add warning

Author: Pierre-vh

clang/include/clang/Basic/DiagnosticDriverKinds.td

@@ -93,6 +93,10 @@ def err_drv_hipspv_no_hip_path : Error<
   "'--hip-path' must be specified when offloading to "
   "SPIR-V%select{| unless %1 is given}0.">;
 
+// TODO: Remove when COV6 is fully supported by ROCm.
+def warn_drv_amdgpu_cov6: Warning<
+  "code object v6 is still in development and not ready for production use yet;"
+  " use at your own risk">;
 def err_drv_undetermined_gpu_arch : Error<
   "cannot determine %0 architecture: %1; consider passing it via "
   "'%2'">;

clang/lib/Driver/ToolChains/CommonArgs.cpp

@@ -2661,6 +2661,12 @@ void tools::checkAMDGPUCodeObjectVersion(const Driver &D,
       if (Remnant || CodeObjVer < MinCodeObjVer || CodeObjVer > MaxCodeObjVer)
         D.Diag(diag::err_drv_invalid_int_value)
             << CodeObjArg->getAsString(Args) << CodeObjArg->getValue();
+
+      // COV6 is only supported by LLVM at the time of writing this, and it's
+      // expected to take some time before all ROCm components fully
+      // support it. In the meantime, make sure users are aware of this.
+      if (CodeObjVer == 6)
+        D.Diag(diag::warn_drv_amdgpu_cov6);
     }
   }
 }

clang/test/Driver/hip-code-object-version.hip

@@ -30,6 +30,7 @@
 // RUN:   --offload-arch=gfx906 --rocm-path=%S/Inputs/rocm \
 // RUN:   %s 2>&1 | FileCheck -check-prefix=V6 %s
 
+// V6: warning: code object v6 is still in development and not ready for production use yet; use at your own risk
 // V6: "-mcode-object-version=6"
 // V6: "-mllvm" "--amdhsa-code-object-version=6"
 // V6: "-targets=host-x86_64-unknown-linux,hipv4-amdgcn-amd-amdhsa--gfx906"