[Clang] Properly use CommaJoined for --offload-arch (llvm#146687)

Summary:
This didn't use the built-in 'CommaJoined' feature for arguments and
parsed out the strings manually. This patch simplifies this by just
using the present functionality.

Author: jhuber6

clang/include/clang/Driver/Options.td

@@ -1138,7 +1138,7 @@ def fno_convergent_functions : Flag<["-"], "fno-convergent-functions">,
 
 // Common offloading options
 let Group = offload_Group in {
-def offload_arch_EQ : Joined<["--"], "offload-arch=">,
+def offload_arch_EQ : CommaJoined<["--"], "offload-arch=">,
   Visibility<[ClangOption, FlangOption]>,
   HelpText<"Specify an offloading device architecture for CUDA, HIP, or OpenMP. (e.g. sm_35). "
            "If 'native' is used the compiler will detect locally installed architectures. "

clang/lib/Driver/Driver.cpp

@@ -1090,19 +1090,16 @@ void Driver::CreateOffloadingDeviceToolChains(Compilation &C,
       llvm::Triple AMDTriple("amdgcn-amd-amdhsa");
       llvm::Triple NVPTXTriple("nvptx64-nvidia-cuda");
 
-      for (StringRef A :
+      for (StringRef Arch :
            C.getInputArgs().getAllArgValues(options::OPT_offload_arch_EQ)) {
-        for (StringRef Arch : llvm::split(A, ",")) {
-          bool IsNVPTX = IsNVIDIAOffloadArch(
-              StringToOffloadArch(getProcessorFromTargetID(NVPTXTriple, Arch)));
-          bool IsAMDGPU = IsAMDOffloadArch(
-              StringToOffloadArch(getProcessorFromTargetID(AMDTriple, Arch)));
-          if (!IsNVPTX && !IsAMDGPU && !Arch.empty() &&
-              !Arch.equals_insensitive("native")) {
-            Diag(clang::diag::err_drv_failed_to_deduce_target_from_arch)
-                << Arch;
-            return;
-          }
+        bool IsNVPTX = IsNVIDIAOffloadArch(
+            StringToOffloadArch(getProcessorFromTargetID(NVPTXTriple, Arch)));
+        bool IsAMDGPU = IsAMDOffloadArch(
+            StringToOffloadArch(getProcessorFromTargetID(AMDTriple, Arch)));
+        if (!IsNVPTX && !IsAMDGPU && !Arch.empty() &&
+            !Arch.equals_insensitive("native")) {
+          Diag(clang::diag::err_drv_failed_to_deduce_target_from_arch) << Arch;
+          return;
         }
       }
 
@@ -4792,7 +4789,7 @@ Driver::getOffloadArchs(Compilation &C, const llvm::opt::DerivedArgList &Args,
     // Add or remove the seen architectures in order of appearance. If an
     // invalid architecture is given we simply exit.
     if (Arg->getOption().matches(options::OPT_offload_arch_EQ)) {
-      for (StringRef Arch : llvm::split(Arg->getValue(), ",")) {
+      for (StringRef Arch : Arg->getValues()) {
         if (Arch == "native" || Arch.empty()) {
           auto GPUsOrErr = TC->getSystemGPUArchs(Args);
           if (!GPUsOrErr) {