/D105295

Author: Artem-B

clang/lib/Driver/Driver.cpp

@@ -2785,7 +2785,7 @@ class OffloadingActionBuilder final {
 
     StringRef getCanonicalOffloadArch(StringRef ArchStr) override {
       CudaArch Arch = StringToCudaArch(ArchStr);
-      if (Arch == CudaArch::UNKNOWN) {
+      if (Arch == CudaArch::UNKNOWN || !IsNVIDIAGpuArch(Arch)) {
         C.getDriver().Diag(clang::diag::err_drv_cuda_bad_gpu_arch) << ArchStr;
         return StringRef();
       }

clang/test/Driver/cuda-bad-arch.cu

@@ -10,6 +10,8 @@
 // RUN: | FileCheck -check-prefix BAD %s
 // RUN: %clang -### -target x86_64-linux-gnu --cuda-gpu-arch=sm_19 -c %s 2>&1 \
 // RUN: | FileCheck -check-prefix BAD %s
+// RUN: %clang -### -target x86_64-linux-gnu --cuda-gpu-arch=gfx900 -c %s 2>&1 \
+// RUN: | FileCheck -check-prefix BAD %s
 
 // BAD: error: Unsupported CUDA gpu architecture