[clang] [Clang] Rework creating offloading toolchains (PR #125556)

[Joseph Huber via cfe-commits]

================
@@ -950,221 +930,261 @@ static bool addSYCLDefaultTriple(Compilation &C,
   return true;
 }
 
-void Driver::CreateOffloadingDeviceToolChains(Compilation &C,
-                                              InputList &Inputs) {
-
-  //
-  // CUDA/HIP
-  //
-  // We need to generate a CUDA/HIP toolchain if any of the inputs has a CUDA
-  // or HIP type. However, mixed CUDA/HIP compilation is not supported.
-  bool IsCuda =
-      llvm::any_of(Inputs, [](std::pair<types::ID, const llvm::opt::Arg *> &I) {
-        return types::isCuda(I.first);
-      });
-  bool IsHIP =
-      llvm::any_of(Inputs,
-                   [](std::pair<types::ID, const llvm::opt::Arg *> &I) {
-                     return types::isHIP(I.first);
-                   }) ||
-      C.getInputArgs().hasArg(options::OPT_hip_link) ||
-      C.getInputArgs().hasArg(options::OPT_hipstdpar);
-  bool UseLLVMOffload = C.getInputArgs().hasArg(
-      options::OPT_foffload_via_llvm, options::OPT_fno_offload_via_llvm, false);
-  if (IsCuda && IsHIP) {
-    Diag(clang::diag::err_drv_mix_cuda_hip);
-    return;
+// Handles `native` offload architectures by using the 'offload-arch' utility.
+static llvm::SmallVector<std::string>
+getSystemOffloadArchs(Compilation &C, Action::OffloadKind Kind) {
+  StringRef Program = C.getArgs().getLastArgValue(
+      options::OPT_offload_arch_tool_EQ, "offload-arch");
+
+  SmallVector<std::string, 1> GPUArchs;
+  if (llvm::ErrorOr<std::string> Executable =
+          llvm::sys::findProgramByName(Program)) {
+    llvm::SmallVector<StringRef> Args{*Executable};
+    if (Kind == Action::OFK_HIP)
+      Args.push_back("--only=amdgpu");
+    else if (Kind == Action::OFK_Cuda)
+      Args.push_back("--only=nvptx");
+    auto StdoutOrErr = C.getDriver().executeProgram(Args);
+
+    if (!StdoutOrErr) {
+      C.getDriver().Diag(diag::err_drv_undetermined_gpu_arch)
+          << Action::GetOffloadKindName(Kind)
+          << llvm::toString(StdoutOrErr.takeError()) << "--offload-arch";
----------------
jhuber6 wrote:

It's possible, I'll check.

https://github.com/llvm/llvm-project/pull/125556